0001547903-24-000035 | 10-K | XBRL Viewer

Regulatory Information

Statutory Requirements

Our insurance subsidiaries, NMIC and Re One, file financial statements in conformity with statutory accounting principles (SAP) prescribed or permitted by the Wisconsin OCI, NMIC's principal regulator. Prescribed SAP includes state laws, regulations and general administrative rules, as well as a variety of publications of the National Association of Insurance Commissioners (NAIC). The Wisconsin OCI recognizes only statutory accounting practices prescribed or permitted by the state of Wisconsin for determining and reporting the financial condition and results of operations of an insurance company and for determining its solvency under Wisconsin insurance laws.

The Wisconsin OCI has imposed a prescribed accounting practice for the treatment of statutory contingency reserves that differs from the treatment promulgated by the NAIC. Under Wisconsin OCI's prescribed practice mortgage guaranty insurers are required to reflect changes in their contingency reserves through statutory income. Such approach contrasts with the NAIC's treatment, which records changes to contingency reserves directly to unassigned funds. As a Wisconsin-domiciled insurer, NMIC's statutory net income reflects an expense associated with the change in its contingency reserve. While such treatment impacts NMIC's statutory net income, it does not have an effect on NMIC's statutory capital position.

The following table presents NMIC's statutory net income, statutory surplus, contingency reserve, statutory capital and risk-to-capital (RTC) ratio as of and for the years ended December 31, 2023, 2022 and 2021:


	As of and for the years ended December 31,
	2023		2022		2021
	(In Thousands)
Statutory net income	$	104,464	$	107,418	$	34,975

Statutory surplus	963,085		980,225		893,848
Contingency reserve	1,573,360		1,266,038		1,036,639
Statutory capital (1)	$	2,536,445	$	2,246,263	$	1,930,487

Risk-to-capital	11.4:1		11.1:1		11.6:1

(1) Represents the total of the statutory surplus and contingency reserve.

Under applicable law in Wisconsin and 15 other states, mortgage insurers must maintain minimum amounts of statutory capital relative to RIF to continue writing new business. While formulations of minimum statutory capital may vary in each state, the most common measure allows for a maximum permitted RTC ratio of 25:1. Wisconsin and certain other states, including California and Illinois, apply a substantially similar requirement referred to as minimum policyholders' position.

As of December 31, 2023, NMIC's performing primary RIF, net of reinsurance, was approximately $29.0 billion and its RTC ratio was 11.4:1. As of December 31, 2022, NMIC's performing primary RIF, net of reinsurance, was approximately $25.0 billion and its RTC ratio was 11.1:1.

Effective October 1, 2021, the reinsurance agreement between NMIC and Re One was commuted and all ceded risk was transferred back to NMIC. Following the commutation, Re One has no risk in force or further obligation on future claims. Re One recorded a statutory loss of $0.4 million and $58 thousand for the years ended December 31, 2023 and 2022, respectively, and statutory income of $3.0 million for the year ended December 31, 2021. Re One had $2.0 million and $5.6 million of statutory capital at December 31, 2023 and 2022, respectively.

Debt Service Allocation

The Wisconsin OCI has approved the allocation of interest expense on the $400 million Notes and $250 million 2021 Revolving Credit Facility to NMIC, to the extent proceeds from such offering and facility are distributed to NMIC or used to repay, redeem or otherwise defease amounts raised by NMIC under prior credit arrangements that have previously been distributed to NMIC.

Dividend Restrictions

NMIH is not subject to any limitations on its ability to pay dividends except those generally applicable to corporations that are incorporated in Delaware. Delaware law provides that dividends are only payable out of a corporation's capital surplus or, subject to certain limitations, recent net profits.

NMIC and Re One are subject to certain capital and dividend rules and regulations prescribed by jurisdictions in which they are authorized to operate and the GSEs that may restrict their ability to pay dividends to NMIH. Under Wisconsin law, NMIC and Re One may pay dividends up to specified levels (i.e., "ordinary" dividends) with 30 days' prior notice to the Wisconsin OCI. Dividends in larger amounts (i.e.,"extraordinary" dividends), are subject to the Wisconsin OCI's prior approval. Under Wisconsin law, an extraordinary dividend is defined as any payment or distribution that together with other dividends and distributions made within the preceding twelve months exceeds the lesser of (i) 10% of the insurer's statutory policyholders' surplus as of the preceding December 31 or (ii) adjusted statutory net income for the twelve-month period ending the preceding December 31. During the year ended December 31, 2023, NMIC paid a $98.0 million ordinary course dividend to NMIH. NMIC has the capacity to pay aggregate ordinary dividends of $96.3 million to NMIH during the twelve-month period ending December 31, 2024.

As an approved insurer under PMIERs, NMIC would generally be subject to additional restrictions on its ability to pay dividends to NMIH if it failed to meet the financial requirements prescribed by PMIERs. Approved insurers that fail to meet the prescribed PMIERs financial requirements are not permitted to pay dividends without prior approval from the GSEs.

Investments - Fair Values and Gross Unrealized Gains and Losses (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 2,542,862	$ 2,352,747
Gross Unrealized Gains	12,498	1,334
Gross Unrealized Losses	(184,339)	(254,692)
Fair Value	2,371,021	2,099,389
U.S. Treasury securities and obligations of U.S. government agencies
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	164,278	82,301
Gross Unrealized Gains	3,374	0
Gross Unrealized Losses	(1,264)	(2,369)
Fair Value	166,388	79,932
Municipal debt securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	678,339	563,972
Gross Unrealized Gains	1,253	0
Gross Unrealized Losses	(58,462)	(80,796)
Fair Value	621,130	483,176
Corporate debt securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	1,624,187	1,457,589
Gross Unrealized Gains	7,868	1,149
Gross Unrealized Losses	(120,576)	(165,096)
Fair Value	1,511,479	1,293,642
Asset-backed securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	52,242	74,762
Gross Unrealized Gains	1	0
Gross Unrealized Losses	(4,032)	(6,204)
Fair Value	48,211	68,558
Total bonds
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	2,519,046	2,178,624
Gross Unrealized Gains	12,496	1,149
Gross Unrealized Losses	(184,334)	(254,465)
Fair Value	2,347,208	1,925,308
Short-term investments
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	23,816	174,123
Gross Unrealized Gains	2	185
Gross Unrealized Losses	(5)	(227)
Fair Value	$ 23,813	$ 174,081

SCHEDULE II - FINANCIAL INFORMATION OF REGISTRANT- PARENT COMPANY ONLY - Statements of Cash Flows - Parent Company Only (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2023	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Dec. 31, 2022	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Cash flows from operating activities
Net income	$ 83,413	$ 83,955	$ 80,284	$ 74,458	$ 72,940	$ 76,838	$ 75,444	$ 67,680	$ 322,110	$ 292,902	$ 231,130
Adjustments to reconcile net income to net cash provided by operating activities:
Gain from change in fair value of warrant liability					0	$ 0	$ (1,020)	(93)	0	(1,113)	(566)
Net realized investment losses (gains)									33	(481)	(729)
Depreciation and amortization									11,541	11,870	11,232
Amortization of debt discount and debt issuance costs									1,961	1,846	1,861
Deferred income taxes									90,593	84,393	65,510
Share-based compensation expense									16,914	15,425	16,678
Changes in operating assets and liabilities:
Accrued investment income									(5,641)	(2,244)	(2,038)
Other assets									(316)	236	(218)
Accounts payable and accrued expenses									10,389	1,394	16,908
Net cash provided by operating activities									342,683	313,394	325,719
Cash flows from investing activities
Purchase of short-term investments									(166,224)	(313,926)	(10,640)
Purchase of fixed-maturity investments, available-for-sale									(488,562)	(233,586)	(514,405)
Proceeds from maturity of short-term investments									320,545	151,635	0
Proceeds from redemptions, maturities and sale of fixed-maturity investments, available-for-sale									143,613	116,663	163,103
Software and equipment									(9,372)	(10,572)	(12,238)
Net cash used in investing activities									(200,000)	(289,786)	(374,180)
Cash flows from financing activities
Proceeds from issuance of common stock related to employee equity plans									10,549	5,442	4,201
Proceeds from issuance of common stock related to warrant exercises									0	518	503
Taxes paid related to net share settlement of equity awards									(9,356)	(5,213)	(5,426)
Payments of debt issuance costs									0	0	(1,108)
Repurchases of common stock									(91,613)	(56,575)	0
Net cash used in financing activities									(90,420)	(55,828)	(1,830)
Net increase (decrease) in cash, cash equivalents and restricted cash									52,263	(32,220)	(50,291)
Cash, cash equivalents and restricted cash, beginning of period				44,426				76,646	44,426	76,646	126,937
Cash, cash equivalents and restricted cash, end of period	96,689				44,426				96,689	44,426	76,646
Parent
Cash flows from operating activities
Net income									322,110	292,902	231,130
Adjustments to reconcile net income to net cash provided by operating activities:
Gain from change in fair value of warrant liability									0	(1,113)	(566)
Net realized investment losses (gains)									31	13	(10)
Depreciation and amortization									(890)	789	801
Amortization of debt discount and debt issuance costs									1,962	1,846	1,861
Deferred income taxes									88,192	81,057	66,941
Share-based compensation expense									16,914	15,425	16,678
Changes in operating assets and liabilities:
Investment in subsidiaries, at equity in net assets									(314,556)	(343,477)	(302,165)
Accrued investment income									205	(73)	(104)
Receivable from affiliates									(8,108)	3,348	(9,474)
Other assets									(57)	518	(496)
Accounts payable and accrued expenses									2,605	(8,731)	10,068
Net cash provided by operating activities									108,408	42,504	14,664
Cash flows from investing activities
Capitalization of subsidiaries									(800)	(800)	(800)
Purchase of short-term investments									(89,068)	(110,076)	(10,640)
Purchase of fixed-maturity investments, available-for-sale									0	0	(2,797)
Proceeds from maturity of short-term investments									100,607	86,995	0
Proceeds from redemptions, maturities and sale of fixed-maturity investments, available-for-sale									30,538	19,673	4,464
Software and equipment									2,169	1,291	(1,026)
Net cash used in investing activities									43,446	(2,917)	(10,799)
Cash flows from financing activities
Proceeds from issuance of common stock related to employee equity plans									10,549	5,442	4,201
Proceeds from issuance of common stock related to warrant exercises									0	518	503
Taxes paid related to net share settlement of equity awards									(9,356)	(5,213)	(5,426)
Payments of debt issuance costs									0	0	(1,108)
Repurchases of common stock									(91,613)	(56,575)	0
Net cash used in financing activities									(90,420)	(55,828)	(1,830)
Net increase (decrease) in cash, cash equivalents and restricted cash									61,434	(16,241)	2,035
Cash, cash equivalents and restricted cash, beginning of period				$ 4,940				$ 21,181	4,940	21,181	19,146
Cash, cash equivalents and restricted cash, end of period	$ 66,374				$ 4,940				$ 66,374	$ 4,940	$ 21,181

Regulatory Information - Narrative (Details)	12 Months Ended
Regulatory Information - Narrative (Details)	Dec. 31, 2023 USD ($) state	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	Nov. 29, 2021 USD ($)
Statutory Accounting Practices [Line Items]
Number of states, in addition to wisconsin, with minimum statutory capital relative to RIF requirement \| state	15
Maximum permitted RTC ratio	25
Statutory net income (loss)	$ (400,000)	$ (58,000)	$ 3,000,000
Dividends, restriction with regards to capital surplus	10.00%
Revolving credit facility \| 2021 Revolving credit facility
Statutory Accounting Practices [Line Items]
Credit facility borrowing capacity	$ 250,000,000			$ 250,000,000
Senior Debt
Statutory Accounting Practices [Line Items]
Debt instrument face amount	400,000,000
NMIC
Statutory Accounting Practices [Line Items]
Mortgage insurance risk in force	$ 29,000,000,000	$ 25,000,000,000
Risk-to-capital	11.4	11.1	11.6
Statutory capital	$ 2,536,445,000	$ 2,246,263,000	$ 1,930,487,000
NMIC and Re One Combined
Statutory Accounting Practices [Line Items]
Ordinary course dividend paid	98,000,000
Dividends, restriction with regards to capital surplus	96,300,000
Re One
Statutory Accounting Practices [Line Items]
Statutory capital	$ 2,000,000	$ 5,600,000

Income Taxes - Effective Income Tax Rate Reconciliation (Details)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Income Tax Disclosure [Abstract]
Federal statutory income tax rate	21.00%	21.00%	21.00%
State provision	0.60%	0.60%	0.50%
Share-based and other compensation	0.40%	0.50%	0.60%
Warrant gain	0.00%	(0.10%)	0.00%
Other	0.00%	0.40%	0.00%
Effective income tax rate	22.00%	22.40%	22.10%

Regulatory Information (Tables)

12 Months Ended

Dec. 31, 2023

Schedule of statutory net income, surplus, contingency reserve and risk-to-capital ratio


	As of and for the years ended December 31,
	2023		2022		2021
	(In Thousands)
Statutory net income	$	104,464	$	107,418	$	34,975

Statutory surplus	963,085		980,225		893,848
Contingency reserve	1,573,360		1,266,038		1,036,639
Statutory capital (1)	$	2,536,445	$	2,246,263	$	1,930,487

Risk-to-capital	11.4:1		11.1:1		11.6:1

(1) Represents the total of the statutory surplus and contingency reserve.

Tabular disclosure of how the entity's reporting under GAAP as of the balance sheet date differs from the results based on prescribed and permitted accounting practices of the state or country of domicile in which a relevant statutory filing is made, or differences in results based on the National Association of Insurance Commissioners (NAIC) prescribed practices, or a combination thereof. Describes the accounting practices used and the related monetary effect on statutory surplus, net income, and risk-based capital. If an insurance enterprise's risk-based capital would have triggered a regulatory event had it not used a permitted practice, that fact is disclosed in the financial statements. Permitted statutory accounting practices include practices not prescribed but allowed by the domiciliary state insurance department regulatory authority.

Leases - Right-of-Use Asset and Lease Liability Assumptions (Details)	Dec. 31, 2023
Leases [Abstract]
Weighted average remaining lease term	6 years 2 months 12 days
Weighted average discount rate	6.50%

Share-Based Compensation - Stock Option Activity (Details) - $ / shares	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Shares
Options beginning balance (in shares)	1,146,000
Options granted (in shares)	0	0	0
Options exercised (in shares)	(415,000)
Options forfeited (in shares)	0
Options expired (in shares)	0
Options ending balance (in shares)	731,000	1,146,000
Weighted Average Grant Date Fair Value per Share
Options beginning balance (in dollars per share)	$ 4.93
Options granted (in dollars per share)	0
Options exercised (in dollars per share)	3.74
Options forfeited (in dollars per share)	0
Options expired (in dollars per share)	0
Options ending balance (in dollars per share)	5.61	$ 4.93
Weighted Average Exercise Price
Options beginning balance (in dollars per share)	13.48
Options granted (in dollars per share)	0
Options exercised (in dollars per share)	9.87
Options forfeited (in dollars per share)	0
Options expired (in dollars per share)	0
Options beginning balance (in dollars per share)	$ 15.53	$ 13.48

Investments - Narrative (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Debt Securities, Available-for-sale [Line Items]
Unrealized loss position, accumulated loss	$ 184,339	$ 254,692
Unrealized loss position, 12 months or greater	183,065	218,467
U.S. Treasury securities and obligations of U.S. government agencies
Debt Securities, Available-for-sale [Line Items]
Cash and investments held with various state insurance departments	5,300	5,400
Unrealized loss position, accumulated loss	1,264	2,369
Unrealized loss position, 12 months or greater	$ 1,202	$ 109

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Quarterly Financial Information Disclosure [Abstract]

SCHEDULE II - FINANCIAL INFORMATION OF REGISTRANT- PARENT COMPANY ONLY - Balance Sheets - Parent Company Only (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Assets
Fixed maturities, available-for-sale, at fair value (amortized cost of $2,542,862 and $2,352,747 as of December 31, 2023 and December 31, 2022, respectively)	$ 2,371,021	$ 2,099,389
Cash and cash equivalents	96,689	44,426	$ 76,646	$ 126,937
Accrued investment income	19,785	14,144
Software and equipment, net	30,252	31,930
Other assets	16,965	18,267
Total assets	2,940,507	2,516,030
Liabilities
Debt	397,595	396,051
Accounts payable and accrued expenses	86,189	74,576
Deferred tax liability, net	301,573	193,859
Other liabilities	11,456	12,272
Total liabilities	1,014,503	902,303
Shareholders' equity
Common stock - class A shares, $0.01 par value; 87,334,138 shares issued and 80,881,280 shares outstanding as of December 31, 2023 and 86,472,742 shares issued and 83,549,879 shares outstanding as of December 31, 2022 (250,000,000 shares authorized)	873	865
Additional paid-in capital	990,816	972,717
Treasury stock, at cost: 6,452,858 and 2,922,863 common shares as of December 31, 2023 and December 31, 2022, respectively	(148,921)	(56,575)
Accumulated other comprehensive loss, net of tax	(139,917)	(204,323)
Retained earnings	1,223,153	901,043
Total shareholders' equity	1,926,004	1,613,727	1,565,786	1,369,591
Total liabilities and shareholders' equity	2,940,507	2,516,030
Parent
Assets
Fixed maturities, available-for-sale, at fair value (amortized cost of $2,542,862 and $2,352,747 as of December 31, 2023 and December 31, 2022, respectively)	47,290	83,918
Cash and cash equivalents	66,374	4,940	$ 21,181	$ 19,146
Investment in subsidiaries, at equity in net assets	2,468,333	2,092,457
Accrued investment income	235	440
Due from affiliates, net	91,126	83,018
Software and equipment, net	30,252	31,930
Other assets	13,858	15,408
Total assets	2,717,468	2,312,111
Liabilities
Debt	397,595	396,051
Accounts payable and accrued expenses	38,524	34,697
Deferred tax liability, net	343,956	255,550
Other liabilities	11,389	12,086
Total liabilities	791,464	698,384
Shareholders' equity
Common stock - class A shares, $0.01 par value; 87,334,138 shares issued and 80,881,280 shares outstanding as of December 31, 2023 and 86,472,742 shares issued and 83,549,879 shares outstanding as of December 31, 2022 (250,000,000 shares authorized)	873	865
Additional paid-in capital	990,816	972,717
Treasury stock, at cost: 6,452,858 and 2,922,863 common shares as of December 31, 2023 and December 31, 2022, respectively	(148,921)	(56,575)
Accumulated other comprehensive loss, net of tax	(139,917)	(204,323)
Retained earnings	1,223,153	901,043
Total shareholders' equity	1,926,004	1,613,727
Total liabilities and shareholders' equity	$ 2,717,468	$ 2,312,111

SCHEDULE II - FINANCIAL INFORMATION OF REGISTRANT- PARENT COMPANY ONLY - Supplemental Notes - Parent Company Only (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
NMIC and Re One Combined
Condensed Financial Statements, Captions [Line Items]
Ordinary course dividend paid	$ 98,000
Dividends, restriction with regards to capital surplus	96,300
Parent
Condensed Financial Statements, Captions [Line Items]
Investment in subsidiaries, at equity in net assets	2,468,333	$ 2,092,457
Parent \| NMIC and Re One Combined
Condensed Financial Statements, Captions [Line Items]
Ordinary course dividend paid	98,000
Subsidiaries
Condensed Financial Statements, Captions [Line Items]
Operating underwriting and operating expenses	$ 163,900	$ 148,400	$ 149,400

CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Common Stock - Class A	Additional Paid-in Capital	Treasury Stock, At Cost	Accumulated Other Comprehensive Income (Loss)	Retained Earnings
Beginning balance (in shares) at Dec. 31, 2020		85,163,000
Beginning balance at Dec. 31, 2020	$ 1,369,591	$ 852	$ 937,872	$ 0	$ 53,856	$ 377,011
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock: class A shares issued related to warrant exercises (in shares)		86,000
Common stock: class A shares issued related to warrant exercises	1,983	$ 1	1,982
Common stock: class A shares issued under stock plans, net of shares withheld for employee taxes (in shares)		544,000
Common stock: class A shares issued under stock plans, net of shares withheld for employee taxes	(1,225)	$ 5	(1,230)
Share-based compensation expense	16,678		16,678
Change in unrealized investment gains/losses, tax expense (benefit)	(52,371)				(52,371)
Net income	231,130					231,130
Ending balance (in shares) at Dec. 31, 2021		85,793,000
Ending balance at Dec. 31, 2021	1,565,786	$ 858	955,302	0	1,485	608,141
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock: class A shares issued related to warrant exercises (in shares)		84,000
Common stock: class A shares issued related to warrant exercises	1,768	$ 1	1,767
Common stock: class A shares issued under stock plans, net of shares withheld for employee taxes (in shares)		596,000
Common stock: class A shares issued under stock plans, net of shares withheld for employee taxes	229	$ 6	223
Repurchase of common stock (in shares)		(2,923,000)
Repurchase of common stock	(56,575)			(56,575)
Share-based compensation expense	15,425		15,425
Change in unrealized investment gains/losses, tax expense (benefit)	(205,808)				(205,808)
Net income	$ 292,902					292,902
Ending balance (in shares) at Dec. 31, 2022	83,549,879	83,550,000
Ending balance at Dec. 31, 2022	$ 1,613,727	$ 865	972,717	(56,575)	(204,323)	901,043
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock: class A shares issued under stock plans, net of shares withheld for employee taxes (in shares)		861,000
Common stock: class A shares issued under stock plans, net of shares withheld for employee taxes	1,193	$ 8	1,185
Repurchase of common stock (in shares)		(3,530,000)
Repurchase of common stock	(92,346)			(92,346)
Share-based compensation expense	16,914		16,914
Change in unrealized investment gains/losses, tax expense (benefit)	64,406				64,406
Net income	$ 322,110					322,110
Ending balance (in shares) at Dec. 31, 2023	80,881,280	80,881,000
Ending balance at Dec. 31, 2023	$ 1,926,004	$ 873	$ 990,816	$ (148,921)	$ (139,917)	$ 1,223,153

Summary of Accounting Principles (Details) - USD ($)	12 Months Ended
Summary of Accounting Principles (Details) - USD ($)	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Finite-Lived Intangible Assets [Line Items]
Accrued interest receivable	$ 19,800,000	$ 14,100,000
Amortization of deferred acquisition expense	3,600,000	11,900,000	$ 22,800,000
Premium deficiency reserve expense	0	0	$ 0
Reinsurance recoverable	27,514,000	21,587,000
Impairments of goodwill	0
Impairment of indefinite-lived intangible assets	$ 0
Premium receivable, number of days to be written off	120 days
Premium receivable, write-off reserve	$ 2,700,000	$ 2,300,000
Software \| Minimum
Finite-Lived Intangible Assets [Line Items]
Estimated useful life		3 years
Software \| Maximum
Finite-Lived Intangible Assets [Line Items]
Estimated useful life		5 years
Equipment \| Minimum
Finite-Lived Intangible Assets [Line Items]
Estimated useful life	3 years
Equipment \| Maximum
Finite-Lived Intangible Assets [Line Items]
Estimated useful life	5 years
Geographic Concentration Risk \| Risk-in-Force \| CALIFORNIA
Finite-Lived Intangible Assets [Line Items]
Concentration risk	10.00%	11.00%	10.00%

Reinsurance

12 Months Ended

Dec. 31, 2023

Reinsurance Disclosures [Abstract]

Reinsurance

We enter into third-party reinsurance transactions to actively manage our risk, ensure compliance with PMIERs, state regulatory and other applicable capital requirements, (respectively, as defined therein), and support the growth of our business. The Wisconsin Office of the Commissioner of Insurance (Wisconsin OCI) has approved and the GSEs have indicated their non-objection to all such transactions (subject to certain conditions and ongoing review).

The effect of our reinsurance agreements on premiums written and earned is as follows:


	For the years ended December 31,
	2023		2022		2021
	(In Thousands)
Net premiums written
Direct	$	619,670	$	577,926	$	557,050
Ceded (1)	(139,130)		(117,680)		(88,539)
Net premiums written	$	480,540	$	460,246	$	468,511

Net premiums earned
Direct	$	650,411	$	594,127	$	536,630
Ceded (1)	(139,643)		(118,861)		(92,336)
Net premiums earned	$	510,768	$	475,266	$	444,294

(1) Net of profit commission.

Excess-of-loss Reinsurance

Insurance-Linked Notes

NMIC is a party to reinsurance agreements with Oaktown Re III Ltd., Oaktown Re V Ltd., Oaktown Re VI Ltd., and Oaktown Re VII Ltd. (special purpose reinsurance entities collectively referred to as the Oaktown Re Vehicles) effective July 30, 2019, October 29, 2020, April 27, 2021, and October 26, 2021, respectively. Each agreement provides NMIC with aggregate excess-of-loss reinsurance coverage on a defined portfolio of mortgage insurance policies. Under each agreement, NMIC retains a first layer of aggregate loss exposure on covered policies and the respective Oaktown Re Vehicle then provides second layer loss protection up to a defined reinsurance coverage amount. NMIC then retains losses in excess of the respective reinsurance coverage amounts.

NMIC makes risk premium payments to the Oaktown Re Vehicles for the applicable outstanding reinsurance coverage amount and pays an additional amount for anticipated operating expenses (capped at $250 thousand per year). NMIC ceded aggregate premiums to the Oaktown Re Vehicles of $31.1 million, $41.9 million and $41.3 million during the years ended December 31, 2023, 2022 and 2021, respectively.

NMIC applies claims paid on covered policies against its first layer aggregate retained loss exposure under each excess-of-loss agreement. NMIC did not cede any incurred losses on covered policies to the Oaktown Re Vehicles during the years ended December 31, 2023, 2022 and 2021, as the aggregate first layer risk retention for each applicable agreement was not exhausted during such periods.

Under the terms of each excess-of-loss reinsurance agreement, the Oaktown Re Vehicles are required to fully collateralize their outstanding reinsurance coverage amount to NMIC with funds deposited into segregated reinsurance trusts. Such trust funds are required to be invested in short-term U.S. Treasury money market funds at all times. Each Oaktown Re Vehicle financed its respective collateral requirement through the issuance of mortgage insurance-linked notes to unaffiliated investors. Such insurance-linked notes mature ten years (in the case of the notes issued by Oaktown Re III Ltd. and Oaktown Re V Ltd.) and 12.5 years (in the case of the notes issued by Oaktown Re VI Ltd. and Oaktown Re VII Ltd.) from the inception date of their associated reinsurance agreement. We refer to NMIC’s reinsurance agreements with and the insurance-linked note issuances by Oaktown Re Vehicles individually as the 2019 ILN Transaction, 2020-2 ILN Transaction, 2021-1 ILN Transaction, and 2021-2 ILN Transaction, and collectively as the ILN Transactions.

The respective reinsurance coverage amounts provided by the Oaktown Re Vehicles decrease (over a ten-year period in the case of Oaktown Re III Ltd. and Oaktown Re V Ltd. and 12.5-year period in the case of Oaktown Re VI Ltd. and Oaktown Re VII Ltd.) as the underlying insured mortgages are amortized or repaid, and/or the mortgage insurance coverage is canceled. As the reinsurance coverage decreases, a prescribed amount of collateral held in trust by the Oaktown Re Vehicles is distributed to ILN Transaction noteholders as amortization of the outstanding insurance-linked note principal balances. The outstanding reinsurance coverage amounts stop amortizing, and the distribution of collateral assets to ILN Transaction noteholders and amortization of insurance-linked note principal is suspended if certain credit enhancement or delinquency thresholds, as defined in each agreement, are triggered (each, a Lock-Out Event). At December 31, 2023, the 2019 ILN Transaction was deemed to be in Lock-Out due to the default experience of its underlying pool.

NMIC holds optional termination rights under each ILN Transaction, including, among others, an optional call feature which provides NMIC the discretion to terminate the transaction on or after a prescribed date, and a clean-up call if the outstanding reinsurance coverage amount amortizes to 10% or less of the reinsurance coverage amount at inception or if NMIC reasonably determines that changes to GSE or rating agency asset requirements would cause a material and adverse effect on the capital treatment afforded to NMIC under a given agreement. In addition, there are certain events that trigger mandatory termination of an agreement, including NMIC's failure to pay premiums or consent to reductions in a trust account to make principal payments to noteholders, among others.

Effective July 25, 2023, NMIC exercised its optional call to terminate and commute its previously outstanding excess of loss reinsurance agreement with Oaktown Re II Ltd. In connection with the termination and commutation of the agreement, the insurance-linked notes issued by Oaktown Re II Ltd. were redeemed in full with a distribution of remaining collateral assets.

The following table presents the inception date, covered production period, initial and current reinsurance coverage amount, and initial and current first layer retained aggregate loss under each outstanding ILN Transaction. Current amounts are presented as of December 31, 2023.


($ values in thousands)	Inception Date	Covered Production	Initial Reinsurance Coverage	Current Reinsurance Coverage	Initial First Layer Retained Loss	Current First Layer Retained Loss (1)


2019 ILN Transaction	July 30, 2019	6/1/2018 – 6/30/2019	$326,905	$159,476	$123,424	$121,751

2020-2 ILN Transaction	October 29, 2020	4/1/2020 – 9/30/2020 (2)	242,351	55,792	121,777	121,177
2021-1 ILN Transaction	April 27, 2021	10/1/2020 – 3/31/2021 (3)	367,238	217,630	163,708	163,394
2021-2 ILN Transaction	October 26, 2021	4/1/2021 – 9/30/2021 (4)	363,596	310,567	146,229	145,858

(1) NMIC applies claims paid on covered policies against its first layer aggregate retained loss exposure and cedes reserves for incurred claims and claim expenses to each applicable ILN Transaction and recognizes a reinsurance recoverable if such incurred claims and claim expenses exceed its current first layer retained loss.

(2) Approximately 1% of the production covered by the 2020-2 ILN Transaction has coverage reporting dates between July 1, 2019 and March 31, 2020.

(3) Approximately 1% of the production covered by the 2021-1 ILN Transaction has coverage reporting dates between July 1, 2019 and September 30, 2020.

(4) Approximately 2% of the production covered by the 2021-2 ILN Transaction has coverage reporting dates between July 1, 2019 and March 31, 2021.

Under the terms of our ILN Transactions, we are required to maintain a certain level of restricted funds in premium deposit accounts with Bank of New York Mellon until the respective notes have been redeemed in full. “Cash and Cash Equivalents” on our consolidated balance sheets includes restricted amounts of $1.3 million and $2.2 million as of December 31, 2023 and 2022, respectively. The restricted balances required under these transactions will decline over time as the outstanding principal balance of the respective insurance-linked notes are amortized.

Traditional Reinsurance

NMIC is party to five excess-of-loss reinsurance agreements with broad panels of third-party reinsurers – the 2022-1 XOL Transaction, effective April 1, 2022, the 2022-2 XOL Transaction, effective July 1, 2022, the 2022-3 XOL Transaction, effective October 1, 2022, the 2023-1 XOL Transaction, effective January 1, 2023, and the 2023-2 XOL Transaction, effective July 1, 2023 – which we refer to collectively as the XOL Transactions. Each XOL Transaction provides NMIC with aggregate excess-of-loss reinsurance coverage on a defined portfolio of mortgage insurance policies. Under each agreement, NMIC retains a first layer of aggregate loss exposure on covered policies and the reinsurers then provide second layer loss protection up to a defined reinsurance coverage amount. The reinsurance coverage amount of each XOL Transaction is set to approximate the PMIERs minimum required assets of its reference pool and decreases from its peak over a ten-year period in the event the PMIERs minimum required assets of the pool declines. NMIC retains losses in excess of the outstanding reinsurance coverage amount.

Under the terms of the XOL Transactions, NMIC makes risk premium payments to its third-party reinsurance providers for the outstanding reinsurance coverage amount and ceded aggregate premiums of $31.2 million and $13.9 million during the years ended December 31, 2023 and 2022, respectively. NMIC applies claims paid on covered policies against its first layer aggregate retained loss exposure under each agreement. NMIC did not cede any incurred losses on covered policies under the XOL Transactions during the years ended December 31, 2023 and 2022, as the aggregate first layer risk retention for each agreement was not exhausted during such periods.

NMIC holds optional termination rights which provide it the discretion to terminate each XOL Transaction on or after a specified date. NMIC may also elect to terminate the XOL Transactions at any point if the outstanding reinsurance coverage amount amortizes to 10% or less of the reinsurance coverage amount provided at inception, or if it determines that it will no

longer be able to take full PMIERs asset credit for the coverage. Additionally, under the terms of the treaties, NMIC may selectively terminate its engagement with individual reinsurers under certain circumstances. Such selective termination rights arise when, among other reasons, a reinsurer experiences a deterioration in its capital position below a prescribed threshold, and/or a reinsurer breaches (and fails to cure) its collateral posting obligation.

Each of the third-party reinsurance providers that is party to the XOL Transactions has an insurer financial strength rating of A- or better by S&P Global Ratings (S&P), A.M. Best Company Inc. (A.M. Best) or both.

The following table presents the inception date, covered production period, initial and current reinsurance coverage amount, and initial and current first layer retained aggregate loss under each outstanding XOL Transaction. Current amounts are presented as of December 31, 2023.


($ values in thousands)	Inception Date	Covered Production	Initial Reinsurance Coverage	Current Reinsurance Coverage	Initial First Layer Retained Loss	Current First Layer Retained Loss (1)
2022-1 XOL Transaction	April 1, 2022	10/1/2021 – 3/31/2022 (2)	$289,741	$253,252	$133,366	$133,123
2022-2 XOL Transaction	July 1, 2022	4/1/2022 – 6/30/2022 (3)	154,306	152,347	78,906	78,736
2022-3 XOL Transaction	October 1, 2022	7/1/2022 – 9/30/2022	96,779	96,197	106,265	106,265
2023-1 XOL Transaction	January 1, 2023	10/1/2022 – 6/30/2023	89,864	88,351	146,513	146,348
2023-2 XOL Transaction (4)	July 1, 2023	7/1/2023 – 12/31/2023	71,602	71,602	113,372	113,372

(1) NMIC applies claims paid on covered policies against its first layer aggregate retained loss exposure and cedes reserves for incurred claims and claim expenses to each applicable XOL Transaction and recognizes a reinsurance recoverable if such incurred claims and claim expenses exceed its current first layer retained loss.

(2) Approximately 1% of the production covered by the 2022-1 XOL Transaction has coverage reporting dates between October 21, 2019 and September 30, 2021.

(3) Approximately 1% of the production covered by the 2022-2 XOL Transaction has coverage reporting dates between January 4, 2021 and March 31, 2022.

(4) The 2023-2 XOL Transaction provides coverage for production generated between July 1, 2023 and December 31, 2023. The current reinsurance coverage and current first layer retained loss will decrease in future periods to the extent the PMIERs minimum required assets of the covered pool declines.

Quota Share Reinsurance

NMIC is party to seven quota share reinsurance treaties – the 2016 QSR Transaction, effective September 1, 2016, the 2018 QSR Transaction, effective January 1, 2018, the 2020 QSR Transaction, effective April 1, 2020 (and amended effective January 1, 2024), the 2021 QSR Transaction, effective January 1, 2021, the 2022 QSR Transaction, effective October 1, 2021, the 2022 Seasoned QSR Transaction, effective July 1, 2022 and the 2023 QSR Transaction, effective January 1, 2023 – which we refer to collectively as the QSR Transactions. Under each of the QSR Transactions, NMIC cedes a proportional share of its risk on eligible policies to panels of third-party reinsurance providers. Each of the third-party reinsurance providers that is party to the QSR Transactions has an insurer financial strength rating of A- or better by S&P, A.M. Best or both.

Under the terms of the 2016 QSR Transaction, NMIC cedes premiums written related to 25% of the risk on eligible primary policies written for all periods through December 31, 2017 and 100% of the risk under our pool agreement with Fannie Mae. The 2016 QSR Transaction is scheduled to terminate on December 31, 2027, except with respect to the ceded pool risk, which expired on August 31, 2023. NMIC has the option, based on certain conditions and subject to a termination fee, to terminate the agreement as of December 31, 2020, or at the end of any calendar quarter thereafter, which could result in NMIC recapturing the related risk.

Under the terms of the 2018 QSR Transaction, NMIC cedes premiums earned related to 25% of the risk on eligible policies written in 2018 and 20% of the risk on eligible policies written in 2019. The 2018 QSR Transaction is scheduled to terminate on December 31, 2029. NMIC has the option, based on certain conditions and subject to a termination fee, to terminate the agreement as of December 31, 2022, or at the end of any calendar quarter thereafter, which could result in NMIC recapturing the related risk.

Under the terms of the 2020 QSR Transaction, NMIC cedes premiums earned related to 21% of the risk on eligible policies written from April 1, 2020 to December 31, 2020. The 2020 QSR Transaction is scheduled to terminate on December 31, 2030. NMIC has the option, based on certain conditions and subject to a termination fee, to terminate the agreement as of December 31, 2023, or at the end of any calendar quarter thereafter, which could result in NMIC recapturing the related risk.

Under the terms of the 2021 QSR Transaction, NMIC cedes premiums earned related to 22.5% of the risk on eligible policies written from January 1, 2021 to October 30, 2021. The 2021 QSR Transaction is scheduled to terminate on December 31,

2031. NMIC has the option, based on certain conditions and subject to a termination fee, to terminate the agreement as of December 31, 2024, or at the end of any calendar quarter thereafter, which could result in NMIC recapturing the related risk.

Under the terms of the 2022 QSR Transaction, NMIC cedes premiums earned related to 20% of the risk on eligible policies written primarily between October 30, 2021 and December 31, 2022. The 2022 QSR Transaction is scheduled to terminate on December 31, 2032. NMIC has the option, based on certain conditions and subject to a termination fee, to terminate the agreement as of December 31, 2024 or semi-annually thereafter, which could result in NMIC recapturing the related risk.

In connection with the 2022 QSR Transaction, NMIC entered into the 2023 QSR Transaction as a springing back-to-back quota share agreement. Under the terms of the 2023 QSR Transaction, NMIC cedes premiums earned related to 20% of the risk on eligible policies written from January 1, 2023 to December 31, 2023. The 2023 QSR Transaction is scheduled to terminate on December 31, 2033. NMIC has the option, based on certain conditions and subject to a termination fee, to terminate the agreement as of December 31, 2025 or semi-annually thereafter, which could result in NMIC recapturing the related risk.

Under the terms of the 2022 Seasoned QSR Transaction, NMIC cedes premiums earned related to 95% of the net risk on eligible policies primarily for a seasoned pool of mortgage insurance policies that had previously been covered under the retired Oaktown Re Ltd. and Oaktown Re IV Ltd. reinsurance transactions, after the consideration of coverage provided by other QSR Transactions. The 2022 Seasoned QSR Transaction is scheduled to terminate on June 30, 2032. NMIC has the option, based on certain conditions, to terminate the agreement as of June 30, 2025 or quarterly thereafter through December 31, 2027 with the payment of a termination fee, and as of March 31, 2028 or quarterly thereafter without the payment of a termination fee. Such termination could result in NMIC recapturing the related risk.

NMIC may terminate any or all of the QSR Transactions without penalty if, due to a change in PMIERs requirements, it is no longer able to take full PMIERs asset credit for the RIF ceded under the respective agreements. Additionally, under the terms of the QSR Transactions, NMIC may elect to selectively terminate its engagement with individual reinsurers on a run-off basis (i.e., reinsurers continue providing coverage on all risk ceded prior to the termination date, with no new cessions going forward) or cut-off basis (i.e., the reinsurance arrangement is completely terminated with NMIC recapturing all previously ceded risk) under certain circumstances. Such selective termination rights arise when, among other reasons, a reinsurer experiences a deterioration in its capital position below a prescribed threshold and/or a reinsurer breaches (and fails to cure) its collateral posting obligations under the relevant agreement.

Effective April 1, 2019, NMIC elected to terminate its engagement with one reinsurer under the 2016 QSR Transaction on a cut-off basis. In connection with the termination, NMIC recaptured approximately $500 million of previously ceded primary RIF and stopped ceding new premiums earned or written with respect to the recaptured risk. With the termination, ceded premiums written under the 2016 QSR Transaction decreased from 25% to 20.5% on eligible policies. The termination had no effect on the cession of pool risk under the 2016 QSR Transaction.

Effective December 31, 2023, NMIC elected to selectively terminate its engagement with certain reinsurers under the 2020 QSR Transaction and concurrently entered into an amended agreement effective January 1, 2024 (the Amended 2020 QSR Transaction) with the remaining reinsurance participants. Under the Amended 2020 QSR Transaction, NMIC will retain consistent coverage with that provided under the original 2020 QSR Transaction and continue to cede premiums earned related to 21% of the risk on eligible policies written from April 1, 2020 to December 31, 2020. NMIC will receive an enhanced ceding commission under the Amended 2020 QSR Transaction. The Amended 2020 QSR Transaction is scheduled to terminate on December 31, 2030 and NMIC has the option, based on certain conditions and subject to a termination fee, to terminate the agreement as of December 31, 2025, or at the end of any calendar quarter thereafter, which could result in NMIC recapturing the related risk.

The following table shows amounts related to the QSR Transactions:


	As of and for the years ended December 31,
	2023		2022		2021
	(In Thousands)
Ceded risk-in-force	$	12,626,541	$	12,617,169	$	8,194,604

Ceded premiums earned	(167,331)		(143,747)		(110,140)
Ceded claims and claim expenses	7,436		1,620		3,233

Ceding commission earned	39,211		32,314		23,473
Profit commission	90,006		80,714		59,104

Ceded premiums written under the 2016 QSR Transaction are recorded as prepaid reinsurance premiums in "Other Assets" on our consolidated balance sheets and amortized to ceded premiums earned in a manner consistent with the recognition of revenue on direct premiums. Under all other QSR Transactions, premiums are ceded on an earned basis as defined in the agreement. NMIC receives a 20% ceding commission for premiums ceded under the QSR Transactions, except with respect to the 2022 Seasoned QSR Transaction under which it receives a 35% ceding commission and the Amended 2020 QSR Transaction under which it receives a 36% ceding commission. NMIC also receives a profit commission under each of the QSR Transactions, provided that the loss ratios on loans covered under the 2016, 2018, 2020 (2020 Amended), 2021, 2022, 2022 Seasoned and 2023 QSR Transactions, generally remain below 60%, 61%, 50% (50% as amended), 57.5%, 62%, 55% and 62%, respectively, as measured annually. Ceded claims and claim expenses under each of the QSR Transactions reduce the respective profit commission received by NMIC on a dollar-for-dollar basis.

In accordance with the terms of the 2016 QSR Transaction, rather than making a cash payment or transferring investments for ceded premiums written, NMIC established a funds withheld liability, which also includes amounts due to NMIC for ceding and profit commissions. Any loss recoveries and any potential profit commission to NMIC will be realized from this account until exhausted. NMIC’s reinsurance recoverable balance is further supported by trust accounts established and maintained by each reinsurer in accordance with the PMIERs funding requirements for risk ceded to non-affiliates. The reinsurance recoverable on loss reserves related to the 2016 QSR Transaction was $1.7 million and $2.6 million as of December 31, 2023 and 2022, respectively.

In accordance with the terms of the 2018, 2020 (2020 Amended), 2021, 2022, 2022 Seasoned and 2023 QSR Transactions, cash payments for ceded premiums earned are settled on a quarterly basis, offset by amounts due to NMIC for ceding and profit commissions. Any loss recoveries and any potential profit commission to NMIC are also recognized quarterly. NMIC's reinsurance recoverable balance is supported by trust accounts established and maintained by each reinsurer in accordance with the PMIERs funding requirements for risk ceded to non-affiliates. The aggregate reinsurance recoverable on loss reserves related to the 2018, 2020, 2021, 2022, 2022 Seasoned and 2023 QSR Transactions was $25.8 million and $19.0 million as of December 31, 2023 and 2022, respectively.

Commitments and Contingencies - Narrative (Details) $ in Millions	12 Months Ended
	Dec. 31, 2023 USD ($)
Commitments and Contingencies Disclosure [Abstract]
Approved insurers, required assets (equal or greater than)	$ 400
Approved insurers, risked-based required assets, primary insurance floor	5.60%

Quarterly Financial Data (Unaudited) (Tables)

12 Months Ended

Dec. 31, 2023

Schedule of quarterly financial information


	2023 Quarters								2023
	First		Second		Third		Fourth		Year
	(In Thousands, except per share data)

Net premiums earned	$	121,754	$	125,985	$	130,089	$	132,940	$	510,768
Net investment income	14,894		16,518		17,853		18,247		67,512
Net realized investment losses	(33)		—		—		—		(33)
Other revenues	164		182		217		193		756
Insurance claims and claim expenses	6,701		2,873		4,812		8,232		22,618

Underwriting and operating expenses	25,786		27,448		27,749		29,716		110,699
Service expenses	80		267		239		185		771
Interest expense	8,039		8,048		8,059		8,066		32,212

Income before income taxes	96,173		104,049		107,300		105,181		412,703
Income tax expense	21,715		23,765		23,345		21,768		90,593
Net income	$	74,458	$	80,284	$	83,955	$	83,413	$	322,110

Basic earnings per share (1)	$	0.89	$	0.97	$	1.02	$	1.03	$	3.91
Diluted earnings per share (1)	$	0.88	$	0.95	$	1.00	$	1.01	$	3.84

Weighted average common shares outstanding - basic	83,600		82,958		82,096		81,005		82,407
Weighted average common shares outstanding - diluted	84,840		84,190		83,670		82,685		83,854

(1) Due to the use of weighted average shares outstanding when calculating EPS, the sum of quarterly per share data may not equal the per share data for the year.


	2022 Quarters								2022
	First		Second		Third		Fourth		Year
	(In Thousands, except per share data)

Net premiums earned	$	116,495	$	120,870	$	118,317	$	119,584	$	475,266
Net investment income	10,199		10,921		11,945		13,341		46,406
Net realized investment gains	408		53		14		6		481
Other revenues	339		376		301		176		1,192

Insurance claims and claim (benefits) expenses	(619)		(3,036)		(3,389)		3,450		(3,594)
Underwriting and operating expenses	32,935		30,700		27,144		26,711		117,490
Service expenses	430		336		197		131		1,094
Interest expense	8,041		8,051		8,036		8,035		32,163
Gain from change in fair value of warrant liability	(93)		(1,020)		—		—		(1,113)
Income before income taxes	86,747		97,189		98,589		94,780		377,305
Income tax expense	19,067		21,745		21,751		21,840		84,403
Net income	$	67,680	$	75,444	$	76,838	$	72,940	$	292,902

Basic earnings per share (1)	$	0.79	$	0.88	$	0.91	$	0.87	$	3.45
Diluted earnings per share (1)	$	0.77	$	0.86	$	0.90	$	0.86	$	3.39

Weighted average common shares outstanding - basic	85,953		85,734		84,444		83,592		84,921
Weighted average common shares outstanding - diluted	87,310		86,577		85,485		84,809		85,999

(1) Due to the use of weighted average shares outstanding when calculating EPS, the sum of quarterly per share data may not equal the per share data for the year.

Intangible Assets and Goodwill (Details) - USD ($)	12 Months Ended
Intangible Assets and Goodwill (Details) - USD ($)	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Indefinite-lived Intangible Assets [Line Items]
Goodwill	$ 3,244,000	$ 3,244,000
Total intangible assets and goodwill	3,634,000	3,634,000
Impairment loss related to intangible assets or goodwill	0	0	$ 0
State licenses
Indefinite-lived Intangible Assets [Line Items]
Intangible assets	260,000	260,000
GSE applications
Indefinite-lived Intangible Assets [Line Items]
Intangible assets	$ 130,000	$ 130,000

Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

SCHEDULE I - SUMMARY OF INVESTMENTS - OTHER THAN INVESTMENTS IN RELATED PARTIES (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Amortized Cost	$ 2,542,862
Fair Value	2,371,021
Amount Reflected on Balance Sheet	2,371,021	$ 2,099,389
U.S. Treasury securities and obligations of U.S. government agencies
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Amortized Cost	164,278
Fair Value	166,388
Amount Reflected on Balance Sheet	166,388	79,932
Municipal debt securities
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Amortized Cost	678,339
Fair Value	621,130
Amount Reflected on Balance Sheet	621,130	483,176
Corporate debt securities
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Amortized Cost	1,624,187
Fair Value	1,511,479
Amount Reflected on Balance Sheet	1,511,479	1,293,642
Asset-backed securities
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Amortized Cost	52,242
Fair Value	48,211
Amount Reflected on Balance Sheet	48,211	68,558
Total bonds
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Amortized Cost	2,519,046
Fair Value	2,347,208
Amount Reflected on Balance Sheet	2,347,208	1,925,308
Short-term investments
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Amortized Cost	23,816
Fair Value	23,813
Amount Reflected on Balance Sheet	$ 23,813	$ 174,081

Common Stock	12 Months Ended
Common Stock	Dec. 31, 2023
Equity [Abstract]
Common Stock	Common Stock As of December 31, 2023 and 2022, we had 80.9 million and 83.5 million outstanding shares of Class A common stock, respectively. Holders of our common stock have no preemptive or conversion rights or other subscription rights, and there are no redemption or sinking fund provisions applicable to the common stock. Each holder of our common stock is entitled to one vote per share on all matters to be voted upon by stockholders, and there are no cumulative voting rights. Holders of common stock are entitled to receive dividends ratably if any are declared. Share repurchase program On February 10, 2022, our Board of Directors authorized a $125 million share repurchase program (excluding associated costs and applicable taxes) effective through December 31, 2023. On July 31, 2023, our Board of Directors authorized a new $200 million share repurchase program (excluding associated costs and applicable taxes) effective through December 31, 2025. Concurrent with the new authorization, our Board of Directors also approved an extension of our existing $125 million share repurchase program through December 31, 2025 to align its remaining tenor with that of the $200 million program. The authorization provides us the flexibility, based on market and business conditions, stock price and other factors, to repurchase stock from time to time through open market purchases, privately negotiated transactions, or other means, including pursuant to Rule 10b5-1 trading plans. During the year ended December 31, 2023, we repurchased 3.5 million shares at an average price of $25.93 per share (excluding associated costs and applicable taxes). During the year ended December 31, 2022, we repurchased 2.9 million shares at an average price of $19.34 per share (excluding associated costs). As of December 31, 2023, we had $176.9 million of repurchase authority remaining.

The entire disclosure for equity.

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SCHEDULE II - FINANCIAL INFORMATION OF REGISTRANT- PARENT COMPANY ONLY - Balance Sheets Additional Information - Parent Company Only (Details) - $ / shares	Dec. 31, 2023	Dec. 31, 2022
Condensed Balance Sheet Statements, Captions [Line Items]
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, issued (in shares)	87,334,138	86,472,742
Common stock, outstanding (in shares)	80,881,280	83,549,879
Common stock, authorized (in shares)	250,000,000	250,000,000
Treasury stock, common shares (in shares)	6,452,858	2,922,863

Investments - Corporate Debt Securities by Industry Group (Details)	Dec. 31, 2023	Dec. 31, 2022
Debt Securities, Available-for-sale [Line Items]
Corporate debt securities as component of total (percent)	100.00%	100.00%
Financial
Debt Securities, Available-for-sale [Line Items]
Corporate debt securities as component of total (percent)	35.00%	38.00%
Consumer
Debt Securities, Available-for-sale [Line Items]
Corporate debt securities as component of total (percent)	26.00%	24.00%
Utilities
Debt Securities, Available-for-sale [Line Items]
Corporate debt securities as component of total (percent)	13.00%	11.00%
Industrial
Debt Securities, Available-for-sale [Line Items]
Corporate debt securities as component of total (percent)	9.00%	8.00%
Communications
Debt Securities, Available-for-sale [Line Items]
Corporate debt securities as component of total (percent)	9.00%	11.00%
Technology
Debt Securities, Available-for-sale [Line Items]
Corporate debt securities as component of total (percent)	8.00%	8.00%

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

Fair Value of Financial Instruments

Fair Value of Financial Instruments

12 Months Ended

Dec. 31, 2023

Fair Value Disclosures [Abstract]

The following describes the valuation techniques used by us to determine the fair value of our financial instruments:

We established a fair value hierarchy by prioritizing the inputs to valuation techniques used to measure fair value. The hierarchy gives the highest priority to unadjusted quoted prices in active markets for identical assets or liabilities (Level 1 measurements) and the lowest priority to unobservable inputs (Level 3 measurements). The three levels of the fair value hierarchy under this standard are described below:

Level 1 – Fair value measurements based on quoted prices in active markets that we have the ability to access for identical assets or liabilities. Market price data generally is obtained from exchange or dealer markets. We do not adjust the quoted price for such instruments.

Level 2 – Fair value measurements based on inputs other than quoted prices included in Level 1 that are observable for the asset or liability, either directly or indirectly. Level 2 inputs include quoted prices for similar assets and liabilities in active markets, quoted prices for identical or similar assets or liabilities in markets that are not active, and inputs other than quoted prices that are observable for the asset or liability, such as interest rates and yield curves that are observable at commonly quoted intervals.

Level 3 – Fair value measurements based on valuation techniques that use significant inputs that are unobservable. Both observable and unobservable inputs may be used to determine the fair values of positions classified in Level 3. The circumstances for using these measurements include those in which there is little, if any, market activity for the asset or liability. Therefore, we must make certain assumptions, which require significant management judgment or estimation about the inputs a hypothetical market participant would use to value that asset or liability.

In certain cases, the inputs used to measure fair value may fall into different levels of the fair value hierarchy. In such cases, the level in the fair value hierarchy is determined based on the lowest level input that is significant to the fair value measurement in its entirety.

Assets classified as Level 1 and Level 2

To determine the fair value of securities available-for-sale in Level 1 and Level 2 of the fair value hierarchy, independent pricing sources have been utilized. One price is provided per security based on observable market data. To ensure securities are appropriately classified in the fair value hierarchy, we review the pricing techniques and methodologies of the independent pricing sources and believe that their policies adequately consider market activity, either based on specific transactions for the issue valued or based on modeling of securities with similar credit quality, duration, yield and structure that were recently traded. A variety of inputs are utilized by the independent pricing sources including benchmark yields, reported trades, non-binding broker/dealer quotes, issuer spreads, two sided markets, benchmark securities, bids, offers and reference data including data published in market research publications. Inputs may be weighted differently for any security, and not all inputs are used for each security evaluation. Market indicators, industry and economic events are also considered. This information is evaluated using a multidimensional pricing model. Quality controls are performed by the independent pricing sources throughout this process, which include reviewing tolerance reports, trading information and data changes, and directional moves compared to market moves. This model combines all inputs to arrive at a value assigned to each security. We have not made any adjustments to the prices obtained from the independent pricing sources.

The following tables present the level within the fair value hierarchy at which our financial instruments were measured:


	Fair Value Measurements Using
	Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)		Fair Value
As of December 31, 2023	(In Thousands)
U.S. Treasury securities and obligations of U.S. government agencies	$	166,388	$	—	$	—	$	166,388
Municipal debt securities	—		621,130		—		621,130
Corporate debt securities	—		1,511,479		—		1,511,479
Asset-backed securities	—		48,211		—		48,211

Cash, cash equivalents and short-term investments	120,502		—		—		120,502
Total assets	$	286,890	$	2,180,820	$	—	$	2,467,710


	Fair Value Measurements Using
	Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)		Fair Value
As of December 31, 2022	(In Thousands)
U.S. Treasury securities and obligations of U.S. government agencies	$	79,932	$	—	$	—	$	79,932
Municipal debt securities	—		483,176		—		483,176
Corporate debt securities	—		1,293,642		—		1,293,642
Asset-backed securities	—		68,558		—		68,558

Cash, cash equivalents and short-term investments	218,507		—		—		218,507
Total assets	$	298,439	$	1,845,376	$	—	$	2,143,815

There were no transfers between Level 2 and Level 3 of the fair value hierarchy during the years ended December 31, 2023 or 2022.

Financial Instruments Not Measured at Fair Value

On June 19, 2020, we issued $400 million aggregate principal amount of senior secured notes that mature on June 1, 2025 (the Notes) and used a portion of the proceeds from the Notes offering to repay amounts due under our then outstanding $150 million term loan. At December 31, 2023, the Notes were carried at a cost of $397.6 million, net of unamortized debt issuance costs of $2.4 million, and had a fair value of $401.9 million as assessed under our Level 2 hierarchy. At December 31, 2022, the Notes were carried at a cost of $396.1 million, net of unamortized debt issuance costs of $3.9 million, and had a fair value of $405.9 million.

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

Reserve for Insurance Claims and Claim Expenses

12 Months Ended

Dec. 31, 2023

Reserves for Insurance Claims and Claim Expenses

We hold gross reserves in an amount equal to the estimated liability for insurance claims and claim expenses related to defaults on insured mortgage loans. A loan is considered to be in “default” as of the payment date at which a borrower has missed the preceding two or more consecutive monthly payments. We establish reserves for loans that have been reported to us in default by servicers, referred to as case reserves, and additional loans that we estimate (based on actuarial review and other factors) to be in default that have not yet been reported to us by servicers, referred to as IBNR reserves. We also establish reserves for claim expenses, which represent the estimated cost of the claim administration process, including legal and other fees, as well as other general expenses of administering the claim settlement process. As of December 31, 2023, we held gross reserves for insurance claims and claim expenses of $124.0 million. During the year ended December 31, 2023, we paid 199 claims totaling $5.2 million, including 186 claims covered under the QSR Transactions representing $1.0 million of ceded claims and claim expenses.

We had 5,099 loans in default in our primary insured portfolio as of December 31, 2023, which represented a 0.81% default rate against 629,690 total policies in-force and 4,449 loans in default in our primary portfolio as of December 31, 2022, which represented a 0.75% default rate against 594,142 total policies in-force. The size of the reserve we establish for each defaulted loan (and by extension our aggregate reserve for claims and claim expenses) reflects our best estimate of the future claim payment to be made for each individual loan in default. Our future claims exposure is a function of the number of defaulted loans that progress to claim payment (which we refer to as frequency) and the amount to be paid to settle such claims (which we refer to as severity). Our estimates of claims frequency and severity are not formulaic, rather they are broadly synthesized based on historical observed experience for similarly situated loans and assumptions about future macroeconomic factors.

The following table provides a reconciliation of the beginning and ending gross reserve balances for primary insurance claims and claim expenses (benefits):


	For the years ended December 31,
	2023		2022		2021
	(In Thousands)
Beginning balance	$	99,836	$	103,551	$	90,567
Less reinsurance recoverables (1)	(21,587)		(20,320)		(17,608)
Beginning balance, net of reinsurance recoverables	78,249		83,231		72,959

Add claims incurred:
Claims and claim expenses (benefits) incurred:
Current year (2)	78,285		45,168		23,433
Prior years (3)	(56,390)		(48,762)		(11,128)
Total claims and claim expenses (benefits) incurred (4)	21,895		(3,594)		12,305

Less claims paid:
Claims and claim expenses paid:
Current year (2)	600		74		16
Prior years (3)	3,575		1,314		2,017
Reinsurance terminations	(491)		—		—
Total claims and claim expenses paid	3,684		1,388		2,033

Reserve at end of period, net of reinsurance recoverables	96,460		78,249		83,231
Add reinsurance recoverables (1)	27,514		21,587		20,320
Ending balance	$	123,974	$	99,836	$	103,551

(1) Related to ceded losses recoverable under the QSR Transactions. See Note 6, “Reinsurance” for additional information.

(2) Related to insured loans with their most recent defaults occurring in the current year. For example, if a loan defaulted in a prior year and subsequently cured and later re-defaulted in the current year, the default would be included in the current year. Amounts are presented net of reinsurance and included $70.6 million attributed to net case reserves and $6.3 million attributed to net IBNR reserves for the year ended December 31, 2023, $39.9 million attributed to net case reserves and $4.5 million attributed to net IBNR reserves for the year ended December 31, 2022, and $18.1 million attributed to net case reserves and $4.7 million attributed to net IBNR reserves for the year ended December 31, 2021.

(3) Related to insured loans with defaults occurring in prior years, which have been continuously in default before the start of the current year. Amounts are presented net of reinsurance and included $50.9 million attributed to net case reserves and $4.5 million attributed to net IBNR reserves for the year ended December 31, 2023, $42.5 million attributed to net case reserves and $4.7 million attributed to net IBNR reserves for the year ended December 31, 2022, and $6.3 million attributed to net case reserves and $5.0 million attributed to net IBNR reserves for the year ended December 31, 2021.

(4) Excludes a $0.7 million termination fee for the year ended December 31, 2023 incurred in connection with the amendment of the 2020 QSR Transaction.

The “claims incurred” section of the table above shows claims and claim expenses (benefits) incurred on defaults occurring in current and prior years, including IBNR reserves, and is presented net of reinsurance. The amount of claims incurred relating to current year defaults increased during the year ended December 31, 2023, compared to the years ended December 31, 2022 and 2021, primarily due to an increase in the average case reserve established against newly defaulted loans, as well as an increase in the total number of new delinquencies emerging during the period tied to the growth and natural seasoning of our portfolio. Our provision for claims and claim expenses during the years ended December 31, 2023, 2022 and 2021 benefited from favorable development on prior year defaults. We recognized $56.4 million, $48.8 million and $11.1 million of favorable prior year development during the years ended December 31, 2023, 2022 and 2021, respectively, primarily due to cure activity and ongoing analysis of recent loss development trends. We may increase or decrease our claim estimates and reserves as we learn additional information about individual defaulted loans, and continue to observe and analyze loss development trends in our portfolio. Gross reserves of $24.0 million related to prior year defaults remained as of December 31, 2023.

The following tables provide claim development data by accident year (or the year in which a default has occurred) and a reconciliation to the reserve for insurance claims and claim expenses. The information about net incurred losses and paid claims development for the years ended prior to 2023 is presented as supplementary information.


	Cumulative Incurred Claims and Allocated Claims Adjustment Expenses, net of Reinsurance (1)																				As of December 31, 2023
Accident Year	2014		2015		2016		2017		2018		2019		2020		2021		2022		2023		Total of IBNR		Defaults (2)
	Unaudited
($ In Thousands)
2014	$	83	$	34	$	4	$	4	$	4	$	4	$	4	$	4	$	4	$	4	$	—	—
2015			699		664		743		764		894		894		894		894		894		—		—
2016					2,394		1,568		1,790		1,934		1,936		1,930		1,893		1,986		1		1
2017							6,028		3,475		3,570		3,807		3,716		3,718		3,712		4		2
2018									7,779		5,271		4,709		4,533		4,282		4,312		15		11
2019											14,391		7,229		5,781		4,604		4,606		74		40
2020													65,769		56,154		18,862		7,472		315		164
2021															22,847		14,337		4,092		501		139
2022																	44,334		11,023		733		522
2023																			76,967		4,694		4,220
																	Total		$	115,068	$	6,337	5,099

(1) Amounts include case and IBNR reserves.

(2) Number of defaults outstanding as of December 31, 2023.


	Cumulative Paid Claims and Claims Adjustment Expenses, net of Reinsurance
Accident Year	2014		2015		2016		2017		2018		2019		2020		2021		2022		2023
	Unaudited
	(In Thousands)
2014	$	—	$	4	$	4	$	4	$	4	$	4	$	4	$	4	$	4	$	4
2015			50		246		684		720		804		894		894		894		894
2016					171		890		1,596		1,826		1,827		1,877		1,878		1,978
2017							27		1,655		2,925		3,494		3,640		3,655		3,661
2018									130		1,981		3,537		3,780		3,909		4,116
2019											69		2,368		3,212		3,534		3,621
2020													586		1,320		1,909		3,265
2021															16		274		914
2022																	74		1,252
2023																			600
																	Total		$	20,305


Reconciliation of Disclosure of Incurred and Paid Claims Development to the Liability for Unpaid Claims and Claim Adjustment Expenses
(In Thousands)
	As of December 31, 2023
Cumulative Incurred Claims and Allocated Claims Adjustment Expenses, net of Reinsurance	$	115,068
Cumulative Paid Claims and Claims Adjustment Expenses, net of Reinsurance	(20,305)
All outstanding liabilities before 2014, net of reinsurance	—
Liabilities for unpaid claims and allocated claims adjustment expenses, net of reinsurance	94,763
Reinsurance recoverable on unpaid claims	27,514
Unallocated claims adjustment expenses	1,697
Total gross liability for unpaid claims and claim adjustment expenses	$	123,974

The following is supplementary information shows the average percentage of claims and allocated claims adjustment expenses paid in the years following the incurrence of a claim as of December 31, 2023:


	Average annual percentage payout of incurred claims and allocated claims adjustment expenses by age, net of reinsurance (unaudited)
	Year 1	Year 2	Year 3	Year 4	Year 5	Year 6	Year 7	Year 8		Year 9		Year 10
Claims duration disclosure	3%	36%	25%	9%	3%	4%	0%	2	%	0	%	0	%

Intangible Assets and Goodwill (Tables)

12 Months Ended

Dec. 31, 2023

Goodwill and Intangible Assets Disclosure [Abstract]

Schedule of identifiable intangible assets and goodwill

Intangible assets and goodwill consist of identifiable intangible assets and goodwill purchased in connection with the acquisition of our insurance subsidiaries. Intangible assets and goodwill as of both December 31, 2023 and 2022 were as follows:


	(In Thousands)		Expected Lives
Goodwill	$	3,244	Indefinite
State licenses	260		Indefinite
GSE applications	130		Indefinite
Total intangible assets and goodwill	$	3,634

SCHEDULE II - FINANCIAL INFORMATION OF REGISTRANT- PARENT COMPANY ONLY - Statement of Operations - Parent Company Only (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2023	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Dec. 31, 2022	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Revenues
Net investment income	$ 18,247	$ 17,853	$ 16,518	$ 14,894	$ 13,341	$ 11,945	$ 10,921	$ 10,199	$ 67,512	$ 46,406	$ 38,072
Net realized investment (losses) gains	0	0	0	(33)	6	14	53	408	(33)	481	729
Total revenues									579,003	523,345	485,072
Expenses
Interest expense	8,066	8,059	8,048	8,039	8,035	8,036	8,051	8,041	32,212	32,163	31,796
Gain from change in fair value of warrant liability					0	0	(1,020)	(93)	0	(1,113)	(566)
Total expenses									166,300	146,040	188,347
Income before income taxes	105,181	107,300	104,049	96,173	94,780	98,589	97,189	86,747	412,703	377,305	296,725
Income tax expense	21,768	23,345	23,765	21,715	21,840	21,751	21,745	19,067	90,593	84,403	65,595
Net income	$ 83,413	$ 83,955	$ 80,284	$ 74,458	$ 72,940	$ 76,838	$ 75,444	$ 67,680	322,110	292,902	231,130
Other comprehensive income (loss), net of tax:
Unrealized gains (losses) in accumulated other comprehensive income, net of tax expense (benefit) of $312, $(748), and $(95) for each of the years in the three-year period ended December 31, 2023, respectively									64,380	(205,428)	(51,795)
Reclassification adjustment for realized losses (gains) included in net income, net of tax (benefit) expense of $(7), $(3) and $2 for each of the years in the three-year period ended December 31, 2023, respectively									26	(380)	(576)
Other comprehensive income (loss), net of tax									64,406	(205,808)	(52,371)
Comprehensive income									386,516	87,094	178,759
Parent
Revenues
Net investment income									3,920	1,204	327
Net realized investment (losses) gains									(31)	(13)	10
Total revenues									3,889	1,191	337
Expenses
Other operating expenses									7,828	7,590	8,264
Interest expense									0	0	68
Gain from change in fair value of warrant liability									0	(1,113)	(566)
Total expenses									7,828	6,477	7,766
Equity in net income of subsidiaries									412,974	378,406	303,970
Income before income taxes									409,035	373,120	296,541
Income tax expense									86,925	80,218	65,411
Net income									322,110	292,902	231,130
Other comprehensive income (loss), net of tax:
Unrealized gains (losses) in accumulated other comprehensive income, net of tax expense (benefit) of $312, $(748), and $(95) for each of the years in the three-year period ended December 31, 2023, respectively									1,173	(2,815)	(357)
Reclassification adjustment for realized losses (gains) included in net income, net of tax (benefit) expense of $(7), $(3) and $2 for each of the years in the three-year period ended December 31, 2023, respectively									25	10	(8)
Equity in other comprehensive income (loss) of subsidiaries									63,208	(203,003)	(52,006)
Other comprehensive income (loss), net of tax									64,406	(205,808)	(52,371)
Comprehensive income									$ 386,516	$ 87,094	$ 178,759

Reinsurance (Tables)

12 Months Ended

Dec. 31, 2023

Reinsurance Disclosures [Abstract]

Schedule of effects of reinsurance agreements

The effect of our reinsurance agreements on premiums written and earned is as follows:


	For the years ended December 31,
	2023		2022		2021
	(In Thousands)
Net premiums written
Direct	$	619,670	$	577,926	$	557,050
Ceded (1)	(139,130)		(117,680)		(88,539)
Net premiums written	$	480,540	$	460,246	$	468,511

Net premiums earned
Direct	$	650,411	$	594,127	$	536,630
Ceded (1)	(139,643)		(118,861)		(92,336)
Net premiums earned	$	510,768	$	475,266	$	444,294

(1) Net of profit commission.

The following table shows amounts related to the QSR Transactions:


	As of and for the years ended December 31,
	2023		2022		2021
	(In Thousands)
Ceded risk-in-force	$	12,626,541	$	12,617,169	$	8,194,604

Ceded premiums earned	(167,331)		(143,747)		(110,140)
Ceded claims and claim expenses	7,436		1,620		3,233

Ceding commission earned	39,211		32,314		23,473
Profit commission	90,006		80,714		59,104

Schedule of ILN transactions


($ values in thousands)	Inception Date	Covered Production	Initial Reinsurance Coverage	Current Reinsurance Coverage	Initial First Layer Retained Loss	Current First Layer Retained Loss (1)


2019 ILN Transaction	July 30, 2019	6/1/2018 – 6/30/2019	$326,905	$159,476	$123,424	$121,751

2020-2 ILN Transaction	October 29, 2020	4/1/2020 – 9/30/2020 (2)	242,351	55,792	121,777	121,177
2021-1 ILN Transaction	April 27, 2021	10/1/2020 – 3/31/2021 (3)	367,238	217,630	163,708	163,394
2021-2 ILN Transaction	October 26, 2021	4/1/2021 – 9/30/2021 (4)	363,596	310,567	146,229	145,858

(2) Approximately 1% of the production covered by the 2020-2 ILN Transaction has coverage reporting dates between July 1, 2019 and March 31, 2020.

(3) Approximately 1% of the production covered by the 2021-1 ILN Transaction has coverage reporting dates between July 1, 2019 and September 30, 2020.

(4) Approximately 2% of the production covered by the 2021-2 ILN Transaction has coverage reporting dates between July 1, 2019 and March 31, 2021.

Schedule of XOL transactions

The following table presents the inception date, covered production period, initial and current reinsurance coverage amount, and initial and current first layer retained aggregate loss under each outstanding XOL Transaction. Current amounts are presented as of December 31, 2023.


($ values in thousands)	Inception Date	Covered Production	Initial Reinsurance Coverage	Current Reinsurance Coverage	Initial First Layer Retained Loss	Current First Layer Retained Loss (1)
2022-1 XOL Transaction	April 1, 2022	10/1/2021 – 3/31/2022 (2)	$289,741	$253,252	$133,366	$133,123
2022-2 XOL Transaction	July 1, 2022	4/1/2022 – 6/30/2022 (3)	154,306	152,347	78,906	78,736
2022-3 XOL Transaction	October 1, 2022	7/1/2022 – 9/30/2022	96,779	96,197	106,265	106,265
2023-1 XOL Transaction	January 1, 2023	10/1/2022 – 6/30/2023	89,864	88,351	146,513	146,348
2023-2 XOL Transaction (4)	July 1, 2023	7/1/2023 – 12/31/2023	71,602	71,602	113,372	113,372

(1) NMIC applies claims paid on covered policies against its first layer aggregate retained loss exposure and cedes reserves for incurred claims and claim expenses to each applicable XOL Transaction and recognizes a reinsurance recoverable if such incurred claims and claim expenses exceed its current first layer retained loss.

(2) Approximately 1% of the production covered by the 2022-1 XOL Transaction has coverage reporting dates between October 21, 2019 and September 30, 2021.

(3) Approximately 1% of the production covered by the 2022-2 XOL Transaction has coverage reporting dates between January 4, 2021 and March 31, 2022.

Income Taxes

12 Months Ended

Dec. 31, 2023

Income Tax Disclosure [Abstract]

Income Taxes

We are a U.S. taxpayer and are subject to a statutory U.S. federal corporate income tax rate of 21%. NMIH files a consolidated U.S. federal and various state income tax returns on behalf of itself and its subsidiaries.

Total income tax expense consists of the following components:


	For the years ended December 31,
	2023		2022		2021
	(In Thousands)
Current	$	—	$	10	$	85
Deferred	90,593		84,393		65,510
Total income tax expense	$	90,593	$	84,403	$	65,595

The following table presents a reconciliation between the federal statutory income tax rate and our effective income tax rate:


	For the years ended December 31,
	2023		2022		2021
Federal statutory income tax rate	21.0	%	21.0	%	21.0	%
State provision	0.6		0.6		0.5
Share-based and other compensation	0.4		0.5		0.6
Warrant gain	—		(0.1)		—

Other	—		0.4		—
Effective income tax rate	22.0	%	22.4	%	22.1	%

The components of our net deferred tax liability are summarized as follows:


	As of December 31,
	2023		2022
Deferred tax asset:	(In Thousands)
Unrealized loss on investments	$	36,085	$	53,205
Net operating loss carryforward	8,910		8,898
Share-based compensation	6,026		6,320
Unearned premium reserve	3,957		5,264
Accrued expenses	1,369		1,430



Other	1,190		957
Total gross deferred tax asset	57,537		76,074
Less: valuation allowance	(9,169)		(8,888)
Total deferred tax asset	48,368		67,186
Deferred tax liability:
Contingency reserve	(331,342)		(242,192)
Deferred acquisition costs	(13,586)		(12,653)
Capitalized software	(2,496)		(4,737)


Other	(2,517)		(1,463)
Total deferred tax liability	(349,941)		(261,045)
Net deferred income tax (liability)	$	(301,573)	$	(193,859)

As a mortgage guaranty insurance company, we are eligible to claim a tax deduction for our statutory contingency reserve balance, subject to certain limitations outlined under IRC Section 832(e), to the extent we acquire tax and loss bonds in an amount equal to the tax benefit derived from the claimed deduction, which is our intent.

During the years ended December 31, 2023, 2022 and 2021, we purchased $80.9 million, $65.2 million and $42.9 million, of tax and loss bonds, respectively. As a result, we had no current federal income tax provision for the years ended December 31, 2023, 2022 and 2021. As of December 31, 2023 and 2022, we held $235.3 million and $154.4 million of tax and loss bonds, respectively, in "Prepaid Federal Income Taxes" on our consolidated balance sheets.

At December 31, 2023, we had a federal net operating loss carryforward of $1.2 million which expires in varying amounts in 2030 and 2031, and state net operating loss carryforwards of $136.5 million, which begin to expire in varying amounts in 2031. Section 382 of the IRC imposes annual limitations on a corporation's ability to utilize its net operating loss carryforward if it experiences an "ownership change." As a result of the acquisition of our insurance subsidiaries in 2012, $7.3 million of federal net operating losses were subject to annual limitations of $0.8 million through 2016, $0.5 million in 2017 and $0.3 million, thereafter, through 2028. Our federal net operating loss carryforward arises from this limitation and the constraint on our ability to utilize the net operating loss carryforward in full during the current period.

We are required to establish a valuation allowance against our deferred tax assets when it is more likely than not that all or a portion of the asset will not be realized. We assess our need for a valuation allowance on a quarterly basis. In the course of our review, we assess all available evidence, both positive and negative, including our expectations for future sources of income and contractual cash flows, the availability and application of tax planning strategies, and the potential reversal of temporary tax differences. At December 31, 2023 and 2022, we recorded valuation allowances of $9.2 million and $8.9 million, respectively, against state net deferred tax assets. The valuation allowances for both years primarily relate to state net operating losses generated by NMIH, as NMIH operates at a loss and currently only generates revenue from its investment portfolio.

As of December 31, 2023 and 2022, we had zero reserves for unrecognized tax benefits as we have taken no material uncertain tax positions that would have required a reserve to be measured and recognized.

We file income tax returns with the U.S. federal government and various state jurisdictions that are subject to potential examination by tax authorities. We are not currently under examination by federal or state jurisdictions. Our U.S. federal income tax returns for 2020 and subsequent years, and state income tax returns for 2019 and subsequent years, remain open by statute.

The entire disclosure for income taxes. Disclosures may include net deferred tax liability or asset recognized in an enterprise's statement of financial position, net change during the year in the total valuation allowance, approximate tax effect of each type of temporary difference and carryforward that gives rise to a significant portion of deferred tax liabilities and deferred tax assets, utilization of a tax carryback, and tax uncertainties information.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480990/946-20-50-13

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
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Reference 4: http://www.xbrl.org/2003/role/disclosureRef
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Reference 6: http://www.xbrl.org/2003/role/disclosureRef
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Reference 10: http://www.xbrl.org/2003/role/disclosureRef
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CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Cash flows from operating activities
Net income	$ 322,110	$ 292,902	$ 231,130
Adjustments to reconcile net income to net cash provided by operating activities:
Net realized investment loss (gains)	33	(481)	(729)
Gain from change in fair value of warrant liability	0	(1,113)	(566)
Depreciation and amortization	11,541	11,870	11,232
Net amortization of premium on investment securities	481	5,721	6,733
Amortization of debt discount and debt issuance costs	1,961	1,846	1,861
Deferred income taxes	90,593	84,393	65,510
Share-based compensation expense	16,914	15,425	16,678
Changes in operating assets and liabilities:
Premiums receivable	(6,776)	(9,322)	(10,579)
Accrued investment income	(5,641)	(2,244)	(2,038)
Deferred policy acquisition costs, net	(4,341)	1,020	2,641
Reinsurance recoverable	(5,927)	(1,267)	(2,712)
Prepaid federal income taxes	(80,877)	(65,165)	(42,853)
Other assets	(316)	236	(218)
Unearned premiums	(30,740)	(16,202)	20,420
Reserve for insurance claims and claim expenses	24,138	(3,715)	12,984
Reinsurance balances, net	(859)	(1,904)	(683)
Accounts payable and accrued expenses	10,389	1,394	16,908
Net cash provided by operating activities	342,683	313,394	325,719
Cash flows from investing activities
Purchase of short-term investments	(166,224)	(313,926)	(10,640)
Purchase of fixed-maturity investments, available-for-sale	(488,562)	(233,586)	(514,405)
Proceeds from maturity of short-term investments	320,545	151,635	0
Proceeds from redemptions, maturities and sale of fixed-maturity investments, available-for-sale	143,613	116,663	163,103
Additions to software and equipment	(9,372)	(10,572)	(12,238)
Net cash used in investing activities	(200,000)	(289,786)	(374,180)
Cash flows from financing activities
Proceeds from issuance of common stock related to employee equity plans	10,549	5,442	4,201
Proceeds from issuance of common stock related to warrant exercises	0	518	503
Taxes paid related to net share settlement of equity awards	(9,356)	(5,213)	(5,426)
Payments of debt issuance costs	0	0	(1,108)
Repurchases of common stock	(91,613)	(56,575)	0
Net cash used in financing activities	(90,420)	(55,828)	(1,830)
Net increase (decrease) in cash, cash equivalents and restricted cash	52,263	(32,220)	(50,291)
Cash, cash equivalents and restricted cash, beginning of period	44,426	76,646	126,937
Cash, cash equivalents and restricted cash, end of period	96,689	44,426	76,646
Supplemental disclosures of cash flow information
Interest paid	29,500	29,500	29,500
Income taxes (paid) refunded	$ (20)	$ 20	$ 457

Income Taxes - Components of Income Tax Expense (Benefit) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2023	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Dec. 31, 2022	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Income Tax Disclosure [Abstract]
Current									$ 0	$ 10	$ 85
Deferred									90,593	84,393	65,510
Total income tax expense	$ 21,768	$ 23,345	$ 23,765	$ 21,715	$ 21,840	$ 21,751	$ 21,745	$ 19,067	$ 90,593	$ 84,403	$ 65,595

Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

Reserves for Insurance Claims and Claim Expenses - Average Annual Percentage Payout of Incurred Claims by Age, Net of Reinsurance (Details) - Financial Guarantee Insurance Product Line	Dec. 31, 2023
Short-Duration Insurance Contracts, Historical Claims Duration [Line Items]
Year 1	3.00%
Year 2	36.00%
Year 3	25.00%
Year 4	9.00%
Year 5	3.00%
Year 6	4.00%
Year 7	0.00%
Year 8	2.00%
Year 9	0.00%
Year 10	0.00%

Commitments and Contingencies	12 Months Ended
Commitments and Contingencies	Dec. 31, 2023
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies PMIERs As an approved insurer, NMIC is subject to ongoing compliance with the PMIERs established by each of the GSEs (italicized terms have the same meaning that such terms have in the PMIERs, as described below). The PMIERs establish operational, business, remedial and financial requirements applicable to approved insurers. The PMIERs financial requirements prescribe a risk-based methodology whereby the amount of assets required to be held against each insured loan is determined based on certain loan-level risk characteristics, such as FICO, vintage (year of origination), performing vs. non-performing (i.e., current vs. delinquent), LTV ratio and other risk features. In general, higher quality loans carry lower charges. Under the PMIERs, approved insurers must maintain available assets that equal or exceed minimum required assets, which is an amount equal to the greater of (i) $400 million or (ii) a total risk-based required asset amount. The risk-based required asset amount is a function of the risk profile of an approved insurer's RIF, assessed on a loan-by-loan basis against certain risk-based factors derived from tables set out in the PMIERs, which is then adjusted on an aggregate basis for reinsurance transactions approved by the GSEs, such as with respect to our ILN Transactions, XOL Transactions and QSR Transactions. The aggregate gross risk-based required asset amount for performing, primary insurance is subject to a floor of 5.6% of performing primary adjusted RIF. By April 15th of each year, NMIC must certify it met all PMIERs requirements as of December 31st of the prior year. We certified to the GSEs by April 15, 2023 that NMIC was in full compliance with the PMIERs as of December 31, 2022. NMIC also has an ongoing obligation to immediately notify the GSEs in writing upon discovery of a failure to meet one or more of the PMIERs requirements. We continuously monitor NMIC's compliance with the PMIERs. Litigation We record a litigation liability when we determine that it is probable a litigation loss will be incurred and the amount of such anticipated loss can be reasonably estimated. In the event we determine that a litigation loss is reasonably possible (though not probable), we disclose an estimate of the possible loss if such estimate can be reasonably established or disclose the matter with no estimate if such estimate cannot be reasonably made. We evaluate litigation and other legal developments that could affect our accrual for probable losses or our estimated disclosure of possible losses and make ongoing adjustments to our accruals and disclosures as appropriate. Significant judgment is required to determine both the likelihood and the estimated amount of potential losses related to such matters. We are currently named as a defendant in a litigation proceeding pertaining to the refund of certain mortgage insurance premiums under the Homeowners Protection Act. The case was dismissed in September 2023 and is currently pending appeal. We do not currently expect that it is reasonably possible that we will incur a material loss in connection with the case and have not recorded a litigation liability for this matter.

Organization and Basis of Presentation	12 Months Ended
Organization and Basis of Presentation	Dec. 31, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization and Basis of Presentation	Organization and Basis of Presentation NMI Holdings, Inc. (NMIH) is a Delaware corporation, incorporated in May 2011 to provide private mortgage guaranty insurance (which we refer to as mortgage insurance or MI) through its wholly-owned insurance subsidiaries, National Mortgage Insurance Corporation (NMIC) and National Mortgage Reinsurance Inc One (Re One). Our common stock is listed on the Nasdaq exchange under the ticker symbol "NMIH." NMIC, our primary insurance subsidiary, issued its first mortgage insurance policy in April 2013. NMIC is licensed to write mortgage insurance in all 50 states and the District of Columbia (D.C.). Re One historically provided reinsurance coverage to NMIC in accordance with certain statutory risk retention requirements. Such requirements have been repealed and the reinsurance coverage provided by Re One to NMIC has been commuted. Re One remains a wholly-owned, licensed insurance subsidiary; however, it does not currently have active insurance exposures. In August 2015, NMIH capitalized a wholly-owned subsidiary, NMI Services, Inc. (NMIS), through which we offer outsourced loan review services to mortgage loan originators. We operate as a single segment for the purposes of assessing performance and making operating decisions. Basis of Presentation The accompanying consolidated financial statements include the results of NMIH and its wholly-owned subsidiaries. All inter-company transactions have been eliminated. These financial statements have been prepared in accordance with accounting principles generally accepted in the U.S. (GAAP) and our accounts are maintained in U.S. dollars. The preparation of financial statements in accordance with GAAP requires management to make estimates and assumptions that affect reported amounts of assets and liabilities, as well as disclosure of contingent assets and liabilities as of the balance sheet date. Estimates also affect the reported amounts of income and expenses for the reporting period. Actual results could differ from those estimates.

Leases

12 Months Ended

Dec. 31, 2023

Leases [Abstract]

Leases

We have two operating lease agreements related to our corporate headquarters and a data center facility for which we recognized operating ROU assets and lease liabilities of $9.1 million and $11.4 million in "Other Assets" and "Other Liabilities," respectively, on our consolidated balance sheets as of December 31, 2023. As of December 31, 2022, we recognized operating ROU assets and lease liabilities of $10.4 million and $12.1 million, respectively. As of December 31, 2023 and 2022, we did not have any finance leases.

In January 2022 we modified the lease for our corporate headquarters, securing a reduction in pricing and incremental leasehold improvement concessions, reducing the square footage of leased space and extending the remaining term through March 2030. In February 2022, we renewed the lease of our data center facility, extending its term through January 2024. Upon the respective modification and extension, the ROU asset and liability associated with each lease was remeasured, using our current estimated incremental borrowing rate, resulting in an aggregate increase to ROU assets and lease liabilities of $9.7 million. We did not enter any new operating leases or recognize any new ROU assets or lease liabilities during the year ended December 31, 2023.

The following table provides a summary of our ROU asset and lease liability assumptions as of December 31, 2023:


Weighted average remaining lease term	6.2 years
Weighted average discount rate	6.50	%

Cash paid on our operating leases for the years ended December 31, 2023, 2022 and 2021 was $1.5 million, $0.8 million and $2.6 million and lease expense incurred was $2.0 million, $2.0 million and $2.3 million during each respective period.

Future payments due under our existing operating leases as of December 31, 2023 are as follows:


Years ending December 31,	(In Thousands)
2024	$	2,080
2025	2,128
2026	2,190
2027	2,256
2028	2,322
2029 and thereafter	2,995
Total undiscounted lease payments	13,971
Less effects of discounting	(2,582)
Present value of lease payments	$	11,389

Lease expense is recorded in “Underwriting and Operating Expenses” on the consolidated statements of operations and comprehensive income. Our existing leases have original terms that range from two to eight years. The lease for our corporate headquarters includes an option to renew for an additional five years at prevailing market rates at time of renewal. This renewal option is not included in the calculation of future lease payments due under the existing lease as presented above as it is not reasonably certain to be exercised.

Leases

The following table provides a summary of our ROU asset and lease liability assumptions as of December 31, 2023:


Weighted average remaining lease term	6.2 years
Weighted average discount rate	6.50	%

Future payments due under our existing operating leases as of December 31, 2023 are as follows:


Years ending December 31,	(In Thousands)
2024	$	2,080
2025	2,128
2026	2,190
2027	2,256
2028	2,322
2029 and thereafter	2,995
Total undiscounted lease payments	13,971
Less effects of discounting	(2,582)
Present value of lease payments	$	11,389

Common Stock - Narrative (Details)	12 Months Ended
Common Stock - Narrative (Details)	Dec. 31, 2023 USD ($) vote $ / shares shares	Dec. 31, 2022 $ / shares shares	Jul. 31, 2023 USD ($)	Feb. 10, 2022 USD ($)
Class of Stock [Line Items]
Common stock, outstanding (in shares) \| shares	80,881,280	83,549,879
Number of votes per common share \| vote	1
Share repurchase program, authorized amount				$ 125,000,000
Repurchased shares (in shares) \| shares	3,500,000	2,900,000
Shares repurchased, average price per share (in dollar per share) \| $ / shares	$ 25.93	$ 19.34
Remaining authorized repurchase amount	$ 176,900,000
July 2023 Share Repurchase Program
Class of Stock [Line Items]
Share repurchase program, authorized amount			$ 200,000,000
2022 Extended Share Repurchase Program
Class of Stock [Line Items]
Share repurchase program, authorized amount			$ 125,000,000

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-13

Reference 2: http://www.xbrl.org/2003/role/recommendedDisclosureRef
-Topic 272
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Quarterly Financial Information Disclosure [Abstract]

Regulatory Information - Schedule of Combined Statutory Net Income, Statutory Surplus, Contingency Reserve and RTC Ratios (Details) - NMIC $ in Thousands	12 Months Ended
	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)
Statutory Accounting Practices [Line Items]
Statutory net income	$ 104,464	$ 107,418	$ 34,975
Statutory surplus	963,085	980,225	893,848
Contingency reserve	1,573,360	1,266,038	1,036,639
Statutory capital	$ 2,536,445	$ 2,246,263	$ 1,930,487
Risk-to-capital	11.4	11.1	11.6

Summary of Accounting Principles (Policies)	12 Months Ended
Summary of Accounting Principles (Policies)	Dec. 31, 2023
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying consolidated financial statements include the results of NMIH and its wholly-owned subsidiaries. All inter-company transactions have been eliminated. These financial statements have been prepared in accordance with accounting principles generally accepted in the U.S. (GAAP) and our accounts are maintained in U.S. dollars. The preparation of financial statements in accordance with GAAP requires management to make estimates and assumptions that affect reported amounts of assets and liabilities, as well as disclosure of contingent assets and liabilities as of the balance sheet date. Estimates also affect the reported amounts of income and expenses for the reporting period. Actual results could differ from those estimates.
Use of Estimates	Use of Estimates We use accounting principles and methods that conform to GAAP. We are required to apply significant judgment and make material estimates in the preparation of our financial statements and with regard to various accounting, reporting and disclosure matters. Assumptions and estimates are required to apply these principles where actual measurement is not possible or practical.
Insurance Premium Revenue Recognition	Insurance Premium Revenue Recognition Premiums for primary mortgage insurance policies may be paid in a single payment at origination (single premium), on a monthly installment basis (monthly premium) or on an annual installment basis (annual premium), with such election and payment type fixed at policy inception. Premiums written at origination for single premium policies are initially deferred as unearned premiums and amortized into earnings over the estimated policy life, in accordance with the anticipated expiration of risk. Monthly premiums are recognized as revenue in the month billed and when the coverage is effective. Annual premiums are initially deferred and earned on a straight-line basis over the year of coverage. Upon cancellation of a policy, all remaining non-refundable deferred and unearned premium is immediately earned, and any refundable deferred and unearned premium is returned to the policyholder and recorded as a reduction to written premium and unearned premium reserve in the period paid. Premiums written on pool transactions are earned over the period that coverage is provided. Our pool insurance agreement with Fannie Mae expired on August 31, 2023 and we will not recognize any pool premiums written or earned in connection with the agreement in future periods.
Reserve for Insurance Claims and Claims Expenses	Reserves for Insurance Claims and Claim Expenses We establish reserves for claims based on our best estimate of the ultimate claim costs for defaulted loans using the general principles contained in ASC 944, Financial Services - Insurance (ASC 944). A loan is considered to be in "default" as of the payment date at which a borrower has missed the preceding two or more consecutive monthly payments. We establish reserves for loans that have been reported to us in default by servicers, referred to as case reserves, and additional loans that we estimate (based on actuarial review and other factors) to be in default that have not yet been reported to us by servicers, referred to as incurred but not reported (IBNR) reserves. We also establish reserves for claim expenses, which represent the estimated cost of the claim administration process, including legal and other fees, as well as other general expenses of administering the claim settlement process. Claim expense reserves are either allocated (i.e., associated with a specific claim) or unallocated (i.e., not associated with a specific claim). The establishment of claims and claim expense reserves is subject to inherent uncertainty and requires significant judgment by management. Reserves are established by estimating the number of loans in default that will result in a claim payment, which is referred to as claim frequency, and the amount of claim payment expected to be paid on each such loan in default, which is referred to as claim severity. Claim frequency and severity estimates are established based on historical observed experience regarding certain loan factors, such as age of the default, size of the loan and loan-to-value (LTV) ratios, and are strongly influenced by assumptions about the path of certain economic factors, such as house price appreciation, trends in unemployment and mortgage rates. We consider the appropriateness of such inputs at each fiscal quarter and conduct an actuarial review annually to evaluate and, if necessary, update these assumptions.
Investments	Investments We have designated our investment portfolio as available-for-sale and report our invested assets at fair value. Unrealized gains and losses in the portfolio, net of related tax expense or benefit, are recognized as a component of accumulated other comprehensive income (AOCI) in shareholders' equity. We measure fair value and classify invested assets in a hierarchy for disclosure purposes consisting of three "levels" based on the observability of inputs available in the marketplace used to measure fair value. The hierarchy gives the highest priority to unadjusted quoted prices in active markets for identical assets (Level 1 measurements) and the lowest priority to unobservable inputs (Level 3 measurements). See Note 4, "Fair Value of Financial Instruments" for further discussion. Purchases and sales of investments are recorded on a trade date basis. Net investment income is recognized when earned, and includes interest and dividend income together with amortization of market premiums and discounts using the effective yield method, and is net of investment management fees and other investment related expenses. For asset-backed securities and any other holdings for which there is a prepayment risk, prepayment assumptions are evaluated and revised as necessary. Any adjustments required due to changes in effective yields and prepayment assumptions are recognized on a prospective basis. We recognize an impairment on a security through the consolidated statement of operations and comprehensive income if (i) we intend to sell the impaired security; or (ii) it is more likely than not that we will be required to sell the impaired security prior to recovery of its amortized cost basis. If a sale is intended or likely to be required, we write down the amortized cost basis of the security to fair value and recognize the full amount of the impairment through the statement of operations as a "Realized Investment Loss." For securities in an unrealized loss position where a sale is not intended or likely to be required, we further assess if the decline in fair value below amortized cost is driven by a credit related impairment, considering several items including, but not limited to: •the severity of the decline in fair value; •the financial condition of the issuer; •the failure of the issuer to make scheduled interest or principal payments; •recent rating downgrades of the applicable security or issuer by one or more nationally recognized statistical ratings organization; and •other adverse conditions related to or impacting the security or issuer. To the extent we determine that a security impairment is credit-related, an impairment loss is recognized through the statement of operations as a provision for credit loss expense, and presented as a "Realized Investment Loss." We recognize an allowance for credit losses for the difference between the amortized cost and present value of future expected cash flows, limited by the amount the fair value of the security is below its amortized cost. Subsequent changes (favorable and unfavorable) in credit losses are recognized through the statement of operations as a provision for or a reversal of credit loss expense, and presented as a "Realized Investment Gain or Loss." The portion of a security impairment attributed to other non-credit related factors is recognized in other comprehensive income, net of taxes. We have elected to present accrued interest receivable separately from available for sale securities on our consolidated balance sheets. Accrued interest receivable was $19.8 million and $14.1 million as of December 31, 2023 and 2022, respectively, and is included in "Accrued Investment Income." We have elected not to measure an allowance for credit losses for accrued interest receivable on available for sale securities. Accrued interest for available for sale securities is written off against interest income when the receivable has aged 90 days past due. We did not write off any accrued interest receivable during the years ended December 31, 2023, 2022 or 2021. We consider items such as U.S. Treasury Bills and commercial paper with original maturities of 12 months or less to be short-term investments.
Deferred Policy Acquisition Costs (DAC)	Deferred Policy Acquisition Costs (DAC) Costs directly associated with the successful acquisition of mortgage insurance policies, consisting of certain selling expenses and other policy issuance and underwriting expenses, are initially deferred and reported as DAC. DAC is reviewed periodically to determine that it does not exceed recoverable amounts. DAC is amortized to expense in proportion to estimated gross profits over the life of the associated policies. We revise the rate of amortization to reflect actual experience and any changes to persistency or loss development.
Premium Deficiency Reserves	Premium Deficiency Reserves We consider whether a premium deficiency exists and a premium deficiency reserve is required at each fiscal quarter using best estimate assumptions as of the testing date. A premium deficiency reserve is established if the net present value of expected future claim costs, claim adjustment expenses, policyholder dividends, unamortized acquisition costs and maintenance costs exceeds the net present value of expected future premiums, anticipated investment income and existing reserves for a specified group of policies.
Reinsurance	Reinsurance We cede insurance risk through the use of reinsurance contracts and follow reinsurance accounting for those transactions where significant risk is transferred. We account for premiums, claims and claim expenses that are ceded to reinsurers on basis consistent with that which we use to account for the original policies we issue and pursuant to the terms of our reinsurance contracts. We account for premiums ceded or otherwise paid to reinsurers as a reduction to premium revenue. NMIC entered into quota share reinsurance treaties effective September 1, 2016 (the 2016 QSR Transaction), January 1, 2018 (the 2018 QSR Transaction), April 1, 2020 (the 2020 QSR Transaction and, as amended January 1, 2024, the Amended 2020 QSR Transaction), January 1, 2021 (the 2021 QSR Transaction), October 1, 2021 (the 2022 QSR Transaction), July 1, 2022 (the 2022 Seasoned QSR Transaction), and January 1, 2023 (the 2023 QSR Transaction), which we refer to collectively as the QSR Transactions. We earn profit and ceding commissions in connection with the QSR Transactions (see Note 6, "Reinsurance"). Profit commissions represent a percentage of the profits recognized by reinsurers that are returned to us, based on the level of claims and claim expenses that we cede. We recognize any profit commissions we earn as a decrease to ceded earned premiums. Ceding commissions are calculated as a percentage of ceded written premiums under the 2016 QSR Transaction and as a percentage of ceded earned premiums under the 2018, 2020 (and Amended 2020), 2021, 2022, 2022 Seasoned and 2023 QSR Transactions, and are intended to cover our costs of acquiring and servicing direct policies. We recognize any ceding commissions generated under the QSR Transactions in a manner consistent with our recognition of earnings on the underlying reinsured policies. We account for ceding commissions earned as a reduction to underwriting and operating expenses. Under the QSR Transactions, we cede a portion of claims and claim expenses and reserves to our reinsurers, and account for such ceded reserves as "Reinsurance Recoverables" on the consolidated balance sheets and such ceded expenses as reductions to claims and claim expenses on the consolidated statements of operations. As of December 31, 2023 and 2022, we had $27.5 million and $21.6 million, respectively, of reinsurance recoverables under the QSR Transactions. We remain directly liable for all claim payments if we are unable to collect the recoverables due from our reinsurers and, as such, we actively monitor and manage our counterparty credit exposure to our reinsurance providers. We establish an allowance for expected credit loss against our reinsurance recoverables if we do not expect to recover amounts due from one or more of our reinsurance counterparties, and report our reinsurance recoverables net of such allowance, if any. We actively monitor the counterparty credit profiles of our reinsurers and each is required to partially collateralize its obligations under the terms of our QSR Transactions. The allowance for credit loss established with respect to our reinsurance recoverables was deemed immaterial as of December 31, 2023 and 2022.
Variable Interest Entities	Variable Interest Entities NMIC is a party to excess-of-loss reinsurance agreements with Oaktown Re III Ltd., Oaktown Re V Ltd., Oaktown Re VI Ltd., and Oaktown Re VII Ltd. (special purpose reinsurance entities collectively referred to as the Oaktown Re Vehicles) effective July 30, 2019, October 29, 2020, April 27, 2021, and October 26, 2021, respectively. At inception of the respective reinsurance agreements, we determined that each of the Oaktown Re Vehicles was a variable interest entity (VIE), as defined under GAAP Accounting Standards Codification (ASC) 810, because they did not have sufficient equity at risk to finance their respective activities. We evaluated the VIEs at inception to determine whether NMIC was the primary beneficiary under each deal and, if so, whether we were required to consolidate the assets and liabilities of each VIE. The primary beneficiary of a VIE is an enterprise that (1) has the power to direct the activities of the VIE, which most significantly impact its economic performance and (2) has significant economic exposure to the VIE, i.e., the obligation to absorb losses or receive benefits that could potentially be significant. The determination of whether an entity is the primary beneficiary of a VIE is complex and requires management judgment regarding determinative factors, including the expected results of the VIE and how those results are absorbed by beneficial interest holders, as well as which party has the power to direct activities that most significantly impact the performance of the VIE. We concluded that we are not the primary beneficiary of each VIE and, as such, we do not consolidate them in our consolidated financial statements.
Income Taxes	Income Taxes We account for income taxes using the liability method in accordance with ASC Topic 740, Income Taxes. The liability method measures the expected future tax effects of temporary differences at the enacted tax rates applicable for the period in which the deferred asset or liability is expected to be realized or settled. Temporary differences are differences between the tax basis of an asset or liability and its reported amount in the consolidated financial statements that would result in future increases or decreases in taxes owed on a cash basis compared to amounts already recognized as tax expense in the consolidated statements of operations. We purchase non-interest bearing U.S. Mortgage Guaranty Tax and Loss Bonds issued by the Treasury Department in order to claim a tax deduction for our contingency reserve balance. The tax and loss bonds are carried at cost and are reported as "Prepaid Federal Income Taxes" on the consolidated balance sheets.
Share-Based Compensation	Share-Based Compensation We account for stock compensation in accordance with ASC 718, Compensation - Stock Compensation, which addresses accounting for share-based awards and recognition of compensation expense, measured using grant date fair value, over the requisite service or performance period of the award. Share-based compensation includes restricted stock units (RSUs) and stock option grants under our stock incentive plans. We calculate the fair value of stock option grants using a Black-Scholes option pricing model, which takes into account various subjective assumptions. Key assumptions used in the model include the expected volatility of our stock price, dividend yield and the risk-free interest rate, as well as the expected option term, giving consideration to the contractual terms of any award. We use the simplified method to estimate expected option term during the period as sufficient historical exercise data is not available. RSU grants may contain a service condition, or performance and service conditions. RSU grants are valued at our stock price on the date of grant less the present value of anticipated dividends, and we recognize their fair value as compensation expense over their requisite service or performance and service periods. We account for stock option and RSU forfeitures as they occur. Share-based compensation is recorded in “Underwriting and Operating Expenses” on the consolidated statements of operations and comprehensive income.
Earnings Per Share (EPS)	Earnings Per Share (EPS) Basic earnings per share is based on the weighted average number of common shares outstanding. Diluted earnings per share is based on the weighted average number of common shares outstanding and common share equivalents that would be issuable upon the vesting of existing service-based and certain performance and service-based RSUs, and exercise of vested and unvested stock options and outstanding warrants. Common share equivalents are excluded from EPS computations in the periods in which they have an anti-dilutive effect. Basic EPS is based on the weighted average number of shares of common stock outstanding. Diluted EPS is based on the weighted average number of shares of common stock outstanding and common stock equivalents that would be issuable upon the vesting of service-based and performance and service-based RSUs, and the exercise of vested and unvested stock options and outstanding warrants.
Share Repurchases	Share Repurchases Common stock repurchases are recorded at cost and presented as “Treasury Stock” on the consolidated balance sheets and statements of changes in shareholders’ equity. At the date of repurchase, shareholders’ equity is reduced by the aggregate repurchase price plus commissions, applicable taxes and other expenses that arise from the repurchase transaction
Cash and Cash Equivalents	Cash and Cash Equivalents We consider items such as U.S. Treasury Bills, certificates of deposit and money market funds with original maturities of 90 days or less to be cash equivalents.
Software and Equipment	Software and Equipment We capitalize certain costs associated with the development of internal-use software and equipment. Software and equipment are stated at cost, less accumulated amortization and depreciation. Amortization of software and depreciation of equipment commences at the beginning of the month following our placement of the assets into use. Amortization and depreciation are calculated on a straight-line basis over the estimated useful life of the respective assets, typically from three to five years, unless factors indicate a shorter useful life. We amortize leasehold improvements over the shorter of the lives of the leases or estimated service lives of the leasehold improvements. Amortization and depreciation expense is recorded in “Underwriting and Operating Expenses” on the consolidated statements of operations and comprehensive income.
Leases	Leases We recognize right-of-use (ROU) assets and corresponding lease liabilities for our lease arrangements. Lease liabilities are established based on the estimated present value of lease payments over the relevant lease term. We estimate a discount rate for each lease based on our estimated incremental borrowing rate at the commencement date of the relevant lease, taking into consideration the cost of any outstanding collateralized borrowings we have at such time with adjustment for the terms of the lease agreement, and prevailing market conditions and macroeconomic factors at the time of its commencement. ROU assets are measured as the associated lease liability plus any direct costs incurred in connection with the initial establishment of the lease, less any lease incentives received.
Business Combinations, Goodwill and Intangible Assets	Business Combinations, Goodwill and Intangible Assets Goodwill represents the excess of the purchase price over the estimated fair value of net assets acquired from a business combination. In accordance with ASC 350, Intangibles – Goodwill and Other, we test goodwill for impairment annually or more frequently if we believe indicators of impairment exist. We have not identified any impairments of goodwill through December 31, 2023. Our intangible assets consist of state licenses and Fannie Mae and Freddie Mac (collectively, the GSEs) applications which have indefinite lives. We test indefinite-lived intangible assets for impairment annually or more frequently if we believe indicators of impairment exist.
Premiums Receivable	Premiums Receivable Premiums receivable consists of premiums due on our mortgage insurance policies. If a mortgage insurance premium is unpaid for more than 120 days, the associated receivable is written off against earned premium and the related insurance policy is canceled. We recognize an allowance for credit losses for premiums receivable based on credit losses expected to arise over the life of the receivable. Due to the nature of our insurance policies (a necessary precondition for access to mortgage credit for covered borrowers) and the short duration of the related receivables, we do not typically experience credit losses against our premium receivables and the allowance for credit loss established on premium receivables was deemed immaterial at December 31, 2023 and 2022. Premiums receivable may be written off prior to 120 days in the ordinary course of business for non-credit events including, but not limited to, the modification or refinancing of an underlying insured loan. We established a $2.7 million and $2.3 million reserve for premium write-offs at December 31, 2023 and 2022, respectively.
Other Revenues	Other Revenues Other revenues represent underwriting fee revenue from our subsidiary, NMIS, which provides outsourced loan review services to mortgage loan originators. NMIS fees are earned and recognized as services are provided.
Recent Accounting Pronouncements - Adopted and Not Yet Adopted	Recent Accounting Pronouncements – Adopted In August 2018, the Financial Accounting Standards Board (FASB) issued ASU 2018-12, Targeted Improvements to the Accounting for Long-Duration Contracts (Topic 944). The update provides guidance to the existing recognition, measurement, presentation and disclosure requirements for long-duration contracts issued by an insurance entity. The FASB subsequently issued ASU 2019-09 in November 2019 and ASU 2020-11 in November 2020, which amended the effective date for this standard and provided transition relief to facilitate early application for long duration contracts. The standard will now take effect for public business entities for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2022. We adopted this ASU on January 1, 2023 and determined it did not have a material impact on our consolidated financial statements as none of our contracts were within scope of the update. In March 2020, the FASB issued ASU 2020-04, Reference Rate Reform (Topic 848). The update provides optional guidance to ease the potential burden in accounting for reference rate reform on financial reporting. Reference rate reform refers to the global transition away from referencing the London Interbank Offered Rate (LIBOR) in financial contracts. Topic 848 includes optional expedients and exceptions for applying GAAP to contracts, hedging relationships and other transactions affected by reference rate reform if certain criteria are met. This standard may be elected and applied prospectively over time from March 12, 2020 through December 31, 2022 as reference rate reform activities occur. In December 2022, the FASB issued ASU 2022-06, which extended the sunset date of Topic 848 from December 31, 2022 to December 31, 2024. We adopted Topic 848 on September 30, 2023 and determined it did not have a material impact on our consolidated financial statements. Recent Accounting Pronouncements – Not yet Adopted In November 2023, the FASB issued ASU 2023-07, Segment Reporting (Topic 280). The update expands annual and interim disclosure requirements for reportable segments, primarily through enhanced disclosures about significant segment expenses. The standard will take effect for all public business entities, including those that have only a single reportable segment for fiscal years beginning after December 15, 2023. We are currently evaluating the impact the adoption of this ASU will have, if any, on our consolidated financial statements. In December 2023, the FASB issued ASU 2023-09, Income Taxes (Topic 740). The update enhances the disclosure requirements related to tax rate reconciliations and income taxes paid. The standard will take effect for public business entities for fiscal years beginning after December 15, 2025. Early adoption is permitted. We are currently evaluating the impact the adoption of this ASU will have, if any, on our consolidated financial statements.
Fair Value of Financial Instruments	The following describes the valuation techniques used by us to determine the fair value of our financial instruments: We established a fair value hierarchy by prioritizing the inputs to valuation techniques used to measure fair value. The hierarchy gives the highest priority to unadjusted quoted prices in active markets for identical assets or liabilities (Level 1 measurements) and the lowest priority to unobservable inputs (Level 3 measurements). The three levels of the fair value hierarchy under this standard are described below: Level 1 – Fair value measurements based on quoted prices in active markets that we have the ability to access for identical assets or liabilities. Market price data generally is obtained from exchange or dealer markets. We do not adjust the quoted price for such instruments. Level 2 – Fair value measurements based on inputs other than quoted prices included in Level 1 that are observable for the asset or liability, either directly or indirectly. Level 2 inputs include quoted prices for similar assets and liabilities in active markets, quoted prices for identical or similar assets or liabilities in markets that are not active, and inputs other than quoted prices that are observable for the asset or liability, such as interest rates and yield curves that are observable at commonly quoted intervals. Level 3 – Fair value measurements based on valuation techniques that use significant inputs that are unobservable. Both observable and unobservable inputs may be used to determine the fair values of positions classified in Level 3. The circumstances for using these measurements include those in which there is little, if any, market activity for the asset or liability. Therefore, we must make certain assumptions, which require significant management judgment or estimation about the inputs a hypothetical market participant would use to value that asset or liability. In certain cases, the inputs used to measure fair value may fall into different levels of the fair value hierarchy. In such cases, the level in the fair value hierarchy is determined based on the lowest level input that is significant to the fair value measurement in its entirety. Assets classified as Level 1 and Level 2 To determine the fair value of securities available-for-sale in Level 1 and Level 2 of the fair value hierarchy, independent pricing sources have been utilized. One price is provided per security based on observable market data. To ensure securities are appropriately classified in the fair value hierarchy, we review the pricing techniques and methodologies of the independent pricing sources and believe that their policies adequately consider market activity, either based on specific transactions for the issue valued or based on modeling of securities with similar credit quality, duration, yield and structure that were recently traded. A variety of inputs are utilized by the independent pricing sources including benchmark yields, reported trades, non-binding broker/dealer quotes, issuer spreads, two sided markets, benchmark securities, bids, offers and reference data including data published in market research publications. Inputs may be weighted differently for any security, and not all inputs are used for each security evaluation. Market indicators, industry and economic events are also considered. This information is evaluated using a multidimensional pricing model. Quality controls are performed by the independent pricing sources throughout this process, which include reviewing tolerance reports, trading information and data changes, and directional moves compared to market moves. This model combines all inputs to arrive at a value assigned to each security. We have not made any adjustments to the prices obtained from the independent pricing sources

Subsequent events	12 Months Ended
Subsequent events	Dec. 31, 2023
Subsequent Events [Abstract]
Subsequent events	Subsequent events Quota Share Reinsurance Effective January 1, 2024, NMIC entered into a quota share reinsurance treaty with a broad panel of highly rated reinsurers that will provide coverage for mortgage insurance policies to be written between January 1, 2024 and December 31, 2024 (the 2024 QSR Transaction). Under the terms of the agreement, NMIC will cede premiums earned related to 20% of the risk on eligible policies in exchange for reimbursement of ceded claims and claim expenses on covered policies, a ceding commission equal to 20% and profit commission of up to 56% that varies directly and inversely with ceded claims. Excess-of-Loss Reinsurance Effective January 1, 2024, NMIC entered into a reinsurance agreement with a broad panel of highly rated reinsurers that provides for up to $162.5 million of aggregate excess-of-loss reinsurance coverage for delinquencies that emerge on mortgage insurance policies written between January 1, 2024 and December 31, 2024 (the 2024 XOL Transaction). For the reinsurance coverage period, NMIC will retain a first layer of aggregate losses on covered policies and the reinsurers then provide second layer loss protection up to $162.5 million. NMIC retains losses in excess of the outstanding reinsurance coverage amount.

Quarterly Financial Data (Unaudited)

12 Months Ended

Dec. 31, 2023

Quarterly Financial Data (Unaudited)


	2023 Quarters								2023
	First		Second		Third		Fourth		Year
	(In Thousands, except per share data)

Net premiums earned	$	121,754	$	125,985	$	130,089	$	132,940	$	510,768
Net investment income	14,894		16,518		17,853		18,247		67,512
Net realized investment losses	(33)		—		—		—		(33)
Other revenues	164		182		217		193		756
Insurance claims and claim expenses	6,701		2,873		4,812		8,232		22,618

Underwriting and operating expenses	25,786		27,448		27,749		29,716		110,699
Service expenses	80		267		239		185		771
Interest expense	8,039		8,048		8,059		8,066		32,212

Income before income taxes	96,173		104,049		107,300		105,181		412,703
Income tax expense	21,715		23,765		23,345		21,768		90,593
Net income	$	74,458	$	80,284	$	83,955	$	83,413	$	322,110

Basic earnings per share (1)	$	0.89	$	0.97	$	1.02	$	1.03	$	3.91
Diluted earnings per share (1)	$	0.88	$	0.95	$	1.00	$	1.01	$	3.84

Weighted average common shares outstanding - basic	83,600		82,958		82,096		81,005		82,407
Weighted average common shares outstanding - diluted	84,840		84,190		83,670		82,685		83,854

(1) Due to the use of weighted average shares outstanding when calculating EPS, the sum of quarterly per share data may not equal the per share data for the year.


	2022 Quarters								2022
	First		Second		Third		Fourth		Year
	(In Thousands, except per share data)

Net premiums earned	$	116,495	$	120,870	$	118,317	$	119,584	$	475,266
Net investment income	10,199		10,921		11,945		13,341		46,406
Net realized investment gains	408		53		14		6		481
Other revenues	339		376		301		176		1,192

Insurance claims and claim (benefits) expenses	(619)		(3,036)		(3,389)		3,450		(3,594)
Underwriting and operating expenses	32,935		30,700		27,144		26,711		117,490
Service expenses	430		336		197		131		1,094
Interest expense	8,041		8,051		8,036		8,035		32,163
Gain from change in fair value of warrant liability	(93)		(1,020)		—		—		(1,113)
Income before income taxes	86,747		97,189		98,589		94,780		377,305
Income tax expense	19,067		21,745		21,751		21,840		84,403
Net income	$	67,680	$	75,444	$	76,838	$	72,940	$	292,902

Basic earnings per share (1)	$	0.79	$	0.88	$	0.91	$	0.87	$	3.45
Diluted earnings per share (1)	$	0.77	$	0.86	$	0.90	$	0.86	$	3.39

Weighted average common shares outstanding - basic	85,953		85,734		84,444		83,592		84,921
Weighted average common shares outstanding - diluted	87,310		86,577		85,485		84,809		85,999

(1) Due to the use of weighted average shares outstanding when calculating EPS, the sum of quarterly per share data may not equal the per share data for the year.

Fair Value of Financial Instruments - Assets and Liabilities at Fair Value (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	$ 2,371,021	$ 2,099,389
U.S. Treasury securities and obligations of U.S. government agencies
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	166,388	79,932
Municipal debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	621,130	483,176
Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	1,511,479	1,293,642
Asset-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	48,211	68,558
Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash, cash equivalents and short-term investments	120,502	218,507
Total assets	2,467,710	2,143,815
Recurring \| U.S. Treasury securities and obligations of U.S. government agencies
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	166,388	79,932
Recurring \| Municipal debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	621,130	483,176
Recurring \| Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	1,511,479	1,293,642
Recurring \| Asset-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	48,211	68,558
Recurring \| Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash, cash equivalents and short-term investments	120,502	218,507
Total assets	286,890	298,439
Recurring \| Quoted Prices in Active Markets for Identical Assets (Level 1) \| U.S. Treasury securities and obligations of U.S. government agencies
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	166,388	79,932
Recurring \| Quoted Prices in Active Markets for Identical Assets (Level 1) \| Municipal debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	0	0
Recurring \| Quoted Prices in Active Markets for Identical Assets (Level 1) \| Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	0	0
Recurring \| Quoted Prices in Active Markets for Identical Assets (Level 1) \| Asset-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	0	0
Recurring \| Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash, cash equivalents and short-term investments	0	0
Total assets	2,180,820	1,845,376
Recurring \| Significant Other Observable Inputs (Level 2) \| U.S. Treasury securities and obligations of U.S. government agencies
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	0	0
Recurring \| Significant Other Observable Inputs (Level 2) \| Municipal debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	621,130	483,176
Recurring \| Significant Other Observable Inputs (Level 2) \| Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	1,511,479	1,293,642
Recurring \| Significant Other Observable Inputs (Level 2) \| Asset-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	48,211	68,558
Recurring \| Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash, cash equivalents and short-term investments	0	0
Total assets	0	0
Recurring \| Significant Unobservable Inputs (Level 3) \| U.S. Treasury securities and obligations of U.S. government agencies
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	0	0
Recurring \| Significant Unobservable Inputs (Level 3) \| Municipal debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	0	0
Recurring \| Significant Unobservable Inputs (Level 3) \| Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	0	0
Recurring \| Significant Unobservable Inputs (Level 3) \| Asset-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	$ 0	$ 0

Investments - Aging of Unrealized Losses (Details) $ in Thousands	Dec. 31, 2023 USD ($) security	Dec. 31, 2022 USD ($) security
Debt Securities, Available-for-sale [Line Items]
Number of securities, less than 12 months \| security	36	241
Fair value, less than 12 months	$ 127,266	$ 772,198
Unrealized losses, less than 12 months	$ (1,274)	$ (36,225)
Number of securities,12 months or greater \| security	523	367
Fair value, 12 months or greater	$ 1,737,189	$ 1,188,415
Unrealized losses, 12 months or greater	$ (183,065)	$ (218,467)
Number of securities, total \| security	559	608
Fair Value	$ 1,864,455	$ 1,960,613
Unrealized Losses	$ (184,339)	$ (254,692)
U.S. Treasury securities and obligations of U.S. government agencies
Debt Securities, Available-for-sale [Line Items]
Number of securities, less than 12 months \| security	8	19
Fair value, less than 12 months	$ 5,022	$ 77,164
Unrealized losses, less than 12 months	$ (62)	$ (2,260)
Number of securities,12 months or greater \| security	17	4
Fair value, 12 months or greater	$ 72,003	$ 2,768
Unrealized losses, 12 months or greater	$ (1,202)	$ (109)
Number of securities, total \| security	25	23
Fair Value	$ 77,025	$ 79,932
Unrealized Losses	$ (1,264)	$ (2,369)
Municipal debt securities
Debt Securities, Available-for-sale [Line Items]
Number of securities, less than 12 months \| security	14	57
Fair value, less than 12 months	$ 56,280	$ 143,097
Unrealized losses, less than 12 months	$ (502)	$ (12,942)
Number of securities,12 months or greater \| security	217	181
Fair value, 12 months or greater	$ 467,098	$ 340,079
Unrealized losses, 12 months or greater	$ (57,960)	$ (67,854)
Number of securities, total \| security	231	238
Fair Value	$ 523,378	$ 483,176
Unrealized Losses	$ (58,462)	$ (80,796)
Corporate debt securities
Debt Securities, Available-for-sale [Line Items]
Number of securities, less than 12 months \| security	13	141
Fair value, less than 12 months	$ 56,039	$ 434,174
Unrealized losses, less than 12 months	$ (705)	$ (19,699)
Number of securities,12 months or greater \| security	266	168
Fair value, 12 months or greater	$ 1,150,662	$ 790,537
Unrealized losses, 12 months or greater	$ (119,871)	$ (145,397)
Number of securities, total \| security	279	309
Fair Value	$ 1,206,701	$ 1,224,711
Unrealized Losses	$ (120,576)	$ (165,096)
Asset-backed securities
Debt Securities, Available-for-sale [Line Items]
Number of securities, less than 12 months \| security	0	12
Fair value, less than 12 months	$ 0	$ 13,527
Unrealized losses, less than 12 months	$ 0	$ (1,097)
Number of securities,12 months or greater \| security	23	14
Fair value, 12 months or greater	$ 47,426	$ 55,031
Unrealized losses, 12 months or greater	$ (4,032)	$ (5,107)
Number of securities, total \| security	23	26
Fair Value	$ 47,426	$ 68,558
Unrealized Losses	$ (4,032)	$ (6,204)
Short-term investments
Debt Securities, Available-for-sale [Line Items]
Number of securities, less than 12 months \| security	1	12
Fair value, less than 12 months	$ 9,925	$ 104,236
Unrealized losses, less than 12 months	$ (5)	$ (227)
Number of securities,12 months or greater \| security	0	0
Fair value, 12 months or greater	$ 0	$ 0
Unrealized losses, 12 months or greater	$ 0	$ 0
Number of securities, total \| security	1	12
Fair Value	$ 9,925	$ 104,236
Unrealized Losses	$ (5)	$ (227)

Summary of Accounting Principles	12 Months Ended
Summary of Accounting Principles	Dec. 31, 2023
Accounting Policies [Abstract]
Summary of Accounting Principles	Summary of Accounting Principles Use of Estimates We use accounting principles and methods that conform to GAAP. We are required to apply significant judgment and make material estimates in the preparation of our financial statements and with regard to various accounting, reporting and disclosure matters. Assumptions and estimates are required to apply these principles where actual measurement is not possible or practical. Insurance Premium Revenue Recognition Premiums for primary mortgage insurance policies may be paid in a single payment at origination (single premium), on a monthly installment basis (monthly premium) or on an annual installment basis (annual premium), with such election and payment type fixed at policy inception. Premiums written at origination for single premium policies are initially deferred as unearned premiums and amortized into earnings over the estimated policy life, in accordance with the anticipated expiration of risk. Monthly premiums are recognized as revenue in the month billed and when the coverage is effective. Annual premiums are initially deferred and earned on a straight-line basis over the year of coverage. Upon cancellation of a policy, all remaining non-refundable deferred and unearned premium is immediately earned, and any refundable deferred and unearned premium is returned to the policyholder and recorded as a reduction to written premium and unearned premium reserve in the period paid. Premiums written on pool transactions are earned over the period that coverage is provided. Our pool insurance agreement with Fannie Mae expired on August 31, 2023 and we will not recognize any pool premiums written or earned in connection with the agreement in future periods. Concentrations For the years ended December 31, 2023, 2022 and 2021, no customer accounted for more than 10% of our consolidated revenues. At December 31, 2023, 2022 and 2021 approximately 10%, 11% and 10%, respectively, of our total risk-in-force (RIF) was concentrated in California. Reserves for Insurance Claims and Claim Expenses We establish reserves for claims based on our best estimate of the ultimate claim costs for defaulted loans using the general principles contained in ASC 944, Financial Services - Insurance (ASC 944). A loan is considered to be in "default" as of the payment date at which a borrower has missed the preceding two or more consecutive monthly payments. We establish reserves for loans that have been reported to us in default by servicers, referred to as case reserves, and additional loans that we estimate (based on actuarial review and other factors) to be in default that have not yet been reported to us by servicers, referred to as incurred but not reported (IBNR) reserves. We also establish reserves for claim expenses, which represent the estimated cost of the claim administration process, including legal and other fees, as well as other general expenses of administering the claim settlement process. Claim expense reserves are either allocated (i.e., associated with a specific claim) or unallocated (i.e., not associated with a specific claim). The establishment of claims and claim expense reserves is subject to inherent uncertainty and requires significant judgment by management. Reserves are established by estimating the number of loans in default that will result in a claim payment, which is referred to as claim frequency, and the amount of claim payment expected to be paid on each such loan in default, which is referred to as claim severity. Claim frequency and severity estimates are established based on historical observed experience regarding certain loan factors, such as age of the default, size of the loan and loan-to-value (LTV) ratios, and are strongly influenced by assumptions about the path of certain economic factors, such as house price appreciation, trends in unemployment and mortgage rates. We consider the appropriateness of such inputs at each fiscal quarter and conduct an actuarial review annually to evaluate and, if necessary, update these assumptions. Investments We have designated our investment portfolio as available-for-sale and report our invested assets at fair value. Unrealized gains and losses in the portfolio, net of related tax expense or benefit, are recognized as a component of accumulated other comprehensive income (AOCI) in shareholders' equity. We measure fair value and classify invested assets in a hierarchy for disclosure purposes consisting of three "levels" based on the observability of inputs available in the marketplace used to measure fair value. The hierarchy gives the highest priority to unadjusted quoted prices in active markets for identical assets (Level 1 measurements) and the lowest priority to unobservable inputs (Level 3 measurements). See Note 4, "Fair Value of Financial Instruments" for further discussion. Purchases and sales of investments are recorded on a trade date basis. Net investment income is recognized when earned, and includes interest and dividend income together with amortization of market premiums and discounts using the effective yield method, and is net of investment management fees and other investment related expenses. For asset-backed securities and any other holdings for which there is a prepayment risk, prepayment assumptions are evaluated and revised as necessary. Any adjustments required due to changes in effective yields and prepayment assumptions are recognized on a prospective basis. We recognize an impairment on a security through the consolidated statement of operations and comprehensive income if (i) we intend to sell the impaired security; or (ii) it is more likely than not that we will be required to sell the impaired security prior to recovery of its amortized cost basis. If a sale is intended or likely to be required, we write down the amortized cost basis of the security to fair value and recognize the full amount of the impairment through the statement of operations as a "Realized Investment Loss." For securities in an unrealized loss position where a sale is not intended or likely to be required, we further assess if the decline in fair value below amortized cost is driven by a credit related impairment, considering several items including, but not limited to: •the severity of the decline in fair value; •the financial condition of the issuer; •the failure of the issuer to make scheduled interest or principal payments; •recent rating downgrades of the applicable security or issuer by one or more nationally recognized statistical ratings organization; and •other adverse conditions related to or impacting the security or issuer. To the extent we determine that a security impairment is credit-related, an impairment loss is recognized through the statement of operations as a provision for credit loss expense, and presented as a "Realized Investment Loss." We recognize an allowance for credit losses for the difference between the amortized cost and present value of future expected cash flows, limited by the amount the fair value of the security is below its amortized cost. Subsequent changes (favorable and unfavorable) in credit losses are recognized through the statement of operations as a provision for or a reversal of credit loss expense, and presented as a "Realized Investment Gain or Loss." The portion of a security impairment attributed to other non-credit related factors is recognized in other comprehensive income, net of taxes. We have elected to present accrued interest receivable separately from available for sale securities on our consolidated balance sheets. Accrued interest receivable was $19.8 million and $14.1 million as of December 31, 2023 and 2022, respectively, and is included in "Accrued Investment Income." We have elected not to measure an allowance for credit losses for accrued interest receivable on available for sale securities. Accrued interest for available for sale securities is written off against interest income when the receivable has aged 90 days past due. We did not write off any accrued interest receivable during the years ended December 31, 2023, 2022 or 2021. We consider items such as U.S. Treasury Bills and commercial paper with original maturities of 12 months or less to be short-term investments. Deferred Policy Acquisition Costs (DAC) Costs directly associated with the successful acquisition of mortgage insurance policies, consisting of certain selling expenses and other policy issuance and underwriting expenses, are initially deferred and reported as DAC. DAC is reviewed periodically to determine that it does not exceed recoverable amounts. DAC is amortized to expense in proportion to estimated gross profits over the life of the associated policies. We revise the rate of amortization to reflect actual experience and any changes to persistency or loss development. Total amortization of DAC for the years ended December 31, 2023, 2022 and 2021, net of a portion of the ceding commissions earned under our quota share reinsurance agreements (see "Reinsurance", below), was $3.6 million, $11.9 million and $22.8 million, respectively. Premium Deficiency Reserves We consider whether a premium deficiency exists and a premium deficiency reserve is required at each fiscal quarter using best estimate assumptions as of the testing date. A premium deficiency reserve is established if the net present value of expected future claim costs, claim adjustment expenses, policyholder dividends, unamortized acquisition costs and maintenance costs exceeds the net present value of expected future premiums, anticipated investment income and existing reserves for a specified group of policies. We have determined that no premium deficiency reserves were necessary for any of the years in the three-year period ended December 31, 2023. Reinsurance We cede insurance risk through the use of reinsurance contracts and follow reinsurance accounting for those transactions where significant risk is transferred. We account for premiums, claims and claim expenses that are ceded to reinsurers on basis consistent with that which we use to account for the original policies we issue and pursuant to the terms of our reinsurance contracts. We account for premiums ceded or otherwise paid to reinsurers as a reduction to premium revenue. NMIC entered into quota share reinsurance treaties effective September 1, 2016 (the 2016 QSR Transaction), January 1, 2018 (the 2018 QSR Transaction), April 1, 2020 (the 2020 QSR Transaction and, as amended January 1, 2024, the Amended 2020 QSR Transaction), January 1, 2021 (the 2021 QSR Transaction), October 1, 2021 (the 2022 QSR Transaction), July 1, 2022 (the 2022 Seasoned QSR Transaction), and January 1, 2023 (the 2023 QSR Transaction), which we refer to collectively as the QSR Transactions. We earn profit and ceding commissions in connection with the QSR Transactions (see Note 6, "Reinsurance"). Profit commissions represent a percentage of the profits recognized by reinsurers that are returned to us, based on the level of claims and claim expenses that we cede. We recognize any profit commissions we earn as a decrease to ceded earned premiums. Ceding commissions are calculated as a percentage of ceded written premiums under the 2016 QSR Transaction and as a percentage of ceded earned premiums under the 2018, 2020 (and Amended 2020), 2021, 2022, 2022 Seasoned and 2023 QSR Transactions, and are intended to cover our costs of acquiring and servicing direct policies. We recognize any ceding commissions generated under the QSR Transactions in a manner consistent with our recognition of earnings on the underlying reinsured policies. We account for ceding commissions earned as a reduction to underwriting and operating expenses. Under the QSR Transactions, we cede a portion of claims and claim expenses and reserves to our reinsurers, and account for such ceded reserves as "Reinsurance Recoverables" on the consolidated balance sheets and such ceded expenses as reductions to claims and claim expenses on the consolidated statements of operations. As of December 31, 2023 and 2022, we had $27.5 million and $21.6 million, respectively, of reinsurance recoverables under the QSR Transactions. We remain directly liable for all claim payments if we are unable to collect the recoverables due from our reinsurers and, as such, we actively monitor and manage our counterparty credit exposure to our reinsurance providers. We establish an allowance for expected credit loss against our reinsurance recoverables if we do not expect to recover amounts due from one or more of our reinsurance counterparties, and report our reinsurance recoverables net of such allowance, if any. We actively monitor the counterparty credit profiles of our reinsurers and each is required to partially collateralize its obligations under the terms of our QSR Transactions. The allowance for credit loss established with respect to our reinsurance recoverables was deemed immaterial as of December 31, 2023 and 2022. Variable Interest Entities NMIC is a party to excess-of-loss reinsurance agreements with Oaktown Re III Ltd., Oaktown Re V Ltd., Oaktown Re VI Ltd., and Oaktown Re VII Ltd. (special purpose reinsurance entities collectively referred to as the Oaktown Re Vehicles) effective July 30, 2019, October 29, 2020, April 27, 2021, and October 26, 2021, respectively. At inception of the respective reinsurance agreements, we determined that each of the Oaktown Re Vehicles was a variable interest entity (VIE), as defined under GAAP Accounting Standards Codification (ASC) 810, because they did not have sufficient equity at risk to finance their respective activities. We evaluated the VIEs at inception to determine whether NMIC was the primary beneficiary under each deal and, if so, whether we were required to consolidate the assets and liabilities of each VIE. The primary beneficiary of a VIE is an enterprise that (1) has the power to direct the activities of the VIE, which most significantly impact its economic performance and (2) has significant economic exposure to the VIE, i.e., the obligation to absorb losses or receive benefits that could potentially be significant. The determination of whether an entity is the primary beneficiary of a VIE is complex and requires management judgment regarding determinative factors, including the expected results of the VIE and how those results are absorbed by beneficial interest holders, as well as which party has the power to direct activities that most significantly impact the performance of the VIE. We concluded that we are not the primary beneficiary of each VIE and, as such, we do not consolidate them in our consolidated financial statements. See Note 6, "Reinsurance" for further discussion of the reinsurance arrangements. Income Taxes We account for income taxes using the liability method in accordance with ASC Topic 740, Income Taxes. The liability method measures the expected future tax effects of temporary differences at the enacted tax rates applicable for the period in which the deferred asset or liability is expected to be realized or settled. Temporary differences are differences between the tax basis of an asset or liability and its reported amount in the consolidated financial statements that would result in future increases or decreases in taxes owed on a cash basis compared to amounts already recognized as tax expense in the consolidated statements of operations. We purchase non-interest bearing U.S. Mortgage Guaranty Tax and Loss Bonds issued by the Treasury Department in order to claim a tax deduction for our contingency reserve balance. The tax and loss bonds are carried at cost and are reported as "Prepaid Federal Income Taxes" on the consolidated balance sheets. See Note 10, "Income Taxes", for further discussion of the tax and loss bonds and other income tax matters. Share-Based Compensation We account for stock compensation in accordance with ASC 718, Compensation - Stock Compensation, which addresses accounting for share-based awards and recognition of compensation expense, measured using grant date fair value, over the requisite service or performance period of the award. Share-based compensation includes restricted stock units (RSUs) and stock option grants under our stock incentive plans. We calculate the fair value of stock option grants using a Black-Scholes option pricing model, which takes into account various subjective assumptions. Key assumptions used in the model include the expected volatility of our stock price, dividend yield and the risk-free interest rate, as well as the expected option term, giving consideration to the contractual terms of any award. We use the simplified method to estimate expected option term during the period as sufficient historical exercise data is not available. RSU grants may contain a service condition, or performance and service conditions. RSU grants are valued at our stock price on the date of grant less the present value of anticipated dividends, and we recognize their fair value as compensation expense over their requisite service or performance and service periods. We account for stock option and RSU forfeitures as they occur. Share-based compensation is recorded in “Underwriting and Operating Expenses” on the consolidated statements of operations and comprehensive income. Earnings Per Share (EPS) Basic earnings per share is based on the weighted average number of common shares outstanding. Diluted earnings per share is based on the weighted average number of common shares outstanding and common share equivalents that would be issuable upon the vesting of existing service-based and certain performance and service-based RSUs, and exercise of vested and unvested stock options and outstanding warrants. Common share equivalents are excluded from EPS computations in the periods in which they have an anti-dilutive effect. Share Repurchases Common stock repurchases are recorded at cost and presented as “Treasury Stock” on the consolidated balance sheets and statements of changes in shareholders’ equity. At the date of repurchase, shareholders’ equity is reduced by the aggregate repurchase price plus commissions, applicable taxes and other expenses that arise from the repurchase transaction. Cash and Cash Equivalents We consider items such as U.S. Treasury Bills, certificates of deposit and money market funds with original maturities of 90 days or less to be cash equivalents. Software and Equipment We capitalize certain costs associated with the development of internal-use software and equipment. Software and equipment are stated at cost, less accumulated amortization and depreciation. Amortization of software and depreciation of equipment commences at the beginning of the month following our placement of the assets into use. Amortization and depreciation are calculated on a straight-line basis over the estimated useful life of the respective assets, typically from three to five years, unless factors indicate a shorter useful life. We amortize leasehold improvements over the shorter of the lives of the leases or estimated service lives of the leasehold improvements. Amortization and depreciation expense is recorded in “Underwriting and Operating Expenses” on the consolidated statements of operations and comprehensive income. For further detail, see Note 11, “Software and Equipment.” Leases We recognize right-of-use (ROU) assets and corresponding lease liabilities for our lease arrangements. Lease liabilities are established based on the estimated present value of lease payments over the relevant lease term. We estimate a discount rate for each lease based on our estimated incremental borrowing rate at the commencement date of the relevant lease, taking into consideration the cost of any outstanding collateralized borrowings we have at such time with adjustment for the terms of the lease agreement, and prevailing market conditions and macroeconomic factors at the time of its commencement. ROU assets are measured as the associated lease liability plus any direct costs incurred in connection with the initial establishment of the lease, less any lease incentives received. Business Combinations, Goodwill and Intangible Assets Goodwill represents the excess of the purchase price over the estimated fair value of net assets acquired from a business combination. In accordance with ASC 350, Intangibles – Goodwill and Other, we test goodwill for impairment annually or more frequently if we believe indicators of impairment exist. We have not identified any impairments of goodwill through December 31, 2023. Our intangible assets consist of state licenses and Fannie Mae and Freddie Mac (collectively, the GSEs) applications which have indefinite lives. We test indefinite-lived intangible assets for impairment annually or more frequently if we believe indicators of impairment exist. We have not identified any impairments of indefinite-lived intangible assets through December 31, 2023. Premiums Receivable Premiums receivable consists of premiums due on our mortgage insurance policies. If a mortgage insurance premium is unpaid for more than 120 days, the associated receivable is written off against earned premium and the related insurance policy is canceled. We recognize an allowance for credit losses for premiums receivable based on credit losses expected to arise over the life of the receivable. Due to the nature of our insurance policies (a necessary precondition for access to mortgage credit for covered borrowers) and the short duration of the related receivables, we do not typically experience credit losses against our premium receivables and the allowance for credit loss established on premium receivables was deemed immaterial at December 31, 2023 and 2022. Premiums receivable may be written off prior to 120 days in the ordinary course of business for non-credit events including, but not limited to, the modification or refinancing of an underlying insured loan. We established a $2.7 million and $2.3 million reserve for premium write-offs at December 31, 2023 and 2022, respectively. Other Revenues Other revenues represent underwriting fee revenue from our subsidiary, NMIS, which provides outsourced loan review services to mortgage loan originators. NMIS fees are earned and recognized as services are provided. Recent Accounting Pronouncements – Adopted In August 2018, the Financial Accounting Standards Board (FASB) issued ASU 2018-12, Targeted Improvements to the Accounting for Long-Duration Contracts (Topic 944). The update provides guidance to the existing recognition, measurement, presentation and disclosure requirements for long-duration contracts issued by an insurance entity. The FASB subsequently issued ASU 2019-09 in November 2019 and ASU 2020-11 in November 2020, which amended the effective date for this standard and provided transition relief to facilitate early application for long duration contracts. The standard will now take effect for public business entities for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2022. We adopted this ASU on January 1, 2023 and determined it did not have a material impact on our consolidated financial statements as none of our contracts were within scope of the update. In March 2020, the FASB issued ASU 2020-04, Reference Rate Reform (Topic 848). The update provides optional guidance to ease the potential burden in accounting for reference rate reform on financial reporting. Reference rate reform refers to the global transition away from referencing the London Interbank Offered Rate (LIBOR) in financial contracts. Topic 848 includes optional expedients and exceptions for applying GAAP to contracts, hedging relationships and other transactions affected by reference rate reform if certain criteria are met. This standard may be elected and applied prospectively over time from March 12, 2020 through December 31, 2022 as reference rate reform activities occur. In December 2022, the FASB issued ASU 2022-06, which extended the sunset date of Topic 848 from December 31, 2022 to December 31, 2024. We adopted Topic 848 on September 30, 2023 and determined it did not have a material impact on our consolidated financial statements. Recent Accounting Pronouncements – Not yet Adopted In November 2023, the FASB issued ASU 2023-07, Segment Reporting (Topic 280). The update expands annual and interim disclosure requirements for reportable segments, primarily through enhanced disclosures about significant segment expenses. The standard will take effect for all public business entities, including those that have only a single reportable segment for fiscal years beginning after December 15, 2023. We are currently evaluating the impact the adoption of this ASU will have, if any, on our consolidated financial statements. In December 2023, the FASB issued ASU 2023-09, Income Taxes (Topic 740). The update enhances the disclosure requirements related to tax rate reconciliations and income taxes paid. The standard will take effect for public business entities for fiscal years beginning after December 15, 2025. Early adoption is permitted. We are currently evaluating the impact the adoption of this ASU will have, if any, on our consolidated financial statements.

Cover - USD ($)	12 Months Ended
Cover - USD ($)	Dec. 31, 2023	Feb. 09, 2024	Jun. 30, 2023
Cover [Abstract]
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2023
Current Fiscal Year End Date	--12-31
Document Transition Report	false
Entity File Number	001-36174
Entity Registrant Name	NMI Holdings, Inc.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	45-4914248
Entity Address, Address Line One	2100 Powell Street
Entity Address, City or Town	Emeryville
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	94608
City Area Code	855
Local Phone Number	530-6642
Title of 12(b) Security	Class A Common Stock, $.01 par value per share
Trading Symbol	NMIH
Security Exchange Name	NASDAQ
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
ICFR Auditor Attestation Flag	true
Document Financial Statement Error Correction Flag	false
Entity Shell Company	false
Entity Public Float			$ 1,710,584,967
Entity Common Stock, Shares Outstanding		80,879,843
Documents Incorporated by Reference	Portions of the registrant's Proxy Statement for the 2024 Annual Meeting of Stockholders are incorporated herein by reference in Part III of this Annual Report on Form 10-K to the extent stated herein. Such Proxy Statement will be filed with the Securities and Exchange Commission within 120 days of the registrant's fiscal year ended December 31, 2023.
Entity Central Index Key	0001547903
Amendment Flag	false
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	FY

Reinsurance - Amounts Ceded Related to QSR Transactions (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Ceded Credit Risk [Line Items]
Ceded premiums earned	$ (139,643)	$ (118,861)	$ (92,336)
Third-Party Reinsurers
Ceded Credit Risk [Line Items]
Ceded risk-in-force	12,626,541	12,617,169	8,194,604
Ceded premiums earned	(167,331)	(143,747)	(110,140)
Ceded claims and claim expenses	7,436	1,620	3,233
Ceding commission earned	39,211	32,314	23,473
Profit commission	$ 90,006	$ 80,714	$ 59,104

CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE INCOME (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Income Statement [Abstract]
Unrealized gains (losses) in accumulated other comprehensive income, tax expense (benefit)	$ 17,113	$ (54,608)	$ (13,768)
Reclassification adjustment for realized losses (gains) included in net income, tax (benefit) expense	$ (7)	$ 101	$ 153

Leases - Narrative (Details) $ in Thousands	12 Months Ended
Leases - Narrative (Details) $ in Thousands	Dec. 31, 2023 USD ($) operatingLeaseAgreement	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	Feb. 28, 2022 USD ($)
Lessee, Lease, Description [Line Items]
Number of operating leases related to corporate headquarters and data center facility \| operatingLeaseAgreement	2
Right-of-use lease assets	$ 9,100	$ 10,400		$ 9,700
Operating lease liabilities	$ 11,389	$ 12,100		$ 9,700
Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]	Other assets	Other assets		Other assets
Operating Lease, Liability, Statement of Financial Position [Extensible List]	Other liabilities	Other liabilities		Other liabilities
Cash paid for amounts included in the measurement of operating lease liabilities	$ 1,500	$ 800	$ 2,600
Operating lease expense	$ 2,000	$ 2,000	$ 2,300
Operating lease option to renew, term	5 years
Minimum
Lessee, Lease, Description [Line Items]
Operating lease terms	2 years
Maximum
Lessee, Lease, Description [Line Items]
Operating lease terms	8 years

Leases - Future Payment Due Under Operating Leases (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022	Feb. 28, 2022
Leases [Abstract]
2024	$ 2,080
2025	2,128
2026	2,190
2027	2,256
2028	2,322
2029 and thereafter	2,995
Total undiscounted lease payments	13,971
Less effects of discounting	(2,582)
Operating lease liabilities	$ 11,389	$ 12,100	$ 9,700

Investments

12 Months Ended

Dec. 31, 2023

Investments, Debt and Equity Securities [Abstract]

Investments

We hold all investments on an available-for-sale basis at fair value on our consolidated balance sheets and evaluate each position quarterly for impairment. We recognize an impairment on a security through the statement of operations if (i) we intend to sell the impaired security; or (ii) it is more likely than not that we will be required to sell the impaired security prior to recovery of its amortized cost basis. If a sale is intended or likely to be required, we recognize an impairment loss equivalent to the difference of the amortized cost basis of the security and its fair value through the consolidated statements of operations and comprehensive income as a “Net Realized Investment Loss.” In the event of an impairment of a security that we intend to and have the ability to hold to maturity, we evaluate the drivers of the impairment to determine the portion that is credit related and the portion that is non-credit related. The portion of impairment loss that is attributed to credit related factors is recognized through the statement of operations as a provision for credit loss and the portion that is attributed to non-credit related factors is recognized in other comprehensive income, net of taxes.

Fair Values and Gross Unrealized Gains and Losses on Investments


	Amortized Cost		Gross Unrealized				Fair Value
			Gains		Losses
As of December 31, 2023	(In Thousands)
U.S. Treasury securities and obligations of U.S. government agencies	$	164,278	$	3,374	$	(1,264)	$	166,388
Municipal debt securities	678,339		1,253		(58,462)		621,130
Corporate debt securities	1,624,187		7,868		(120,576)		1,511,479
Asset-backed securities	52,242		1		(4,032)		48,211
Total bonds	2,519,046		12,496		(184,334)		2,347,208

Short-term investments	23,816		2		(5)		23,813
Total investments	$	2,542,862	$	12,498	$	(184,339)	$	2,371,021


	Amortized Cost		Gross Unrealized				Fair Value
			Gains		Losses
As of December 31, 2022	(In Thousands)
U.S. Treasury securities and obligations of U.S. government agencies	$	82,301	$	—	$	(2,369)	$	79,932
Municipal debt securities	563,972		—		(80,796)		483,176
Corporate debt securities	1,457,589		1,149		(165,096)		1,293,642
Asset-backed securities	74,762		—		(6,204)		68,558
Total bonds	2,178,624		1,149		(254,465)		1,925,308

Short-term investments	174,123		185		(227)		174,081
Total investments	$	2,352,747	$	1,334	$	(254,692)	$	2,099,389

We did not own any mortgage-backed securities in our asset-backed securities portfolio at December 31, 2023 or 2022.

The following table presents a breakdown of the fair value of our corporate debt securities by issuer industry group as of December 31, 2023 and 2022:


	December 31, 2023		December 31, 2022
Financial	35	%	38	%
Consumer	26		24
Utilities	13		11
Industrial	9		8
Communications	9		11
Technology	8		8
Total	100	%	100	%

As of December 31, 2023 and 2022, approximately $5.3 million and $5.4 million, respectively, of our cash and investments were held in the form of U.S. Treasury securities on deposit with various state insurance departments to satisfy regulatory requirements.

Scheduled Maturities

The amortized cost and fair value of available-for-sale securities as of December 31, 2023 and 2022, by contractual maturity, are shown below. Expected maturities will differ from contractual maturities because issuers may have the right to call or prepay obligations with or without call or prepayment penalties. Because most asset-backed securities provide for periodic payments throughout their lives, they are listed below in a separate category.


As of December 31, 2023	Amortized Cost		Fair Value
	(In Thousands)
Due in one year or less	$	191,375	$	189,729
Due after one through five years	1,237,192		1,162,259
Due after five through ten years	1,050,989		959,633
Due after ten years	11,064		11,189
Asset-backed securities	52,242		48,211
Total investments	$	2,542,862	$	2,371,021


As of December 31, 2022	Amortized Cost		Fair Value
	(In Thousands)
Due in one year or less	$	271,613	$	270,428
Due after one through five years	935,615		862,747
Due after five through ten years	1,047,461		875,947
Due after ten years	23,296		21,709
Asset-backed securities	74,762		68,558
Total investments	$	2,352,747	$	2,099,389

Aging of Unrealized Losses

As of December 31, 2023, the investment portfolio had gross unrealized losses of $184.3 million, of which $183.1 million were associated with securities that had been in an unrealized loss position for a period of twelve months or longer. As of December 31, 2022, the investment portfolio had gross unrealized losses of $254.7 million, of which $218.5 million were associated with securities that had been in an unrealized loss position for a period of twelve months or longer. For those securities in an unrealized loss position, the length of time the securities were in such a position is as follows:


	Less Than Twelve Months					Twelve Months or Greater					Total
	# of Securities	Fair Value		Unrealized Losses		# of Securities	Fair Value		Unrealized Losses		# of Securities	Fair Value		Unrealized Losses
As of December 31, 2023		($ In Thousands)
U.S. Treasury securities and obligations of U.S. government agencies	8	$	5,022	$	(62)	17	$	72,003	$	(1,202)	25	$	77,025	$	(1,264)
Municipal debt securities	14	56,280		(502)		217	467,098		(57,960)		231	523,378		(58,462)
Corporate debt securities	13	56,039		(705)		266	1,150,662		(119,871)		279	1,206,701		(120,576)
Asset-backed securities	—	—		—		23	47,426		(4,032)		23	47,426		(4,032)
Short-term investments	1	9,925		(5)		—	—		—		1	9,925		(5)
Total	36	$	127,266	$	(1,274)	523	$	1,737,189	$	(183,065)	559	$	1,864,455	$	(184,339)


	Less Than Twelve Months					Twelve Months or Greater					Total
	# of Securities	Fair Value		Unrealized Losses		# of Securities	Fair Value		Unrealized Losses		# of Securities	Fair Value		Unrealized Losses
As of December 31, 2022		($ In Thousands)
U.S. Treasury securities and obligations of U.S. government agencies	19	$	77,164	$	(2,260)	4	$	2,768	$	(109)	23	$	79,932	$	(2,369)
Municipal debt securities	57	143,097		(12,942)		181	340,079		(67,854)		238	483,176		(80,796)
Corporate debt securities	141	434,174		(19,699)		168	790,537		(145,397)		309	1,224,711		(165,096)
Asset-backed securities	12	13,527		(1,097)		14	55,031		(5,107)		26	68,558		(6,204)
Short-term investments	12	104,236		(227)		—	—		—		12	104,236		(227)
Total	241	$	772,198	$	(36,225)	367	$	1,188,415	$	(218,467)	608	$	1,960,613	$	(254,692)

Allowance for Credit Losses

As of December 31, 2023 and 2022, we did not recognize an allowance for credit loss for any security in the investment portfolio and we did not record any provision for credit loss for investment securities during the years ended December 31, 2023 or 2022.

We evaluated the securities in an unrealized loss position as of December 31, 2023, assessing their credit ratings as well as any adverse conditions specifically related to the security. Based upon our assessment of the amount and timing of cash flows to be collected over the remaining life of each instrument, we believe the unrealized losses as of December 31, 2023 are not indicative of the ultimate collectability of the current amortized cost of the securities. Rather, the unrealized losses on securities held as of December 31, 2023 were primarily driven by fluctuations in interest rates, and to a lesser extent, movements in credit spreads following the purchase of those securities.

Net Investment Income

The following table presents the components of net investment income:


	For the years ended December 31,
	2023		2022		2021
	(In Thousands)
Investment income (1)	$	68,214	$	47,720	$	39,385
Investment expenses	(702)		(1,314)		(1,313)
Net investment income	$	67,512	$	46,406	$	38,072

(1) Includes interest income recognized on cash and cash equivalents of $2.3 million and $0.4 million for the years ended December 31, 2023 and 2022, respectively. Interest income recognized on cash and cash equivalents was de minimis for the year ended December 31, 2021.

The following table presents the components of net realized investment (losses) gains:


	For the years ended December 31,
		2023		2022		2021
		(In Thousands)
Gross realized investment gains		$	—	$	490	$	729
Gross realized investment losses		(33)		(9)		—
Net realized investment (losses) gains		$	(33)	$	481	$	729

Reserves for Insurance Claims and Claim Expenses - Reconciliation of Disclosure of Incurred and Paid Claims Development to the Liability for Unpaid Claims and Claims Adjustment Expenses (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Cumulative Incurred Claims and Allocated Claims Adjustment Expenses, net of Reinsurance	$ 115,068
Reinsurance recoverable on unpaid claims	27,514	$ 21,587	$ 20,320	$ 17,608
Reserve for insurance claims and claim expenses	123,974	$ 99,836	$ 103,551	$ 90,567
Financial Guarantee Insurance Product Line
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Cumulative Incurred Claims and Allocated Claims Adjustment Expenses, net of Reinsurance	115,068
Cumulative Paid Claims and Claims Adjustment Expenses, net of Reinsurance	(20,305)
All outstanding liabilities before 2014, net of reinsurance	0
Liabilities for unpaid claims and allocated claims adjustment expenses, net of reinsurance	94,763
Reinsurance recoverable on unpaid claims	27,514
Unallocated claims adjustment expenses	1,697
Reserve for insurance claims and claim expenses	$ 123,974

Subsequent events (Details) - USD ($) $ in Thousands		12 Months Ended
Subsequent events (Details) - USD ($) $ in Thousands	Jan. 01, 2024	Dec. 31, 2023
Reinsurance Policy, Type [Axis]: 2019 ILN Transaction
Subsequent Event [Line Items]
Current first layer retained loss		$ 121,751
Reinsurance Policy, Type [Axis]: 2020-2 ILN Transaction
Subsequent Event [Line Items]
Current first layer retained loss		121,177
Reinsurance Policy, Type [Axis]: 2021-1 ILN Transaction
Subsequent Event [Line Items]
Current first layer retained loss		163,394
Reinsurance Policy, Type [Axis]: 2021-2 ILN Transaction
Subsequent Event [Line Items]
Current first layer retained loss		145,858
Reinsurance Policy, Type [Axis]: 2022-1 XOL Transaction
Subsequent Event [Line Items]
Current first layer retained loss		133,123
Reinsurance Policy, Type [Axis]: 2022-2 XOL Transaction
Subsequent Event [Line Items]
Current first layer retained loss		78,736
Reinsurance Policy, Type [Axis]: 2022-3 XOL Transaction
Subsequent Event [Line Items]
Current first layer retained loss		106,265
Reinsurance Policy, Type [Axis]: 2023-1 XOL Transaction
Subsequent Event [Line Items]
Current first layer retained loss		146,348
Reinsurance Policy, Type [Axis]: 2023-2 XOL Transaction
Subsequent Event [Line Items]
Current first layer retained loss		$ 113,372
Third-Party Reinsurers \| Reinsurance Policy, Type [Axis]: 2016 QSR Transaction
Subsequent Event [Line Items]
Threshold for loss ratio on loans to qualify for profit commission		60.00%
Third-Party Reinsurers \| Reinsurance Policy, Type [Axis]: 2016 QSR Transaction, Eligible Primary Policies
Subsequent Event [Line Items]
Premiums of premiums earned under QSR Transaction		25.00%
Third-Party Reinsurers \| Reinsurance Policy, Type [Axis]: 2016 QSR Transaction, Pool Agreement with Fannie Mae
Subsequent Event [Line Items]
Premiums of premiums earned under QSR Transaction		100.00%
Third-Party Reinsurers \| Reinsurance Policy, Type [Axis]: 2018 QSR Transaction
Subsequent Event [Line Items]
Premiums of premiums earned under QSR Transaction		25.00%
Threshold for loss ratio on loans to qualify for profit commission		61.00%
Third-Party Reinsurers \| Reinsurance Policy, Type [Axis]: 2019 QSR Transaction
Subsequent Event [Line Items]
Premiums of premiums earned under QSR Transaction		20.00%
Third-Party Reinsurers \| Reinsurance Policy, Type [Axis]: 2020 Amended QSR Transaction
Subsequent Event [Line Items]
Threshold for loss ratio on loans to qualify for profit commission		50.00%
Third-Party Reinsurers \| Reinsurance Policy, Type [Axis]: 2020 QSR Transaction
Subsequent Event [Line Items]
Premiums of premiums earned under QSR Transaction		21.00%
Threshold for loss ratio on loans to qualify for profit commission		50.00%
Third-Party Reinsurers \| Reinsurance Policy, Type [Axis]: 2021 QSR Transaction
Subsequent Event [Line Items]
Premiums of premiums earned under QSR Transaction		22.50%
Threshold for loss ratio on loans to qualify for profit commission		57.50%
Third-Party Reinsurers \| Reinsurance Policy, Type [Axis]: 2022 QSR Transaction
Subsequent Event [Line Items]
Premiums of premiums earned under QSR Transaction		20.00%
Threshold for loss ratio on loans to qualify for profit commission		62.00%
Third-Party Reinsurers \| Reinsurance Policy, Type [Axis]: 2022 Seasoned QSR Transaction
Subsequent Event [Line Items]
Premiums of premiums earned under QSR Transaction		95.00%
Threshold for loss ratio on loans to qualify for profit commission		55.00%
Third-Party Reinsurers \| Reinsurance Policy, Type [Axis]: 2023 QSR Transaction
Subsequent Event [Line Items]
Premiums of premiums earned under QSR Transaction		20.00%
Threshold for loss ratio on loans to qualify for profit commission		62.00%
Third-Party Reinsurers \| Reinsurance Policy, Type [Axis]: QSR Transactions
Subsequent Event [Line Items]
Ceding commissions under QSR Transaction		20.00%
Subsequent Event
Subsequent Event [Line Items]
Aggregate excess-of-loss reinsurance coverage	$ 162,500
Subsequent Event \| Reinsurance Policy, Type [Axis]: 2024 XOL Transaction
Subsequent Event [Line Items]
Current first layer retained loss	162,500
Current second layer retained loss	$ 162,500
Subsequent Event \| Third-Party Reinsurers \| Reinsurance Policy, Type [Axis]: 2024 QSR Transaction
Subsequent Event [Line Items]
Premiums of premiums earned under QSR Transaction	20.00%
Ceding commissions under QSR Transaction	20.00%
Threshold for loss ratio on loans to qualify for profit commission	56.00%
Subsequent Event \| Third-Party Reinsurers \| Reinsurance Policy, Type [Axis]: Amended 2020 QSR Transaction
Subsequent Event [Line Items]
Premiums of premiums earned under QSR Transaction	21.00%

Reserves for Insurance Claims and Claim Expenses - Reconciliation of Reserve Balances for Insurance Claims and Claim Expenses (Benefits) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Beginning balance	$ 99,836	$ 103,551	$ 90,567
Less reinsurance recoverables	(21,587)	(20,320)	(17,608)
Beginning balance, net of reinsurance recoverables	78,249	83,231	72,959
Claims and claim expenses (benefits) incurred:
Current year	78,285	45,168	23,433
Prior years	(56,390)	(48,762)	(11,128)
Total claims and claim expenses (benefits) incurred	21,895	(3,594)	12,305
Claims and claim expenses paid:
Current year	600	74	16
Prior years	3,575	1,314	2,017
Reinsurance terminations	(491)	0	0
Total claims and claim expenses paid	3,684	1,388	2,033
Reserve at end of period, net of reinsurance recoverables	96,460	78,249	83,231
Add reinsurance recoverables	27,514	21,587	20,320
Ending balance	123,974	99,836	103,551
Current year case reserves	70,600	39,900	18,100
Current year IBNR	6,300	4,500	4,700
Prior year case reserves	50,900	42,500	6,300
Prior year, IBNR	4,500	4,700	$ (5,000)
Reinsurance Policy, Type [Axis]: Amendment 2020 QSR Transaction
Claims and claim expenses (benefits) incurred:
Total claims and claim expenses (benefits) incurred	700
Reinsurance Policy, Type [Axis]: QSR Transactions
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Less reinsurance recoverables	(19,000)
Claims and claim expenses paid:
Add reinsurance recoverables	$ 25,800	$ 19,000

Reserves for Insurance Claims and Claim Expenses - Claim Development by Accident Year and Reconciliation of Reserve for Insurance Claims and Claims Expense (Details) $ in Thousands	Dec. 31, 2023 USD ($) claim	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Claims Development [Line Items]
Cumulative Incurred Claims and Allocated Claims Adjustment Expenses, net of Reinsurance	$ 115,068
Financial Guarantee Insurance Product Line
Claims Development [Line Items]
Cumulative Incurred Claims and Allocated Claims Adjustment Expenses, net of Reinsurance	115,068
Total of IBNR	$ 6,337
Defaults \| claim	5,099
Cumulative Paid Claims and Claims Adjustment Expenses, net of Reinsurance	$ 20,305
Financial Guarantee Insurance Product Line \| 2014
Claims Development [Line Items]
Cumulative Incurred Claims and Allocated Claims Adjustment Expenses, net of Reinsurance	4	$ 4	$ 4	$ 4	$ 4	$ 4	$ 4	$ 4	$ 34	$ 83
Total of IBNR	$ 0
Defaults \| claim	0
Cumulative Paid Claims and Claims Adjustment Expenses, net of Reinsurance	$ 4	4	4	4	4	4	4	4	4	$ 0
Financial Guarantee Insurance Product Line \| 2015
Claims Development [Line Items]
Cumulative Incurred Claims and Allocated Claims Adjustment Expenses, net of Reinsurance	894	894	894	894	894	764	743	664	699
Total of IBNR	$ 0
Defaults \| claim	0
Cumulative Paid Claims and Claims Adjustment Expenses, net of Reinsurance	$ 894	894	894	894	804	720	684	246	$ 50
Financial Guarantee Insurance Product Line \| 2016
Claims Development [Line Items]
Cumulative Incurred Claims and Allocated Claims Adjustment Expenses, net of Reinsurance	1,986	1,893	1,930	1,936	1,934	1,790	1,568	2,394
Total of IBNR	$ 1
Defaults \| claim	1
Cumulative Paid Claims and Claims Adjustment Expenses, net of Reinsurance	$ 1,978	1,878	1,877	1,827	1,826	1,596	890	$ 171
Financial Guarantee Insurance Product Line \| 2017
Claims Development [Line Items]
Cumulative Incurred Claims and Allocated Claims Adjustment Expenses, net of Reinsurance	3,712	3,718	3,716	3,807	3,570	3,475	6,028
Total of IBNR	$ 4
Defaults \| claim	2
Cumulative Paid Claims and Claims Adjustment Expenses, net of Reinsurance	$ 3,661	3,655	3,640	3,494	2,925	1,655	$ 27
Financial Guarantee Insurance Product Line \| 2018
Claims Development [Line Items]
Cumulative Incurred Claims and Allocated Claims Adjustment Expenses, net of Reinsurance	4,312	4,282	4,533	4,709	5,271	7,779
Total of IBNR	$ 15
Defaults \| claim	11
Cumulative Paid Claims and Claims Adjustment Expenses, net of Reinsurance	$ 4,116	3,909	3,780	3,537	1,981	130
Financial Guarantee Insurance Product Line \| 2019
Claims Development [Line Items]
Cumulative Incurred Claims and Allocated Claims Adjustment Expenses, net of Reinsurance	4,606	4,604	5,781	7,229	14,391
Total of IBNR	$ 74
Defaults \| claim	40
Cumulative Paid Claims and Claims Adjustment Expenses, net of Reinsurance	$ 3,621	3,534	3,212	2,368	$ 69
Financial Guarantee Insurance Product Line \| 2020
Claims Development [Line Items]
Cumulative Incurred Claims and Allocated Claims Adjustment Expenses, net of Reinsurance	7,472	18,862	56,154	65,769
Total of IBNR	$ 315
Defaults \| claim	164
Cumulative Paid Claims and Claims Adjustment Expenses, net of Reinsurance	$ 3,265	1,909	1,320	$ 586
Financial Guarantee Insurance Product Line \| 2021
Claims Development [Line Items]
Cumulative Incurred Claims and Allocated Claims Adjustment Expenses, net of Reinsurance	4,092	14,337	22,847
Total of IBNR	$ 501
Defaults \| claim	139
Cumulative Paid Claims and Claims Adjustment Expenses, net of Reinsurance	$ 914	274	$ 16
Financial Guarantee Insurance Product Line \| 2022
Claims Development [Line Items]
Cumulative Incurred Claims and Allocated Claims Adjustment Expenses, net of Reinsurance	11,023	44,334
Total of IBNR	$ 733
Defaults \| claim	522
Cumulative Paid Claims and Claims Adjustment Expenses, net of Reinsurance	$ 1,252	$ 74
Financial Guarantee Insurance Product Line \| 2023
Claims Development [Line Items]
Cumulative Incurred Claims and Allocated Claims Adjustment Expenses, net of Reinsurance	76,967
Total of IBNR	$ 4,694
Defaults \| claim	4,220
Cumulative Paid Claims and Claims Adjustment Expenses, net of Reinsurance	$ 600

CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Statement of Financial Position [Abstract]
Amortized Cost	$ 2,542,862	$ 2,352,747
Restricted cash	$ 1,338	$ 2,176
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, issued (in shares)	87,334,138	86,472,742
Common stock, outstanding (in shares)	80,881,280	83,549,879
Common stock, authorized (in shares)	250,000,000	250,000,000
Treasury stock, common shares (in shares)	6,452,858	2,922,863

Reinsurance - ILN Transactions And XOL Transactions (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Oct. 26, 2021	Apr. 27, 2021	Oct. 29, 2020	Jul. 30, 2019
Reinsurance Policy, Type [Axis]: 2019 ILN Transaction
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Initial Reinsurance Coverage					$ 326,905
Current Reinsurance Coverage	$ 159,476
Initial First Layer Retained Loss					$ 123,424
Current First Layer Retained Loss	121,751
Reinsurance Policy, Type [Axis]: 2020-2 ILN Transaction
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Initial Reinsurance Coverage				$ 242,351
Current Reinsurance Coverage	55,792
Initial First Layer Retained Loss				$ 121,777
Current First Layer Retained Loss	$ 121,177
Percentage of population with production prior to period start date	1.00%
Reinsurance Policy, Type [Axis]: 2021-1 ILN Transaction
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Initial Reinsurance Coverage			$ 367,238
Current Reinsurance Coverage	$ 217,630
Initial First Layer Retained Loss			$ 163,708
Current First Layer Retained Loss	$ 163,394
Percentage of population with production prior to period start date	1.00%
Reinsurance Policy, Type [Axis]: 2021-2 ILN Transaction
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Initial Reinsurance Coverage		$ 363,596
Current Reinsurance Coverage	$ 310,567
Initial First Layer Retained Loss		$ 146,229
Current First Layer Retained Loss	$ 145,858
Percentage of population with production prior to period start date	2.00%
Reinsurance Policy, Type [Axis]: 2022-1 XOL Transaction
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Initial Reinsurance Coverage	$ 289,741
Current Reinsurance Coverage	253,252
Initial First Layer Retained Loss	133,366
Current First Layer Retained Loss	$ 133,123
Percentage of population with production prior to period start date	1.00%
Reinsurance Policy, Type [Axis]: 2022-2 XOL Transaction
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Initial Reinsurance Coverage	$ 154,306
Current Reinsurance Coverage	152,347
Initial First Layer Retained Loss	78,906
Current First Layer Retained Loss	$ 78,736
Percentage of population with production prior to period start date	1.00%
Reinsurance Policy, Type [Axis]: 2022-3 XOL Transaction
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Initial Reinsurance Coverage	$ 96,779
Current Reinsurance Coverage	96,197
Initial First Layer Retained Loss	106,265
Current First Layer Retained Loss	106,265
Reinsurance Policy, Type [Axis]: 2023-1 XOL Transaction
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Initial Reinsurance Coverage	89,864
Current Reinsurance Coverage	88,351
Initial First Layer Retained Loss	146,513
Current First Layer Retained Loss	146,348
Reinsurance Policy, Type [Axis]: 2023-2 XOL Transaction
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Initial Reinsurance Coverage	71,602
Current Reinsurance Coverage	71,602
Initial First Layer Retained Loss	113,372
Current First Layer Retained Loss	$ 113,372

SCHEDULE II - FINANCIAL INFORMATION OF REGISTRANT- PARENT COMPANY ONLY - Statement of Operations Additional Information - Parent Company Only (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Condensed Income Statements, Captions [Line Items]
Unrealized gains (losses) in accumulated other comprehensive income, tax expense (benefit)	$ 17,113	$ (54,608)	$ (13,768)
Reclassification adjustment for realized losses (gains) included in net income, tax (benefit) expense	(7)	101	153
Parent
Condensed Income Statements, Captions [Line Items]
Unrealized gains (losses) in accumulated other comprehensive income, tax expense (benefit)	312	(748)	(95)
Reclassification adjustment for realized losses (gains) included in net income, tax (benefit) expense	$ (7)	$ (3)	$ 2

Intangible Assets and Goodwill

12 Months Ended

Dec. 31, 2023

Goodwill and Intangible Assets Disclosure [Abstract]

Intangible Assets and Goodwill


	(In Thousands)		Expected Lives
Goodwill	$	3,244	Indefinite
State licenses	260		Indefinite
GSE applications	130		Indefinite
Total intangible assets and goodwill	$	3,634

We test goodwill and intangible assets for impairment annually or more frequently if we believe indicators of impairment exist. No impairments of indefinite-lived intangibles or goodwill were identified during the years ended December 31, 2023, 2022 and 2021.

Share-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2023

Share-Based Payment Arrangement [Abstract]

Schedule of stock option activity

A summary of option activity during the year ended December 31, 2023 is as follows:


For the year ended December 31, 2023	Shares	Weighted Average Grant Date Fair Value per Share		Weighted Average Exercise Price
	(Shares in Thousands)
Options outstanding at December 31, 2022	1,146	$	4.93	$	13.48
Options granted	—	—		—
Options exercised	(415)	3.74		9.87
Options forfeited	—	—		—
Options expired	—	—		—
Options outstanding at December 31, 2023	731	$	5.61	$	15.53

Schedule of restricted stock units activity

A summary of RSU activity during the year ended December 31, 2023 is as follows:


For the year ended December 31, 2023	Shares	Weighted Average Grant Date Fair Value per Share
	(Shares in Thousands)
Non-vested restricted stock units at December 31, 2022	1,190	$	24.06
Restricted stock units granted	708	22.75
Performance adjustment (1)	48	31.00
Restricted stock units vested (2)	(575)	24.68
Restricted stock units forfeited	(35)	21.77
Non-vested restricted stock units at December 31, 2023	1,336	$	23.41

(2) Represents amounts vested during the year, including the impact of performance adjustments for service and performance-based RSUs.

Software and Equipment - Net Balances (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Property, Plant and Equipment [Line Items]
Property plant and equipment	$ 105,283	$ 96,258
Accumulated amortization and depreciation	(75,031)	(64,328)
Software and equipment, net	30,252	31,930
Software
Property, Plant and Equipment [Line Items]
Property plant and equipment	91,363	83,016
Equipment
Property, Plant and Equipment [Line Items]
Property plant and equipment	11,409	10,731
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property plant and equipment	$ 2,511	$ 2,511

SCHEDULE II - FINANCIAL INFORMATION OF REGISTRANT- PARENT COMPANY ONLY

12 Months Ended

Dec. 31, 2023

Condensed Financial Information Disclosure [Abstract]

Financial Information of Registrant - Parent Company Only


	December 31, 2023		December 31, 2022
	(In Thousands, except for share data)
Assets
Fixed maturities, available-for-sale, at fair value	$	47,290	$	83,918
Cash and cash equivalents	66,374		4,940
Investment in subsidiaries, at equity in net assets	2,468,333		2,092,457
Accrued investment income	235		440

Due from affiliates, net	91,126		83,018
Software and equipment, net	30,252		31,930

Other assets	13,858		15,408
Total assets	$	2,717,468	$	2,312,111

Liabilities
Debt	$	397,595	$	396,051
Accounts payable and accrued expenses	38,524		34,697

Deferred tax liability, net	343,956		255,550
Other liabilities	11,389		12,086
Total liabilities	791,464		698,384

Shareholders' equity
Common stock - class A shares, $0.01 par value; 87,334,138 shares issued and 80,881,280 shares outstanding as of December 31, 2023 and 86,472,742 shares issued and 83,549,879 shares outstanding as of December 31, 2022 (250,000,000 shares authorized)	873		865
Additional paid-in capital	990,816		972,717
Treasury stock, at cost: 6,452,858 and 2,922,863 common shares as of December 31, 2023 and December 31, 2022, respectively	(148,921)		(56,575)
Accumulated other comprehensive loss, net of tax	(139,917)		(204,323)
Retained earnings	1,223,153		901,043
Total shareholders' equity	1,926,004		1,613,727
Total liabilities and shareholders' equity	$	2,717,468	$	2,312,111


	For the years ended December 31,
	2023		2022		2021
	(In Thousands)
Revenues
Net investment income	$	3,920	$	1,204	$	327
Net realized investment (losses) gains	(31)		(13)		10
Total revenues	3,889		1,191		337

Expenses
Other operating expenses	7,828		7,590		8,264
Interest expense	—		—		68
Gain from change in fair value of warrant liability	—		(1,113)		(566)
Total expenses	7,828		6,477		7,766

Equity in net income of subsidiaries	412,974		378,406		303,970

Income before income taxes	409,035		373,120		296,541
Income tax expense	86,925		80,218		65,411
Net income	$	322,110	$	292,902	$	231,130

Other comprehensive income (loss), net of tax:
Unrealized gains (losses) in accumulated other comprehensive income, net of tax expense (benefit) of $312, $(748), and $(95) for each of the years in the three-year period ended December 31, 2023, respectively	1,173		(2,815)		(357)
Reclassification adjustment for realized losses (gains) included in net income, net of tax (benefit) expense of $(7), $(3) and $2 for each of the years in the three-year period ended December 31, 2023, respectively	25		10		(8)
Equity in other comprehensive income (loss) of subsidiaries	63,208		(203,003)		(52,006)
Other comprehensive income (loss), net of tax	64,406		(205,808)		(52,371)
Comprehensive income	$	386,516	$	87,094	$	178,759


	For the years ended December 31,
	2023		2022		2021
Cash flows from operating activities	(In Thousands)
Net income	$	322,110	$	292,902	$	231,130
Adjustments to reconcile net income to net cash provided by operating activities:
Gain from change in fair value of warrant liability	—		(1,113)		(566)
Net realized investment losses (gains)	31		13		(10)
Depreciation and amortization	(890)		789		801
Amortization of debt discount and debt issuance costs	1,962		1,846		1,861
Deferred income taxes	88,192		81,057		66,941
Share-based compensation expense	16,914		15,425		16,678
Changes in operating assets and liabilities:
Investment in subsidiaries, at equity in net assets	(314,556)		(343,477)		(302,165)
Accrued investment income	205		(73)		(104)
Receivable from affiliates	(8,108)		3,348		(9,474)

Other assets	(57)		518		(496)
Accounts payable and accrued expenses	2,605		(8,731)		10,068
Net cash provided by operating activities	108,408		42,504		14,664
Cash flows from investing activities
Capitalization of subsidiaries	(800)		(800)		(800)
Purchase of short-term investments	(89,068)		(110,076)		(10,640)
Purchase of fixed-maturity investments, available-for-sale	—		—		(2,797)
Proceeds from maturity of short-term investments	100,607		86,995		—
Proceeds from redemptions, maturities and sale of fixed-maturity investments, available-for-sale	30,538		19,673		4,464
Software and equipment	2,169		1,291		(1,026)
Net cash provided by (used in) investing activities	43,446		(2,917)		(10,799)
Cash flows from financing activities

Proceeds from issuance of common stock related to employee equity plans	10,549		5,442		4,201
Proceeds from issuance of common stock related to warrant exercises	—		518		503
Taxes paid related to net share settlement of equity awards	(9,356)		(5,213)		(5,426)


Payments of debt issuance costs	—		—		(1,108)
Repurchase of common stock	(91,613)		(56,575)		—
Net cash used in financing activities	(90,420)		(55,828)		(1,830)

Net increase (decrease) in cash, cash equivalents and restricted cash	61,434		(16,241)		2,035
Cash, cash equivalents and restricted cash, beginning of period	4,940		21,181		19,146
Cash, cash equivalents and restricted cash, end of period	$	66,374	$	4,940	$	21,181

Note A

The NMI Holdings, Inc. (Parent Company) financial statements represent the stand-alone financial statements of the Parent Company. These financial statements have been prepared on the same basis and using the same accounting policies as described in the consolidated financial statements included herein. Refer to the Parent Company's consolidated financial statements for additional information.

NMIH and its subsidiaries entered into a tax sharing agreement effective August 23, 2012, which was subsequently amended on September 1, 2016. Under original and amended agreements, each of the parties agreed to file consolidated federal income tax returns for all tax years beginning in and subsequent to 2012, with NMIH as the direct tax filer. The tax liability of each subsidiary that is party to the agreement is limited to the amount of the liability it would incur if it filed separate returns.

Note B

NMIC and Re One are subject to certain capital and dividend rules and regulations prescribed by jurisdictions in which they are authorized to operate and the GSEs that may restrict their ability to pay dividends to NMIH. Under Wisconsin law, NMIC and Re One may pay dividends up to specified levels (i.e., "ordinary" dividends) with 30 days' prior notice to the Wisconsin OCI. Dividends in larger amounts (i.e.,"extraordinary" dividends), are subject to the Wisconsin OCI's prior approval. Under Wisconsin law, an extraordinary dividend is defined as any payment or distribution that together with other dividends and distributions made within the preceding twelve months exceeds the lesser of (i) 10% of the insurer's statutory policyholders' surplus as of the preceding December 31 or (ii) adjusted statutory net income for the twelve-month period ending the preceding December 31. During the year ended December 31, 2023, NMIC paid a $98.0 million ordinary course dividend to NMIH, representing its full ordinary course dividend capacity payable under Wisconsin law for the twelve-month period ending December 31, 2023. NMIC has the capacity to pay aggregate ordinary dividends of $96.3 million to NMIH during the twelve-month period ending December 31, 2024.

The remaining net assets from dividend capacity are considered restricted. As of December 31, 2023, the amount of restricted net assets held by our consolidated insurance subsidiaries, which represents our equity investment in those insurance subsidiaries less their aggregate dividend capacity, totaled $2.5 billion, compared to $2.1 billion as of December 31, 2022.

Note C

The Parent Company provides certain services to its subsidiaries. The Parent Company allocates to its subsidiaries corporate expense it incurs in the capacity of supporting those subsidiaries, based on either an allocated percentage of time spent or internally allocated capital. Total operating expenses allocated to subsidiaries for each of the years in the three-year period ended December 31, 2023 were $163.9 million, $148.4 million and $149.4 million, respectively. Amounts charged to the subsidiaries for operating expenses are based on actual cost, without any mark-up. The Parent Company considers these charges fair and reasonable. The subsidiaries reimburse the Parent Company for these costs in a timely manner, which has the impact of improving the cash flows of the Parent Company.

Investments - Scheduled Maturities (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Amortized Cost
Due in one year or less	$ 191,375	$ 271,613
Due after one through five years	1,237,192	935,615
Due after five through ten years	1,050,989	1,047,461
Due after ten years	11,064	23,296
Asset-backed securities	52,242	74,762
Amortized Cost	2,542,862	2,352,747
Fair Value
Due in one year or less	189,729	270,428
Due after one through five years	1,162,259	862,747
Due after five through ten years	959,633	875,947
Due after ten years	11,189	21,709
Asset-backed securities	48,211	68,558
Fair Value	$ 2,371,021	$ 2,099,389

SCHEDULE IV - FINANCIAL INFORMATION OF REGISTRANT REINSURANCE (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2023	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Dec. 31, 2022	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
SEC Schedule, 12-17, Insurance Companies, Reinsurance [Line Items]
Gross Amount									$ 650,411	$ 594,127	$ 536,630
Ceded to Other Companies									139,643	118,861	92,336
Net premiums earned	$ 132,940	$ 130,089	$ 125,985	$ 121,754	$ 119,584	$ 118,317	$ 120,870	$ 116,495	510,768	475,266	444,294
Parent
SEC Schedule, 12-17, Insurance Companies, Reinsurance [Line Items]
Gross Amount									650,411	594,127	536,630
Ceded to Other Companies									139,643	118,861	92,336
Assumed from Other Companies									0	0	0
Net premiums earned									$ 510,768	$ 475,266	$ 444,294
Percentage of Amount Assumed to Net									0.00%	0.00%	0.00%

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

Reserves for Insurance Claims and Claim Expenses - Narrative (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2023 USD ($) claim loan policy	Dec. 31, 2022 USD ($) loan policy	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)
Liability for Claims and Claims Adjustment Expense [Line Items]
Reserve for insurance claims and claim expenses	$ 123,974	$ 99,836	$ 103,551	$ 90,567
Number of claims paid \| claim	199
Claims paid, including amounts covered by insurance	$ 5,200
Primary loans in default \| loan	5,099	4,449
Default rate (in percent)	0.81%	0.75%
Total policies in-force \| policy	629,690	594,142
Favorable development on prior year defaults	$ 56,400	$ 48,800	$ 11,100
Reserve for prior year insurance claims and claims expense	$ 24,000
Reinsurance Policy, Type [Axis]: QSR Transactions
Liability for Claims and Claims Adjustment Expense [Line Items]
Number of covered claims included in number of claims paid \| claim	186
Claims paid QSR transaction	$ 1,000

CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE INCOME - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Revenues
Net premiums earned	$ 510,768	$ 475,266	$ 444,294
Net investment income	67,512	46,406	38,072
Net realized investment (losses) gains	(33)	481	729
Other revenues	756	1,192	1,977
Total revenues	579,003	523,345	485,072
Expenses
Insurance claims and claim expenses (benefits)	22,618	(3,594)	12,305
Underwriting and operating expenses	110,699	117,490	142,303
Service expenses	771	1,094	2,509
Interest expense	32,212	32,163	31,796
Gain from change in fair value of warrant liability	0	(1,113)	(566)
Total expenses	166,300	146,040	188,347
Income before income taxes	412,703	377,305	296,725
Income tax expense	90,593	84,403	65,595
Net income	$ 322,110	$ 292,902	$ 231,130
Earnings per share
Basic (in dollars per share)	$ 3.91	$ 3.45	$ 2.70
Diluted (in dollars per share)	$ 3.84	$ 3.39	$ 2.65
Weighted average common shares outstanding
Basic (in shares)	82,407	84,921	85,620
Diluted (in shares)	83,854	85,999	86,885
Comprehensive income:
Net income	$ 322,110	$ 292,902	$ 231,130
Other comprehensive income (loss), net of tax:
Unrealized gains (losses) in accumulated other comprehensive income, net of tax expense (benefit) of $17,113, $(54,608) and $(13,768) for each of the years in the three-year period ended December 31, 2023, respectively	64,380	(205,428)	(51,795)
Reclassification adjustment for realized losses (gains) included in net income, net of tax (benefit) expense of $(7), $101 and $153 for each of the years in the three-years ended December 31, 2023, respectively	26	(380)	(576)
Other comprehensive income (loss), net of tax	64,406	(205,808)	(52,371)
Comprehensive income	$ 386,516	$ 87,094	$ 178,759

Investments - Net Realized Investments (Losses) Gains (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Investments, Debt and Equity Securities [Abstract]
Gross realized investment gains	$ 0	$ 490	$ 729
Gross realized investment losses	(33)	(9)	0
Net realized investment (losses) gains	$ (33)	$ 481	$ 729

Fair Value of Financial Instruments - Narrative (Details) - Secured Debt - USD ($)	Dec. 31, 2023	Dec. 31, 2022	Jun. 19, 2020
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt instrument face amount			$ 400,000,000
Debt	$ 397,600,000	$ 396,100,000
Deferred debt issuance costs	2,400,000	3,900,000	7,400,000
Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of term loan	$ 401,900,000	$ 405,900,000
Senior Secured Term Loan
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt instrument face amount			$ 150,000,000

Amount, after deduction of unamortized premium (discount) and debt issuance cost, of long-term debt. Excludes lease obligation.

SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Abstract]

SCHEDULE I - SUMMARY OF INVESTMENTS - OTHER THAN INVESTMENTS IN RELATED PARTIES

12 Months Ended

Dec. 31, 2023

Summary of Investments - Other than Investments in Related Parties


December 31, 2023	Amortized Cost		Fair Value		Amount Reflected on Balance Sheet
	(In Thousands)
U.S. Treasury securities and obligations of U.S. government agencies	$	164,278	$	166,388	$	166,388
Municipal debt securities	678,339		621,130		621,130
Corporate debt securities	1,624,187		1,511,479		1,511,479
Asset-backed securities	52,242		48,211		48,211
Total bonds	2,519,046		2,347,208		2,347,208

Short-term investments	23,816		23,813		23,813
Total investments	$	2,542,862	$	2,371,021	$	2,371,021

Reinsurance - Narrative (Details) $ in Thousands				12 Months Ended
Reinsurance - Narrative (Details) $ in Thousands	Jan. 01, 2024	Apr. 01, 2019 USD ($) reinsurance_engagement	Mar. 31, 2019	Dec. 31, 2023 USD ($) reinsuranceAgreement quota_share_agreement	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)
Ceded Credit Risk [Line Items]
Optional termination right, percent of reinsurance coverage threshold				10.00%
Restricted cash				$ 1,338	$ 2,176
Number of excess-of-loss reinsurance agreements \| reinsuranceAgreement				5
Reinsurance coverage amount				$ 31,200	13,900
Number of quota share reinsurance treaties \| quota_share_agreement				7
Reinsurance recoverable on unpaid claims				$ 27,514	21,587	$ 20,320	$ 17,608
Reinsurance Policy, Type [Axis]: Oaktown Re Vehicles
Ceded Credit Risk [Line Items]
Reinsurance coverage, term of underlying mortgage amortization (in years)				10 years
Reinsurance Policy, Type [Axis]: QSR Transactions
Ceded Credit Risk [Line Items]
Reinsurance recoverable on unpaid claims				$ 25,800	19,000
Maximum
Ceded Credit Risk [Line Items]
Reinsurance coverage, term of underlying mortgage amortization (in years)				12 years 6 months
Minimum
Ceded Credit Risk [Line Items]
Reinsurance coverage, term of underlying mortgage amortization (in years)				10 years
Third-Party Reinsurers \| Reinsurance Policy, Type [Axis]: 2016 QSR Transaction
Ceded Credit Risk [Line Items]
Number of reinsurance engagements terminated \| reinsurance_engagement		1
Previously ceded primary risk-in-force recaptured		$ 500,000
Threshold for loss ratio on loans to qualify for profit commission				60.00%
Reinsurance recoverable on unpaid claims				$ 1,700	2,600
Third-Party Reinsurers \| Reinsurance Policy, Type [Axis]: 2016 QSR Transaction, Eligible Primary Policies
Ceded Credit Risk [Line Items]
Premiums of premiums earned under QSR Transaction				25.00%
Third-Party Reinsurers \| Reinsurance Policy, Type [Axis]: 2016 QSR Transaction, Pool Agreement with Fannie Mae
Ceded Credit Risk [Line Items]
Premiums of premiums earned under QSR Transaction				100.00%
Third-Party Reinsurers \| Reinsurance Policy, Type [Axis]: 2018 QSR Transaction
Ceded Credit Risk [Line Items]
Premiums of premiums earned under QSR Transaction				25.00%
Threshold for loss ratio on loans to qualify for profit commission				61.00%
Third-Party Reinsurers \| Reinsurance Policy, Type [Axis]: 2019 QSR Transaction
Ceded Credit Risk [Line Items]
Premiums of premiums earned under QSR Transaction				20.00%
Third-Party Reinsurers \| Reinsurance Policy, Type [Axis]: 2020 Amended QSR Transaction
Ceded Credit Risk [Line Items]
Threshold for loss ratio on loans to qualify for profit commission				50.00%
Third-Party Reinsurers \| Reinsurance Policy, Type [Axis]: 2020 QSR Transaction
Ceded Credit Risk [Line Items]
Premiums of premiums earned under QSR Transaction				21.00%
Threshold for loss ratio on loans to qualify for profit commission				50.00%
Third-Party Reinsurers \| Reinsurance Policy, Type [Axis]: 2021 QSR Transaction
Ceded Credit Risk [Line Items]
Premiums of premiums earned under QSR Transaction				22.50%
Threshold for loss ratio on loans to qualify for profit commission				57.50%
Third-Party Reinsurers \| Reinsurance Policy, Type [Axis]: 2022 QSR Transaction
Ceded Credit Risk [Line Items]
Premiums of premiums earned under QSR Transaction				20.00%
Threshold for loss ratio on loans to qualify for profit commission				62.00%
Third-Party Reinsurers \| Reinsurance Policy, Type [Axis]: 2022 Seasoned QSR Transaction
Ceded Credit Risk [Line Items]
Premiums of premiums earned under QSR Transaction				95.00%
Threshold for loss ratio on loans to qualify for profit commission				55.00%
Third-Party Reinsurers \| Reinsurance Policy, Type [Axis]: 2023 QSR Transaction
Ceded Credit Risk [Line Items]
Premiums of premiums earned under QSR Transaction				20.00%
Threshold for loss ratio on loans to qualify for profit commission				62.00%
Third-Party Reinsurers \| Reinsurance Policy, Type [Axis]: 2024 QSR Transaction \| Subsequent Event
Ceded Credit Risk [Line Items]
Premiums of premiums earned under QSR Transaction	20.00%
Ceding commissions under QSR Transaction	20.00%
Threshold for loss ratio on loans to qualify for profit commission	56.00%
Third-Party Reinsurers \| Reinsurance Policy, Type [Axis]: Amended 2020 QSR Transaction \| Subsequent Event
Ceded Credit Risk [Line Items]
Premiums of premiums earned under QSR Transaction	21.00%
Third-Party Reinsurers \| Reinsurance Policy, Type [Axis]: Oaktown Re Vehicles
Ceded Credit Risk [Line Items]
Risk premiums paid				$ 31,100	$ 41,900	$ 41,300
Third-Party Reinsurers \| Reinsurance Policy, Type [Axis]: QSR Transactions
Ceded Credit Risk [Line Items]
Ceding commissions under QSR Transaction				20.00%
Third-Party Reinsurers \| Maximum \| Reinsurance Policy, Type [Axis]: 2016 QSR Transaction
Ceded Credit Risk [Line Items]
Percent of premiums ceded under QSR Transaction			25.00%
Third-Party Reinsurers \| Maximum \| Reinsurance Policy, Type [Axis]: Oaktown Re Vehicles
Ceded Credit Risk [Line Items]
Anticipated payment related to annual operating expenses				$ 250
Third-Party Reinsurers \| Minimum \| Reinsurance Policy, Type [Axis]: 2016 QSR Transaction
Ceded Credit Risk [Line Items]
Percent of premiums ceded under QSR Transaction		20.50%
Third-Party Reinsurers \| Minimum \| Reinsurance Policy, Type [Axis]: 2022 Seasoned QSR Transaction
Ceded Credit Risk [Line Items]
Ceding commissions under QSR Transaction				35.00%
Third-Party Reinsurers \| Minimum \| Reinsurance Policy, Type [Axis]: Amended 2020 QSR Transaction
Ceded Credit Risk [Line Items]
Ceding commissions under QSR Transaction				36.00%

SCHEDULE IV - FINANCIAL INFORMATION OF REGISTRANT REINSURANCE

12 Months Ended

Dec. 31, 2023

SEC Schedule, 12-17, Insurance Companies, Reinsurance [Abstract]

Financial Information of Registrant Reinsurance


	Gross Amount		Ceded to Other Companies		Assumed from Other Companies		Net Amount		Percentage of Amount Assumed to Net
For the years ended December 31,	(In Thousands)
2023	$	650,411	$	139,643	$	—	$	510,768	—	%
2022	594,127		118,861		—		475,266		—
2021	536,630		92,336		—		444,294		—

Reserves for Insurance Claims and Claim Expenses (Tables)

12 Months Ended

Dec. 31, 2023

Schedule of reconciliation of liability for insurance claims and claims expenses (benefits)

The following table provides a reconciliation of the beginning and ending gross reserve balances for primary insurance claims and claim expenses (benefits):


	For the years ended December 31,
	2023		2022		2021
	(In Thousands)
Beginning balance	$	99,836	$	103,551	$	90,567
Less reinsurance recoverables (1)	(21,587)		(20,320)		(17,608)
Beginning balance, net of reinsurance recoverables	78,249		83,231		72,959

Add claims incurred:
Claims and claim expenses (benefits) incurred:
Current year (2)	78,285		45,168		23,433
Prior years (3)	(56,390)		(48,762)		(11,128)
Total claims and claim expenses (benefits) incurred (4)	21,895		(3,594)		12,305

Less claims paid:
Claims and claim expenses paid:
Current year (2)	600		74		16
Prior years (3)	3,575		1,314		2,017
Reinsurance terminations	(491)		—		—
Total claims and claim expenses paid	3,684		1,388		2,033

Reserve at end of period, net of reinsurance recoverables	96,460		78,249		83,231
Add reinsurance recoverables (1)	27,514		21,587		20,320
Ending balance	$	123,974	$	99,836	$	103,551

(1) Related to ceded losses recoverable under the QSR Transactions. See Note 6, “Reinsurance” for additional information.

(4) Excludes a $0.7 million termination fee for the year ended December 31, 2023 incurred in connection with the amendment of the 2020 QSR Transaction.

Schedule of claims development data


	Cumulative Incurred Claims and Allocated Claims Adjustment Expenses, net of Reinsurance (1)																				As of December 31, 2023
Accident Year	2014		2015		2016		2017		2018		2019		2020		2021		2022		2023		Total of IBNR		Defaults (2)
	Unaudited
($ In Thousands)
2014	$	83	$	34	$	4	$	4	$	4	$	4	$	4	$	4	$	4	$	4	$	—	—
2015			699		664		743		764		894		894		894		894		894		—		—
2016					2,394		1,568		1,790		1,934		1,936		1,930		1,893		1,986		1		1
2017							6,028		3,475		3,570		3,807		3,716		3,718		3,712		4		2
2018									7,779		5,271		4,709		4,533		4,282		4,312		15		11
2019											14,391		7,229		5,781		4,604		4,606		74		40
2020													65,769		56,154		18,862		7,472		315		164
2021															22,847		14,337		4,092		501		139
2022																	44,334		11,023		733		522
2023																			76,967		4,694		4,220
																	Total		$	115,068	$	6,337	5,099

(1) Amounts include case and IBNR reserves.

(2) Number of defaults outstanding as of December 31, 2023.


	Cumulative Paid Claims and Claims Adjustment Expenses, net of Reinsurance
Accident Year	2014		2015		2016		2017		2018		2019		2020		2021		2022		2023
	Unaudited
	(In Thousands)
2014	$	—	$	4	$	4	$	4	$	4	$	4	$	4	$	4	$	4	$	4
2015			50		246		684		720		804		894		894		894		894
2016					171		890		1,596		1,826		1,827		1,877		1,878		1,978
2017							27		1,655		2,925		3,494		3,640		3,655		3,661
2018									130		1,981		3,537		3,780		3,909		4,116
2019											69		2,368		3,212		3,534		3,621
2020													586		1,320		1,909		3,265
2021															16		274		914
2022																	74		1,252
2023																			600
																	Total		$	20,305

Schedule of reconciliation of claims development to liability


Reconciliation of Disclosure of Incurred and Paid Claims Development to the Liability for Unpaid Claims and Claim Adjustment Expenses
(In Thousands)
	As of December 31, 2023
Cumulative Incurred Claims and Allocated Claims Adjustment Expenses, net of Reinsurance	$	115,068
Cumulative Paid Claims and Claims Adjustment Expenses, net of Reinsurance	(20,305)
All outstanding liabilities before 2014, net of reinsurance	—
Liabilities for unpaid claims and allocated claims adjustment expenses, net of reinsurance	94,763
Reinsurance recoverable on unpaid claims	27,514
Unallocated claims adjustment expenses	1,697
Total gross liability for unpaid claims and claim adjustment expenses	$	123,974

Schedule of historical claims duration


	Average annual percentage payout of incurred claims and allocated claims adjustment expenses by age, net of reinsurance (unaudited)
	Year 1	Year 2	Year 3	Year 4	Year 5	Year 6	Year 7	Year 8		Year 9		Year 10
Claims duration disclosure	3%	36%	25%	9%	3%	4%	0%	2	%	0	%	0	%

Fair Value of Financial Instruments (Tables)

12 Months Ended

Dec. 31, 2023

Fair Value Disclosures [Abstract]

Schedule of fair value measurements of financial instruments

The following tables present the level within the fair value hierarchy at which our financial instruments were measured:


	Fair Value Measurements Using
	Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)		Fair Value
As of December 31, 2023	(In Thousands)
U.S. Treasury securities and obligations of U.S. government agencies	$	166,388	$	—	$	—	$	166,388
Municipal debt securities	—		621,130		—		621,130
Corporate debt securities	—		1,511,479		—		1,511,479
Asset-backed securities	—		48,211		—		48,211

Cash, cash equivalents and short-term investments	120,502		—		—		120,502
Total assets	$	286,890	$	2,180,820	$	—	$	2,467,710


	Fair Value Measurements Using
	Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)		Fair Value
As of December 31, 2022	(In Thousands)
U.S. Treasury securities and obligations of U.S. government agencies	$	79,932	$	—	$	—	$	79,932
Municipal debt securities	—		483,176		—		483,176
Corporate debt securities	—		1,293,642		—		1,293,642
Asset-backed securities	—		68,558		—		68,558

Cash, cash equivalents and short-term investments	218,507		—		—		218,507
Total assets	$	298,439	$	1,845,376	$	—	$	2,143,815

Leases (Tables)

12 Months Ended

Dec. 31, 2023

Leases [Abstract]

Summary of right-of-use asset and lease liability activity and assumptions

The following table provides a summary of our ROU asset and lease liability assumptions as of December 31, 2023:


Weighted average remaining lease term	6.2 years
Weighted average discount rate	6.50	%

Schedule of future payments due under operating leases

Future payments due under our existing operating leases as of December 31, 2023 are as follows:


Years ending December 31,	(In Thousands)
2024	$	2,080
2025	2,128
2026	2,190
2027	2,256
2028	2,322
2029 and thereafter	2,995
Total undiscounted lease payments	13,971
Less effects of discounting	(2,582)
Present value of lease payments	$	11,389

Software and Equipment

12 Months Ended

Dec. 31, 2023

Property, Plant and Equipment [Abstract]

Software and Equipment

Software and equipment consist largely of capitalized software developed to support our mortgage insurance operations. Software and equipment, net of accumulated amortization and depreciation, as of December 31, 2023 and 2022, consists of the following:


	December 31, 2023		December 31, 2022
	(In Thousands)
Software	$	91,363	$	83,016
Equipment	11,409		10,731
Leasehold improvements	2,511		2,511
Subtotal	105,283		96,258
Accumulated amortization and depreciation	(75,031)		(64,328)
Software and equipment, net	$	30,252	$	31,930

Capitalized costs for software, equipment, and leasehold improvements during the years ended December 31, 2023, 2022 and 2021 were $9.9 million, $11.8 million and $13.6 million, respectively. Amortization and depreciation expense for software, equipment, and leasehold improvements for the years ended December 31, 2023, 2022 and 2021 were $11.5 million, $11.9 million and $11.2 million, respectively.

Software and Equipment - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Property, Plant and Equipment [Abstract]
Capitalized costs related to software, equipment, and leaseholds	$ 9.9	$ 11.8	$ 13.6
Depreciation and amortization	$ 11.5	$ 11.9	$ 11.2

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Assets
Fixed maturities, available-for-sale, at fair value (amortized cost of $2,542,862 and $2,352,747 as of December 31, 2023 and December 31, 2022, respectively)	$ 2,371,021	$ 2,099,389
Cash and cash equivalents (including restricted cash of $1,338 and $2,176 as of December 31, 2023 and December 31, 2022, respectively)	96,689	44,426
Premiums receivable	76,456	69,680
Accrued investment income	19,785	14,144
Deferred policy acquisition costs, net	62,905	58,564
Software and equipment, net	30,252	31,930
Intangible assets and goodwill	3,634	3,634
Reinsurance recoverable	27,514	21,587
Prepaid federal income taxes	235,286	154,409
Other assets	16,965	18,267
Total assets	2,940,507	2,516,030
Liabilities
Debt	397,595	396,051
Unearned premiums	92,295	123,035
Accounts payable and accrued expenses	86,189	74,576
Reserve for insurance claims and claim expenses	123,974	99,836
Reinsurance funds withheld	1,421	2,674
Deferred tax liability, net	301,573	193,859
Other liabilities	11,456	12,272
Total liabilities	1,014,503	902,303
Commitments and contingencies (see Note 14)
Shareholders' equity
Common stock - class A shares, $0.01 par value; 87,334,138 shares issued and 80,881,280 shares outstanding as of December 31, 2023 and 86,472,742 shares issued and 83,549,879 shares outstanding as of December 31, 2022 (250,000,000 shares authorized)	873	865
Additional paid-in capital	990,816	972,717
Treasury stock, at cost: 6,452,858 and 2,922,863 common shares as of December 31, 2023 and December 31, 2022, respectively	(148,921)	(56,575)
Accumulated other comprehensive loss, net of tax	(139,917)	(204,323)
Retained earnings	1,223,153	901,043
Total shareholders' equity	1,926,004	1,613,727
Total liabilities and shareholders' equity	$ 2,940,507	$ 2,516,030

Income Taxes - Narrative (Details) - USD ($)	3 Months Ended								12 Months Ended
Income Taxes - Narrative (Details) - USD ($)	Dec. 31, 2023	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Dec. 31, 2022	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Income Tax Contingency [Line Items]
Purchases of tax and loss Bonds									$ 80,900,000	$ 65,200,000	$ 42,900,000
Income tax expense	$ 21,768,000	$ 23,345,000	$ 23,765,000	$ 21,715,000	$ 21,840,000	$ 21,751,000	$ 21,745,000	$ 19,067,000	90,593,000	84,403,000	65,595,000
Prepaid federal income taxes	235,286,000				154,409,000				235,286,000	154,409,000
Loss carry forward subject to expiration	7,300,000								7,300,000
Valuation allowance	9,169,000				8,888,000				9,169,000	8,888,000
Unrecognized tax benefits reserve	0				$ 0				0	0
Annual Limitation Through 2016
Income Tax Contingency [Line Items]
Loss carry forward subject to expiration	800,000								800,000
Annual Limitation, 2017
Income Tax Contingency [Line Items]
Loss carry forward subject to expiration	500,000								500,000
Annual Limitations Through 2028
Income Tax Contingency [Line Items]
Loss carry forward subject to expiration	300,000								300,000
Domestic Tax Authority \| IRS
Income Tax Contingency [Line Items]
Income tax expense									0	$ 0	$ 0
Operating loss carryforward	1,200,000								1,200,000
State and Local Jurisdiction
Income Tax Contingency [Line Items]
Operating loss carryforward	$ 136,500,000								$ 136,500,000

Organization and Basis of Presentation (Details)	Dec. 31, 2023 state
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Number of states in which the entity operates	50

CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS' EQUITY (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Statement of Stockholders' Equity [Abstract]
Change in unrealized investment gains/losses, tax expense (benefit)	$ 17,120	$ (54,709)	$ (13,921)

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2023

Income Tax Disclosure [Abstract]

Schedule of components of income tax expense (benefit)

Total income tax expense consists of the following components:


	For the years ended December 31,
	2023		2022		2021
	(In Thousands)
Current	$	—	$	10	$	85
Deferred	90,593		84,393		65,510
Total income tax expense	$	90,593	$	84,403	$	65,595

Schedule of effective income tax rate reconciliation

The following table presents a reconciliation between the federal statutory income tax rate and our effective income tax rate:


	For the years ended December 31,
	2023		2022		2021
Federal statutory income tax rate	21.0	%	21.0	%	21.0	%
State provision	0.6		0.6		0.5
Share-based and other compensation	0.4		0.5		0.6
Warrant gain	—		(0.1)		—

Other	—		0.4		—
Effective income tax rate	22.0	%	22.4	%	22.1	%

Schedule of net deferred tax asset (liability)

The components of our net deferred tax liability are summarized as follows:


	As of December 31,
	2023		2022
Deferred tax asset:	(In Thousands)
Unrealized loss on investments	$	36,085	$	53,205
Net operating loss carryforward	8,910		8,898
Share-based compensation	6,026		6,320
Unearned premium reserve	3,957		5,264
Accrued expenses	1,369		1,430



Other	1,190		957
Total gross deferred tax asset	57,537		76,074
Less: valuation allowance	(9,169)		(8,888)
Total deferred tax asset	48,368		67,186
Deferred tax liability:
Contingency reserve	(331,342)		(242,192)
Deferred acquisition costs	(13,586)		(12,653)
Capitalized software	(2,496)		(4,737)


Other	(2,517)		(1,463)
Total deferred tax liability	(349,941)		(261,045)
Net deferred income tax (liability)	$	(301,573)	$	(193,859)

Audit Information	12 Months Ended
Audit Information	Dec. 31, 2023
Audit Information [Abstract]
Auditor Name	BDO USA, P.C.
Auditor Location	San Francisco, CA
Auditor Firm ID	243

Investments (Tables)

12 Months Ended

Dec. 31, 2023

Investments, Debt and Equity Securities [Abstract]

Schedule of fair values and gross unrealized gains and losses

Fair Values and Gross Unrealized Gains and Losses on Investments


	Amortized Cost		Gross Unrealized				Fair Value
			Gains		Losses
As of December 31, 2023	(In Thousands)
U.S. Treasury securities and obligations of U.S. government agencies	$	164,278	$	3,374	$	(1,264)	$	166,388
Municipal debt securities	678,339		1,253		(58,462)		621,130
Corporate debt securities	1,624,187		7,868		(120,576)		1,511,479
Asset-backed securities	52,242		1		(4,032)		48,211
Total bonds	2,519,046		12,496		(184,334)		2,347,208

Short-term investments	23,816		2		(5)		23,813
Total investments	$	2,542,862	$	12,498	$	(184,339)	$	2,371,021


	Amortized Cost		Gross Unrealized				Fair Value
			Gains		Losses
As of December 31, 2022	(In Thousands)
U.S. Treasury securities and obligations of U.S. government agencies	$	82,301	$	—	$	(2,369)	$	79,932
Municipal debt securities	563,972		—		(80,796)		483,176
Corporate debt securities	1,457,589		1,149		(165,096)		1,293,642
Asset-backed securities	74,762		—		(6,204)		68,558
Total bonds	2,178,624		1,149		(254,465)		1,925,308

Short-term investments	174,123		185		(227)		174,081
Total investments	$	2,352,747	$	1,334	$	(254,692)	$	2,099,389

Schedule of investments by industry group

The following table presents a breakdown of the fair value of our corporate debt securities by issuer industry group as of December 31, 2023 and 2022:


	December 31, 2023		December 31, 2022
Financial	35	%	38	%
Consumer	26		24
Utilities	13		11
Industrial	9		8
Communications	9		11
Technology	8		8
Total	100	%	100	%

Schedule of investments by maturity


As of December 31, 2023	Amortized Cost		Fair Value
	(In Thousands)
Due in one year or less	$	191,375	$	189,729
Due after one through five years	1,237,192		1,162,259
Due after five through ten years	1,050,989		959,633
Due after ten years	11,064		11,189
Asset-backed securities	52,242		48,211
Total investments	$	2,542,862	$	2,371,021


As of December 31, 2022	Amortized Cost		Fair Value
	(In Thousands)
Due in one year or less	$	271,613	$	270,428
Due after one through five years	935,615		862,747
Due after five through ten years	1,047,461		875,947
Due after ten years	23,296		21,709
Asset-backed securities	74,762		68,558
Total investments	$	2,352,747	$	2,099,389

Schedule of aging unrealized losses

For those securities in an unrealized loss position, the length of time the securities were in such a position is as follows:


	Less Than Twelve Months					Twelve Months or Greater					Total
	# of Securities	Fair Value		Unrealized Losses		# of Securities	Fair Value		Unrealized Losses		# of Securities	Fair Value		Unrealized Losses
As of December 31, 2023		($ In Thousands)
U.S. Treasury securities and obligations of U.S. government agencies	8	$	5,022	$	(62)	17	$	72,003	$	(1,202)	25	$	77,025	$	(1,264)
Municipal debt securities	14	56,280		(502)		217	467,098		(57,960)		231	523,378		(58,462)
Corporate debt securities	13	56,039		(705)		266	1,150,662		(119,871)		279	1,206,701		(120,576)
Asset-backed securities	—	—		—		23	47,426		(4,032)		23	47,426		(4,032)
Short-term investments	1	9,925		(5)		—	—		—		1	9,925		(5)
Total	36	$	127,266	$	(1,274)	523	$	1,737,189	$	(183,065)	559	$	1,864,455	$	(184,339)


	Less Than Twelve Months					Twelve Months or Greater					Total
	# of Securities	Fair Value		Unrealized Losses		# of Securities	Fair Value		Unrealized Losses		# of Securities	Fair Value		Unrealized Losses
As of December 31, 2022		($ In Thousands)
U.S. Treasury securities and obligations of U.S. government agencies	19	$	77,164	$	(2,260)	4	$	2,768	$	(109)	23	$	79,932	$	(2,369)
Municipal debt securities	57	143,097		(12,942)		181	340,079		(67,854)		238	483,176		(80,796)
Corporate debt securities	141	434,174		(19,699)		168	790,537		(145,397)		309	1,224,711		(165,096)
Asset-backed securities	12	13,527		(1,097)		14	55,031		(5,107)		26	68,558		(6,204)
Short-term investments	12	104,236		(227)		—	—		—		12	104,236		(227)
Total	241	$	772,198	$	(36,225)	367	$	1,188,415	$	(218,467)	608	$	1,960,613	$	(254,692)

Schedule of net investment income

The following table presents the components of net investment income:


	For the years ended December 31,
	2023		2022		2021
	(In Thousands)
Investment income (1)	$	68,214	$	47,720	$	39,385
Investment expenses	(702)		(1,314)		(1,313)
Net investment income	$	67,512	$	46,406	$	38,072

Schedule of net realized investment (losses) gains

The following table presents the components of net realized investment (losses) gains:


	For the years ended December 31,
		2023		2022		2021
		(In Thousands)
Gross realized investment gains		$	—	$	490	$	729
Gross realized investment losses		(33)		(9)		—
Net realized investment (losses) gains		$	(33)	$	481	$	729

Tabular disclosure of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Debt	12 Months Ended
Debt	Dec. 31, 2023
Debt Disclosure [Abstract]
Debt	Debt Senior Secured Notes At December 31, 2023, we had $400 million aggregate principal amount of senior secured notes outstanding. The Notes were issued pursuant to an indenture dated June 19, 2020 and bear interest at a rate of 7.375%, payable semi-annually on June 1 and December 1. The Notes mature on June 1, 2025. We may elect to redeem the Notes in whole or in part at any time prior to March 1, 2025 at a price based on 100% of the aggregate principal amount of any Notes redeemed plus the “Applicable Premium,” plus accrued and unpaid interest thereon. Applicable Premium is defined as the greater of (1) 1.0% of the principal amount of the Notes, or (2) the excess of the present value of the principal value of the Notes plus all future interest payments over the principal amount. We may elect to redeem the Notes in whole or in part at any time prior to March 1, 2025 at a price equal to 100% of the aggregate principal amount of the Notes to be redeemed plus accrued and unpaid interest thereon. Interest expense for the Notes includes interest and the amortization of capitalized debt issuance costs. In connection with the Notes offering, we recorded capitalized debt issuance costs of $7.4 million. Such amounts will be amortized over the contractual life of the Notes using the effective interest method. The effective interest rate on the Notes is 7.825%. At December 31, 2023 and 2022, approximately $2.4 million and $3.9 million, respectively, of unamortized debt issuance costs remained. At December 31, 2023 and 2022, $2.5 million of accrued and unpaid interest on the Notes was included in “Accounts Payable and Accrued Expenses” on the consolidated balance sheets. 2021 Revolving Credit Facility On November 29, 2021, we amended our $110 million senior secured revolving credit facility (the 2020 Revolving Credit Facility and as amended, the 2021 Revolving Credit Facility), expanding the lender group, increasing the revolving capacity to $250 million, and extending the maturity from February 22, 2023 to the earlier of (x) November 29, 2025, or (y) if any existing senior secured notes remain outstanding on such date, February 28, 2025. Borrowings under the 2021 Revolving Credit Facility may be used for general corporate purposes, including to support the growth of our new business production and operations, and accrue interest at a variable rate equal to, at our discretion, (i) a Base Rate (as defined in the 2021 Revolving Credit Facility) subject to a floor of 1.00% per annum plus a margin of 0.375% to 1.875% per annum, or (ii) the Adjusted Term Secured Overnight Financing Rate (as defined in the 2021 Revolving Credit Facility) plus a margin of 1.375% to 2.875% per annum, with the margin in each of (i) or (ii) based on our applicable corporate credit rating at the time. As of December 31, 2023 and 2022, no amounts were drawn under the 2021 Revolving Credit Facility. Under the 2021 Revolving Credit Facility, we are required to pay a quarterly commitment fee on the average daily undrawn amount of 0.175% to 0.525%, based on the applicable corporate credit rating at the time. As of December 31, 2023, the applicable commitment fee was 0.30%. For the years ended December 31, 2023, 2022 and 2021, we recorded $0.8 million, $0.8 million and $0.4 million of commitment fees in interest expense, respectively. In January 2024, Moody's upgraded its insurance financial strength rating of NMIC and its rating of the Notes. As a result of the upgrade, the commitment fee due under the 2021 Revolving Credit Facility will be reduced to 0.225% in future periods. We incurred debt issuance costs of $1.1 million in connection with the 2021 Revolving Credit Facility and had $0.6 million of unamortized debt issuance costs associated with the 2020 Revolving Credit Facility remaining at the time of its amendment and replacement. Combined unamortized debt issuance costs are amortized through interest expense on a straight-line basis over the contractual life of the 2021 Revolving Credit Facility. At December 31, 2023 and 2022, remaining unamortized deferred debt issuance costs were $0.8 million and $1.2 million, respectively, in “Other Assets” on our consolidated balance sheets. We are subject to certain covenants under the 2021 Revolving Credit Facility, including, but not limited to, the following: a maximum debt-to-total capitalization ratio of 35%, compliance with the private mortgage insurer eligibility requirements (PMIERs) financial requirements (subject to any GSE approved waivers), and minimum consolidated net worth and statutory capital requirements (respectively, as defined therein). We were in compliance with all covenants at December 31, 2023.

The entire disclosure for information about short-term and long-term debt arrangements, which includes amounts of borrowings under each line of credit, note payable, commercial paper issue, bonds indenture, debenture issue, own-share lending arrangements and any other contractual agreement to repay funds, and about the underlying arrangements, rationale for a classification as long-term, including repayment terms, interest rates, collateral provided, restrictions on use of assets and activities, whether or not in compliance with debt covenants, and other matters important to users of the financial statements, such as the effects of refinancing and noncompliance with debt covenants.

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