Investments, Debt and Equity Securities [Abstract] Schedule of Available-for-sale Securities [Table] Schedule of Available-for-sale Securities [Table] Major Types of Debt and Equity Securities [Axis] Major Types of Debt and Equity Securities [Axis] Major Types of Debt and Equity Securities [Domain] Major Types of Debt and Equity Securities [Domain] U.S. Treasury securities and obligations of U.S. government agencies [Member] US Treasury and Government [Member] Municipal bonds [Member] US States and Political Subdivisions Debt Securities [Member] Corporate debt securities [Member] Corporate Debt Securities [Member] Asset-backed securities [Member] Asset-backed Securities [Member] Schedule of Available-for-sale Securities [Line Items] Schedule of Available-for-sale Securities [Line Items] Amortized Cost Available-for-sale Securities, Amortized Cost Basis Gross Unrealized Gains Available-for-sale Securities, Gross Unrealized Gain, Accumulated in Investments Available-for-sale Securities, Gross Unrealized Gain, Accumulated in Investments Gross Unrealized (Losses) Available-for-sale Securities, Gross Unrealized Loss, Accumulated in Investments Available-for-sale Securities, Gross Unrealized Loss, Accumulated in Investments Fair Value Available-for-sale Securities Disclosure of Compensation Related Costs, Share-based Payments [Abstract] Schedule of Stock Option Activity Schedule of Share-based Compensation, Stock Options, Activity [Table Text Block] Schedule of Restricted Stock Units Activity Schedule of Share-based Compensation, Restricted Stock Units Award Activity [Table Text Block] Fair Value Disclosures [Abstract] Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Table] Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Table] Fair Value, Hierarchy [Axis] Fair Value, Hierarchy [Axis] Fair Value Hierarchy [Domain] Fair Value Hierarchy [Domain] Significant Unobservable Inputs (Level 3) [Member] Fair Value, Inputs, Level 3 [Member] Liability Class [Axis] Liability Class [Axis] Fair Value by Liability Class [Domain] Fair Value by Liability Class [Domain] Warrant Liability [Member] Warrant Liability [Member] Warrant Liability [Member] Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] Beginning balance Fair Value, Measurement with Unobservable Inputs Reconciliations, Recurring Basis, Liability Value Change in fair value of warrant liability included in earnings Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Gain (Loss) Included in Earnings Gain on settlement of warrants Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Settlements Issuance of common stock on warrant exercise Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Issuances Ending balance Income Statement [Abstract] Change in unrealized investment gains (losses), tax amount Other Comprehensive Income (Loss), Unrealized Holding Gain (Loss) on Securities Arising During Period, Tax Investments Investments in Debt and Marketable Equity Securities (and Certain Trading Assets) Disclosure [Text Block] Insurance [Abstract] Reserves for Insurance Claims and Claim Expenses Liability for Future Policy Benefits and Unpaid Claims Disclosure [Text Block] Organization, Consolidation and Presentation of Financial Statements [Abstract] Schedule of Business Acquisitions, by Acquisition [Table] Schedule of Business Acquisitions, by Acquisition [Table] Legal Entity [Axis] Legal Entity [Axis] Entity [Domain] Entity [Domain] Combined [Member] NMic and Re one Combined [Member] NMic and Re one Combined [Member] Sale of Stock [Axis] Sale of Stock [Axis] Sale of Stock [Axis] Sale of Stock [Domain] Sale of Stock [Domain] [Domain] for Sale of Stock [Axis] IPO [Member] IPO [Member] Class of Stock [Axis] Class of Stock [Axis] Class of Stock [Domain] Class of Stock [Domain] Class A Common Class A [Member] Business Acquisition [Axis] Business Acquisition [Axis] Business Acquisition, Acquiree [Domain] Business Acquisition, Acquiree [Domain] MAC Financial Holding Corporation and Subsidiaries [Member] MAC Financial Holding Corporation and Subsidiaries [Member] MAC Financial Holding Corporation and Subsidiaries [Member] Business Acquisition [Line Items] Business Acquisition [Line Items] Primary insurance in force Mortgage Insurance in Force, Primary Mortgage Insurance in Force, Primary Pool insurance in force Mortgage Insurance in Force, Pool Mortgage Insurance in Force, Pool Risk in Force Primary Risk in Force Primary This concept represents the risk in force (an estimate of the maximum loss exposure that an entity has at any point in time) for insurance writtten on a primary basis. Primary insurance may be written on a flow basis, in which loans are insured in individual, loan-by-loan transactions, or may be written on a bulk basis, in which each loan in a portfolio of loans is individually insured in a single, bulk transaction. Pool risk in force Mortgage Insurance in Force, Gross, Pool Mortgage Insurance in Force, Gross, Pool Cash, common stock and warrants issued for acquisition Business Combination, Consideration Transferred, Cash and Equity Interests Issued and Issuable Business Combination, Consideration Transferred, Cash and Equity Interests Issued and Issuable Liabilities assumed in acquisition Business Combination, Consideration Transferred, Liabilities Incurred Tax liabilities assumed in acquisition Business Combination, Consideration Transferred, Tax Liabilities Incurred Business Combination, Consideration Transferred, Tax Liabilities Incurred Common stock offered and sold, (in shares) Stock Issued During Period, Shares, New Issues Number of States in which Entity Operates Number of States in which Entity Operates Common stock issue price (usd per share) Share Price Issuance of common stock Proceeds from Issuance of Common Stock Underwriting fee and other offering expense (percent) Stock Issued During Period, Underwriting Fee and Other Offering Expense, Percentage Stock Issued During Period, Underwriting Fee and Other Offering Expense, Percentage Underwriting fee and other offering expense Proceeds from Issuance Initial Public Offering, Net Proceeds from Issuance Initial Public Offering, Net Statutory capital and surplus required Statutory Accounting Practices, Statutory Capital and Surplus Required Required Risk-to-Capital Ratio on Agreements Per GSE Approval, Maximum Required Risk-to-Capital Ratio on Agreements Per GSE Approval, Maximum Required Risk-to-Capital Ratio on Agreements Per GSE Approval, Maximum Antidilutive securities excluded from computation of earnings per share (in shares) Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount Deferred policy acquisition costs, net Deferred Policy Acquisition Costs Statutory Accounting Practices [Table] Statutory Accounting Practices [Table] Jurisdiction [Axis] Jurisdiction [Axis] Statutory Accounting Practices, Jurisdiction [Domain] Statutory Accounting Practices, Jurisdiction [Domain] WISCONSIN [Member] WISCONSIN Fannie Mae [Member] Fannie Mae [Member] Fannie Mae [Member] Range [Axis] Range [Axis] Range [Domain] Range [Domain] Maximum [Member] Maximum [Member] NMIC [Member] NMIC [Member] NMIC [Member] Subsidiaries [Member] Subsidiaries [Member] Statutory Accounting Practices [Line Items] Statutory Accounting Practices [Line Items] Number of states which require minimum amount of statutory capital relative to risk in force Number of States Which Require Minimum Amount of Statutory Capital Relative to Risk In Force Number of States Which Require Minimum Amount of Statutory Capital Relative to Risk In Force Risk-to-capital Risk To Capital Ratio Regulatory Maximum Risk To Capital Ratio Regulatory Maximum Potential risk In force to capital, ratio Potential Risk In Force to Capital, Ratio Potential Risk In Force to Capital, Ratio Mortgage insurance, percentage of indebtedness on single loan Mortgage Insurance, Percentage of Indebtedness on Single Loan, Limit Mortgage Insurance, Percentage of Indebtedness on Single Loan, Limit Number of policies in force Number of Policies in Force Number of Policies in Force Shareholders' equity Stockholders' Equity Attributable to Parent Investment in subsidiaries, at equity in net assets Equity Method Investments Ordinary dividends, restriction with regards to capital surplus Ordinary Dividends, Restriction with Regards to Capital Surplus This concept represents the maximum percentage of surplus as of the prior year that an insurer may pay out in ordinary dividends without prior approval of the Wisconsin Office of the Commissioner of Insurance under Wisconsin law. Mortgage Insurance Risk in Force Mortgage Insurance Risk in Force This concept represents the risk in force (an estimate of the maximum loss exposure that an entity has at any point in time). Goodwill and Intangible Assets Disclosure [Abstract] Schedule of Indefinite-Lived Intangible Assets Schedule of Indefinite-Lived Intangible Assets [Table Text Block] Property, Plant and Equipment [Abstract] Schedule of Equipment and Software Property, Plant and Equipment [Table Text Block] Unrealized losses Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Loss, Accumulated in Investments Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Loss, Accumulated in Investments Unrealized Losses, 12 Months or Greater Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Loss, Accumulated in Investments Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Loss, Accumulated in Investments Cash and investments held with various state insurance departments Cash, Cash Equivalents, and Short-term Investments Schedule of Significant Acquisitions and Disposals [Table] Schedule of Significant Acquisitions and Disposals [Table] Significant Acquisitions and Disposals by Transaction [Axis] Significant Acquisitions and Disposals by Transaction [Axis] Significant Acquisitions and Disposals, Transaction [Domain] Significant Acquisitions and Disposals, Transaction [Domain] Significant Acquisitions and Disposals [Line Items] Significant Acquisitions and Disposals [Line Items] Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment Depreciation and amortization Depreciation, Depletion and Amortization Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Plan Name [Axis] Plan Name [Axis] Plan Name [Domain] Plan Name [Domain] The 2012 Stock Incentive Plan [Member] The 2012 Stock Incentive Plan [Member] The 2012 Stock Incentive Plan [Member] Award Type [Axis] Award Type [Axis] Equity Award [Domain] Equity Award [Domain] Restricted Stock Units [Member] Restricted Stock Units (RSUs) [Member] Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward] Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward] Restricted Stock beginning balance (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number Restricted stock units granted (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period Less: Restricted stock units vested (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period Less: Restricted stock units forfeited (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period Restricted Stock ending balance (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract] Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract] Restricted Stock beginning balance (in dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value Restricted Stock Units Granted (in dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value Less: Restricted Stock Units Vested (in dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Weighted Average Grant Date Fair Value Less: Restricted Stock Units Forfeited (in dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeitures, Weighted Average Grant Date Fair Value Restricted Stock ending balance (in dollars per share) Total bonds [Member] Bonds [Member] Available-for-sale Securities, Debt Maturities, Single Maturity Date, Amortized Cost Basis [Abstract] Available-for-sale Securities, Debt Maturities, Single Maturity Date, Amortized Cost Basis [Abstract] Amortized Cost, Due in one year or less Available-for-sale Securities, Debt Maturities, Next Twelve Months, Amortized Cost Basis Amortized Cost, Due after one through five years Available-for-sale Securities, Debt Maturities, Year Two Through Five, Amortized Cost Basis Amortized Cost, Due after five through ten years Available-for-sale Securities, Debt Maturities, Year Six Through Ten, Amortized Cost Basis Amortized Cost, Due after ten years Available-for-sale Securities, Debt Maturities, after Ten Years, Amortized Cost Basis Amortized Cost, Total Investments Available-for-sale Securities, Debt Maturities, Single Maturity Date [Abstract] Available-for-sale Securities, Debt Maturities, Single Maturity Date [Abstract] Fair Value, Due in one year or less Available-for-sale Securities, Debt Maturities, Next Twelve Months, Fair Value Fair Value, Due after one through five years Available-for-sale Securities, Debt Maturities, Year Two Through Five, Fair Value Fair Value, Due after five through ten years Available-for-sale Securities, Debt Maturities, Year Six Through Ten, Fair Value Fair Value Due after ten years Available-for-sale Securities, Debt Maturities, after Ten Years, Fair Value Fair Value, Total Investments Property, Plant and Equipment [Table] Property, Plant and Equipment [Table] Property, Plant and Equipment, Type [Axis] Property, Plant and Equipment, Type [Axis] Property, Plant and Equipment, Type [Domain] Property, Plant and Equipment, Type [Domain] Software Software and Software Development Costs [Member] Equipment Equipment [Member] Leasehold improvements Leasehold Improvements [Member] Property, Plant and Equipment [Line Items] Property, Plant and Equipment [Line Items] Property plant and equipment Property, Plant and Equipment, Gross Accumulated amortization and depreciation Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment Software and equipment, net Property, Plant and Equipment, Net Debt Disclosure [Abstract] Warrants Line of Credit and Related Warrants [Text Block] Line of Credit and Related Warrants [Text Block] Statement of Cash Flows [Abstract] Cash Flows From Operating Activities Net Cash Provided by (Used in) Operating Activities [Abstract] Net loss Net Income (Loss) Attributable to Parent Adjustments to reconcile net loss to net cash used in operating activities: Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract] Net realized investment gains Available-for-sale Securities, Gross Realized Gain (Loss) (Gain) loss from change in fair value of warrant liability Gain (Loss) on Change in Fair Value of Warrant Liability Gain (Loss) on Change in Fair Value of Warrant Liability Gain from settlement of warrants Gain (Loss) From Settlement of Warrants Gain (Loss) From Settlement of Warrants Depreciation and other amortization Depreciation, Amortization and Accretion, Net Share-based compensation expense Share-based Compensation Benefit for taxes on current year unrealized gains Expense (Benefit) for Taxes on Current Year Unrealized Gains Expense (Benefit) for Taxes on Current Year Unrealized Gains Changes in operating assets and liabilities: Increase (Decrease) in Other Operating Assets and Liabilities, Net [Abstract] Accrued investment income Increase (Decrease) in Accrued Investment Income Receivable Premiums receivable Increase (Decrease) in Premiums Receivable Prepaid expenses Increase (Decrease) in Prepaid Expense Deferred policy acquisition costs, net Increase (Decrease) in Deferred Policy Acquisition Costs Other assets Increase (Decrease) in Prepaid Expense and Other Assets Unearned premiums (Increase) Decrease in Unearned Premiums, Net Reserve for insurance claims and claims expenses Increase (Decrease) in Loss and Loss Adjustment Expense Reserve Accounts payable and accrued expenses Increase (Decrease) in Accounts Payable and Accrued Liabilities Net Cash Used in Operating Activities Net Cash Provided by (Used in) Operating Activities, Continuing Operations Cash Flows From Investing Activities Net Cash Provided by (Used in) Investing Activities [Abstract] Purchase of short-term investments Payments to Acquire Short-term Investments Purchase of fixed-maturity investments, available-for-sale Payments to Acquire Available-for-sale Securities, Debt Proceeds from maturity of short-term investments Proceeds from Sale of Short-term Investments Proceeds from redemptions, maturities and sale of fixed-maturity investments, available-for-sale Proceeds from Sale of Available-for-sale Securities, Debt Purchase of software and equipment Payments to Acquire Property, Plant, and Equipment Net Cash Used in Investing Activities Net Cash Provided by (Used in) Investing Activities Cash Flows From Financing Activities Net Cash Provided by (Used in) Financing Activities [Abstract] Taxes paid related to net share settlement of equity awards Payments Related to Tax Withholding for Share-based Compensation Net Cash Provided by (Used in) Financing Activities Net Cash Provided by (Used in) Financing Activities Net Decrease in Cash and Cash Equivalents Cash and Cash Equivalents, Period Increase (Decrease) Cash and Cash Equivalents, beginning of period Cash and Cash Equivalents, at Carrying Value Cash and Cash Equivalents, end of period Statement of Financial Position [Abstract] Statement [Table] Statement [Table] Statement [Line Items] Statement [Line Items] Assets Assets [Abstract] Investments, available-for-sale, at fair value: Marketable Securities, Fixed Maturities [Abstract] Fixed maturities (amortized cost of $413,816 and $416,135 as of June 30, 2014 and December 31, 2013, respectively) Available-for-sale Securities, Debt Securities Total investments Investments Cash and cash equivalents Accrued investment income Accrued Investment Income Receivable Premiums receivable Premiums Receivable, Net Prepaid expenses Prepaid Expense Goodwill and other indefinite lived intangible assets Intangible Assets, Net (Including Goodwill) Software and equipment, net Other assets Other Assets Total Assets Assets Liabilities Liabilities [Abstract] Unearned premiums Unearned Premiums Reserve for insurance claims and claims expenses Liability for Claims and Claims Adjustment Expense Accounts payable and accrued expenses Accounts Payable and Accrued Liabilities Warrant liability, at fair value Warrant Liability Warrant Liability Current tax payable Taxes Payable, Current Deferred tax liability Deferred Tax Liabilities, Net Total Liabilities Liabilities Commitments and contingencies Commitments and Contingencies Shareholders' Equity Stockholders' Equity Attributable to Parent [Abstract] Common stock - Class A shares, $0.01 par value, 58,363,334 and 58,052,480 shares issued and outstanding as of June 30, 2014 and December 31, 2013, respectively (250,000,000 shares authorized) Common Stock, Value, Outstanding Additional paid-in capital Additional Paid in Capital Accumulated other comprehensive loss, net of tax Accumulated Other Comprehensive Income (Loss), Net of Tax Accumulated deficit Retained Earnings (Accumulated Deficit) Total Shareholders' Equity Total Liabilities and Shareholders' Equity Liabilities and Equity Income Tax Disclosure [Abstract] Federal statutory income tax rate Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent Effective Income Tax Rate Reconciliation, Percent Effective Income Tax Rate Reconciliation, Percent Income tax benefit Income Tax Expense (Benefit) Tax provision expense netted against unrealized gains in OCI Income Tax Expense (Benefit) Netted Against Income Tax Expense (Benefit) Netted Against Deferred tax liabilities, net Class B Common Class B [Member] Fixed maturity, amortized cost Available-for-sale Debt Securities, Amortized Cost Basis Common stock, par value (in dollars per share) Common Stock, Par or Stated Value Per Share Common stock, shares issued Common Stock, Shares, Issued Common stock, shares outstanding Common Stock, Shares, Outstanding Common stock, shares authorized Common Stock, Shares Authorized Fair Value of Financial Instruments Fair Value Disclosures [Text Block] Organization and Basis of Presentation Business Description and Basis of Presentation [Text Block] Commitments and Contingencies Disclosure [Abstract] Litigation Legal Matters and Contingencies [Text Block] Statutory Information Insurance Disclosure [Text Block] Schedule of Indefinite-Lived Intangible Assets [Table] Schedule of Indefinite-Lived Intangible Assets [Table] Indefinite-lived Intangible Assets [Axis] Indefinite-lived Intangible Assets [Axis] Indefinite-lived Intangible Assets, Major Class Name [Domain] Indefinite-lived Intangible Assets, Major Class Name [Domain] State licenses [Member] State Licenses [Member] State Licenses [Member] GSE Approvals [Member] GSE Approvals [Member] GSE Approvals [Member] Indefinite-lived Intangible Assets [Line Items] Indefinite-lived Intangible Assets [Line Items] Goodwill Goodwill Intangible assets Indefinite-Lived Intangible Assets (Excluding Goodwill) Goodwill impairment Goodwill, Impaired, Accumulated Impairment Loss Statement of Stockholders' Equity [Abstract] Equity Components [Axis] Equity Components [Axis] Equity Component [Domain] Equity Component [Domain] Common stock Common Stock [Member] Issuance of Class A shares of common stock as part of cashless exercise of warrants, shares Stock Issued During Period, Shares, Other Issuance of shares of common stock, shares Payments of stock issuance costs Payments of Stock Issuance Costs Document and Entity Information [Abstract] Document and Entity Information [Abstract] Entity Registrant Name Entity Registrant Name Entity Central Index Key Entity Central Index Key Document Type Document Type Document Period End Date Document Period End Date Amendment Flag Amendment Flag Document Fiscal Year Focus Document Fiscal Year Focus Document Fiscal Period Focus Document Fiscal Period Focus Current Fiscal Year End Date Current Fiscal Year End Date Entity Current Reporting Status Entity Current Reporting Status Entity Filer Category Entity Filer Category Entity Common Stock, Shares Outstanding Entity Common Stock, Shares Outstanding Schedule of Fair Values and Gross Unrealized Gains and Losses Available-for-sale Securities [Table Text Block] Schedule of Investments by Maturity Investments Classified by Contractual Maturity Date [Table Text Block] Schedule of Net Realized Gain (Loss) on Investments Realized Gain (Loss) on Investments [Table Text Block] Schedule of Aging Unrealized Losses Schedule of Unrealized Loss on Investments [Table Text Block] Schedule of Net Investment Income Investment Income [Table Text Block] Net realized investment gains Schedule of Risk to Capital Statutory Accounting Practices Disclosure [Table Text Block] Additional Paid-in Capital Additional Paid-in Capital [Member] Accumulated Other Comprehensive Loss Accumulated Other Comprehensive Income (Loss) [Member] Accumulated Deficit Retained Earnings [Member] Increase (Decrease) in Stockholders' Equity [Roll Forward] Increase (Decrease) in Stockholders' Equity [Roll Forward] Beginning Balance Common stock Class A shares issued related to warrants Stock and Warrants Issued During Period, Value, Preferred Stock and Warrants Common stock Class A shares issued under stock plans, net of shares withheld for employee taxes Stock Issued During Period, Value, Share-based Compensation, Gross Issuance of shares of common stock Stock Issued During Period, Value, New Issues Conversion of Class B shares of common stock into Class A shares of common stock Stock Issued During Period, Value, Acquisitions Share-based compensation expense Adjustments to Additional Paid in Capital, Share-based Compensation, Requisite Service Period Recognition Change in unrealized investment gains/losses, net of tax Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, Net of Tax Net loss Ending Balance Vesting [Axis] Vesting [Axis] Vesting [Domain] Vesting [Domain] Subject to Market and Service Conditions [Member] Subject to Market and Service Conditions [Member] Subject to Market and Service Conditions [Member] Subject to Service Conditions [Member] Subject to Service Conditions [Member] Subject to Service Conditions [Member] Minimum [Member] Minimum [Member] 2014 Omnibus Incentive Plan Two Thousand Fourteen Omnibus Incentive Plan [Member] Two Thousand Fourteen Omnibus Incentive Plan [Member] Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period Number of options vested (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Exercisable, Number Weighted average exercise price for options vested (in dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Exercisable, Weighted Average Exercise Price Weighted average remaining contractual term Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Exercisable, Weighted Average Remaining Contractual Term Options vested aggregate value Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Exercisable, Aggregate Intrinsic Value Restricted stock units outstanding (in shares) Restricted stock vesting period Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period Shares authorized for grant under the Plan Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant Equity [Abstract] Schedule of Stock by Class [Table] Schedule of Stock by Class [Table] Class of Stock [Line Items] Class of Stock [Line Items] Statutory net loss Statutory Accounting Practices, Statutory Net Income Amount Statutory surplus Statutory Accounting Practices, Statutory Capital and Surplus, Balance Contingency reserve Statutory Accounting Practices, Contingency Reserve Statutory Accounting Practices, Contingency Reserve Software and Equipment Property, Plant and Equipment Disclosure [Text Block] Fair Value Measurements, Recurring and Nonrecurring [Table] Fair Value Measurements, Recurring and Nonrecurring [Table] Measurement Frequency [Axis] Measurement Frequency [Axis] Fair Value, Measurement Frequency [Domain] Fair Value, Measurement Frequency [Domain] Fair Value, Measurements, Recurring [Member] Fair Value, Measurements, Recurring [Member] Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] Fair Value, Inputs, Level 1 [Member] Significant Other Observable Inputs (Level 2) [Member] Fair Value, Inputs, Level 2 [Member] Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Available-for-sale Securities Cash and cash equivalents Cash and Cash Equivalents, Fair Value Disclosure Total Assets Assets, Fair Value Disclosure Financial and Nonfinancial Liabilities, Fair Value Disclosure Financial and Nonfinancial Liabilities, Fair Value Disclosure Fair Value Measurements, Recurring and Nonrecurring Fair Value Measurements, Recurring and Nonrecurring [Table Text Block] Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Table Text Block] Investment Type [Axis] Investment Type [Axis] Investments [Domain] Investments [Domain] Fixed maturities [Member] Fixed Maturities [Member] Cash equivalents [Member] Cash and Cash Equivalents [Member] Investment income Investment Income Gross Investment Income Gross Investment expenses Investment Income, Investment Expense Net Investment Income Investment Income, Net Re One [Member] NMI Re One [Member] NMI Re One [Member] Primary risk-in-force Primary Risk in Force [Abstract] Primary Risk in Force [Abstract] Direct Primary Risk in Force, Gross Primary Risk in Force, Gross Assumed Primary Risk in Force, Assumed Primary Risk in Force, Assumed Ceded Primary Risk in Force, Ceded Primary Risk in Force, Ceded Total primary risk-in-force Pool risk-in-force Mortgage Insurance, Risk in Force, Pool [Abstract] Mortgage Insurance, Risk in Force, Pool [Abstract] Direct Assumed Mortgage Insurance in Force, Assumed, Pool Mortgage Insurance in Force, Assumed, Pool Ceded Mortgage Insurance in Force, Ceded, Pool Mortgage Insurance in Force, Ceded, Pool Total pool risk-in-force Mortgage Insurance Risk In Force, Pool This concept represents the risk in force (an estimate of the maximum loss exposure that an entity has at any point in time) for insurance written on a pool basis. In a pool policy, where a group of loans (or pool) are insured under a single contract. Pool insurance may have a stated aggregate loss limit for a pool of loans and may also have a deductible under which no losses are paid by the insurer until losses on the pool of loans exceed the deductible. Total risk-in-force Statutory policyholders' surplus Statutory contingency reserve Contingency Reserve Funds separated from retained earnings and held to cover any unforseen future business losses. Total statutory policyholders' position Statutory Accounting Practices Statutory Policyholders Surplus Plus Contingency Reserves Statutory Accounting Practices Statutory Policyholders Surplus Plus Contingency Reserves Risk to capital ratio Risk To Capital Ratio Regulatory Actual This concept represents an entity's ratio of net risk in force (excludes risk ceded through reinsurance contracts and risk in force on defaulted loans) to the amount of statutory capital (defined as the sum of statutory policyholders' surplus plus statutory contingency reserves). Common Stock Offering Stockholders' Equity Note Disclosure [Text Block] Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward] Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward] Options beginning balance (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number Options granted (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross Less: Options exercised (in shares) Less: Options forfeited (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Options, Forfeitures in Period Options ending balance (in shares) Weighted Average Grant Date Fair Value per Share Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract] Options beginning balance (in dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price Options granted (in dollars per share) Share-based Compensation Arrangements by Share-based Payment Award, Options, Grants in Period, Weighted Average Exercise Price Less: Options exercised (in dollars per share) Share-based Compensation Arrangements by Share-based Payment Award, Options, Exercises in Period, Weighted Average Exercise Price Less: Options forfeited (in dollars per share) Share-based Compensation Arrangements by Share-based Payment Award, Options, Forfeitures in Period, Weighted Average Exercise Price Options ending balance (in dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested, Number of Shares [Roll Forward] Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested, Number of Shares [Roll Forward] Options beginning balance (in dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested, Weighted Average Grant Date Fair Value Options granted (in dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value Less: Options exercised (in dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Weighted Average Grant Date Fair Value Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Weighted Average Grant Date Fair Value Less: Options forfeited (in dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested Options Forfeited, Weighted Average Grant Date Fair Value Options ending balance (in dollars per share) Intangible Assets and Goodwill Intangible Assets Disclosure [Text Block] Income Taxes Income Tax Disclosure [Text Block] Share Price (in dollars per share) Risk free rate Fair Value Assumptions, Risk Free Interest Rate Expected term Fair Value Assumptions, Expected Term Volatility Assumption Fair Value Assumptions, Expected Volatility Rate Expected dividend rate Fair Value Assumptions, Expected Dividend Rate Deductible on policy Mortgage Pool Insurance, Claim Deductible Mortgage Pool Insurance, Claim Deductible Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward] Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward] Reserve at beginning of period Liability for Unpaid Claims and Claims Adjustment Expense, Gross Liability for Unpaid Claims and Claims Adjustment Expense, Incurred Claims [Abstract] Liability for Unpaid Claims and Claims Adjustment Expense, Incurred Claims [Abstract] Current year Liability for Unpaid Claims and Claims Adjustment Expense, Incurred Claims Current Year Prior years Liability for Unpaid Claims and Claims Adjustment Expense, Incurred Claims, Prior Years Total claims incurred Liability for Unpaid Claims and Claims Adjustment Expense, Incurred Claims Liability for Unpaid Claims and Claims Adjustment Expense, Claims Paid [Abstract] Liability for Unpaid Claims and Claims Adjustment Expense, Claims Paid [Abstract] Current year Liability for Unpaid Claims and Claims Adjustment Expense, Claims Paid, Current Year Prior years Liability for Unpaid Claims and Claims Adjustment Expense, Claims Paid, Prior Years Total claims paid Liability for Unpaid Claims and Claims Adjustment Expense, Claims Paid Reserve at end of period Line of Credit Facility [Table] Line of Credit Facility [Table] Line of Credit Facility [Line Items] Line of Credit Facility [Line Items] Warrants issued (in shares) Class of Warrant or Right, Number of Securities Called by Warrants or Rights Exercise price of warrants (in dollars per warrant) Class of Warrant or Right, Exercise Price of Warrants or Rights Warrants value Warrants and Rights Outstanding Class of Warrant or Right, Number of Warrants Exercised During Period Class of Warrant or Right, Number of Warrants Exercised During Period Class of Warrant or Right, Number of Warrants Exercised During Period Gain from settlement of warrants Number of securities, less than 12 months Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Less than One Year Fair Value, Less than 12 Months Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value Unrealized Losses, Less than 12 Months Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Loss Accumulated In Investments Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Loss Accumulated In Investments Number of securities,12 months or greater Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Greater than or Equal to One Year Fair Value, 12 Months or Greater Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value Number of securities, Total Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions Fair Value, Total Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value Unrealized Losses Reconciliation of Liability for Insurance Claims and Claims Expenses Schedule of Liability for Unpaid Claims and Claims Adjustment Expense [Table Text Block] Revenues Revenues [Abstract] Premiums written Premiums Written, Net [Abstract] Direct Direct Premiums Written Net premiums written Premiums Written, Net Increase in unearned premiums Net premiums earned Premiums Earned, Net Net investment income Net Investment Income Gain (loss) from change in fair value of warrant liability Total Revenues Revenues Expenses Costs and Expenses [Abstract] Insurance claims and claims expenses Policyholder Benefits and Claims Incurred, Net, Property, Casualty and Liability Amortization of deferred policy acquisition costs Deferred Policy Acquisition Cost, Amortization Expense Other underwriting and operating expenses Other Cost and Expense, Operating Total Expenses Costs and Expenses Loss before income taxes Income (Loss) from Continuing Operations before Income Taxes, Extraordinary Items, Noncontrolling Interest Net Loss Other Comprehensive Income (Loss), net of tax Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent [Abstract] Net unrealized holding gains (losses) for the period included in accumulated other comprehensive loss, net of tax expense of $2,664 and $0 for the three months ended June 30, 2014 and 2013, respectively, and $2,664 and $0 for the six months ended June 30, 2014 and 2013, respectively Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, Net of Tax, Portion Attributable to Parent Other Comprehensive Income (Loss), net of tax Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent Total Comprehensive Loss Comprehensive Income (Loss), Net of Tax, Attributable to Parent Loss per share Earnings Per Share, Basic and Diluted [Abstract] Basic and Diluted loss per share (in dollars per share) Earnings Per Share, Basic and Diluted Weighted average common shares outstanding (in shares) Weighted Average Number of Shares Outstanding, Basic and Diluted Share-Based Compensation Disclosure of Compensation Related Costs, Share-based Payments [Text Block]