0001547903-23-000140 | 10-Q | XBRL Viewer

Investments

9 Months Ended

Sep. 30, 2023

Investments, Debt and Equity Securities [Abstract]

We hold all investments on an available-for-sale basis at fair value on our condensed 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 condensed consolidated statement 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 September 30, 2023	(In Thousands)
U.S. Treasury securities and obligations of U.S. government agencies	$	82,373	$	—	$	(2,201)	$	80,172
Municipal debt securities	676,519		—		(79,448)		597,071
Corporate debt securities	1,595,468		97		(178,459)		1,417,106
Asset-backed securities	67,820		—		(5,064)		62,756
Total bonds	2,422,180		97		(265,172)		2,157,105

Short-term investments	40,598		1		(18)		40,581
Total investments	$	2,462,778	$	98	$	(265,190)	$	2,197,686


	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 September 30, 2023 or December 31, 2022.

The following table presents a breakdown of the fair value of our corporate debt securities by issuer industry group as of September 30, 2023 and December 31, 2022:


	September 30, 2023		December 31, 2022
Financial	34	%	38	%
Consumer	27		24
Utilities	13		11
Communications	9		11
Industrial	9		8
Technology	8		8



Total	100	%	100	%

As of September 30, 2023 and December 31, 2022, approximately $5.1 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 September 30, 2023 and December 31, 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 September 30, 2023	Amortized Cost		Fair Value
	(In Thousands)
Due in one year or less	$	211,754	$	209,298
Due after one through five years	1,111,356		1,008,847
Due after five through ten years	1,040,729		887,169
Due after ten years	31,119		29,616
Asset-backed securities	67,820		62,756
Total investments	$	2,462,778	$	2,197,686


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 September 30, 2023, the investment portfolio had gross unrealized losses of $265.2 million, of which $250.1 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 September 30, 2023		($ In Thousands)
U.S. Treasury securities and obligations of U.S. government agencies	9	$	4,962	$	(224)	18	$	75,210	$	(1,977)	27	$	80,172	$	(2,201)
Municipal debt securities	28	133,262		(4,594)		223	457,059		(74,854)		251	590,321		(79,448)
Corporate debt securities	51	286,184		(10,281)		271	1,119,098		(168,178)		322	1,405,282		(178,459)
Asset-backed securities	—	—		—		25	62,756		(5,064)		25	62,756		(5,064)
Short-term investments	2	27,772		(18)		—	—		—		2	27,772		(18)
Total	90	$	452,180	$	(15,117)	537	$	1,714,123	$	(250,073)	627	$	2,166,303	$	(265,190)


	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 September 30, 2023 and December 31, 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 three or nine month periods ended September 30, 2023 or September 30, 2022.

We evaluated the securities in an unrealized loss position as of September 30, 2023, assessing their credit ratings as well as any adverse conditions specifically related to the security. Based upon our estimate 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 September 30, 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 September 30, 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 three months ended September 30,				For the nine months ended September 30,
	2023		2022		2023		2022
	(In Thousands)
Investment income (1)	$	18,037	$	12,314	$	49,802	$	34,084
Investment expenses	(184)		(369)		(537)		(1,019)
Net investment income	$	17,853	$	11,945	$	49,265	$	33,065

(1) Includes interest income recognized on cash and cash equivalents of $0.8 million and $1.4 million during the three and nine months ended September 30, 2023, respectively, and $0.1 million and $0.2 million during the three and nine months ended September 30, 2022, respectively.

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


	For the three months ended September 30,				For the nine months ended September 30,
	2023		2022		2023		2022
	(In Thousands)
Gross realized investment gains	$	—	$	24	$	—	$	490
Gross realized investment losses	—		(10)		(33)		(15)
Net realized investment gains (losses)	$	—	$	14	$	(33)	$	475

Earnings per Share (EPS) - Schedule of Earnings Per Share, Basic and Diluted (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Sep. 30, 2023	Sep. 30, 2022
Basic EPS
Net income	$ 83,955	$ 80,284	$ 74,458	$ 76,838	$ 75,444	$ 67,680	$ 238,697	$ 219,962
Basic weighted average shares outstanding (in shares)	82,096			84,444			82,879	85,369
Basic earnings per share (in dollars per share)	$ 1.02			$ 0.91			$ 2.88	$ 2.58
Diluted EPS
Net income	$ 83,955	$ 80,284	$ 74,458	$ 76,838	$ 75,444	$ 67,680	$ 238,697	$ 219,962
Gain from change in fair value of warrant liability	0			0			0	(1,113)
Diluted net income	$ 83,955			$ 76,838			$ 238,697	$ 218,849
Basic weighted average shares outstanding (in shares)	82,096			84,444			82,879	85,369
Dilutive effect of issuable shares (in shares)	1,574			1,041			1,357	1,051
Dilutive weighted average shares outstanding (in shares)	83,670			85,485			84,236	86,420
Diluted earnings per share (in dollars per share)	$ 1.00			$ 0.90			$ 2.83	$ 2.53
Anti-dilutive shares (in shares)	1			30			2	30

Investments - Schedule of Net Realized Investment Gains (Losses) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Investments, Debt and Equity Securities [Abstract]
Gross realized investment gains	$ 0	$ 24	$ 0	$ 490
Gross realized investment losses	0	(10)	(33)	(15)
Net realized investment gains (losses)	$ 0	$ 14	$ (33)	$ 475

Debt	9 Months Ended
Debt	Sep. 30, 2023
Debt Disclosure [Abstract]
Debt	Debt Senior Secured Notes At September 30, 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. At any time, or from time to time, prior to March 1, 2025, we may elect to redeem the Notes in whole or in part 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. At any time on or after March 1, 2025, we may elect to redeem the Notes in whole or in part 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 September 30, 2023 and December 31, 2022, approximately $2.8 million and $3.9 million, respectively, of unamortized debt issuance costs remained. At September 30, 2023 and December 31, 2022, $9.8 million and $2.5 million, respectively, of accrued and unpaid interest on the Notes was included in "Accounts Payable and Accrued Expenses" on the condensed 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 SOFR (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 September 30, 2023 and December 31, 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 September 30, 2023, the applicable commitment fee was 0.30%. For the three and nine months ended September 30, 2023, we recorded $0.2 million and $0.6 million of commitment fees in interest expense, respectively. 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 September 30, 2023 and December 31, 2022, remaining unamortized deferred debt issuance costs were $0.9 million and $1.2 million, respectively. 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 September 30, 2023.

- Definition

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.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 235
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-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(c))
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-URI https://asc.fasb.org//470/tableOfContent

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 8: http://www.xbrl.org/2003/role/disclosureRef
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Reference 9: http://www.xbrl.org/2003/role/disclosureRef
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Reference 10: http://www.xbrl.org/2003/role/disclosureRef
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-URI https://asc.fasb.org//1943274/2147481139/470-20-50-1I

Reference 13: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
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-Name Accounting Standards Codification
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-Paragraph 1I
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-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481139/470-20-50-1I

+ Details

Organization, Basis of Presentation and Summary of Accounting Principles	9 Months Ended
	Sep. 30, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization, Basis of Presentation and Summary of Accounting Principles	Organization, Basis of Presentation and Summary of Accounting Principles 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. Basis of Presentation The accompanying unaudited condensed consolidated financial statements, which include the results of NMIH and its wholly-owned subsidiaries, have been prepared in accordance with the instructions to Form 10-Q as prescribed by the SEC for interim reporting and include other information and disclosures required by accounting principles generally accepted in the U.S. (GAAP). Our accounts are maintained in U.S. dollars. These statements should be read in conjunction with our consolidated financial statements and notes thereto for the year ended December 31, 2022, included in our 2022 10-K. All intercompany transactions have been eliminated. Certain reclassifications to previously reported financial information have been made to conform to our current period presentation. 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. The results of operations for the interim period may not be indicative of the results that may be expected for the full year ending December 31, 2023. Significant Accounting Principles There have been no changes to our significant accounting principles as described in Item 8, "Financial Statements and Supplementary Data - Notes to Consolidated Financial Statements - Note 2 - Summary of Accounting Principles" of our 2022 10-K, except as noted in "Recent Accounting Pronouncements - Adopted" below. Recent Accounting Pronouncements - Adopted In August 2018, the Financial Accounting Standards Board (the 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. 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, which is expected to be discontinued during a transition period from 2021 through 2023. The ASU 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. The adoption of ASU 2020-04 and ASU 2022-06 did not have a material impact on our consolidated financial statements.

Fair Value of Financial Instruments - Narrative (Details) - Secured Debt - USD ($)	Sep. 30, 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
Carried cost	$ 397,200,000	$ 396,100,000
Debt issuance costs	2,800,000	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 long term debt	$ 399,700,000	$ 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

- Definition

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

+ References + Details

CONDENSED CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS' EQUITY (UNAUDITED) - 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, 2021		85,793,000
Beginning 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)		51,000
Common stock: class A shares issued related to warrant exercises	1,144	$ 1	1,143
Common stock: class A shares issued under stock plans, net of shares withheld for employee taxes (in shares)		430,000
Common stock: class A shares issued under stock plans, net of shares withheld for employee taxes	30	$ 4	26
Repurchase of common stock (in shares)		(235,000)
Repurchase of common stock	(5,000)			(5,000)
Share-based compensation expense	4,196		4,196
Change in unrealized investment gains/losses, net of tax benefit/expense	(98,794)				(98,794)
Net income	67,680					67,680
Ending balance (in shares) at Mar. 31, 2022		86,039,000
Ending balance at Mar. 31, 2022	1,535,042	$ 863	960,667	(5,000)	(97,309)	675,821
Beginning balance (in shares) at Dec. 31, 2021		85,793,000
Beginning balance at Dec. 31, 2021	1,565,786	$ 858	955,302	0	1,485	608,141
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	219,962
Ending balance (in shares) at Sep. 30, 2022		83,796,000
Ending balance at Sep. 30, 2022	1,525,866	$ 865	969,359	(51,195)	(221,266)	828,103
Beginning balance (in shares) at Mar. 31, 2022		86,039,000
Beginning balance at Mar. 31, 2022	1,535,042	$ 863	960,667	(5,000)	(97,309)	675,821
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock: class A shares issued related to warrant exercises (in shares)		32,659
Common stock: class A shares issued related to warrant exercises	624		624
Common stock: class A shares issued under stock plans, net of shares withheld for employee taxes (in shares)		68,000
Common stock: class A shares issued under stock plans, net of shares withheld for employee taxes	(503)	$ 1	(504)
Repurchase of common stock (in shares)		(1,439,000)
Repurchase of common stock	(25,371)			(25,371)
Share-based compensation expense	3,867		3,867
Change in unrealized investment gains/losses, net of tax benefit/expense	(64,011)				(64,011)
Net income	75,444					75,444
Ending balance (in shares) at Jun. 30, 2022		84,701,000
Ending balance at Jun. 30, 2022	1,525,092	$ 864	964,654	(30,371)	(161,320)	751,265
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)		89,000
Common stock: class A shares issued under stock plans, net of shares withheld for employee taxes	824	$ 1	823
Repurchase of common stock (in shares)		(994,000)
Repurchase of common stock	(20,824)			(20,824)
Share-based compensation expense	3,882		3,882
Change in unrealized investment gains/losses, net of tax benefit/expense	(59,946)				(59,946)
Net income	76,838					76,838
Ending balance (in shares) at Sep. 30, 2022		83,796,000
Ending balance at Sep. 30, 2022	$ 1,525,866	$ 865	969,359	(51,195)	(221,266)	828,103
Beginning balance (in shares) at Dec. 31, 2022	83,549,879	83,550,000
Beginning 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)		396,000
Common stock: class A shares issued under stock plans, net of shares withheld for employee taxes	(2,606)	$ 4	(2,610)
Repurchase of common stock (in shares)		(666,000)
Repurchase of common stock	(14,862)			(14,862)
Share-based compensation expense	3,492		3,492
Change in unrealized investment gains/losses, net of tax benefit/expense	32,502				32,502
Net income	74,458					74,458
Ending balance (in shares) at Mar. 31, 2023		83,280,000
Ending balance at Mar. 31, 2023	$ 1,706,711	$ 869	973,599	(71,437)	(171,821)	975,501
Beginning balance (in shares) at Dec. 31, 2022	83,549,879	83,550,000
Beginning balance at Dec. 31, 2022	$ 1,613,727	$ 865	972,717	(56,575)	(204,323)	901,043
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	$ 238,697
Ending balance (in shares) at Sep. 30, 2023	81,630,452	81,630,000
Ending balance at Sep. 30, 2023	$ 1,790,961	$ 870	981,044	(117,116)	(213,577)	1,139,740
Beginning balance (in shares) at Mar. 31, 2023		83,280,000
Beginning balance at Mar. 31, 2023	1,706,711	$ 869	973,599	(71,437)	(171,821)	975,501
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)		56,000
Common stock: class A shares issued under stock plans, net of shares withheld for employee taxes	21	$ 1	20
Repurchase of common stock (in shares)		(1,046,000)
Repurchase of common stock	(26,238)			(26,238)
Share-based compensation expense	3,676		3,676
Change in unrealized investment gains/losses, net of tax benefit/expense	(15,499)				(15,499)
Net income	80,284					80,284
Ending balance (in shares) at Jun. 30, 2023		82,290,000
Ending balance at Jun. 30, 2023	1,748,955	$ 870	977,295	(97,675)	(187,320)	1,055,785
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)		15,000
Common stock: class A shares issued under stock plans, net of shares withheld for employee taxes	9		9
Repurchase of common stock (in shares)		(675,000)
Repurchase of common stock	(19,441)			(19,441)
Share-based compensation expense	3,740		3,740
Change in unrealized investment gains/losses, net of tax benefit/expense	(26,257)				(26,257)
Net income	$ 83,955					83,955
Ending balance (in shares) at Sep. 30, 2023	81,630,452	81,630,000
Ending balance at Sep. 30, 2023	$ 1,790,961	$ 870	$ 981,044	$ (117,116)	$ (213,577)	$ 1,139,740

Fair Value of Financial Instruments

9 Months Ended

Sep. 30, 2023

Fair Value Disclosures [Abstract]

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.

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 September 30, 2023	(In Thousands)
U.S. Treasury securities and obligations of U.S. government agencies	$	80,172	$	—	$	—	$	80,172
Municipal debt securities	—		597,071		—		597,071
Corporate debt securities	—		1,417,106		—		1,417,106
Asset-backed securities	—		62,756		—		62,756

Cash, cash equivalents and short-term investments	217,044		—		—		217,044
Total assets	$	297,216	$	2,076,933	$	—	$	2,374,149


	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 nine months ended September 30, 2023, or the year ended December 31, 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 September 30, 2023, the Notes were carried at a cost of $397.2 million, net of unamortized debt issuance costs of $2.8 million, and had a fair value of $399.7 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.

- Definition

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.

+ References + Details

Reinsurance

9 Months Ended

Sep. 30, 2023

Reinsurance Disclosures [Abstract]

Reinsurance

ReinsuranceWe 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, including levels of approved capital credit).

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


	For the three months ended September 30,				For the nine months ended September 30,
	2023		2022		2023		2022
	(In Thousands)
Net premiums written
Direct	$	157,956	$	147,192	$	458,880	$	429,715
Ceded (1)	(34,688)		(33,646)		(105,492)		(81,678)
Net premiums written	$	123,268	$	113,546	$	353,388	$	348,037

Net premiums earned
Direct	$	164,813	$	152,221	$	483,705	$	438,299
Ceded (1)	(34,724)		(33,904)		(105,877)		(82,617)
Net premiums earned	$	130,089	$	118,317	$	377,828	$	355,682

(1) Net of profit commission.

Excess-of-loss Reinsurance

Insurance-linked Notes

NMIC is a party to reinsurance agreements with Oaktown Re II Ltd., 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 25, 2018, 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 $6.9 million and $24.8 million during the three and nine months ended September 30, 2023, respectively, and $10.7 million and $31.8 million during the three and nine months ended September 30, 2022, 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 three and nine months ended September 30, 2023 and 2022, 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 from the inception date of each reinsurance agreement (except the notes issued by Oaktown Re VI Ltd. and Oaktown Re VII Ltd., which have a 12.5-year maturity). We refer to NMIC's reinsurance agreements with and the insurance-linked note issuances by Oaktown Re Vehicles individually as the 2018 ILN Transaction, 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 as the underlying insured mortgages are amortized or repaid, and/or the mortgage insurance coverage is canceled (except the coverage provided by Oaktown Re VI Ltd. and Oaktown Re VII Ltd., which decreases over a 12.5-year period). 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).

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 the 2018 ILN Transaction. In connection with the termination of the transaction, NMIC’s excess of loss reinsurance agreement with Oaktown Re II Ltd. was commuted and 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 September 30, 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	$	163,190	$	123,424	$	121,870

2020-2 ILN Transaction	October 29, 2020	4/1/2020 – 9/30/2020 (2)	242,351		64,181		121,777		121,177
2021-1 ILN Transaction	April 27, 2021	10/1/2020 – 3/31/2021 (3)	367,238		235,584		163,708		163,478
2021-2 ILN Transaction	October 26, 2021	4/1/2021 – 9/30/2021 (4)	363,596		328,555		146,229		145,984

(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 condensed consolidated balance sheets includes restricted amounts of $2.3 million and $2.2 million as of September 30, 2023 and December 31, 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 a 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 $8.0 million and $22.9 million during the three and nine months ended September 30, 2023, respectively, and $4.8 million and $7.7 million during the three and nine months ended September 30, 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 three and nine months ended September 30, 2023, as the aggregate first layer risk retention for each

agreement was not exhausted during the period.

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 Standard & Poor’s Rating Service (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 September 30, 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	$274,934	$133,366	$133,238
2022-2 XOL Transaction	July 1, 2022	4/1/2022 – 6/30/2022 (3)	154,306	152,347	78,906	78,892
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	146,513
2023-2 XOL Transaction (4)	July 1, 2023	7/1/2023 – 12/31/2023	40,264	40,264	62,323	62,323

(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 initial reinsurance coverage, current reinsurance coverage, initial first layer retained loss and current first layer retained loss for the 2023-2 XOL Transaction will increase as incremental covered production is ceded under the transaction through December 31, 2023.

Quota Share Reinsurance

NMIC is a 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, 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 would 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 would 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 would 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 would 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 would 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 would 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 would 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 risk-in-force (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.

The following table shows amounts related to the QSR Transactions:


	As of and for the three months ended				As of and for the nine months ended
	September 30, 2023		September 30, 2022		September 30, 2023		September 30, 2022
	(In Thousands)
Ceded risk-in-force	$	12,753,261	$	12,511,797	$	12,753,261	$	12,511,797

Ceded premiums earned	(42,015)		(42,265)		(126,113)		(101,501)
Ceded claims and claim expenses (benefits)	2,221		248		4,989		(314)

Ceding commission earned	9,808		10,193		29,650		22,225
Profit commission	22,184		23,899		67,949		58,400

Ceded premiums written under the 2016 QSR Transaction are recorded on the balance sheet as prepaid reinsurance premiums 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. 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, 2021, 2022, 2023 QSR and 2022 Seasoned QSR Transactions, generally remain below 60%, 61%, 50%, 57.5%, 62%, 62%, and 55% 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 $2.2 million and $2.6 million as of September 30, 2023 and December 31, 2022, respectively.

In accordance with the terms of the 2018, 2020, 2021, 2022 and 2023 QSR and 2022 Seasoned 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, 2023 QSR and 2022 Seasoned QSR Transactions was $23.8 million and $19.0 million as of September 30, 2023 and December 31, 2022, respectively.

We remain directly liable for all claim payments if we are unable to collect reinsurance recoverable 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 recoverable if we do not expect to recover amounts due from one or more of our reinsurance counterparties, and report our reinsurance recoverable 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 on our reinsurance recoverable was deemed immaterial at September 30, 2023 and December 31, 2022.

CONDENSED CONSOLIDATED BALANCE SHEETS (UNAUDITED) (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Statement of Financial Position [Abstract]
Debt securities, amortized cost	$ 2,462,778	$ 2,352,747
Restricted cash	$ 2,251	$ 2,176
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, issued (in shares)	86,940,460	86,472,742
Common stock, outstanding (in shares)	81,630,452	83,549,879
Common stock, authorized (in shares)	250,000,000	250,000,000
Treasury stock, common shares (in shares)	5,310,008	2,922,863

Organization, Basis of Presentation and Summary of Accounting Principles - Narrative (Details)	Sep. 30, 2023 state
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Number of states in which the entity operates	50

Investments - Narrative (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Debt Securities, Available-for-sale [Line Items]
Unrealized loss position, accumulated loss	$ 265,190	$ 254,692
Unrealized loss position, 12 months or greater	250,073	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	5,100	5,400
Unrealized loss position, accumulated loss	2,201	2,369
Unrealized loss position, 12 months or greater	$ 1,977	$ 109

- Definition

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.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 320
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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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+ Details

CONDENSED CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS' EQUITY (UNAUDITED) (Parenthetical) - USD ($) $ in Thousands	3 Months Ended
	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022
Change in unrealized investment gains/losses, tax expense (benefit)	$ (6,980)	$ (4,120)	$ 8,640	$ (15,935)	$ (17,015)	$ (26,262)
Common stock, par value (in dollars per share)	$ 0.01				$ 0.01
Common stock
Common stock: class A shares issued related to the exercise of options and vesting of restricted stock units (in shares)	15,430
Common stock: class A shares issued related to warrant exercises (in shares)					32,659	51,000

Income Taxes	9 Months Ended
Income Taxes	Sep. 30, 2023
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes We are a U.S. taxpayer and are subject to a statutory U.S. federal corporate income tax rate of 21%. Taxable income is reported on our consolidated U.S. federal and various state income tax returns, filed by NMIH on behalf of itself and its subsidiaries. Our effective tax rate on our pre-tax income was 21.8% and 22.4% for the three and nine months ended September 30, 2023, respectively, compared to 22.1% for both the three and nine months ended September 30, 2022. Our provision for income taxes for interim reporting periods is established based on our estimated annual effective tax rate for a given year. Our effective tax rate may fluctuate between interim periods due to the impact of discrete items not included in our estimated annual effective tax rate, including the tax effects associated with the vesting of RSUs and exercise of options. Such items are treated on a discrete basis in the reporting period in which they occur. 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), and only 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. As a result, our interim provision for income taxes for the three and nine months ended September 30, 2023 primarily represents a change in our net deferred tax liability. As of September 30, 2023 and December 31, 2022, we held $154.4 million of tax and loss bonds in "Prepaid federal income taxes" on our condensed consolidated balance sheets.

- Definition

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.

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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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+ Details

Investments - Schedule of Fair Values and Gross Unrealized Gains and Losses (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 2,462,778	$ 2,352,747
Gross unrealized gains	98	1,334
Gross unrealized losses	(265,190)	(254,692)
Fair Value	2,197,686	2,099,389
U.S. Treasury securities and obligations of U.S. government agencies
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	82,373	82,301
Gross unrealized gains	0	0
Gross unrealized losses	(2,201)	(2,369)
Fair Value	80,172	79,932
Municipal debt securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	676,519	563,972
Gross unrealized gains	0	0
Gross unrealized losses	(79,448)	(80,796)
Fair Value	597,071	483,176
Corporate debt securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	1,595,468	1,457,589
Gross unrealized gains	97	1,149
Gross unrealized losses	(178,459)	(165,096)
Fair Value	1,417,106	1,293,642
Asset-backed securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	67,820	74,762
Gross unrealized gains	0	0
Gross unrealized losses	(5,064)	(6,204)
Fair Value	62,756	68,558
Total bonds
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	2,422,180	2,178,624
Gross unrealized gains	97	1,149
Gross unrealized losses	(265,172)	(254,465)
Fair Value	2,157,105	1,925,308
Short-term investments
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	40,598	174,123
Gross unrealized gains	1	185
Gross unrealized losses	(18)	(227)
Fair Value	$ 40,581	$ 174,081

Investments - Schedule of Investments by Maturity (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Amortized Cost
Due in one year or less	$ 211,754	$ 271,613
Due after one through five years	1,111,356	935,615
Due after five through ten years	1,040,729	1,047,461
Due after ten years	31,119	23,296
Asset-backed securities	67,820	74,762
Amortized Cost	2,462,778	2,352,747
Fair Value
Due in one year or less	209,298	270,428
Due after one through five years	1,008,847	862,747
Due after five through ten years	887,169	875,947
Due after ten years	29,616	21,709
Asset-backed securities	62,756	68,558
Fair Value	$ 2,197,686	$ 2,099,389

Cover - shares	9 Months Ended
Cover - shares	Sep. 30, 2023	Oct. 30, 2023
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2023
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, par value $0.01
Trading Symbol	NMIH
Security Exchange Name	NASDAQ
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
Entity Shell Company	false
Entity Common Stock, Shares Outstanding (in shares)		81,080,694
Entity Central Index Key	0001547903
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	Q3
Amendment Flag	false

Organization, Basis of Presentation and Summary of Accounting Principles (Policies)	9 Months Ended
	Sep. 30, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	Basis of Presentation The accompanying unaudited condensed consolidated financial statements, which include the results of NMIH and its wholly-owned subsidiaries, have been prepared in accordance with the instructions to Form 10-Q as prescribed by the SEC for interim reporting and include other information and disclosures required by accounting principles generally accepted in the U.S. (GAAP). Our accounts are maintained in U.S. dollars. These statements should be read in conjunction with our consolidated financial statements and notes thereto for the year ended December 31, 2022, included in our 2022 10-K. All intercompany transactions have been eliminated. Certain reclassifications to previously reported financial information have been made to conform to our current period presentation. 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. The results of operations for the interim period may not be indicative of the results that may be expected for the full year ending December 31, 2023.
Recent Accounting Pronouncements - Adopted	Recent Accounting Pronouncements - Adopted In August 2018, the Financial Accounting Standards Board (the 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. 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, which is expected to be discontinued during a transition period from 2021 through 2023. The ASU 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. The adoption of ASU 2020-04 and ASU 2022-06 did not have a material impact 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.
Earnings per Share (EPS)	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 restricted stock units (RSUs), and the exercise of vested and unvested stock options and outstanding warrants. The number of shares issuable for RSUs subject to performance and service-based vesting requirements are only included in diluted shares if the relevant performance measurement period has commenced and results during such period meet the necessary performance criteria.
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 receivable was deemed immaterial at September 30, 2023 and December 31, 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 $2.4 million and $2.3 million reserve for premium write-offs at September 30, 2023 and December 31, 2022, respectively.

Fair Value of Financial Instruments -Schedule of Fair Value Measurements of Financial Instruments (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of securities	$ 2,197,686	$ 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 of securities	80,172	79,932
Municipal debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of securities	597,071	483,176
Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of securities	1,417,106	1,293,642
Asset-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of securities	62,756	68,558
Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash, cash equivalents and short-term investments	217,044	218,507
Total assets	2,374,149	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 of securities	80,172	79,932
Recurring \| Municipal debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of securities	597,071	483,176
Recurring \| Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of securities	1,417,106	1,293,642
Recurring \| Asset-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of securities	62,756	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	217,044	218,507
Total assets	297,216	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 of securities	80,172	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 of securities	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 of securities	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 of securities	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	2,076,933	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 of securities	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 of securities	597,071	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 of securities	1,417,106	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 of securities	62,756	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 of securities	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 of securities	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 of securities	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 of securities	$ 0	$ 0

Stockholders' Equity	9 Months Ended
Stockholders' Equity	Sep. 30, 2023
Equity [Abstract]
Stockholders' Equity	Stockholders' Equity 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 nine months ended September 30, 2023, we repurchased 2.4 million shares at an average price of $25.13 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 September 30, 2023, we had $208.5 million of aggregate repurchase authority remaining.

- Definition

The entire disclosure for equity.

+ References

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

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (h)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-13

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 14
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-14

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 235
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481062/946-235-50-2

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 235
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481062/946-235-50-2

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 505
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481004/946-505-50-6

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 815
-SubTopic 40
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480237/815-40-50-6

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.3-04)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480008/505-10-S99-1

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 235
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(e)(1))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480678/235-10-S99-1

Reference 10: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 505
-Name Accounting Standards Codification
-Publisher FASB
-URI https://asc.fasb.org//505/tableOfContent

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-13

Reference 12: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (g)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-13

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

Reference 14: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 14
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-14

Reference 15: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 14
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-14

Reference 16: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 16
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-16

Reference 17: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 18
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-18

Reference 18: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 18
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-18

Reference 19: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 18
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-18

+ Details

Premiums Receivable	9 Months Ended
Premiums Receivable	Sep. 30, 2023
Insurance [Abstract]
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 receivable was deemed immaterial at September 30, 2023 and December 31, 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 $2.4 million and $2.3 million reserve for premium write-offs at September 30, 2023 and December 31, 2022, respectively.

Investments - Schedule of Corporate Debt Securities by Industry Group (Details)	Sep. 30, 2023	Dec. 31, 2022
Debt Securities By Industry [Line Items]
Corporate debt securities as component of total (percent)	100.00%	100.00%
Financial
Debt Securities By Industry [Line Items]
Corporate debt securities as component of total (percent)	34.00%	38.00%
Consumer
Debt Securities By Industry [Line Items]
Corporate debt securities as component of total (percent)	27.00%	24.00%
Utilities
Debt Securities By Industry [Line Items]
Corporate debt securities as component of total (percent)	13.00%	11.00%
Communications
Debt Securities By Industry [Line Items]
Corporate debt securities as component of total (percent)	9.00%	11.00%
Industrial
Debt Securities By Industry [Line Items]
Corporate debt securities as component of total (percent)	9.00%	8.00%
Technology
Debt Securities By Industry [Line Items]
Corporate debt securities as component of total (percent)	8.00%	8.00%

Fair Value of Financial Instruments (Tables)

9 Months Ended

Sep. 30, 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 September 30, 2023	(In Thousands)
U.S. Treasury securities and obligations of U.S. government agencies	$	80,172	$	—	$	—	$	80,172
Municipal debt securities	—		597,071		—		597,071
Corporate debt securities	—		1,417,106		—		1,417,106
Asset-backed securities	—		62,756		—		62,756

Cash, cash equivalents and short-term investments	217,044		—		—		217,044
Total assets	$	297,216	$	2,076,933	$	—	$	2,374,149


	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

Reinsurance (Tables)

9 Months Ended

Sep. 30, 2023

Reinsurance Disclosures [Abstract]

Schedule of Effect of Reinsurance Agreements on Premiums Written and Earned

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


	For the three months ended September 30,				For the nine months ended September 30,
	2023		2022		2023		2022
	(In Thousands)
Net premiums written
Direct	$	157,956	$	147,192	$	458,880	$	429,715
Ceded (1)	(34,688)		(33,646)		(105,492)		(81,678)
Net premiums written	$	123,268	$	113,546	$	353,388	$	348,037

Net premiums earned
Direct	$	164,813	$	152,221	$	483,705	$	438,299
Ceded (1)	(34,724)		(33,904)		(105,877)		(82,617)
Net premiums earned	$	130,089	$	118,317	$	377,828	$	355,682

(1) Net of profit commission.

The following table shows amounts related to the QSR Transactions:


	As of and for the three months ended				As of and for the nine months ended
	September 30, 2023		September 30, 2022		September 30, 2023		September 30, 2022
	(In Thousands)
Ceded risk-in-force	$	12,753,261	$	12,511,797	$	12,753,261	$	12,511,797

Ceded premiums earned	(42,015)		(42,265)		(126,113)		(101,501)
Ceded claims and claim expenses (benefits)	2,221		248		4,989		(314)

Ceding commission earned	9,808		10,193		29,650		22,225
Profit commission	22,184		23,899		67,949		58,400

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	$	163,190	$	123,424	$	121,870

2020-2 ILN Transaction	October 29, 2020	4/1/2020 – 9/30/2020 (2)	242,351		64,181		121,777		121,177
2021-1 ILN Transaction	April 27, 2021	10/1/2020 – 3/31/2021 (3)	367,238		235,584		163,708		163,478
2021-2 ILN Transaction	October 26, 2021	4/1/2021 – 9/30/2021 (4)	363,596		328,555		146,229		145,984

(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 September 30, 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	$274,934	$133,366	$133,238
2022-2 XOL Transaction	July 1, 2022	4/1/2022 – 6/30/2022 (3)	154,306	152,347	78,906	78,892
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	146,513
2023-2 XOL Transaction (4)	July 1, 2023	7/1/2023 – 12/31/2023	40,264	40,264	62,323	62,323

(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.

Earnings per Share (EPS)

9 Months Ended

Sep. 30, 2023

Earnings Per Share [Abstract]

Earnings per Share (EPS)

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 restricted stock units (RSUs), and the exercise of vested and unvested stock options and outstanding warrants. The number of shares issuable for RSUs subject to performance and service-based vesting requirements are only included in diluted shares if the relevant performance measurement period has commenced and results during such period meet the necessary performance criteria.

The following table reconciles the net income and the weighted average shares of common stock outstanding used in the computations of basic and diluted EPS of common stock:


	For the three months ended September 30,				For the nine months ended September 30,
	2023		2022		2023		2022
	(In Thousands, except for per share data)
Net income	$	83,955	$	76,838	$	238,697	$	219,962
Basic weighted average shares outstanding	82,096		84,444		82,879		85,369
Basic earnings per share	$	1.02	$	0.91	$	2.88	$	2.58

Net income	$	83,955	$	76,838	$	238,697	$	219,962
Gain from change in fair value of warrant liability	—		—		—		(1,113)
Diluted net income	$	83,955	$	76,838	$	238,697	$	218,849

Basic weighted average shares outstanding	82,096		84,444		82,879		85,369
Dilutive effect of issuable shares	1,574		1,041		1,357		1,051
Diluted weighted average shares outstanding	83,670		85,485		84,236		86,420

Diluted earnings per share	$	1.00	$	0.90	$	2.83	$	2.53

Anti-dilutive shares	1		30		2		30

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (UNAUDITED) - USD ($)
$ in Thousands

9 Months Ended

Sep. 30, 2023

Sep. 30, 2022

Cash flows from operating activities

Net income

$ 238,697

$ 219,962

Adjustments to reconcile net income to net cash provided by operating activities:

Net realized investment loss (gains)

(475)

Gain from change in fair value of warrant liability

(1,113)

Depreciation and amortization

8,516

8,976

Net (accretion)/amortization of (discount)/premium on investment securities

(55)

4,864

Amortization of debt discount and debt issuance costs

1,460

1,374

Deferred income taxes

65,764

61,647

Share-based compensation expense

10,908

11,945

Changes in operating assets and liabilities:

Premiums receivable

(3,701)

(6,844)

Accrued investment income

(3,828)

(1,442)

Deferred policy acquisition costs, net

(3,631)

101

Reinsurance recoverable

(4,369)

565

Other assets

^[1]

(1,092)

(315)

Unearned premiums

(24,824)

(8,585)

Reserve for insurance claims and claim expenses

16,242

(8,607)

Reinsurance balances, net

(432)

(1,067)

Accounts payable and accrued expenses

12,878

617

Net cash provided by operating activities

312,566

281,603

Cash flows from investing activities

Purchase of short-term investments

(152,716)

(229,816)

Purchase of fixed-maturity investments, available-for-sale

(352,469)

(156,973)

Proceeds from maturity of short-term investments

289,920

129,570

Proceeds from redemptions, maturities and sale of fixed-maturity investments, available-for-sale

105,256

82,865

Software and equipment

(7,899)

(7,757)

Net cash used in investing activities

(117,908)

(182,111)

Cash flows from financing activities

Proceeds from issuance of common stock related to employee equity plans

2,872

5,392

Proceeds from issuance of common stock related to warrant exercises

518

(5,448)

(5,041)

Repurchases of common stock

(60,045)

(51,195)

Net cash used in financing activities

(62,621)

(50,326)

Net increase in cash, cash equivalents and restricted cash

132,037

49,166

Cash, cash equivalents and restricted cash, beginning of period

44,426

76,646

Cash, cash equivalents and restricted cash, end of period

176,463

125,812

Supplemental disclosures of cash flow information

Interest paid

14,750

Income taxes paid

$ 21

$ 0

[1]	"Prepaid expenses" have been reclassified as "Other assets" in prior periods.

Regulatory Information - Narrative (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
	May 12, 2023	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022
NMIC and Re One combined
Statutory Accounting Practices [Line Items]
Net income amount		$ 30,100	$ 23,600	$ 80,000	$ 67,800
Statutory capital		2,437,085		2,437,085		$ 2,246,263
Aggregate dividend capacity		98,000		98,000
Payment of ordinary dividends	$ 98,000
Re One
Statutory Accounting Practices [Line Items]
Statutory capital		$ 5,600		$ 5,600		$ 5,600

Reinsurance - Schedule of ILN Transactions and XOL Transactions (Details) - USD ($) $ in Thousands	Sep. 30, 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	$ 163,190
Initial First Layer Retained Loss					$ 123,424
Current First Layer Retained Loss	$ 121,870
Reinsurance Policy, Type [Axis]: 2020-2 ILN
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Percentage of population with production prior to period start date	1.00%
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	$ 64,181
Initial First Layer Retained Loss				$ 121,777
Current First Layer Retained Loss	$ 121,177
Reinsurance Policy, Type [Axis]: 2021-1 ILN
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
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	$ 235,584
Initial First Layer Retained Loss			$ 163,708
Current First Layer Retained Loss	$ 163,478
Reinsurance Policy, Type [Axis]: 2021-2 ILN
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Percentage of population with production prior to period start date	2.00%
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	$ 328,555
Initial First Layer Retained Loss		$ 146,229
Current First Layer Retained Loss	145,984
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	274,934
Initial First Layer Retained Loss	133,366
Current First Layer Retained Loss	$ 133,238
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	$ 78,892
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	146,513
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	40,264
Current Reinsurance Coverage	40,264
Initial First Layer Retained Loss	62,323
Current First Layer Retained Loss	$ 62,323

Debt - Narrative (Details) - USD ($)			3 Months Ended	9 Months Ended
Debt - Narrative (Details) - USD ($)	Nov. 29, 2021	Jun. 19, 2020	Sep. 30, 2023	Sep. 30, 2023	Dec. 31, 2022
Revolving credit facility
Debt Instrument [Line Items]
Commitment fees in interest expense			$ 200,000	$ 600,000
2018 Term loan
Debt Instrument [Line Items]
Interest payable			9,800,000	9,800,000	$ 2,500,000
2020 Revolving credit facility
Debt Instrument [Line Items]
Debt issuance costs	$ 600,000
2020 Revolving credit facility \| Revolving credit facility
Debt Instrument [Line Items]
Credit facility borrowing capacity	110,000,000
Remaining deferred issuance costs, net of accumulated amortization			900,000	900,000	1,200,000
2021 Revolving credit facility
Debt Instrument [Line Items]
Debt Issuance costs	1,100,000
2021 Revolving credit facility \| Revolving credit facility
Debt Instrument [Line Items]
Credit facility borrowing capacity	$ 250,000,000
Borrowings outstanding			$ 0	$ 0	0
Debt instrument covenant, maximum debt-to-total capitalization ratio				35.00%
2021 Revolving credit facility \| Revolving credit facility \| Minimum
Debt Instrument [Line Items]
Commitment fee (in percent)	0.175%			0.30%
2021 Revolving credit facility \| Revolving credit facility \| Maximum
Debt Instrument [Line Items]
Commitment fee (in percent)	0.525%
2021 Revolving credit facility \| Revolving credit facility \| Base rate
Debt Instrument [Line Items]
Variable rate floor (in percent)	1.00%
2021 Revolving credit facility \| Revolving credit facility \| Base rate \| Minimum
Debt Instrument [Line Items]
Basis spread on variable rate (in percent)	0.375%
2021 Revolving credit facility \| Revolving credit facility \| Base rate \| Maximum
Debt Instrument [Line Items]
Basis spread on variable rate (in percent)	1.875%
2021 Revolving credit facility \| Revolving credit facility \| Secured overnight financing rate \| Minimum
Debt Instrument [Line Items]
Basis spread on variable rate (in percent)	1.375%
2021 Revolving credit facility \| Revolving credit facility \| Secured overnight financing rate \| Maximum
Debt Instrument [Line Items]
Basis spread on variable rate (in percent)	2.875%
Senior debt
Debt Instrument [Line Items]
Effective interest rate (in percent)			7.825%	7.825%
Secured Debt
Debt Instrument [Line Items]
Senior secured notes			$ 400,000,000	$ 400,000,000
Stated interest rate (in percent)			7.375%	7.375%
Applicable premium		1.00%
Debt issuance costs		$ 7,400,000	$ 2,800,000	$ 2,800,000	$ 3,900,000
Secured Debt \| Prior to March 1, 2025
Debt Instrument [Line Items]
Redemption price (in percent)		100.00%
Secured Debt \| After March 1, 2025
Debt Instrument [Line Items]
Redemption price (in percent)		100.00%

Income Taxes - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
Income Taxes - Narrative (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022
Income Tax Disclosure [Abstract]
Effective income tax rate on pre-tax income or loss	21.80%	22.10%	22.40%	22.10%
Prepaid federal income taxes	$ 154,409		$ 154,409		$ 154,409

Stockholders' Equity - Narrative (Details) - USD ($) $ / shares in Units, shares in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2023	Dec. 31, 2022	Jul. 31, 2023	Feb. 10, 2022
Class of Stock [Line Items]
Repurchase authorization				$ 125,000,000
Repurchased shares (in shares)	2.4	2.9
Shares repurchased, average price per share (in dollars per share)	$ 25.13	$ 19.34
Remaining authorized repurchase amount	$ 208,500,000
July 2023 Share Repurchase Program
Class of Stock [Line Items]
Repurchase authorization			$ 200,000,000
2022 Extended Share Repurchase Program
Class of Stock [Line Items]
Repurchase authorization			$ 125,000,000

- Definition

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.

+ References

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
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Reference 2: http://www.xbrl.org/2003/role/recommendedDisclosureRef
-Topic 272
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 272
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Reference 4: http://www.xbrl.org/2009/role/commonPracticeRef
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Reference 5: 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 7: http://www.xbrl.org/2003/role/disclosureRef
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Reference 8: http://www.xbrl.org/2003/role/disclosureRef
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Reference 9: http://www.xbrl.org/2003/role/disclosureRef
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Reference 13: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
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Reference 14: http://www.xbrl.org/2003/role/disclosureRef
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Reference 15: http://www.xbrl.org/2003/role/disclosureRef
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Reference 18: http://www.xbrl.org/2003/role/disclosureRef
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+ Details

CONDENSED CONSOLIDATED BALANCE SHEETS (UNAUDITED) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Assets
Fixed maturities, available-for-sale, at fair value (amortized cost of $2,462,778 and $2,352,747 as of September 30, 2023 and December 31, 2022, respectively)	$ 2,197,686	$ 2,099,389
Cash and cash equivalents (including restricted cash of $2,251 and $2,176 as of September 30, 2023 and December 31, 2022, respectively)	176,463	44,426
Premiums receivable	73,381	69,680
Accrued investment income	17,972	14,144
Deferred policy acquisition costs, net	62,195	58,564
Software and equipment, net	31,991	31,930
Intangible assets and goodwill	3,634	3,634
Reinsurance recoverable	25,956	21,587
Prepaid federal income taxes	154,409	154,409
Other assets	18,344	18,267
Total assets	2,762,031	2,516,030
Liabilities
Debt	397,198	396,051
Unearned premiums	98,211	123,035
Accounts payable and accrued expenses	88,629	74,576
Reserve for insurance claims and claim expenses	116,078	99,836
Reinsurance funds withheld	1,947	2,674
Deferred tax liability, net	257,163	193,859
Other liabilities	11,844	12,272
Total liabilities	971,070	902,303
Commitments and contingencies
Shareholders' equity
Common stock - class A shares, $0.01 par value; 86,940,460 shares issued and 81,630,452 shares outstanding as of September 30, 2023 and 86,472,742 shares issued and 83,549,879 shares outstanding as of December 31, 2022 (250,000,000 shares authorized)	870	865
Additional paid-in capital	981,044	972,717
Treasury Stock, at cost: 5,310,008 and 2,922,863 common shares as of September 30, 2023 and December 31, 2022, respectively	(117,116)	(56,575)
Accumulated other comprehensive loss, net of tax	(213,577)	(204,323)
Retained earnings	1,139,740	901,043
Total shareholders' equity	1,790,961	1,613,727
Total liabilities and shareholders' equity	$ 2,762,031	$ 2,516,030

Reinsurance - Narrative (Details) $ in Thousands			3 Months Ended		9 Months Ended
Reinsurance - Narrative (Details) $ in Thousands	Apr. 01, 2019 USD ($) reinsurance_engagement	Mar. 31, 2019	Sep. 30, 2023 USD ($) reinsuranceAgreement quota_share_agreement	Sep. 30, 2022 USD ($)	Sep. 30, 2023 USD ($) reinsuranceAgreement quota_share_agreement	Sep. 30, 2022 USD ($)	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)
Ceded Credit Risk [Line Items]
Reinsurance coverage amount amortized (as a percent)			10.00%		10.00%
Restricted cash			$ 2,251		$ 2,251		$ 2,176
Number of excess-of-loss reinsurance agreements \| reinsuranceAgreement			5		5
Reinsurance coverage amount			$ 8,000	$ 4,800	$ 22,900	$ 7,700
Number of quota share reinsurance treaties \| quota_share_agreement			7		7
Reinsurance recoverable on unpaid claims			$ 25,956	19,755	$ 25,956	19,755	21,587	$ 20,320
Reinsurance Policy, Type [Axis]: Aggregate 2018 QSR Transactions
Ceded Credit Risk [Line Items]
Reinsurance recoverable on unpaid claims			23,800		23,800		19,000
Reinsurance Policy, Type [Axis]: Aggregate 2020 QSR Transactions
Ceded Credit Risk [Line Items]
Reinsurance recoverable on unpaid claims			23,800		23,800		19,000
Reinsurance Policy, Type [Axis]: Aggregate 2021 QSR Transactions
Ceded Credit Risk [Line Items]
Reinsurance recoverable on unpaid claims			23,800		23,800		19,000
Reinsurance Policy, Type [Axis]: Aggregate 2022 QSR Transactions
Ceded Credit Risk [Line Items]
Reinsurance recoverable on unpaid claims			23,800		23,800		19,000
Reinsurance Policy, Type [Axis]: Aggregate 2022 Seasoned QSR Transactions
Ceded Credit Risk [Line Items]
Reinsurance recoverable on unpaid claims			23,800		23,800		19,000
Reinsurance Policy, Type [Axis]: Aggregate 2023 QSR Transactions
Ceded Credit Risk [Line Items]
Reinsurance recoverable on unpaid claims			23,800		$ 23,800		19,000
Reinsurance Policy, Type [Axis]: Oaktown Re Vehicles
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			2,200		$ 2,200		$ 2,600
Third-party Reinsurers \| Reinsurance Policy, Type [Axis]: 2016 QSR Transaction, Eligible Primary Policies
Ceded Credit Risk [Line Items]
Percent of premiums earned under 2018 QSR Transaction					25.00%
Third-party Reinsurers \| Reinsurance Policy, Type [Axis]: 2016 QSR Transaction, Pool Agreement with Fannie Mae
Ceded Credit Risk [Line Items]
Percent of premiums earned under 2018 QSR Transaction					100.00%
Third-party Reinsurers \| Reinsurance Policy, Type [Axis]: 2018 QSR Transaction
Ceded Credit Risk [Line Items]
Percent of premiums earned under 2018 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]
Percent of premiums earned under 2018 QSR Transaction					20.00%
Third-party Reinsurers \| Reinsurance Policy, Type [Axis]: 2020 QSR Transaction
Ceded Credit Risk [Line Items]
Percent of premiums earned under 2018 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]
Percent of premiums earned under 2018 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]
Percent of premiums earned under 2018 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]
Percent of premiums earned under 2018 QSR Transaction					95.00%
Percentage of ceding commission received					35.00%
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]
Percent of premiums earned under 2018 QSR Transaction					20.00%
Threshold for loss ratio on loans to qualify for profit commission					62.00%
Third-party Reinsurers \| Reinsurance Policy, Type [Axis]: Oaktown Re Vehicles
Ceded Credit Risk [Line Items]
Risk premiums paid			$ 6,900	$ 10,700	$ 24,800	$ 31,800
Third-party Reinsurers \| Reinsurance Policy, Type [Axis]: QSR Transactions
Ceded Credit Risk [Line Items]
Percentage of ceding commission received					20.00%
Maximum
Ceded Credit Risk [Line Items]
Reinsurance coverage, term of underlying mortgage amortization (in years)					12 years 6 months
Maximum \| Third-party Reinsurers \| Reinsurance Policy, Type [Axis]: 2016 QSR Transaction
Ceded Credit Risk [Line Items]
Percent of premiums ceded under QSR Transaction		25.00%
Maximum \| Third-party Reinsurers \| Reinsurance Policy, Type [Axis]: Oaktown Re Vehicles
Ceded Credit Risk [Line Items]
Anticipated payment related to annual operating expenses					$ 250
Minimum
Ceded Credit Risk [Line Items]
Reinsurance coverage, term of underlying mortgage amortization (in years)					10 years
Minimum \| Third-party Reinsurers \| Reinsurance Policy, Type [Axis]: 2016 QSR Transaction
Ceded Credit Risk [Line Items]
Percent of premiums ceded under QSR Transaction	20.50%

Pay vs Performance Disclosure - USD ($) $ in Thousands	3 Months Ended						9 Months Ended
Pay vs Performance Disclosure - USD ($) $ in Thousands	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Sep. 30, 2023	Sep. 30, 2022
Pay vs Performance Disclosure
Net income	$ 83,955	$ 80,284	$ 74,458	$ 76,838	$ 75,444	$ 67,680	$ 238,697	$ 219,962

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 235
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(g)(1)(ii))
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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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-Section S99
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Reference 31: http://www.xbrl.org/2003/role/disclosureRef
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Reference 32: http://www.xbrl.org/2003/role/exampleRef
-Topic 280
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+ Details

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE INCOME (LOSS) (UNAUDITED) (Parenthetical) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Income Statement [Abstract]
Unrealized losses in accumulated other comprehensive loss, net of tax benefit	$ 6,980	$ 15,932	$ 2,467	$ 59,112
Reclassification adjustment for realized (gains) losses included in net income, net of tax expense (benefit)	$ 0	$ 3	$ (7)	$ 100

Regulatory Information

9 Months Ended

Sep. 30, 2023

Insurance [Abstract]

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.

NMIC and Re One generated combined statutory net income of $30.1 million and $80.0 million for the three and nine months ended September 30, 2023, respectively, compared to $23.6 million and $67.8 million for the three and nine months ended September 30, 2022, respectively.

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 surplus, contingency reserve, statutory capital and risk-to-capital (RTC) ratio as of September 30, 2023 and December 31, 2022.



	September 30, 2023		December 31, 2022
	(In Thousands)
Statutory surplus	$	943,761	$	980,225
Contingency reserve	1,493,324		1,266,038
Statutory capital (1)	$	2,437,085	$	2,246,263

Risk-to-capital	11.4:1		11.1:1

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

Re One had $5.6 million of statutory capital at September 30, 2023 and December 31, 2022.

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 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. NMIC has the capacity to pay $98.0 million of aggregate ordinary dividends to NMIH during the twelve-month period ending December 31, 2023, and on May 12, 2023, NMIC paid a $98.0 million ordinary course dividend to NMIH.

Premiums Receivable - Narrative (Details) $ in Millions	9 Months Ended	12 Months Ended
Premiums Receivable - Narrative (Details) $ in Millions	Sep. 30, 2023 USD ($) d	Dec. 31, 2022 USD ($)
Insurance [Abstract]
Number of days to be written off \| d	120
Premium receivable, write-off period	120 days
Premium receivable, allowance for credit loss, uncollected \| $	$ 2.4	$ 2.3

Insider Trading Arrangements	3 Months Ended	9 Months Ended
Insider Trading Arrangements	Sep. 30, 2023 shares	Sep. 30, 2023 shares
Trading Arrangements, by Individual
Non-Rule 10b5-1 Arrangement Adopted	false
Rule 10b5-1 Arrangement Terminated	false
Non-Rule 10b5-1 Arrangement Terminated	false
Bradley M. Shuster [Member]
Trading Arrangements, by Individual
Material Terms of Trading Arrangement		Bradley M. Shuster, our Executive Chairman and Chairman of our Board of Directors adopted a new trading plan on September 21, 2023. The plan's maximum duration is until December 20, 2024, and the first trades will not occur until December 21, 2023, at the earliest. The trading plan covers the sale of up to 418,577 shares of the Company's common stock, including the potential exercise and sale of up to 378,872 shares of the Company's common stock subject to stock options.
Name	Bradley M. Shuster
Title	Executive Chairman and Chairman of our Board of Directors
Rule 10b5-1 Arrangement Adopted	true
Adoption Date	September 21, 2023
Arrangement Duration	365 days
Aggregate Available	418,577	418,577

Regulatory Information (Tables)

9 Months Ended

Sep. 30, 2023

Insurance [Abstract]

Schedule of Statutory Net Income (loss), Surplus, Contingency Reserve and Risk-to-Capital Ratio

The following table presents NMIC's statutory surplus, contingency reserve, statutory capital and risk-to-capital (RTC) ratio as of September 30, 2023 and December 31, 2022.



	September 30, 2023		December 31, 2022
	(In Thousands)
Statutory surplus	$	943,761	$	980,225
Contingency reserve	1,493,324		1,266,038
Statutory capital (1)	$	2,437,085	$	2,246,263

Risk-to-capital	11.4:1		11.1:1

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

- Definition

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.

+ References + Details

Litigation	9 Months Ended
Litigation	Sep. 30, 2023
Commitments and Contingencies Disclosure [Abstract]
Litigation	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 monitoring litigation regarding the refund of certain mortgage insurance premiums as it pertains to provisions of the Homeowners Protection Act and are unable to assess the outcome of such litigation or its potential impact on us at this time.

Reserves for Insurance Claims and Claim Expenses (Tables)

9 Months Ended

Sep. 30, 2023

Insurance [Abstract]

Schedule of Reconciliation of Liability for Insurance Claims and (benefits) Claim Expenses

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


	For the nine months ended September 30,
	2023		2022
	(In Thousands)
Beginning balance	$	99,836	$	103,551
Less reinsurance recoverables (1)	(21,587)		(20,320)
Beginning balance, net of reinsurance recoverables	78,249		83,231

Add claims incurred:
Claims and claim expenses (benefits) incurred:
Current year (2)	60,987		28,135
Prior years (3)	(46,601)		(35,179)
Total claims and claim expenses (benefits) incurred	14,386		(7,044)

Less claims paid:
Claims and claim expenses paid:
Current year (2)	119		73
Prior years (3)	2,394		925

Total claims and claim expenses paid	2,513		998

Reserve at end of period, net of reinsurance recoverables	90,122		75,189
Add reinsurance recoverables (1)	25,956		19,755
Ending balance	$	116,078	$	94,944

(1) Related to ceded losses recoverable under the QSR Transactions. See Note 5, "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 $54.4 million attributed to net case reserves and $5.8 million attributed to net IBNR reserves for the nine months ended September 30, 2023 and $23.3 million attributed to net case reserves and $4.2 million attributed to net IBNR reserves for the nine months ended September 30, 2022.

(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 $41.1 million attributed to net case reserves and $4.5 million attributed to net IBNR reserves for the nine months ended September 30, 2023 and $29.2 million attributed to net case reserves and $4.7 million attributed to net IBNR reserves for the nine months ended September 30, 2022.

Reserves for Insurance Claims and Claim Expenses - Narrative (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2023 USD ($) claim loan policy	Sep. 30, 2022 USD ($)	Dec. 31, 2022 USD ($) loan policy	Dec. 31, 2021 USD ($)
Liability for Claims and Claims Adjustment Expense [Line Items]
Total gross liability for unpaid claims and claim adjustment expenses	$ 116,078	$ 94,944	$ 99,836	$ 103,551
Number of claims paid \| claim	129
Claims paid, including amounts covered by insurance	$ 3,100
Primary loans in default \| loan	4,594		4,449
Primary insured portfolio, loan default rate	0.74%		0.75%
Total number of policies in-force \| policy	622,993		594,142
Favorable development on prior year defaults	$ 46,600	$ 35,200
Reserve for prior year insurance claims and claim expenses	$ 37,500
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 \| claim	123
Component of claims paid covered under QSR Transaction	$ 600

Earnings per Share (EPS) (Tables)

9 Months Ended

Sep. 30, 2023

Earnings Per Share [Abstract]

Schedule of Earnings Per Share, Basic and Diluted

The following table reconciles the net income and the weighted average shares of common stock outstanding used in the computations of basic and diluted EPS of common stock:


	For the three months ended September 30,				For the nine months ended September 30,
	2023		2022		2023		2022
	(In Thousands, except for per share data)
Net income	$	83,955	$	76,838	$	238,697	$	219,962
Basic weighted average shares outstanding	82,096		84,444		82,879		85,369
Basic earnings per share	$	1.02	$	0.91	$	2.88	$	2.58

Net income	$	83,955	$	76,838	$	238,697	$	219,962
Gain from change in fair value of warrant liability	—		—		—		(1,113)
Diluted net income	$	83,955	$	76,838	$	238,697	$	218,849

Basic weighted average shares outstanding	82,096		84,444		82,879		85,369
Dilutive effect of issuable shares	1,574		1,041		1,357		1,051
Diluted weighted average shares outstanding	83,670		85,485		84,236		86,420

Diluted earnings per share	$	1.00	$	0.90	$	2.83	$	2.53

Anti-dilutive shares	1		30		2		30

Investments - Schedule of Net Investment Income (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Investment Income, Net [Abstract]
Investment income	$ 18,037	$ 12,314	$ 49,802	$ 34,084
Investment expenses	(184)	(369)	(537)	(1,019)
Net investment income	17,853	11,945	49,265	33,065
Cash and Cash Equivalents
Investment Income, Net [Abstract]
Investment income	$ 800	$ 100	$ 1,400	$ 200

Reinsurance - Schedule of Amounts Related to QSR Transactions (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Ceded Credit Risk [Line Items]
Ceded premiums earned	$ (34,724)	$ (33,904)	$ (105,877)	$ (82,617)
Third-party Reinsurers
Ceded Credit Risk [Line Items]
Ceded risk-in-force	12,753,261	12,511,797	12,753,261	12,511,797
Ceded premiums earned	(42,015)	(42,265)	(126,113)	(101,501)
Ceded claims and claim expenses (benefits)	2,221	248	4,989	(314)
Ceding commission earned	9,808	10,193	29,650	22,225
Profit commission	$ 22,184	$ 23,899	$ 67,949	$ 58,400

Investments (Tables)

9 Months Ended

Sep. 30, 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 September 30, 2023	(In Thousands)
U.S. Treasury securities and obligations of U.S. government agencies	$	82,373	$	—	$	(2,201)	$	80,172
Municipal debt securities	676,519		—		(79,448)		597,071
Corporate debt securities	1,595,468		97		(178,459)		1,417,106
Asset-backed securities	67,820		—		(5,064)		62,756
Total bonds	2,422,180		97		(265,172)		2,157,105

Short-term investments	40,598		1		(18)		40,581
Total investments	$	2,462,778	$	98	$	(265,190)	$	2,197,686


	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 Corporate Debt Securities by Industry Group

The following table presents a breakdown of the fair value of our corporate debt securities by issuer industry group as of September 30, 2023 and December 31, 2022:


	September 30, 2023		December 31, 2022
Financial	34	%	38	%
Consumer	27		24
Utilities	13		11
Communications	9		11
Industrial	9		8
Technology	8		8



Total	100	%	100	%

Schedule of Investments by Maturity


As of September 30, 2023	Amortized Cost		Fair Value
	(In Thousands)
Due in one year or less	$	211,754	$	209,298
Due after one through five years	1,111,356		1,008,847
Due after five through ten years	1,040,729		887,169
Due after ten years	31,119		29,616
Asset-backed securities	67,820		62,756
Total investments	$	2,462,778	$	2,197,686


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 September 30, 2023		($ In Thousands)
U.S. Treasury securities and obligations of U.S. government agencies	9	$	4,962	$	(224)	18	$	75,210	$	(1,977)	27	$	80,172	$	(2,201)
Municipal debt securities	28	133,262		(4,594)		223	457,059		(74,854)		251	590,321		(79,448)
Corporate debt securities	51	286,184		(10,281)		271	1,119,098		(168,178)		322	1,405,282		(178,459)
Asset-backed securities	—	—		—		25	62,756		(5,064)		25	62,756		(5,064)
Short-term investments	2	27,772		(18)		—	—		—		2	27,772		(18)
Total	90	$	452,180	$	(15,117)	537	$	1,714,123	$	(250,073)	627	$	2,166,303	$	(265,190)


	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 three months ended September 30,				For the nine months ended September 30,
	2023		2022		2023		2022
	(In Thousands)
Investment income (1)	$	18,037	$	12,314	$	49,802	$	34,084
Investment expenses	(184)		(369)		(537)		(1,019)
Net investment income	$	17,853	$	11,945	$	49,265	$	33,065

Schedule of Net Realized Investment Gains (Losses)

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


	For the three months ended September 30,				For the nine months ended September 30,
	2023		2022		2023		2022
	(In Thousands)
Gross realized investment gains	$	—	$	24	$	—	$	490
Gross realized investment losses	—		(10)		(33)		(15)
Net realized investment gains (losses)	$	—	$	14	$	(33)	$	475

- Definition

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

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 9
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-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-9

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
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-Section 50
-Paragraph 3
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-3

Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef
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-URI https://asc.fasb.org//1943274/2147481800/320-10-50-2

Reference 4: http://www.xbrl.org/2009/role/commonPracticeRef
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Reference 5: http://www.xbrl.org/2009/role/commonPracticeRef
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-Section 50
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Reference 6: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
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Reference 7: http://www.xbrl.org/2009/role/commonPracticeRef
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Reference 8: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
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Reference 9: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
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-URI https://asc.fasb.org//1943274/2147481800/320-10-50-3

Reference 10: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
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-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-3

Reference 11: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-3

Reference 12: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-3

+ Details

Reserves for Insurance Claims and Claim Expenses - Reconciliation of Reserve Balances for Insurance Claims and Claim Expense (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Beginning balance	$ 99,836	$ 103,551
Less reinsurance recoverables	(21,587)	(20,320)
Beginning balance, net of reinsurance recoverables	78,249	83,231
Claims and claim expenses (benefits) incurred:
Current year	60,987	28,135
Prior years	(46,601)	(35,179)
Total claims and claim expenses (benefits) incurred	14,386	(7,044)
Claims and claim expenses paid:
Current year	119	73
Prior years	2,394	925
Total claims and claim expenses paid	2,513	998
Reserve at end of period, net of reinsurance recoverables	90,122	75,189
Add reinsurance recoverables	25,956	19,755
Ending balance	116,078	94,944
Current year case reserves	54,400	23,300
Current year IBNR	5,800	4,200
Prior year case reserves	41,100	29,200
Prior year, IBNR	$ 4,500	$ 4,700

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE INCOME (LOSS) (UNAUDITED) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Revenues
Net premiums earned	$ 130,089	$ 118,317	$ 377,828	$ 355,682
Net investment income	17,853	11,945	49,265	33,065
Net realized investment gains (losses)	0	14	(33)	475
Other revenues	217	301	563	1,016
Total revenues	148,159	130,577	427,623	390,238
Expenses
Insurance claims and claim expenses (benefits)	4,812	(3,389)	14,386	(7,044)
Underwriting and operating expenses	27,749	27,144	80,983	90,779
Service expenses	239	197	586	963
Interest expense	8,059	8,036	24,146	24,128
Gain from change in fair value of warrant liability	0	0	0	(1,113)
Total expenses	40,859	31,988	120,101	107,713
Income before income taxes	107,300	98,589	307,522	282,525
Income tax expense	23,345	21,751	68,825	62,563
Net income	$ 83,955	$ 76,838	$ 238,697	$ 219,962
Earnings per share
Basic (in dollars per share)	$ 1.02	$ 0.91	$ 2.88	$ 2.58
Diluted (in dollars per share)	$ 1.00	$ 0.90	$ 2.83	$ 2.53
Weighted average common shares outstanding
Basic (in shares)	82,096	84,444	82,879	85,369
Diluted (in shares)	83,670	85,485	84,236	86,420
Comprehensive income:
Net income	$ 83,955	$ 76,838	$ 238,697	$ 219,962
Other comprehensive loss, net of tax:
Unrealized losses in accumulated other comprehensive loss, net of tax benefit of $6,980 and $15,932 for the three months ended September 30, 2023 and 2022, and $2,467 and $59,112 for the nine months ended September 30, 2023 and 2022, respectively	(26,257)	(59,936)	(9,280)	(222,374)
Reclassification adjustment for realized (gains) losses included in net income, net of tax expense (benefit) of $0 and $3 for the three months ended September 30, 2023 and 2022, and $(7) and $100 for the nine months ended September 30, 2023 and 2022, respectively	0	(10)	26	(377)
Other comprehensive loss, net of tax	(26,257)	(59,946)	(9,254)	(222,751)
Comprehensive income (loss)	$ 57,698	$ 16,892	$ 229,443	$ (2,789)

Reinsurance - Schedule of Effect of Reinsurance Agreements on Premiums Written and Earned (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Net premiums written
Direct	$ 157,956	$ 147,192	$ 458,880	$ 429,715
Ceded	(34,688)	(33,646)	(105,492)	(81,678)
Net premiums written	123,268	113,546	353,388	348,037
Net premiums earned
Direct	164,813	152,221	483,705	438,299
Ceded	(34,724)	(33,904)	(105,877)	(82,617)
Net premiums earned	$ 130,089	$ 118,317	$ 377,828	$ 355,682

Reserves for Insurance Claims and Claim Expenses

9 Months Ended

Sep. 30, 2023

Insurance [Abstract]

Reserves for Insurance Claims and Claim Expenses

Reserves for Insurance Claims and Claim ExpensesWe 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 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. As of September 30, 2023, we held gross reserves for insurance claims and claim expenses of $116.1 million. During the nine months ended September 30, 2023, we paid 129 claims totaling $3.1 million, including 123 claims covered under the QSR Transactions representing $0.6 million of ceded claims and claim expenses.

We had 4,594 loans in default in our primary insured portfolio as of September 30, 2023, which represented a 0.74% default rate against 622,993 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 nine months ended September 30,
	2023		2022
	(In Thousands)
Beginning balance	$	99,836	$	103,551
Less reinsurance recoverables (1)	(21,587)		(20,320)
Beginning balance, net of reinsurance recoverables	78,249		83,231

Add claims incurred:
Claims and claim expenses (benefits) incurred:
Current year (2)	60,987		28,135
Prior years (3)	(46,601)		(35,179)
Total claims and claim expenses (benefits) incurred	14,386		(7,044)

Less claims paid:
Claims and claim expenses paid:
Current year (2)	119		73
Prior years (3)	2,394		925

Total claims and claim expenses paid	2,513		998

Reserve at end of period, net of reinsurance recoverables	90,122		75,189
Add reinsurance recoverables (1)	25,956		19,755
Ending balance	$	116,078	$	94,944

(1) Related to ceded losses recoverable under the QSR Transactions. See Note 5, "Reinsurance" for additional information.

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 nine months ended September 30, 2023, compared to the same period in the prior year, primarily driven by 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 both the nine months ended September 30, 2023 and 2022 benefited from favorable development on prior year defaults. We recognized $46.6 million and $35.2 million of favorable prior year development during the nine months ended September 30, 2023 and 2022, 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 $37.5 million related to prior year defaults remained as of September 30, 2023.

Investments - Schedule of Aging of Unrealized Losses (Details) $ in Thousands	Sep. 30, 2023 USD ($) security	Dec. 31, 2022 USD ($) security
Debt Securities, Available-for-sale [Line Items]
Number of securities, less than 12 months \| security	90	241
Fair value, less than 12 months	$ 452,180	$ 772,198
Unrealized losses, less than 12 months	$ (15,117)	$ (36,225)
Number of securities,12 months or greater \| security	537	367
Fair value, 12 months or greater	$ 1,714,123	$ 1,188,415
Unrealized losses, 12 months or greater	$ (250,073)	$ (218,467)
Number of securities, total \| security	627	608
Fair Value	$ 2,166,303	$ 1,960,613
Unrealized Losses	$ (265,190)	$ (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	9	19
Fair value, less than 12 months	$ 4,962	$ 77,164
Unrealized losses, less than 12 months	$ (224)	$ (2,260)
Number of securities,12 months or greater \| security	18	4
Fair value, 12 months or greater	$ 75,210	$ 2,768
Unrealized losses, 12 months or greater	$ (1,977)	$ (109)
Number of securities, total \| security	27	23
Fair Value	$ 80,172	$ 79,932
Unrealized Losses	$ (2,201)	$ (2,369)
Municipal debt securities
Debt Securities, Available-for-sale [Line Items]
Number of securities, less than 12 months \| security	28	57
Fair value, less than 12 months	$ 133,262	$ 143,097
Unrealized losses, less than 12 months	$ (4,594)	$ (12,942)
Number of securities,12 months or greater \| security	223	181
Fair value, 12 months or greater	$ 457,059	$ 340,079
Unrealized losses, 12 months or greater	$ (74,854)	$ (67,854)
Number of securities, total \| security	251	238
Fair Value	$ 590,321	$ 483,176
Unrealized Losses	$ (79,448)	$ (80,796)
Corporate debt securities
Debt Securities, Available-for-sale [Line Items]
Number of securities, less than 12 months \| security	51	141
Fair value, less than 12 months	$ 286,184	$ 434,174
Unrealized losses, less than 12 months	$ (10,281)	$ (19,699)
Number of securities,12 months or greater \| security	271	168
Fair value, 12 months or greater	$ 1,119,098	$ 790,537
Unrealized losses, 12 months or greater	$ (168,178)	$ (145,397)
Number of securities, total \| security	322	309
Fair Value	$ 1,405,282	$ 1,224,711
Unrealized Losses	$ (178,459)	$ (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	25	14
Fair value, 12 months or greater	$ 62,756	$ 55,031
Unrealized losses, 12 months or greater	$ (5,064)	$ (5,107)
Number of securities, total \| security	25	26
Fair Value	$ 62,756	$ 68,558
Unrealized Losses	$ (5,064)	$ (6,204)
Short-term investments
Debt Securities, Available-for-sale [Line Items]
Number of securities, less than 12 months \| security	2	12
Fair value, less than 12 months	$ 27,772	$ 104,236
Unrealized losses, less than 12 months	$ (18)	$ (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	2	12
Fair Value	$ 27,772	$ 104,236
Unrealized Losses	$ (18)	$ (227)

Regulatory Information - Schedule of Statutory Net Income (loss), Surplus, Contingency Reserve and Risk-to-Capital Ratio (Details) - NMIC and Re One combined $ in Thousands	Sep. 30, 2023 USD ($)	Dec. 31, 2022 USD ($)
Statutory Accounting Practices [Line Items]
Statutory surplus	$ 943,761	$ 980,225
Contingency reserve	1,493,324	1,266,038
Statutory capital	$ 2,437,085	$ 2,246,263
Risk-to-capital	11.4	11.1