NMI (NMIH) 10-Q 1 Nov 17 2017 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2017	Oct. 30, 2017
Document and Entity Information [Abstract]
Entity Registrant Name	NMI HOLDINGS, INC.
Entity Central Index Key	1,547,903
Document Type	10-Q
Document Period End Date	Sep. 30, 2017
Amendment Flag	false
Document Fiscal Year Focus	2,017
Document Fiscal Period Focus	Q3
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Entity Common Stock, Shares Outstanding		60,033,144

CONDENSED CONSOLIDATED BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS (UNAUDITED) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Assets
Fixed maturities, available-for-sale, at fair value (amortized cost of $687,284 and $630,688 as of September 30, 2017 and December 31, 2016, respectively)	$ 692,729	$ 628,969
Cash and cash equivalents	20,698	47,746
Premiums receivable	21,056	13,728
Accrued investment income	4,598	3,421
Prepaid expenses	2,651	1,991
Deferred policy acquisition costs, net	36,101	30,109
Software and equipment, net	21,767	20,402
Intangible assets and goodwill	3,634	3,634
Prepaid reinsurance premiums	39,915	37,921
Deferred tax asset, net	38,490	51,434
Other assets	4,973	542
Total assets	886,612	839,897
Liabilities
Term loan	143,969	144,353
Unearned premiums	161,345	152,906
Accounts payable and accrued expenses	22,028	25,297
Reserve for insurance claims and claim expenses	6,123	3,001
Reinsurance funds withheld	33,105	30,633
Deferred ceding commission	4,971	4,831
Warrant liability, at fair value	4,046	3,367
Total liabilities	375,587	364,388
Commitments and contingencies
Shareholders' Equity
Common stock - class A shares, $0.01 par value; 59,928,092 and 59,145,161 shares issued and outstanding as of September 30, 2017 and December 31, 2016, respectively (250,000,000 shares authorized)	599	591
Additional paid-in capital	583,447	576,927
Accumulated other comprehensive loss, net of tax	(630)	(5,287)
Accumulated deficit	(72,391)	(96,722)
Total shareholders' equity	511,025	475,509
Total liabilities and shareholders' equity	$ 886,612	$ 839,897

CONDENSED CONSOLIDATED BALANCE3

CONDENSED CONSOLIDATED BALANCE SHEETS (UNAUDITED) (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Statement of Financial Position [Abstract]
Fixed maturities, amortized cost	$ 687,284	$ 630,688
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares issued (in shares)	59,928,092	59,145,161
Common stock, shares outstanding (in shares)	59,928,092	59,145,161
Common stock, shares authorized (in shares)	250,000,000	250,000,000

CONDENSED CONSOLIDATED STATEMEN

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE INCOME (UNAUDITED) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Revenues
Net premiums earned	$ 44,519	$ 31,808	$ 115,661	$ 77,656
Net investment income	4,170	3,544	11,885	10,117
Net realized investment gains (losses)	69	66	198	(758)
Other revenues	195	102	461	172
Total revenues	48,953	35,520	128,205	87,187
Expenses
Insurance claims and claims expenses	957	664	2,965	1,592
Underwriting and operating expenses	24,645	24,037	78,682	69,943
Total expenses	25,602	24,701	81,647	71,535
Other expense
Loss from change in fair value of warrant liability	(502)	(797)	(679)	(187)
Interest expense	(3,352)	(3,733)	(10,146)	(11,072)
Total other expense	(3,854)	(4,530)	(10,825)	(11,259)
Income before income taxes	19,497	6,289	35,733	4,393
Income tax expense	7,185	114	11,917	114
Net income	$ 12,312	$ 6,175	$ 23,816	$ 4,279
Earnings per share
Basic earnings per share (in dollars per share)	$ 0.21	$ 0.10	$ 0.40	$ 0.07
Diluted earnings per share (in dollars per share)	$ 0.20	$ 0.10	$ 0.38	$ 0.07
Weighted average common shares outstanding
Basic weighted average shares outstanding (in shares)	59,883,629	59,130,401	59,680,166	59,047,758
Dilutive weighted average shares outstanding (in shares)	63,088,958	60,284,746	62,773,333	59,861,916
Other comprehensive income (loss), net of tax:
Net unrealized gain (loss) in accumulated other comprehensive income, net of tax expense of $366 and $0 for the three months ended September 30, 2017 and 2016, respectively, and $2,439 and $0 for the nine months ended September 30, 2017 and 2016	$ 768	$ (82)	$ 4,786	$ 17,690
Reclassification adjustment for realized losses (gains) included in net income, net of tax expense of $24 and $0 for the three months ended September 30, 2017 and 2016, respectively, and $69 and $0 for the nine months ended September 30, 2017 and 2016	(45)	(66)	(129)	758
Other comprehensive income (loss), net of tax	723	(148)	4,657	18,448
Comprehensive income	$ 13,035	$ 6,027	$ 28,473	$ 22,727

CONDENSED CONSOLIDATED STATEME5

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE INCOME (UNAUDITED) (Parenthetical) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Income Statement [Abstract]
Net unrealized gain (loss) in accumulated other comprehensive income, tax amount	$ 366	$ 0	$ 2,439	$ 0
Reclassification adjustment for realized losses (gains) included in net income, tax amount	$ 24	$ 0	$ 69	$ 0

CONDENSED CONSOLIDATED STATEME6

CONDENSED CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS' EQUITY (UNAUDITED) - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit
Beginning balance at Dec. 31, 2015	$ 402,731	$ 588	$ 570,340	$ (7,474)	$ (160,723)
Beginning balance (in shares) at Dec. 31, 2015		58,808
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock: class A shares issued under stock plans, net of shares withheld for employee taxes	(224)	$ 3	(227)
Common stock: class A shares issued under stock plans, net of shares withheld for employee taxes (in shares)		337
Share-based compensation expense	6,814		6,814
Change in unrealized investment gains/losses, net of tax	2,187			2,187
Net income	64,001				64,001
Ending balance at Dec. 31, 2016	475,509	$ 591	576,927	(5,287)	(96,722)
Ending balance (in shares) at Dec. 31, 2016		59,145
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect of change in accounting principle	903		388		515
Common stock: class A shares issued under stock plans, net of shares withheld for employee taxes	(793)	$ 8	(801)
Common stock: class A shares issued under stock plans, net of shares withheld for employee taxes (in shares)		783
Share-based compensation expense	6,933		6,933
Change in unrealized investment gains/losses, net of tax	4,657			4,657
Net income	23,816				23,816
Ending balance at Sep. 30, 2017	$ 511,025	$ 599	$ 583,447	$ (630)	$ (72,391)
Ending balance (in shares) at Sep. 30, 2017		59,928

CONDENSED CONSOLIDATED STATEME7

CONDENSED CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS' EQUITY (UNAUDITED) (Parenthetical) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2017	Dec. 31, 2016
Statement of Stockholders' Equity [Abstract]
Change in unrealized investment gains/losses, tax amount	$ 2,508	$ 1,178

CONDENSED CONSOLIDATED STATEME8

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (UNAUDITED) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Cash flows from operating activities
Net income	$ 23,816	$ 4,279
Adjustments to reconcile net income to net cash provided by operating activities:
Net realized investment (gains) losses	(198)	758
Loss from change in fair value of warrant liability	679	187
Depreciation and amortization	4,871	4,300
Net amortization of premium on investment securities	1,200	954
Amortization of debt discount and debt issuance costs	1,112	1,416
Share-based compensation expense	6,933	4,987
Deferred income taxes	11,340	0
Changes in operating assets and liabilities:
Premiums receivable	(7,328)	(6,235)
Accrued investment income	(1,177)	(742)
Prepaid expenses	(660)	(885)
Deferred policy acquisition costs, net	(5,992)	(11,381)
Other assets	(1,150)	(2)
Unearned premiums	8,439	54,628
Reserve for insurance claims and claims expenses	3,122	1,454
Reinsurance balances, net	618	(431)
Accounts payable and accrued expenses	(3,847)	(1,075)
Net cash provided by operating activities	41,778	52,212
Cash flows from investing activities
Purchase of short-term investments	(111,551)	(147,639)
Purchase of fixed-maturity investments, available-for-sale	(166,640)	(103,418)
Proceeds from maturity of short-term investments	142,722	93,916
Proceeds from redemptions, maturities and sale of fixed-maturity investments, available-for-sale	75,785	101,874
Additions to software and equipment	(6,869)	(8,449)
Net cash used in investing activities	(66,553)	(63,714)
Cash flows from financing activities
Proceeds from issuance of common stock related to employee equity plans	3,105	526
Taxes paid related to net share settlement of equity awards	(3,883)	(694)
Repayments of term loan	(1,125)	(1,125)
Payments of debt modification costs	(370)	0
Net cash used in financing activities	(2,273)	(1,293)
Net decrease in cash and cash equivalents	(27,048)	(12,795)
Cash and cash equivalents, beginning of period	47,746	57,317
Cash and cash equivalents, end of period	20,698	44,522
Supplemental disclosures of cash flow information
Interest paid	10,350	9,669
Income taxes paid	$ 802	$ 0

Organization and Basis of Prese

Organization and Basis of Presentation	9 Months Ended
	Sep. 30, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization and Basis of Presentation	Organization and Basis of Presentation NMI Holdings, Inc. (NMIH) is a Delaware corporation, incorporated in May 2011, to provide private mortgage guaranty insurance (which we refer to as mortgage insurance or MI) through its wholly owned insurance subsidiaries, National Mortgage Insurance Corporation (NMIC) and National Mortgage Reinsurance Inc One (Re One). In April 2012, we completed a private placement of our securities, through which we offered and sold an aggregate of 55,000,000 of our Class A common stock resulting in net proceeds of approximately $510 million (the Private Placement), and we completed the acquisition of our insurance subsidiaries for $8.5 million in cash, common stock and warrants, plus the assumption of $1.3 million in liabilities. In November 2013, we completed an initial public offering of 2.4 million shares of our common stock, and our common stock began trading on the NASDAQ exchange on November 8, 2013, under the symbol "NMIH." In April 2013, NMIC, our primary insurance subsidiary, issued its first mortgage insurance policy. NMIC is licensed to write mortgage insurance in all 50 states and D.C. In August 2015, NMIH capitalized a wholly owned subsidiary, NMI Services, Inc. (NMIS), through which we offer outsourced loan review services on a limited basis 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, 2016 , included in our 2016 10-K. All intercompany transactions have been eliminated. 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, 2017 . Deferred Policy Acquisition Costs Costs directly associated with the successful acquisition of mortgage insurance policies, consisting of certain selling expenses and other policy issuance and underwriting expenses, are initially deferred and reported as deferred policy acquisition costs (DAC). DAC is reviewed periodically to determine that it does not exceed recoverable amounts and is adjusted as appropriate for policy cancellations to be consistent with our revenue recognition policy. We estimate the rate of amortization to reflect actual experience and any changes to persistency or loss development. For each book year of business, these costs are amortized to expense in proportion to estimated gross profits over the estimated life of the policies. Total amortization of DAC, net of a portion of ceding commission related to the 2016 QSR Transaction (see Note 5, " Reinsurance" ) , was $1.7 million and $1.2 million for the three months ended September 30, 2017 and 2016, respectively, and $4.0 million and $3.4 million for the nine months ended September 30, 2017 and 2016, respectively. Premium Deficiency Reserves We consider whether a premium deficiency exists at each fiscal quarter using best estimate assumptions as of the testing date. Per ASC 944, a premium deficiency reserve shall be recognized if the sum of expected claim costs and claim adjustment expenses, expected dividends to policyholders, unamortized acquisition costs and maintenance costs exceeds related unearned premiums and anticipated investment income. We have determined that no premium deficiency reserves were necessary for the three and nine months ended September 30, 2017 or 2016 . Reinsurance We account for premiums, losses and loss expenses that are ceded to reinsurers on bases consistent with those we use to account for the original policies we issue and pursuant to the terms of our reinsurance contracts. We account for premiums ceded or otherwise paid to reinsurers as reductions to premium revenue. We earn profit and ceding commissions in connection with our 2016 QSR Transaction (see Note 5, "Reinsurance" ). Profit commissions represent a percentage of the profits recognized by reinsurers that are returned to us, based on the level of losses we cede. We recognize any profit commissions we earn as increases to premium revenue. Ceding commissions are calculated as a percentage of ceded written premiums, which are intended to cover our costs to acquire and service the direct policies. We earn the ceding commissions in a manner consistent with our recognition of earnings on the underlying insurance policies, over the terms of the policies reinsured. We account for ceding commissions as reductions to underwriting and operating expenses. We cede a portion of loss reserves, paid losses and loss expenses to our reinsurers, which are accounted for as reinsurance recoverables on the consolidated balance sheets and as reductions to loss expense on the consolidated statements of operations. We remain directly liable for all loss payments in the event we are unable to collect from any reinsurer. Variable interest entity In May 2017, NMIC entered into a reinsurance agreement with Oaktown Re Ltd. (Oaktown Re), a Bermuda-domiciled special purpose reinsurer. At inception of the reinsurance agreement, we determined that Oaktown Re was a variable interest entity (VIE), as defined under GAAP (ASC 810), because it did not have sufficient equity at risk to finance its activities. We evaluated the VIE to determine whether NMIC was its primary beneficiary and, if so, whether we were required to consolidate the assets and liabilities of the VIE. The primary beneficiary of a VIE is an enterprise that (1) has the power to direct the activities of the VIE, which most significantly impact its economic performance and (2) has significant economic exposure to the VIE; i.e., the obligation to absorb losses or receive benefits that could potentially be significant. The determination of whether an entity is the primary beneficiary of a VIE is complex and requires management judgment regarding determinative factors, including the expected results of the VIE and how those results are absorbed by beneficial interest holders, as well as which party has the power to direct activities that most significantly impact the performance of the VIE. We concluded that we are not the primary beneficiary of Oaktown Re and that consolidation is not required, as we do not have significant economic exposure in the entity. See Note 5, "Reinsurance" for further discussion of the reinsurance arrangement. Premiums Receivable Premiums receivable consist of premiums due on our mortgage insurance policies. If a mortgage insurance premium is unpaid for more than 120 days, the receivable is written off against earned premium and the related insurance policy is canceled. We have determined that the receivable write-off was immaterial as of September 30, 2017. Recent Accounting Pronouncements In May 2014, the Financial Accounting Standards Board (the FASB) issued Accounting Standards Update (ASU) 2014-09, Revenue from Contracts with Customers (Topic 606). This update is intended to provide a consistent approach in recognizing revenue. In accordance with the new standard, recognition of revenue occurs when a customer obtains control of promised goods or services in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. In addition, the new standard requires that reporting companies disclose the nature, amount, timing and uncertainty of revenue and cash flows arising from contracts with customers. In August 2015, ASU 2015-14 deferred the provisions of ASU 2014-09 to be effective for interim and annual periods beginning after December 15, 2017. In addition, this guidance amends the existing requirements for the recognition of a gain or loss on the transfer of non-financial assets that are not in a contract with a customer (ASU 2017-05). In September 2017, ASU 2017-13, added guidance from an SEC Staff Announcement, "Transition Related to Accounting Standards Updates No. 2014-09." The adoption of this update for our loan review services revenue, effective January 1, 2018, will have an immaterial impact on our consolidated financial statements and will not affect the Company’s reporting of insurance premiums and investment income. We are still in the process of evaluating the adoption method and the impact on presentation and disclosure. In February 2016, the FASB issued ASU 2016-02, Leases (Topic 842). This update requires that businesses recognize rights and obligations associated with certain leases as assets and liabilities on the balance sheet. The standard also requires additional disclosures regarding the amount, timing, and uncertainty of cash flows arising from leases. For public business entities, this update is effective for annual periods beginning after December 15, 2018 and interim periods therein. Early adoption is permitted in any period. We expect to adopt this guidance on January 1, 2019. In September 2017, ASU 2017-13, added guidance from an SEC Staff Announcement, "Transition Related to Accounting Standards Update No. 2016-02." We anticipate this standard will have an impact on our financial position, primarily due to our office space operating lease, as we will be required to recognize lease assets and lease liabilities on our consolidated balance sheet. We will continue to assess the potential impacts of this standard, including the impact the adoption of this guidance will have on our results of operations or cash flows. In June 2016, the FASB issued ASU 2016-13, Financial Instruments-Credit Losses (Topic 326). This update requires companies to measure all expected credit losses for financial assets held at the reporting date. The accounting for credit losses on available-for-sale debt securities and purchased financial assets with credit deterioration also is amended in the standard. The standard will take effect for public business entities for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2019. We are currently evaluating the impact the adoption of this ASU will have, if any, on the consolidated financial statements. In August 2016, the FASB issued ASU 2016-15, Statement of Cash Flows (Topic 230). This update is intended to reduce diversity in practice in how certain cash receipts and cash payments are presented and classified in the statement of cash flows. The standard will take effect for public business entities for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2017. The adoption of this update, effective January 1, 2018, is not expected to have any impact on our statement of cash flows. In August 2016, the FASB issued ASU 2016-16, Income Taxes- Intra-Entity Transfers of Assets Other Than Inventory (Topic 740). This update is intended to improve the accounting for the income tax consequences of intra-entity transfers of assets other than inventory. The standard will take effect for public business entities for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2017. The adoption of this update, effective January 1, 2018, is not expected to have any impact on our consolidated financial statements. In January 2017, the FASB issued ASU 2017-04, Intangibles - Goodwill and Other (Topic 350). This update is intended to simplify the test for goodwill impairment. The standard will take effect for public business entities for fiscal years, and interim periods within those fiscal years, after December 15, 2020. Early adoption is permitted for interim or annual goodwill impairment tests performed on testing dates after January 1, 2017. We have determined that the adoption of this ASU will have no impact on the consolidated financial statements. In March 2017, the FASB issued ASU 2017-08, Receivables - Nonrefundable Fees and Other Costs (Subtopic 310-20). This update shortens the amortization period for the premium on certain purchased callable debt securities to the earliest call date. The standard will take effect for public business entities for fiscal years beginning after December 15, 2017. Early adoption is permitted, and if an entity early adopts the guidance in an interim period, any adjustments are reflected as of the beginning of the fiscal year that includes that interim period. The adoption of this update, effective January 1, 2018, is not expected to have any impact on our consolidated financial statements. In July 2017, the FASB issued ASU 2017-11, Earnings Per Share (Topic 260), Distinguishing Liabilities from Equity (Topic 480), and Derivatives and Hedging (Topic 815). This update is intended to simplify the accounting for certain financial instruments with down round features. This standard will take effect for public business entities for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2018. Early adoption is permitted in any interim or annual period. The Company is currently evaluating the impact the adoption of this ASU will have, if any, on the consolidated financial statements. Immaterial Correction of Prior Period Amounts During the first quarter of 2017, after filing the 2016 10-K, including the audited financial statements included therein, we discovered that $1.8 million of deferred taxes on vested options associated with employees terminated in previous years had not been reversed. Because our deferred tax asset (DTA) was subject to a valuation allowance prior to December 31, 2016, no expense would have been recognized in periods prior to December 31, 2016. However, at December 31, 2016, when we released the valuation allowance against the DTA, the DTA was overstated by $1.8 million and resulted in a $1.8 million overstatement of our 2016 income tax benefit and net income. In order to provide consistency in the consolidated statements and as permitted by Staff Accounting Bulletin (SAB) 108, revisions for these immaterial amounts to previously reported annual amounts are reflected in the Consolidated Balance Sheet financial information herein and will be reflected in the Consolidated Statement of Operations in future filings containing such financial information as permitted by SAB 108. A comparison of the affected amounts as previously reported and as adjusted are presented below. As of and for the full year ended December 31, 2016 As previously reported As adjusted (In thousands) Income Statement Net income $ 65,841 $ 64,001 Income tax (benefit) (54,389 ) (52,550 ) Basic EPS 1.11 1.08 Diluted EPS 1.08 1.05 Balance Sheet Deferred tax asset, net $ 53,274 $ 51,434 Total assets 841,737 839,897 Accumulated deficit (94,882 ) (96,722 ) Total shareholders' equity 477,349 475,509 Change in Accounting Principle In March 2016, the FASB issued ASU 2016-09, Improvements to Employee Share-Based Payment Accounting (Topic 718), which intends to simplify various aspects of the accounting for and reporting of share-based payments. The new accounting is required to be adopted using a modified retrospective approach, with a cumulative-effect adjustment to opening retained earnings for any outstanding liability awards that qualify for equity classification under the new guidance. As the guidance is effective for annual and interim reporting periods beginning after December 15, 2016, we adopted the new guidance in the first quarter of 2017. This required us to reflect any adjustments as of January 1, 2017, the beginning of the annual period that includes the interim period of adoption. The primary impact of adoption was the recognition of excess tax benefits in our provision for income taxes in the consolidated statements of operations. Additionally, our consolidated statements of cash flows now present excess tax benefits as an operating activity on a prospective basis. Finally, we have elected to account for forfeitures as they occur, rather than estimate expected forfeitures. The net cumulative effect of this change was recognized as a $0.5 million reduction to the accumulated deficit as of January 1, 2017.

Investments

Investments	9 Months Ended
	Sep. 30, 2017
Investments, Debt and Equity Securities [Abstract]
Investments	Investments We have designated our investment portfolio as available-for-sale and report it at fair value. The related unrealized gains and losses are, after considering the related tax expense or benefit, recognized through comprehensive income and loss, and on an accumulated basis in shareholders' equity. Net realized investment gains and losses are reported in income based upon specific identification of securities sold. Fair Values and Gross Unrealized Gains and Losses on Investments Amortized Gross Unrealized Fair Gains Losses As of September 30, 2017 (In Thousands) U.S. Treasury securities and obligations of U.S. government agencies $ 65,669 $ 21 $ (636 ) $ 65,054 Municipal debt securities 90,155 929 (348 ) 90,736 Corporate debt securities 404,467 5,619 (1,246 ) 408,840 Asset-backed securities 96,279 1,142 (101 ) 97,320 Total bonds 656,570 7,711 (2,331 ) 661,950 Short-term investments 30,714 65 — 30,779 Total investments $ 687,284 $ 7,776 $ (2,331 ) $ 692,729 Amortized Gross Unrealized Fair Gains Losses As of December 31, 2016 (In Thousands) U.S. Treasury securities and obligations of U.S. government agencies $ 64,135 $ 6 $ (962 ) $ 63,179 Municipal debt securities 40,801 131 (663 ) 40,269 Corporate debt securities 349,712 1,722 (2,356 ) 349,078 Asset-backed securities 114,456 765 (560 ) 114,661 Total bonds 569,104 2,624 (4,541 ) 567,187 Short-term investments 61,584 198 — 61,782 Total investments $ 630,688 $ 2,822 $ (4,541 ) $ 628,969 As of September 30, 2017 and December 31, 2016 , approximately $7.0 million 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 values of available-for-sale securities as of September 30, 2017 and December 31, 2016 , 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, 2017 Amortized Fair (In Thousands) Due in one year or less $ 108,020 $ 108,048 Due after one through five years 158,353 159,502 Due after five through ten years 309,708 312,697 Due after ten years 14,924 15,162 Asset-backed securities 96,279 97,320 Total investments $ 687,284 $ 692,729 As of December 31, 2016 Amortized Fair (In Thousands) Due in one year or less $ 94,382 $ 94,584 Due after one through five years 173,296 173,251 Due after five through ten years 242,005 240,060 Due after ten years 6,549 6,413 Asset-backed securities 114,456 114,661 Total investments $ 630,688 $ 628,969 Aging of Unrealized Losses As of September 30, 2017 , the investment portfolio had gross unrealized losses of $2.3 million , $1.5 million of which has been in an unrealized loss position for a period of 12 months or greater. We did not consider these securities to be other-than-temporarily impaired as of September 30, 2017 . We based our conclusion that these investments were not other-than-temporarily impaired as of September 30, 2017 on the following facts: (i) the unrealized losses were primarily caused by interest rate movements since the purchase date; (ii) we do not intend to sell these investments; and (iii) we do not believe that it is more likely than not that we will be required to sell these investments before recovery of our amortized cost basis, which may not occur until maturity. For those securities in an unrealized loss position, the length of time the securities were in such a position is as follows: Less Than 12 Months 12 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, 2017 (Dollars in Thousands) U.S. Treasury securities and obligations of U.S. government agencies 22 $ 38,425 $ (263 ) 15 $ 19,621 $ (373 ) 37 $ 58,046 $ (636 ) Municipal debt securities 9 21,567 (212 ) 8 10,319 (136 ) 17 31,886 (348 ) Corporate debt securities 44 69,602 (317 ) 14 34,031 (929 ) 58 103,633 (1,246 ) Asset-backed securities 15 21,173 (89 ) 2 4,988 (12 ) 17 26,161 (101 ) Total 90 $ 150,767 $ (881 ) 39 $ 68,959 $ (1,450 ) 129 $ 219,726 $ (2,331 ) Less Than 12 Months 12 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, 2016 (Dollars in Thousands) U.S. Treasury securities and obligations of U.S. government agencies 33 $ 51,093 $ (962 ) — $ — $ — 33 $ 51,093 $ (962 ) Municipal debt securities 14 28,659 (617 ) 1 1,704 (46 ) 15 30,363 (663 ) Corporate debt securities 77 135,115 (1,955 ) 8 13,873 (401 ) 85 148,988 (2,356 ) Asset-backed securities 30 38,702 (510 ) 6 2,472 (50 ) 36 41,174 (560 ) Total 154 $ 253,569 $ (4,044 ) 15 $ 18,049 $ (497 ) 169 $ 271,618 $ (4,541 ) The following table presents the components of net investment income: For the three months ended September 30, For the nine months ended September 30, 2017 2016 2017 2016 (In Thousands) Investment income $ 4,363 $ 3,727 $ 12,455 $ 10,672 Investment expenses (193 ) (183 ) (570 ) (555 ) Net investment income $ 4,170 $ 3,544 $ 11,885 $ 10,117 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, 2017 2016 2017 2016 (In Thousands) Gross realized investment gains $ 69 $ 66 $ 536 $ 683 Gross realized investment losses — — (338 ) (1,441 ) Net realized investment gains (losses) $ 69 $ 66 $ 198 $ (758 ) Investment Securities - Other-than-Temporary Impairment (OTTI) For the quarter ended September 30, 2017 , we held no other-than-temporarily impaired securities. There were no credit losses recognized in earnings for which a portion of an OTTI loss was recognized in accumulated other comprehensive income (loss).

Fair Value of Financial Instrum

Fair Value of Financial Instruments	9 Months Ended
	Sep. 30, 2017
Fair Value Disclosures [Abstract]
Fair Value of Financial Instruments	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 within which the fair value measurement in its entirety falls 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. There were no transfers between Level 1 and Level 2 of the fair value hierarchy during the quarter ended September 30, 2017 . Liabilities classified as Level 3 We calculate the fair value of outstanding warrants utilizing level 3 inputs, including a Black-Scholes option-pricing model, in combination with a binomial model, and we value the pricing protection features within the warrants using a Monte-Carlo simulation model. Variables in the model include the risk-free rate of return, dividend yield, expected life and expected volatility of our stock price. The following tables present the level within the fair value hierarchy at which the Company’s financial instruments were measured: Fair Value Measurements Using Quoted Prices in Significant Other Significant Fair Value As of September 30, 2017 (In Thousands) U.S. Treasury securities and obligations of U.S. government agencies $ 60,214 $ 4,840 $ — $ 65,054 Municipal debt securities — 90,736 — 90,736 Corporate debt securities — 408,840 — 408,840 Asset-backed securities — 97,320 — 97,320 Cash, cash equivalents and short-term investments 51,477 — — 51,477 Total assets $ 111,691 $ 601,736 $ — $ 713,427 Warrant liability — — 4,046 4,046 Total liabilities $ — $ — $ 4,046 $ 4,046 Fair Value Measurements Using Quoted Prices in Significant Other Significant Fair Value As of December 31, 2016 (In Thousands) U.S. Treasury securities and obligations of U.S. government agencies $ 50,719 $ 12,460 $ — $ 63,179 Municipal debt securities — 40,269 — 40,269 Corporate debt securities — 349,078 — 349,078 Asset-backed securities — 114,661 — 114,661 Cash, cash equivalents and short-term investments 109,528 — — 109,528 Total assets $ 160,247 $ 516,468 $ — $ 676,715 Warrant liability — — 3,367 3,367 Total liabilities $ — $ — $ 3,367 $ 3,367 There were no transfers between Level 1 and Level 2 of the fair value hierarchy during the nine months ended September 30, 2017 and the year-end December 31, 2016. The following is a roll-forward of Level 3 liabilities measured at fair value: For the nine months ended September 30, Warrant Liability 2017 2016 (In Thousands) Balance, January 1 $ 3,367 $ 1,467 Change in fair value of warrant liability included in earnings 679 187 Balance, September 30 $ 4,046 $ 1,654 We revalue the warrant liability quarterly using a Black-Scholes option-pricing model, in combination with a binomial model, and we value the pricing protection features within the warrants using a Monte-Carlo simulation model. As of September 30, 2017 , the assumptions used in the option-pricing model were as follows: a common stock price as of September 30, 2017 of $12.40 , risk free interest rate of 1.66% , expected life of 3.25 years , expected volatility of 30.6% and a dividend yield of 0% . The change in fair value is primarily attributable to an increase in the price of our common stock from December 31, 2016 to September 30, 2017 .

Term Loan

Term Loan	9 Months Ended
	Sep. 30, 2017
Debt Disclosure [Abstract]
Term Loan	Term Loan On November 10, 2015, we entered into a credit agreement (the Credit Agreement) to obtain a three-year senior secured term loan (the Term Loan) for $150 million . On February 10, 2017, we entered into an amendment to the Credit Agreement, to extend the maturity date of the Term Loan by one year and reduce the interest rate. Based on our analysis, we concluded the amendment to the Credit Agreement should be treated as a modification. As of September 30, 2017 , the Term Loan bears interest at the Eurodollar Rate, as defined in the Credit Agreement and subject to a 1.00% floor, plus an annual margin rate of 6.75% (an all-in rate of 7.99% as of September 30, 2017 ), payable monthly or quarterly based on our interest rate election. Quarterly principal payments of $375 thousand are also required. The outstanding balance of the Term Loan as of September 30, 2017 was $147 million . Debt issuance costs totaling $4.8 million , including $370 thousand related to the modification and a 1% original issue discount, are being amortized to interest expense, using the effective interest method, over the contractual life of the Term Loan. Effective interest rate for the Term Loan includes interest, amortization of issuance cost and the discount. For the nine months ended September 30, 2017 , we recorded $10.1 million of interest expense, including amortization of the issuance and modification costs and original issue discount. We are subject to certain quarterly covenants under the Credit Agreement. These covenants include, but are not limited to the following: a maximum debt-to-total capitalization ratio (as defined therein) of 35%, maximum risk-to-capital (RTC) ratio of 22.0:1.0, minimum liquidity (as defined therein), compliance with the PMIERs financial requirements (subject to any GSE-approved waivers), and minimum shareholders' equity requirements. This description is not intended to be complete in all respects and is qualified in its entirety by the terms of the Credit Agreement, including its covenants and events of default. We were in compliance with all covenants as of September 30, 2017 . Future principal payments due under the Term Loan as of September 30, 2017 are as follows: As of September 30, 2017 Principal (In thousands) 2017 $ 375 2018 1,500 2019 145,125 Total $ 147,000

Reinsurance

Reinsurance	9 Months Ended
	Sep. 30, 2017
Reinsurance Disclosures [Abstract]
Reinsurance	Reinsurance We have entered into two third-party reinsurance transactions to actively manage our risk, ensure PMIERs compliance and support the growth of our business. The GSEs and the Wisconsin Office of the Commissioner of Insurance (Wisconsin OCI) approved both transactions (subject to certain conditions and their periodic review of the transactions, 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 For the nine months ended September 30, 2017 September 30, 2016 September 30, 2017 September 30, 2016 (In Thousands) Net premiums written Direct $ 56,217 $ 46,535 $ 142,134 $ 133,526 Ceded (1) (8,501 ) (37,336 ) (20,029 ) (37,336 ) Net premiums written $ 47,716 $ 9,199 $ 122,105 $ 96,190 Net premiums earned Direct $ 52,024 $ 33,052 $ 133,696 $ 78,900 Ceded (1) (7,505 ) (1,244 ) (18,035 ) (1,244 ) Net premiums earned $ 44,519 $ 31,808 $ 115,661 $ 77,656 (1) Net of profit commission Excess-of-loss reinsurance In May 2017, NMIC entered into a reinsurance agreement with Oaktown Re that provides for up to $211.3 million of aggregate excess-of-loss reinsurance coverage at inception for new delinquencies on an existing portfolio of mortgage insurance policies written from 2013 through December 31, 2016. For the coverage period, NMIC will retain the first layer of $126.8 million of aggregate losses and Oaktown Re will then provide second layer coverage up to the outstanding reinsurance coverage amount. NMIC will then retain losses in excess of the outstanding reinsurance coverage amount. The outstanding reinsurance coverage amount decreases from $211.3 million at inception over a ten-year period as the underlying covered mortgages amortize and was $185 million as of September 30, 2017 . The outstanding reinsurance coverage amount will stop amortizing if certain credit enhancement or delinquency thresholds are triggered. Oaktown Re financed the coverage by issuing mortgage insurance-linked notes in an aggregate amount of $211.3 million to unaffiliated investors (the Notes). The Notes mature on April 26, 2027. All of the proceeds paid to Oaktown Re from the sale of the Notes were deposited into a reinsurance trust to collateralize and fund the obligations of Oaktown Re to NMIC under the reinsurance agreement. At all times, funds in the reinsurance trust account are required to be invested in high credit quality money market funds. We refer collectively to NMIC’s reinsurance agreement with Oaktown Re and the issuance of the Notes by Oaktown Re as the 2017 ILN Transaction. Under the terms of the 2017 ILN Transaction, NMIC makes risk premium payments for the applicable outstanding reinsurance coverage amount and pays Oaktown Re for anticipated operating expenses (capped at $300 thousand per year). For the three and nine months ended September 30, 2017 , NMIC paid risk premiums of $1.9 million and $3.3 million , respectively. NMIC did not cede any losses to Oaktown Re. Under the reinsurance agreement, NMIC holds an optional termination right if certain events occur, including, among others, after the reinsurance coverage amount amortizes to 10% or less of the reinsurance coverage amount at inception or if NMIC reasonably determines that GSE or rating agency asset requirements would cause a material and adverse effect on the capital treatment adopted by NMIC. In addition, there are certain events that will result in mandatory termination of the agreement, including NMIC’s failure to pay premiums or consent to reductions in the trust account to make principal payments to noteholders, among others. At the time the 2017 ILN Transaction was entered into with Oaktown Re, we evaluated the applicability of the accounting guidance that addresses VIEs. As a result of the evaluation of the 2017 ILN Transaction, we concluded that Oaktown Re is a VIE. However, given that NMIC does not have significant economic exposure in Oaktown Re, we do not consolidate Oaktown Re in our consolidated financial statements. Quota share reinsurance In September 2016, NMIC entered into a quota-share reinsurance transaction with a panel of third-party reinsurers (2016 QSR Transaction). Each of the third-party reinsurers has an insurer financial strength rating of A- or better by Standard and Poor’s Rating Services (S&P), A.M. Best or both. Under the 2016 QSR Transaction, effective September 1, 2016, NMIC ceded premiums related to: • 25% of existing risk written on eligible policies as of August 31, 2016; • 100% of existing risk under our pool agreement with Fannie Mae; and • 25% of risk on eligible policies written from September 1, 2016 through December 31, 2017. The following table shows the amounts related to the 2016 QSR Transaction: For the three months ended For the nine months ended September 30, 2017 September 30, 2016 September 30, 2017 September 30, 2016 (In Thousands) Ceded risk-in-force $ 2,682,982 $ 1,778,235 $ 2,682,982 $ 1,778,235 Ceded premiums written (14,389 ) (38,977 ) (36,715 ) (38,977 ) Ceded premiums earned (13,393 ) (2,885 ) (34,721 ) (2,885 ) Ceded claims and claims expenses 277 90 887 90 Ceding commission written 2,878 7,795 7,343 7,795 Ceding commission earned 2,581 551 6,921 551 Profit commission 7,758 1,641 19,945 1,641 Ceded premiums written are recorded on the balance sheet as prepaid reinsurance premiums and amortized to ceded premiums earned in a manner consistent with the recognition of income on direct premiums. NMIC receives a 20% ceding commission for premiums ceded pursuant to this transaction. NMIC also receives a profit commission, provided that the loss ratio on the loans covered under the agreement generally remains below 60% , as measured annually. Ceded claims and claims expenses reduce NMIC's profit commission 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 our 2016 QSR Transaction was $1.2 million as of September 30, 2017 . The agreement is scheduled to terminate on December 31, 2027, except with respect to the ceded pool risk, which is scheduled to terminate on August 31, 2023. However, 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 reassuming the related risk.

Reserves for Insurance Claims a

Reserves for Insurance Claims and Claims Expenses	9 Months Ended
	Sep. 30, 2017
Insurance [Abstract]
Reserves for Insurance Claims and Claims Expenses	Reserves for Insurance Claims and Claims Expenses We establish reserves to recognize the estimated liability for insurance claims and claim expenses related to defaults on insured mortgage loans. Our method, consistent with industry practice, is to establish reserves only for loans that have been reported to us as having been in default for at least 60 days. Our reserves also include amounts for estimated claims incurred on loans that have been in default for at least 60 days that have not yet been reported to us by the servicers, often referred to as IBNR. As of September 30, 2017 , we had reserves for insurance claims and claims expenses of $6.1 million for 350 primary loans in default. During the first nine months of 2017, we paid 16 claims totaling $731 thousand , including two claims totaling $11 thousand covered under the 2016 QSR Transaction. In 2013, we entered into a pool insurance transaction with Fannie Mae. We only establish reserves for pool risk if we expect claims to exceed the deductible under the pool agreement, which represents the amount of claims absorbed by Fannie Mae before we are obligated to pay any claims. At September 30, 2017 , 46 loans in the pool were past due by 60 days or more. These 46 loans represent approximately $3.0 million of risk-in-force (RIF). Due to the size of the remaining deductible of $10.0 million , the low level of notices of default (NODs) reported on loans in the pool through September 30, 2017 and the expected severity (all loans in the pool have loan-to-value ratios (LTVs) under 80% ), we have not established any pool reserves for claims or IBNR for the three and nine months ended September 30, 2017 and 2016 . In connection with the settlement of pool claims, we applied $368 thousand to the pool deductible through September 30, 2017 . We have not paid any pool claims to date. 100% of our pool RIF is reinsured under the 2016 QSR Transaction. The following table provides a reconciliation of the beginning and ending reserve balances for primary insurance claims and claims expenses: For the nine months ended September 30, 2017 2016 (In Thousands) Beginning balance $ 3,001 $ 679 Less reinsurance recoverables (1) (297 ) — Beginning balance, net of reinsurance recoverables 2,704 679 Add claims incurred: Claims and claim expenses incurred: Current year (2) 3,546 1,803 Prior years (3) (581 ) (214 ) Total claims and claims expenses incurred 2,965 1,589 Less claims paid: Claims and claim expenses paid: Current year (2) — — Prior years (3) 720 225 Total claims and claim expenses paid 720 225 Reserve at end of period, net of reinsurance recoverables 4,949 2,043 Add reinsurance recoverables (1) 1,174 90 Ending balance $ 6,123 $ 2,133 (1) Related to ceded losses recoverable on the 2016 QSR Transaction, included in "Other Assets" on the Condensed Consolidated Balance Sheets. 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 had defaulted in a prior year and subsequently cured and later re-defaulted in the current year, that default would be included in the current year. (3) Related to insured loans with defaults occurring in prior years, which have been continuously in default since that time. The "claims incurred" section of the table above shows claims and claim expenses incurred on NODs for current and prior years, including IBNR reserves. The amount of claims incurred relating to current year NODs represents the estimated amount to be ultimately paid on such loans in default. We recognized $581 thousand and $214 thousand of favorable prior year development during the nine months ended September 30, 2017 and 2016, respectively, due to NOD cures and ongoing analysis of recent loss development trends. We may increase or decrease our original estimates as we learn additional information about individual defaults and claims and continue to observe and analyze loss development trends in our portfolio. Reserves of $1.7 million related to prior year defaults remained as of September 30, 2017 .

Earnings per Share

Earnings per Share	9 Months Ended
	Sep. 30, 2017
Earnings Per Share [Abstract]
Earnings per Share	Earnings per Share Basic earnings per share is based on the weighted average number of shares of common stock outstanding, while diluted earnings per share is based on the weighted average number of shares of common stock outstanding and common stock equivalents that would be issuable upon the exercise of stock options, other share-based compensation arrangements, and the dilutive effect of outstanding warrants. The following table reconciles the net income and the weighted average shares of common stock outstanding used in the computations of basic and diluted earnings per share of common stock: For the three months ended September 30, For the nine months ended September 30, 2017 2016 2017 2016 (In Thousands, except for per share data) Net income $ 12,312 $ 6,175 $ 23,816 $ 4,279 Basic earnings per share $ 0.21 $ 0.10 $ 0.40 $ 0.07 Basic weighted average shares outstanding 59,883,629 59,130,401 59,680,166 59,047,758 Dilutive effect of non-vested shares and warrants 3,205,329 1,154,345 3,093,167 814,158 Dilutive weighted average shares outstanding 63,088,958 60,284,746 62,773,333 59,861,916 Diluted earnings per share $ 0.20 $ 0.10 $ 0.38 $ 0.07 For the three and nine months ended September 30, 2017 , 830,043 and 832,460 , respectively, and for the three and nine months ended September 30, 2016, 4,012,046 and 4,326,168 , respectively, of our common stock equivalents issued under share-based compensation arrangements were not included in the calculation of diluted earnings per share because they were anti-dilutive. The warrants were not dilutive in 2016.

Warrants

Warrants	9 Months Ended
	Sep. 30, 2017
Debt Disclosure [Abstract]
Warrants	Warrants We issued 992,000 warrants in connection with our Private Placement. Each warrant gives the holder thereof the right to purchase one share of common stock at an exercise price equal to $10.00 . The warrants were issued with an aggregate fair value of $5.1 million . Upon exercise of these warrants, the amounts will be treated as additional paid-in capital. No warrants were exercised during the nine months ended September 30, 2017 and 2016 . We account for these warrants to purchase our common shares in accordance with ASC 470-20, Debt with Conversion and Other Options and ASC 815-40, Derivatives and Hedging - Contracts in Entity's Own Equity.

Income Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2017
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 35% . NMIH files a consolidated U.S. federal and various state income tax returns on behalf of itself and its subsidiaries. Our provision for income taxes for the interim reporting periods are based on an estimated annual effective tax rate for the year ending December 31, 2017. Our effective tax rate on our pre-tax income was 36.9% and 33.3% for the three and nine months ended September 30, 2017 , respectively, compared to 1.8% and 2.6% for the comparable 2016 periods. The increase in the effective tax expense for the three and nine months ended September 30, 2017 , against the comparable 2016 periods is attributable to the elimination of tax benefits during the comparable 2016 periods due to the recognition of a full valuation allowance which had been recorded to reflect the amount of the deferred taxes that may not be realized. We currently pay no regular federal income tax due to the forecasted utilization of federal net operating loss carryforwards, which were $122.9 million as of December 31, 2016. The interim provision for income taxes include current year alternative minimum tax and changes to deferred tax assets. See Note 1 , "Organization and Basis of Presentation - Immaterial Correction of Prior Period Amounts" for further details.

Statutory Information

Statutory Information	9 Months Ended
	Sep. 30, 2017
Insurance [Abstract]
Statutory Information	Statutory Information 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. 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's combined statutory net loss, statutory surplus, contingency reserve and RTC ratios were as follows: As of and for the nine months and year ended September 30, 2017 December 31, 2016 (In Thousands) Statutory net loss $ (29,394 ) $ (26,653 ) Statutory surplus 379,160 413,809 Contingency reserve 157,326 90,479 Risk-to-Capital 11.5:1 11.6:1 NMIH is not subject to any limitations on its ability to pay dividends except those generally applicable to corporations that are incorporated in Delaware, such as NMIH. Delaware corporation law provides that dividends are only payable out of a corporation's surplus or recent net profits (subject to certain limitations). NMIC and Re One are subject to restrictions on their ability to pay dividends without prior approval of the Wisconsin OCI. Certain other states in which NMIC is licensed also have statutes or regulations that restrict its ability to pay dividends. Since inception, NMIC has not paid any dividends to NMIH.

Organization and Basis of Pre19

Organization and Basis of Presentation (Policies)	9 Months Ended
	Sep. 30, 2017
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, 2016 , included in our 2016 10-K. All intercompany transactions have been eliminated. 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, 2017 .
Deferred Policy Acquisition Costs	Deferred Policy Acquisition Costs Costs directly associated with the successful acquisition of mortgage insurance policies, consisting of certain selling expenses and other policy issuance and underwriting expenses, are initially deferred and reported as deferred policy acquisition costs (DAC). DAC is reviewed periodically to determine that it does not exceed recoverable amounts and is adjusted as appropriate for policy cancellations to be consistent with our revenue recognition policy. We estimate the rate of amortization to reflect actual experience and any changes to persistency or loss development. For each book year of business, these costs are amortized to expense in proportion to estimated gross profits over the estimated life of the policies.
Premium Deficiency Reserves	Premium Deficiency Reserves We consider whether a premium deficiency exists at each fiscal quarter using best estimate assumptions as of the testing date. Per ASC 944, a premium deficiency reserve shall be recognized if the sum of expected claim costs and claim adjustment expenses, expected dividends to policyholders, unamortized acquisition costs and maintenance costs exceeds related unearned premiums and anticipated investment income.
Reinsurance	Reinsurance We account for premiums, losses and loss expenses that are ceded to reinsurers on bases consistent with those we use to account for the original policies we issue and pursuant to the terms of our reinsurance contracts. We account for premiums ceded or otherwise paid to reinsurers as reductions to premium revenue. We earn profit and ceding commissions in connection with our 2016 QSR Transaction (see Note 5, "Reinsurance" ). Profit commissions represent a percentage of the profits recognized by reinsurers that are returned to us, based on the level of losses we cede. We recognize any profit commissions we earn as increases to premium revenue. Ceding commissions are calculated as a percentage of ceded written premiums, which are intended to cover our costs to acquire and service the direct policies. We earn the ceding commissions in a manner consistent with our recognition of earnings on the underlying insurance policies, over the terms of the policies reinsured. We account for ceding commissions as reductions to underwriting and operating expenses. We cede a portion of loss reserves, paid losses and loss expenses to our reinsurers, which are accounted for as reinsurance recoverables on the consolidated balance sheets and as reductions to loss expense on the consolidated statements of operations. We remain directly liable for all loss payments in the event we are unable to collect from any reinsurer.
Variable Interest Entity	Variable interest entity In May 2017, NMIC entered into a reinsurance agreement with Oaktown Re Ltd. (Oaktown Re), a Bermuda-domiciled special purpose reinsurer. At inception of the reinsurance agreement, we determined that Oaktown Re was a variable interest entity (VIE), as defined under GAAP (ASC 810), because it did not have sufficient equity at risk to finance its activities. We evaluated the VIE to determine whether NMIC was its primary beneficiary and, if so, whether we were required to consolidate the assets and liabilities of the VIE. The primary beneficiary of a VIE is an enterprise that (1) has the power to direct the activities of the VIE, which most significantly impact its economic performance and (2) has significant economic exposure to the VIE; i.e., the obligation to absorb losses or receive benefits that could potentially be significant. The determination of whether an entity is the primary beneficiary of a VIE is complex and requires management judgment regarding determinative factors, including the expected results of the VIE and how those results are absorbed by beneficial interest holders, as well as which party has the power to direct activities that most significantly impact the performance of the VIE.
Premiums Receivable	Premiums Receivable Premiums receivable consist of premiums due on our mortgage insurance policies. If a mortgage insurance premium is unpaid for more than 120 days, the receivable is written off against earned premium and the related insurance policy is canceled.
Recent Accounting Pronouncements	Recent Accounting Pronouncements In May 2014, the Financial Accounting Standards Board (the FASB) issued Accounting Standards Update (ASU) 2014-09, Revenue from Contracts with Customers (Topic 606). This update is intended to provide a consistent approach in recognizing revenue. In accordance with the new standard, recognition of revenue occurs when a customer obtains control of promised goods or services in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. In addition, the new standard requires that reporting companies disclose the nature, amount, timing and uncertainty of revenue and cash flows arising from contracts with customers. In August 2015, ASU 2015-14 deferred the provisions of ASU 2014-09 to be effective for interim and annual periods beginning after December 15, 2017. In addition, this guidance amends the existing requirements for the recognition of a gain or loss on the transfer of non-financial assets that are not in a contract with a customer (ASU 2017-05). In September 2017, ASU 2017-13, added guidance from an SEC Staff Announcement, "Transition Related to Accounting Standards Updates No. 2014-09." The adoption of this update for our loan review services revenue, effective January 1, 2018, will have an immaterial impact on our consolidated financial statements and will not affect the Company’s reporting of insurance premiums and investment income. We are still in the process of evaluating the adoption method and the impact on presentation and disclosure. In February 2016, the FASB issued ASU 2016-02, Leases (Topic 842). This update requires that businesses recognize rights and obligations associated with certain leases as assets and liabilities on the balance sheet. The standard also requires additional disclosures regarding the amount, timing, and uncertainty of cash flows arising from leases. For public business entities, this update is effective for annual periods beginning after December 15, 2018 and interim periods therein. Early adoption is permitted in any period. We expect to adopt this guidance on January 1, 2019. In September 2017, ASU 2017-13, added guidance from an SEC Staff Announcement, "Transition Related to Accounting Standards Update No. 2016-02." We anticipate this standard will have an impact on our financial position, primarily due to our office space operating lease, as we will be required to recognize lease assets and lease liabilities on our consolidated balance sheet. We will continue to assess the potential impacts of this standard, including the impact the adoption of this guidance will have on our results of operations or cash flows. In June 2016, the FASB issued ASU 2016-13, Financial Instruments-Credit Losses (Topic 326). This update requires companies to measure all expected credit losses for financial assets held at the reporting date. The accounting for credit losses on available-for-sale debt securities and purchased financial assets with credit deterioration also is amended in the standard. The standard will take effect for public business entities for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2019. We are currently evaluating the impact the adoption of this ASU will have, if any, on the consolidated financial statements. In August 2016, the FASB issued ASU 2016-15, Statement of Cash Flows (Topic 230). This update is intended to reduce diversity in practice in how certain cash receipts and cash payments are presented and classified in the statement of cash flows. The standard will take effect for public business entities for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2017. The adoption of this update, effective January 1, 2018, is not expected to have any impact on our statement of cash flows. In August 2016, the FASB issued ASU 2016-16, Income Taxes- Intra-Entity Transfers of Assets Other Than Inventory (Topic 740). This update is intended to improve the accounting for the income tax consequences of intra-entity transfers of assets other than inventory. The standard will take effect for public business entities for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2017. The adoption of this update, effective January 1, 2018, is not expected to have any impact on our consolidated financial statements. In January 2017, the FASB issued ASU 2017-04, Intangibles - Goodwill and Other (Topic 350). This update is intended to simplify the test for goodwill impairment. The standard will take effect for public business entities for fiscal years, and interim periods within those fiscal years, after December 15, 2020. Early adoption is permitted for interim or annual goodwill impairment tests performed on testing dates after January 1, 2017. We have determined that the adoption of this ASU will have no impact on the consolidated financial statements. In March 2017, the FASB issued ASU 2017-08, Receivables - Nonrefundable Fees and Other Costs (Subtopic 310-20). This update shortens the amortization period for the premium on certain purchased callable debt securities to the earliest call date. The standard will take effect for public business entities for fiscal years beginning after December 15, 2017. Early adoption is permitted, and if an entity early adopts the guidance in an interim period, any adjustments are reflected as of the beginning of the fiscal year that includes that interim period. The adoption of this update, effective January 1, 2018, is not expected to have any impact on our consolidated financial statements. In July 2017, the FASB issued ASU 2017-11, Earnings Per Share (Topic 260), Distinguishing Liabilities from Equity (Topic 480), and Derivatives and Hedging (Topic 815). This update is intended to simplify the accounting for certain financial instruments with down round features. This standard will take effect for public business entities for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2018. Early adoption is permitted in any interim or annual period. The Company is currently evaluating the impact the adoption of this ASU will have, if any, on the consolidated financial statements.
Earnings Per Share	Basic earnings per share is based on the weighted average number of shares of common stock outstanding, while diluted earnings per share is based on the weighted average number of shares of common stock outstanding and common stock equivalents that would be issuable upon the exercise of stock options, other share-based compensation arrangements, and the dilutive effect of outstanding warrants.

Organization and Basis of Pre20

Organization and Basis of Presentation (Tables)	9 Months Ended
	Sep. 30, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Schedule of Prior Period Adjustments	A comparison of the affected amounts as previously reported and as adjusted are presented below. As of and for the full year ended December 31, 2016 As previously reported As adjusted (In thousands) Income Statement Net income $ 65,841 $ 64,001 Income tax (benefit) (54,389 ) (52,550 ) Basic EPS 1.11 1.08 Diluted EPS 1.08 1.05 Balance Sheet Deferred tax asset, net $ 53,274 $ 51,434 Total assets 841,737 839,897 Accumulated deficit (94,882 ) (96,722 ) Total shareholders' equity 477,349 475,509

Investments (Tables)

Investments (Tables)	9 Months Ended
	Sep. 30, 2017
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 Gross Unrealized Fair Gains Losses As of September 30, 2017 (In Thousands) U.S. Treasury securities and obligations of U.S. government agencies $ 65,669 $ 21 $ (636 ) $ 65,054 Municipal debt securities 90,155 929 (348 ) 90,736 Corporate debt securities 404,467 5,619 (1,246 ) 408,840 Asset-backed securities 96,279 1,142 (101 ) 97,320 Total bonds 656,570 7,711 (2,331 ) 661,950 Short-term investments 30,714 65 — 30,779 Total investments $ 687,284 $ 7,776 $ (2,331 ) $ 692,729 Amortized Gross Unrealized Fair Gains Losses As of December 31, 2016 (In Thousands) U.S. Treasury securities and obligations of U.S. government agencies $ 64,135 $ 6 $ (962 ) $ 63,179 Municipal debt securities 40,801 131 (663 ) 40,269 Corporate debt securities 349,712 1,722 (2,356 ) 349,078 Asset-backed securities 114,456 765 (560 ) 114,661 Total bonds 569,104 2,624 (4,541 ) 567,187 Short-term investments 61,584 198 — 61,782 Total investments $ 630,688 $ 2,822 $ (4,541 ) $ 628,969
Schedule of Investments by Maturity	The amortized cost and fair values of available-for-sale securities as of September 30, 2017 and December 31, 2016 , 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, 2017 Amortized Fair (In Thousands) Due in one year or less $ 108,020 $ 108,048 Due after one through five years 158,353 159,502 Due after five through ten years 309,708 312,697 Due after ten years 14,924 15,162 Asset-backed securities 96,279 97,320 Total investments $ 687,284 $ 692,729 As of December 31, 2016 Amortized Fair (In Thousands) Due in one year or less $ 94,382 $ 94,584 Due after one through five years 173,296 173,251 Due after five through ten years 242,005 240,060 Due after ten years 6,549 6,413 Asset-backed securities 114,456 114,661 Total investments $ 630,688 $ 628,969
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 12 Months 12 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, 2017 (Dollars in Thousands) U.S. Treasury securities and obligations of U.S. government agencies 22 $ 38,425 $ (263 ) 15 $ 19,621 $ (373 ) 37 $ 58,046 $ (636 ) Municipal debt securities 9 21,567 (212 ) 8 10,319 (136 ) 17 31,886 (348 ) Corporate debt securities 44 69,602 (317 ) 14 34,031 (929 ) 58 103,633 (1,246 ) Asset-backed securities 15 21,173 (89 ) 2 4,988 (12 ) 17 26,161 (101 ) Total 90 $ 150,767 $ (881 ) 39 $ 68,959 $ (1,450 ) 129 $ 219,726 $ (2,331 ) Less Than 12 Months 12 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, 2016 (Dollars in Thousands) U.S. Treasury securities and obligations of U.S. government agencies 33 $ 51,093 $ (962 ) — $ — $ — 33 $ 51,093 $ (962 ) Municipal debt securities 14 28,659 (617 ) 1 1,704 (46 ) 15 30,363 (663 ) Corporate debt securities 77 135,115 (1,955 ) 8 13,873 (401 ) 85 148,988 (2,356 ) Asset-backed securities 30 38,702 (510 ) 6 2,472 (50 ) 36 41,174 (560 ) Total 154 $ 253,569 $ (4,044 ) 15 $ 18,049 $ (497 ) 169 $ 271,618 $ (4,541 )
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, 2017 2016 2017 2016 (In Thousands) Investment income $ 4,363 $ 3,727 $ 12,455 $ 10,672 Investment expenses (193 ) (183 ) (570 ) (555 ) Net investment income $ 4,170 $ 3,544 $ 11,885 $ 10,117
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, 2017 2016 2017 2016 (In Thousands) Gross realized investment gains $ 69 $ 66 $ 536 $ 683 Gross realized investment losses — — (338 ) (1,441 ) Net realized investment gains (losses) $ 69 $ 66 $ 198 $ (758 )

Fair Value of Financial Instr22

Fair Value of Financial Instruments (Tables)	9 Months Ended
	Sep. 30, 2017
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 the Company’s financial instruments were measured: Fair Value Measurements Using Quoted Prices in Significant Other Significant Fair Value As of September 30, 2017 (In Thousands) U.S. Treasury securities and obligations of U.S. government agencies $ 60,214 $ 4,840 $ — $ 65,054 Municipal debt securities — 90,736 — 90,736 Corporate debt securities — 408,840 — 408,840 Asset-backed securities — 97,320 — 97,320 Cash, cash equivalents and short-term investments 51,477 — — 51,477 Total assets $ 111,691 $ 601,736 $ — $ 713,427 Warrant liability — — 4,046 4,046 Total liabilities $ — $ — $ 4,046 $ 4,046 Fair Value Measurements Using Quoted Prices in Significant Other Significant Fair Value As of December 31, 2016 (In Thousands) U.S. Treasury securities and obligations of U.S. government agencies $ 50,719 $ 12,460 $ — $ 63,179 Municipal debt securities — 40,269 — 40,269 Corporate debt securities — 349,078 — 349,078 Asset-backed securities — 114,661 — 114,661 Cash, cash equivalents and short-term investments 109,528 — — 109,528 Total assets $ 160,247 $ 516,468 $ — $ 676,715 Warrant liability — — 3,367 3,367 Total liabilities $ — $ — $ 3,367 $ 3,367
Roll-Forward of Level 3 Liabilities Measured at Fair Value	The following is a roll-forward of Level 3 liabilities measured at fair value: For the nine months ended September 30, Warrant Liability 2017 2016 (In Thousands) Balance, January 1 $ 3,367 $ 1,467 Change in fair value of warrant liability included in earnings 679 187 Balance, September 30 $ 4,046 $ 1,654

Term Loan (Tables)

Term Loan (Tables)	9 Months Ended
	Sep. 30, 2017
Debt Disclosure [Abstract]
Schedule of Future Principal Payments	Future principal payments due under the Term Loan as of September 30, 2017 are as follows: As of September 30, 2017 Principal (In thousands) 2017 $ 375 2018 1,500 2019 145,125 Total $ 147,000

Reinsurance (Tables)

Reinsurance (Tables)	9 Months Ended
	Sep. 30, 2017
Reinsurance Disclosures [Abstract]
Schedule of Effects of Reinsurance	The effect of our reinsurance agreements on premiums written and earned is as follows: For the three months ended For the nine months ended September 30, 2017 September 30, 2016 September 30, 2017 September 30, 2016 (In Thousands) Net premiums written Direct $ 56,217 $ 46,535 $ 142,134 $ 133,526 Ceded (1) (8,501 ) (37,336 ) (20,029 ) (37,336 ) Net premiums written $ 47,716 $ 9,199 $ 122,105 $ 96,190 Net premiums earned Direct $ 52,024 $ 33,052 $ 133,696 $ 78,900 Ceded (1) (7,505 ) (1,244 ) (18,035 ) (1,244 ) Net premiums earned $ 44,519 $ 31,808 $ 115,661 $ 77,656 (1) Net of profit commission The following table shows the amounts related to the 2016 QSR Transaction: For the three months ended For the nine months ended September 30, 2017 September 30, 2016 September 30, 2017 September 30, 2016 (In Thousands) Ceded risk-in-force $ 2,682,982 $ 1,778,235 $ 2,682,982 $ 1,778,235 Ceded premiums written (14,389 ) (38,977 ) (36,715 ) (38,977 ) Ceded premiums earned (13,393 ) (2,885 ) (34,721 ) (2,885 ) Ceded claims and claims expenses 277 90 887 90 Ceding commission written 2,878 7,795 7,343 7,795 Ceding commission earned 2,581 551 6,921 551 Profit commission 7,758 1,641 19,945 1,641

Reserves for Insurance Claims25

Reserves for Insurance Claims and Claims Expenses (Tables)	9 Months Ended
	Sep. 30, 2017
Insurance [Abstract]
Reconciliation of Liability for Insurance Claims and Claims Expenses	The following table provides a reconciliation of the beginning and ending reserve balances for primary insurance claims and claims expenses: For the nine months ended September 30, 2017 2016 (In Thousands) Beginning balance $ 3,001 $ 679 Less reinsurance recoverables (1) (297 ) — Beginning balance, net of reinsurance recoverables 2,704 679 Add claims incurred: Claims and claim expenses incurred: Current year (2) 3,546 1,803 Prior years (3) (581 ) (214 ) Total claims and claims expenses incurred 2,965 1,589 Less claims paid: Claims and claim expenses paid: Current year (2) — — Prior years (3) 720 225 Total claims and claim expenses paid 720 225 Reserve at end of period, net of reinsurance recoverables 4,949 2,043 Add reinsurance recoverables (1) 1,174 90 Ending balance $ 6,123 $ 2,133 (1) Related to ceded losses recoverable on the 2016 QSR Transaction, included in "Other Assets" on the Condensed Consolidated Balance Sheets. 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 had defaulted in a prior year and subsequently cured and later re-defaulted in the current year, that default would be included in the current year. (3) Related to insured loans with defaults occurring in prior years, which have been continuously in default since that time.

Earnings per Share (Tables)

Earnings per Share (Tables)	9 Months Ended
	Sep. 30, 2017
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 earnings per share of common stock: For the three months ended September 30, For the nine months ended September 30, 2017 2016 2017 2016 (In Thousands, except for per share data) Net income $ 12,312 $ 6,175 $ 23,816 $ 4,279 Basic earnings per share $ 0.21 $ 0.10 $ 0.40 $ 0.07 Basic weighted average shares outstanding 59,883,629 59,130,401 59,680,166 59,047,758 Dilutive effect of non-vested shares and warrants 3,205,329 1,154,345 3,093,167 814,158 Dilutive weighted average shares outstanding 63,088,958 60,284,746 62,773,333 59,861,916 Diluted earnings per share $ 0.20 $ 0.10 $ 0.38 $ 0.07

Statutory Information (Tables)

Statutory Information (Tables)	9 Months Ended
	Sep. 30, 2017
Insurance [Abstract]
Schedule of Statutory Net Loss, Surplus, Contingency Reserve and Risk-to-Capital Ratio	NMIC and Re One's combined statutory net loss, statutory surplus, contingency reserve and RTC ratios were as follows: As of and for the nine months and year ended September 30, 2017 December 31, 2016 (In Thousands) Statutory net loss $ (29,394 ) $ (26,653 ) Statutory surplus 379,160 413,809 Contingency reserve 157,326 90,479 Risk-to-Capital 11.5:1 11.6:1

Organization and Basis of Pre28

Organization and Basis of Presentation - Narrative (Details)	1 Months Ended		3 Months Ended		9 Months Ended
	Nov. 30, 2013shares	Apr. 30, 2012USD ($)shares	Sep. 30, 2017USD ($)state	Sep. 30, 2016USD ($)	Sep. 30, 2017USD ($)state	Sep. 30, 2016USD ($)
Business Acquisition [Line Items]
Proceeds from issuance of common stock, net of stock issuance costs		$ 510,000,000
Number of states in which the entity operates | state			50		50
Deferred policy acquisition cost, amortization expense			$ 1,700,000	$ 1,200,000	$ 4,000,000	$ 3,400,000
Premium deficiency reserve			$ 0	$ 0	$ 0	$ 0
Common Stock - Class A
Business Acquisition [Line Items]
Stock issued during period, shares, net issues (in shares) | shares		55,000,000
MAC Financial Holding Corporation and Subsidiaries
Business Acquisition [Line Items]
Consideration transferred, cash and equity interests issued and issuable		$ 8,500,000
Consideration transferred, liabilities incurred		$ 1,300,000
IPO
Business Acquisition [Line Items]
Stock issued during period, shares, net issues (in shares) | shares	2,400,000

Organization and Basis of Pre29

Organization and Basis of Presentation - Prior Period Adjustment (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016	Dec. 31, 2015
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Net income	$ 12,312	$ 6,175	$ 23,816	$ 4,279	$ 64,001
Income tax (benefit)	$ 7,185	$ 114	$ 11,917	$ 114	$ (52,550)
Basic EPS (in dollars per share)	$ 0.21	$ 0.10	$ 0.40	$ 0.07	$ 1.08
Diluted EPS (in dollars per share)	$ 0.20	$ 0.10	$ 0.38	$ 0.07	$ 1.05
Deferred tax asset, net	$ 38,490		$ 38,490		$ 51,434
Total assets	886,612		886,612		839,897
Accumulated deficit	(72,391)		(72,391)		(96,722)
Total shareholders' equity	$ 511,025		$ 511,025		475,509	$ 402,731
Previously Reported
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Net income					65,841
Income tax (benefit)					$ (54,389)
Basic EPS (in dollars per share)					$ 1.11
Diluted EPS (in dollars per share)					$ 1.08
Deferred tax asset, net					$ 53,274
Total assets					841,737
Accumulated deficit					(94,882)
Total shareholders' equity					477,349
Restatement Adjustment
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Deferred tax asset, net					$ (1,800)

Organization and Basis of Pre30

Organization and Basis of Presentation - Change in Accounting Principle (Details) $ in Thousands	Dec. 31, 2016USD ($)
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect adjustment	$ 903
Accumulated Deficit
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect adjustment	515
ASU No. 2016-09 | Accumulated Deficit
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect adjustment	$ 500

Investments - Fair Values and G

Investments - Fair Values and Gross Unrealized Gains and Losses on Investments (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 687,284	$ 630,688
Gross Unrealized Gains	7,776	2,822
Gross Unrealized (Losses)	(2,331)	(4,541)
Fair Value	692,729	628,969
U.S. Treasury securities and obligations of U.S. government agencies
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	65,669	64,135
Gross Unrealized Gains	21	6
Gross Unrealized (Losses)	(636)	(962)
Fair Value	65,054	63,179
Municipal debt securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	90,155	40,801
Gross Unrealized Gains	929	131
Gross Unrealized (Losses)	(348)	(663)
Fair Value	90,736	40,269
Corporate debt securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	404,467	349,712
Gross Unrealized Gains	5,619	1,722
Gross Unrealized (Losses)	(1,246)	(2,356)
Fair Value	408,840	349,078
Asset-backed securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	96,279	114,456
Gross Unrealized Gains	1,142	765
Gross Unrealized (Losses)	(101)	(560)
Fair Value	97,320	114,661
Bonds
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	656,570	569,104
Gross Unrealized Gains	7,711	2,624
Gross Unrealized (Losses)	(2,331)	(4,541)
Fair Value	661,950	567,187
Short-term investments
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	30,714	61,584
Gross Unrealized Gains	65	198
Gross Unrealized (Losses)	0	0
Fair Value	$ 30,779	$ 61,782

Investments - Scheduled Maturit

Investments - Scheduled Maturities (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Amortized Cost
Due in one year or less	$ 108,020	$ 94,382
Due after one through five years	158,353	173,296
Due after five through ten years	309,708	242,005
Due after ten years	14,924	6,549
Asset-backed securities	96,279	114,456
Amortized Cost	687,284	630,688
Fair Value
Due in one year or less	108,048	94,584
Due after one through five years	159,502	173,251
Due after five through ten years	312,697	240,060
Due after ten years	15,162	6,413
Asset-backed securities	97,320	114,661
Fair Value	$ 692,729	$ 628,969

Investments - Unrealized Losses

Investments - Unrealized Losses (Details) $ in Thousands	Sep. 30, 2017USD ($)security	Dec. 31, 2016USD ($)security
Schedule of Available-for-sale Securities [Line Items]
Number of securities, less than 12 months | security	90	154
Fair value, less than 12 months	$ 150,767	$ 253,569
Unrealized losses, less than 12 months	$ (881)	$ (4,044)
Number of securities,12 months or greater | security	39	15
Fair value, 12 months or greater	$ 68,959	$ 18,049
Unrealized losses, 12 months or greater	$ (1,450)	$ (497)
Number of securities, total | security	129	169
Fair value	$ 219,726	$ 271,618
Unrealized Losses	$ (2,331)	$ (4,541)
U.S. Treasury securities and obligations of U.S. government agencies
Schedule of Available-for-sale Securities [Line Items]
Number of securities, less than 12 months | security	22	33
Fair value, less than 12 months	$ 38,425	$ 51,093
Unrealized losses, less than 12 months	$ (263)	$ (962)
Number of securities,12 months or greater | security	15	0
Fair value, 12 months or greater	$ 19,621	$ 0
Unrealized losses, 12 months or greater	$ (373)	$ 0
Number of securities, total | security	37	33
Fair value	$ 58,046	$ 51,093
Unrealized Losses	$ (636)	$ (962)
Municipal debt securities
Schedule of Available-for-sale Securities [Line Items]
Number of securities, less than 12 months | security	9	14
Fair value, less than 12 months	$ 21,567	$ 28,659
Unrealized losses, less than 12 months	$ (212)	$ (617)
Number of securities,12 months or greater | security	8	1
Fair value, 12 months or greater	$ 10,319	$ 1,704
Unrealized losses, 12 months or greater	$ (136)	$ (46)
Number of securities, total | security	17	15
Fair value	$ 31,886	$ 30,363
Unrealized Losses	$ (348)	$ (663)
Corporate debt securities
Schedule of Available-for-sale Securities [Line Items]
Number of securities, less than 12 months | security	44	77
Fair value, less than 12 months	$ 69,602	$ 135,115
Unrealized losses, less than 12 months	$ (317)	$ (1,955)
Number of securities,12 months or greater | security	14	8
Fair value, 12 months or greater	$ 34,031	$ 13,873
Unrealized losses, 12 months or greater	$ (929)	$ (401)
Number of securities, total | security	58	85
Fair value	$ 103,633	$ 148,988
Unrealized Losses	$ (1,246)	$ (2,356)
Asset-backed securities
Schedule of Available-for-sale Securities [Line Items]
Number of securities, less than 12 months | security	15	30
Fair value, less than 12 months	$ 21,173	$ 38,702
Unrealized losses, less than 12 months	$ (89)	$ (510)
Number of securities,12 months or greater | security	2	6
Fair value, 12 months or greater	$ 4,988	$ 2,472
Unrealized losses, 12 months or greater	$ (12)	$ (50)
Number of securities, total | security	17	36
Fair value	$ 26,161	$ 41,174
Unrealized Losses	$ (101)	$ (560)

Investments - Net Investment In

Investments - Net Investment Income (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Investment Income, Net [Abstract]
Investment income	$ 4,363	$ 3,727	$ 12,455	$ 10,672
Investment expenses	(193)	(183)	(570)	(555)
Net investment income	$ 4,170	$ 3,544	$ 11,885	$ 10,117

Investments - Net Realized Inve

Investments - Net Realized Investment Gains (Losses) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Investments, Debt and Equity Securities [Abstract]
Gross realized investment gains	$ 69	$ 66	$ 536	$ 683
Gross realized investment losses	0	0	(338)	(1,441)
Net realized investment gains (losses)	$ 69	$ 66	$ 198	$ (758)

Investments - Narrative (Detail

Investments - Narrative (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Schedule of Available-for-sale Securities [Line Items]
Unrealized loss position, accumulated loss	$ 2,331	$ 4,541
Unrealized loss position, 12 months or greater	1,450	497
U.S. Treasury securities and obligations of U.S. government agencies
Schedule of Available-for-sale Securities [Line Items]
Cash and investments held with various state insurance departments	7,000	7,000
Unrealized loss position, accumulated loss	636	962
Unrealized loss position, 12 months or greater	$ 373	$ 0

Fair Value of Financial Instr37

Fair Value of Financial Instruments - Assets and Liabilities at Fair Value (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	$ 692,729	$ 628,969
Warrant liability	4,046	3,367
U.S. Treasury securities and obligations of U.S. government agencies
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	65,054	63,179
Municipal debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	90,736	40,269
Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	408,840	349,078
Asset-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	97,320	114,661
Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash, cash equivalents and short-term investments	51,477	109,528
Total assets	713,427	676,715
Warrant liability	4,046	3,367
Total liabilities	4,046	3,367
Fair Value, Measurements, 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]
Available-for-sale securities	65,054	63,179
Fair Value, Measurements, Recurring | Municipal debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	90,736	40,269
Fair Value, Measurements, Recurring | Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	408,840	349,078
Fair Value, Measurements, Recurring | Asset-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	97,320	114,661
Fair Value, Measurements, 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	51,477	109,528
Total assets	111,691	160,247
Warrant liability	0	0
Total liabilities	0	0
Fair Value, Measurements, 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]
Available-for-sale securities	60,214	50,719
Fair Value, Measurements, 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]
Available-for-sale securities	0	0
Fair Value, Measurements, 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]
Available-for-sale securities	0	0
Fair Value, Measurements, 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]
Available-for-sale securities	0	0
Fair Value, Measurements, 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	601,736	516,468
Warrant liability	0	0
Total liabilities	0	0
Fair Value, Measurements, 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]
Available-for-sale securities	4,840	12,460
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Municipal debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	90,736	40,269
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	408,840	349,078
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Asset-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	97,320	114,661
Fair Value, Measurements, 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
Warrant liability	4,046	3,367
Total liabilities	4,046	3,367
Fair Value, Measurements, 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]
Available-for-sale securities	0	0
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3) | Municipal debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	0	0
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3) | Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	0	0
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3) | Asset-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	$ 0	$ 0

Fair Value of Financial Instr38

Fair Value of Financial Instruments - Rollforward of Level 3 (Details) - Significant Unobservable Inputs (Level 3) - Warrant Liability - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	$ 3,367	$ 1,467
Change in fair value of warrant liability included in earnings	679	187
Ending balance	$ 4,046	$ 1,654

Fair Value of Financial Instr39

Fair Value of Financial Instruments - Narrative (Details) - Warrant Liability - Significant Unobservable Inputs (Level 3)	9 Months Ended
	Sep. 30, 2017$ / shares
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Share price (in dollars per share)	$ 12.40
Risk free rate	1.66%
Expected term	3 years 3 months
Volatility assumption	30.60%
Expected dividend rate	0.00%

Term Loan - Narrative (Details)

Term Loan - Narrative (Details) - USD ($)	Feb. 10, 2017	Nov. 10, 2015	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Feb. 10, 2017
Debt Instrument [Line Items]
Term loan			$ 147,000,000		$ 147,000,000
Debt issuance cost					370,000	$ 0
Interest expense			3,352,000	$ 3,733,000	10,146,000	$ 11,072,000
Senior Secured Debt | Credit Agreement
Debt Instrument [Line Items]
Debt instrument term		3 years
Debt instrument, face amount		$ 150,000,000
Debt instrument, extension of term	1 year
Periodic payment of principal					375,000
Term loan			$ 147,000,000		$ 147,000,000
Debt issuance cost	$ 370,000						$ 4,800,000
Percentage of debt discount		1.00%
Debt instrument covenant, maximum debt-to-total capitalization ratio					35.00%
Debt instrument covenant, maximum risk-to-capital ratio					22
Senior Secured Debt | Credit Agreement | Eurodollar
Debt Instrument [Line Items]
Variable rate floor					1.00%
Basis spread on variable rate					6.75%
Interest rate during period					7.99%

Term Loan - Schedule of Future

Term Loan - Schedule of Future Principal Payments (Details) $ in Thousands	Sep. 30, 2017USD ($)
Future Principal Payments [Abstract]
2,017	$ 375
2,018	1,500
2,019	145,125
Total	$ 147,000

Reinsurance - Narrative (Detail

Reinsurance - Narrative (Details) $ in Thousands	Sep. 01, 2016	May 31, 2017USD ($)	Sep. 30, 2017USD ($)transaction	Sep. 30, 2017USD ($)transaction	Sep. 30, 2017USD ($)transaction	Dec. 31, 2016USD ($)	Sep. 30, 2016USD ($)	Dec. 31, 2015USD ($)
Ceded Credit Risk [Line Items]
Number of third-party reinsurance transactions, Number | transaction			2	2	2
Reinsurance recoverable on unpaid claims			$ 1,174	$ 1,174	$ 1,174	$ 297	$ 90	$ 0
Mortgage-linked Debt | 2017 ILN Notes | Oaktown Re Ltd
Ceded Credit Risk [Line Items]
Proceeds from issuance of notes		$ 211,300
Third-Party Reinsurers
Ceded Credit Risk [Line Items]
Ceding commissions under 2016 QSR Transaction	20.00%
Threshold for loss ratio on loans under 2016 QSR Transaction to qualify for profit commission	60.00%
Reinsurance recoverable on unpaid claims			1,200	1,200	1,200
Third-Party Reinsurers | 2017 ILN Transaction
Ceded Credit Risk [Line Items]
Aggregate excess of loss reinsurance coverage				$ 185,000
Aggregate excess of loss reinsurance retained by company		126,800
Risk premiums paid			$ 1,900		3,300
Third-Party Reinsurers | 2017 ILN Transaction | Maximum
Ceded Credit Risk [Line Items]
Aggregate excess of loss reinsurance coverage		$ 211,300
Reinsurance coverage, term of underlying mortgage amortization (in years)		10 years
Anticipated payment related annual operating expenses					$ 300
Third-Party Reinsurers | Existing Risk Written Policies
Ceded Credit Risk [Line Items]
Percent of policies ceded under 2016 QSR Transaction	25.00%
Third-Party Reinsurers | Fannie Mae
Ceded Credit Risk [Line Items]
Percent of policies ceded under 2016 QSR Transaction	100.00%
Third-Party Reinsurers | Risk Written Policies from September 1, 2016 through December 31, 2017
Ceded Credit Risk [Line Items]
Percent of policies ceded under 2016 QSR Transaction	25.00%

Reinsurance - Effect of Reinsur

Reinsurance - Effect of Reinsurance on Net Premiums Written and Earned (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Net premiums written
Direct	$ 56,217	$ 46,535	$ 142,134	$ 133,526
Ceded	(8,501)	(37,336)	(20,029)	(37,336)
Net premiums written	47,716	9,199	122,105	96,190
Net premiums earned
Direct	52,024	33,052	133,696	78,900
Ceded	(7,505)	(1,244)	(18,035)	(1,244)
Net premiums earned	$ 44,519	$ 31,808	$ 115,661	$ 77,656

Reinsurance - Amounts Ceded Rel

Reinsurance - Amounts Ceded Related to 2016 QSR Transaction (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Ceded Credit Risk [Line Items]
Ceded premiums written	$ (8,501)	$ (37,336)	$ (20,029)	$ (37,336)
Ceded premiums earned	(7,505)	(1,244)	(18,035)	(1,244)
Third-Party Reinsurers
Ceded Credit Risk [Line Items]
Ceded risk-in-force	2,682,982	1,778,235	2,682,982	1,778,235
Ceded premiums written	(14,389)	(38,977)	(36,715)	(38,977)
Ceded premiums earned	(13,393)	(2,885)	(34,721)	(2,885)
Ceded claims and claims expenses	277	90	887	90
Ceding commission written	2,878	7,795	7,343	7,795
Ceding commission earned	2,581	551	6,921	551
Profit commission	$ 7,758	$ 1,641	$ 19,945	$ 1,641

Reserves for Insurance Claims45

Reserves for Insurance Claims and Claims Expenses - Narrative (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2017USD ($)loanclaim	Sep. 30, 2016USD ($)	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)
Liability for Claims and Claims Adjustment Expense [Line Items]
IBNR, default period (at least)	60 days
Total gross liability for unpaid claims and claim adjustment expenses	$ 6,123	$ 2,133	$ 3,001	$ 679
Primary loans in default | loan	350
Number of claims paid | claim	16
Claims paid, including amounts covered by insurance	$ 731
Favorable prior year development	581	$ 214
Reserve for prior year insurance claims and claim expenses	$ 1,700
Fannie Mae
Liability for Claims and Claims Adjustment Expense [Line Items]
Number of loans in pool past due 60 days or more | loan	46
Risk-in-Force of loans in pool past due 60 days or more	$ 3,000
Deductible on policy	$ 10,000
Loan-to-value ratio (less than)	0.8
Claims applied to pool deductible	$ 368
2016 QSR Transaction
Liability for Claims and Claims Adjustment Expense [Line Items]
Number of covered claims included in number of claims paid | claim	2
Component of claims paid covered under QSR Transaction	$ 11
2016 QSR Transaction | Fannie Mae
Liability for Claims and Claims Adjustment Expense [Line Items]
Percent of pool RIF reinsured	100.00%

Reserves for Insurance Claims46

Reserves for Insurance Claims and Claims Expenses - Reconciliation of Reserve Balances for Insurance Claims Expense (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Beginning balance	$ 3,001	$ 679
Less reinsurance recoverables	297	0
Beginning balance, net of reinsurance recoverables	2,704	679
Claims incurred:
Current year	3,546	1,803
Prior years	(581)	(214)
Total claims and claims expenses incurred	2,965	1,589
Claims and claim expenses paid:
Current year	0	0
Prior years	720	225
Total claims and claim expenses paid	720	225
Ending balance, net of reinsurance recoverables	4,949	2,043
Add reinsurance recoverables	1,174	90
Ending balance	$ 6,123	$ 2,133

Earnings per Share - Computatio

Earnings per Share - Computation of Basic and Diluted Earnings (Loss) per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Earnings Per Share [Abstract]
Net income	$ 12,312	$ 6,175	$ 23,816	$ 4,279	$ 64,001
Basic earnings per share (in dollars per share)	$ 0.21	$ 0.10	$ 0.40	$ 0.07	$ 1.08
Basic weighted average shares outstanding (in shares)	59,883,629	59,130,401	59,680,166	59,047,758
Dilutive effect of non-vested shares and warrants (in shares)	3,205,329	1,154,345	3,093,167	814,158
Dilutive weighted average shares outstanding (in shares)	63,088,958	60,284,746	62,773,333	59,861,916
Diluted earnings per share (in dollars per share)	$ 0.20	$ 0.10	$ 0.38	$ 0.07	$ 1.05

Earnings per Share - Narrative

Earnings per Share - Narrative (Details) - shares	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Share-based Compensation Arrangement
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from EPS calculation (in shares)	830,043	4,012,046	832,460	4,326,168

Warrants - Narrative (Details)

Warrants - Narrative (Details) - USD ($) $ / shares in Units, $ in Millions	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Apr. 30, 2012
Debt Disclosure [Abstract]
Warrants issued (in shares)			992,000
Right to purchase, number of shares per warrant			1
Exercise price of warrants (in dollars per warrant)			$ 10
Warrants value			$ 5.1
Number of warrants exercised during period	0	0

Income Taxes - Narrative (Detai

Income Taxes - Narrative (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Federal statutory income tax rate			35.00%
Effective income tax rate on pre-tax income or loss	36.90%	1.80%	33.30%	2.60%
Net operating loss carryforwards					$ 122.9

Statutory Information - Schedul

Statutory Information - Schedule of Statutory Net Loss, Surplus, Contingency Reserve and Risk-to-Capital Ratio (Details) - Combined $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2017USD ($)	Dec. 31, 2016USD ($)
Statutory Accounting Practices [Line Items]
Statutory net loss	$ (29,394)	$ (26,653)
Statutory surplus	379,160	413,809
Contingency reserve	$ 157,326	$ 90,479
Risk-to-Capital	11.5	11.6