NMI (NMIH) 10-K 20 Feb 15 2014 FY Annual report Financial data

Document_and_Entity_Informatio

Document and Entity Information (USD $)	12 Months Ended
	Dec. 31, 2014	Feb. 16, 2015	Jun. 30, 2014
Document and Entity Information [Abstract]
Entity Registrant Name	NMI HOLDINGS, INC.
Entity Central Index Key	1547903
Document Type	10-K
Document Period End Date	31-Dec-14
Amendment Flag	FALSE
Document Fiscal Year Focus	2014
Document Fiscal Period Focus	FY
Current Fiscal Year End Date	-19
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Non-accelerated Filer
Entity Public Float			$546,126,819
Entity Common Stock, Shares Outstanding		58,519,558

CONSOLIDATED_BALANCE_SHEETS

CONSOLIDATED BALANCE SHEETS (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Assets
Fixed maturities, available-for-sale, at fair value (amortized cost of $337,718 and $416,135 as of December 31, 2014 and December 31, 2013, respectively)	$336,501	$409,088
Cash and cash equivalents	103,021	55,929
Premiums receivable	1,048	19
Accrued investment income	1,707	2,001
Prepaid expenses	2,054	1,519
Deferred policy acquisition costs, net	2,985	90
Software and equipment, net	11,806	8,876
Intangible assets and goodwill	3,634	3,634
Other assets	509	63
Total assets	463,265	481,219
Liabilities
Unearned premiums	22,069	1,446
Reserve for insurance claims and claim expenses	83	0
Accounts payable and accrued expenses	10,646	10,052
Warrant liability, at fair value	3,372	6,371
Deferred tax liability	137	133
Total liabilities	36,307	18,002
Commitments and contingencies
Shareholders' equity
Additional paid-in capital	562,911	553,707
Accumulated other comprehensive loss, net of tax	-3,607	-7,047
Accumulated deficit	-132,930	-84,024
Total shareholders' equity	426,958	463,217
Total liabilities and shareholders' equity	463,265	481,219
Common Class A [Member]
Shareholders' equity
Common stock - class A shares, $0.01 par value; 58,428,548 and 58,052,480 shares issued and outstanding as of December 31, 2014 and December 31, 2013, respectively (250,000,000 shares authorized)	$584	$581

CONSOLIDATED_BALANCE_SHEETS_Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, except Share data, unless otherwise specified
Fixed maturity, amortized cost	$337,718	$416,135
Common Class A [Member]
Common stock, par value (in dollars per share)	$0.01	$0.01
Common stock, shares issued	58,428,548	58,052,480
Common stock, shares outstanding	58,428,548	58,052,480
Common stock, shares authorized	250,000,000	250,000,000

CONSOLIDATED_STATEMENTS_OF_COM

CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS (USD $)	12 Months Ended
In Thousands, except Share data, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013		Dec. 31, 2012
Premiums written
Direct	$34,029	$3,541		$0
Net premiums written	34,029	3,541		0
Increase in unearned premiums	-20,622	-1,446		0
Net premiums earned	13,407	2,095		0
Net investment income	5,618	4,808		6
Net realized investment gains	197	186		0
Gain (loss) from change in fair value of warrant liability	2,949	-1,529		278
Gain from settlement of warrants	37	0		0
Total revenues	22,208	5,560		284
Expenses
Insurance claims and claims expenses	83	0		0
Amortization of deferred policy acquisition costs	373	1		0
Underwriting and operating expenses	73,044	60,743		27,775
Total expenses	73,500	60,744		27,775
Loss before income taxes	-51,292	-55,184		-27,491
Income tax benefit	-2,386	0		0
Net loss	-48,906	-55,184		-27,491
Other comprehensive income (loss), net of tax:
Net unrealized holding gains (losses) for the period included in accumulated other comprehensive loss, net of tax expense of $2,390, $0 and $0 for each of the years in the three-year period ended December 31, 2014, respectively	3,440	-7,047		1
Other comprehensive income (loss), net of tax	3,440	-7,047		1
Total comprehensive loss	($45,466)	($62,231)		($27,490)
Loss per share
Basic and diluted loss per share (in dollars per share)	($0.84)	($0.99)	[1]	($0.73)
Weighted average common shares outstanding (in shares)	58,281,425	56,005,326	[1]	37,909,936
[1]	Due to the use of weighted average shares outstanding when calculating earnings per share, the sum of quarterly per share data may not equal the per share data for the year.

CONSOLIDATED_STATEMENTS_OF_COM1

CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS Parenthetical (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Statement of Comprehensive Income [Abstract]
Other comprehensive income (loss), tax	$2,390	$0	$0

CONSOLIDATED_STATEMENTS_OF_SHA

CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY (USD $)	Total		Common Class A [Member]		Common Class B [Member]	Common Stock [Member]	Common Stock [Member]	Additional Paid-in Capital [Member]	Additional Paid-in Capital [Member]	Accumulated Other Comprehensive Loss [Member]	Accumulated Deficit [Member]
In Thousands, unless otherwise specified						Common Class A [Member]	Common Class B [Member]		Common Class A [Member]
Beginning Balance at Dec. 31, 2011	($1,349)	[1]					$0	$0		$0	($1,349)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of shares of common stock, net of expenses of $3,483 in 2013			508,970		2	551	2		508,419
Issuance of common stock related to acquisition of subsidiaries			2,500			2			2,498
Share-based compensation expense	6,115							6,115
Change in unrealized investment gains/losses, net of tax of $0, $0 and $2,390	1									1
Net loss	-27,491										-27,491
Ending Balance at Dec. 31, 2012	488,748					553	2	517,032		1	-28,840
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of shares of common stock, net of expenses of $3,483 in 2013			27,912			25	0		27,887
Common stock: class A shares issued under stock plans, net of shares withheld (for) from employee taxes			-1,578			1			-1,579
Conversion of class B shares of common stock into Class A shares of common stock	0					2	-2	0
Share-based compensation expense	10,367							10,367
Change in unrealized investment gains/losses, net of tax of $0, $0 and $2,390	-7,048									-7,048
Net loss	-55,184										-55,184
Ending Balance at Dec. 31, 2013	463,217					581	0	553,707		-7,047	-84,024
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock: class A shares issued under stock plans, net of shares withheld (for) from employee taxes			14			3			11
Common stock: class A shares issued related to warrants			13	[2]					13
Share-based compensation expense	9,180							9,180
Change in unrealized investment gains/losses, net of tax of $0, $0 and $2,390	3,440									3,440
Net loss	-48,906										-48,906
Ending Balance at Dec. 31, 2014	$426,958					$584	$0	$562,911		($3,607)	($132,930)
[1]	At inception, we issued 100 common shares with a par value of $0.01 to FBR & Co. in consideration of their investment of $1 in the Company, which are not visible in this schedule due to rounding.
[2]	During 2014, we issued 1,115 common shares with a par value of $0.01 related to the exercise of warrants, which is not identifiable in this schedule due to rounding.

CONSOLIDATED_STATEMENTS_OF_SHA1

CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY - (Parenthetical) (USD $)	12 Months Ended			1 Months Ended
In Thousands, except Share data, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Apr. 30, 2012
Price per share				$1
Payments of stock issuance costs		$3,483
Change in unrealized investment gains (losses), tax amount	$2,390	$0	$0
Common Class A [Member]
Common stock, par value (in dollars per share)	$0.01	$0.01
Common Class A [Member] | Common Stock [Member]
Common stock issued at inception				100
Common stock issued	1,115
Common stock, par value (in dollars per share)				$0.01

CONSOLIDATED_STATEMENTS_OF_CAS

CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $)	12 Months Ended
Share data in Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Cash flows from operating activities
Net loss	($48,906,000)	($55,184,000)	($27,491,000)
Adjustments to reconcile net loss to net cash used in operating activities:
Net realized investment gains	-197,000	-186,000	0
(Gain) loss from change in fair value of warrant liability	-2,949,000	1,529,000	-278,000
Gain from settlement of warrants	-37,000	0	0
Depreciation and other amortization	8,080,000	8,116,000	3,000
Share-based compensation expense	9,180,000	10,367,000	6,115,000
Noncash intraperiod tax allocation	-2,386,000	0	0
Warrants issued in connection with line of credit	0	0	1,620,000
Loss on impairment	0	0	1,200,000
Changes in operating assets and liabilities:
Accrued investment income	294,000	-2,001,000	-6,000
Premiums receivable	-1,029,000	-19,000	0
Prepaid expenses	-535,000	-1,102,000	-234,000
Deferred policy acquisition costs, net	-2,895,000	-90,000	0
Other assets	-446,000	46,000	-78,000
Unearned premiums	20,622,000	1,446,000	0
Reserve for insurance claims and claims expenses	83,000	0	0
Accounts payable and accrued expenses	117,000	767,000	4,553,000
Net cash used in operating activities	-21,004,000	-36,311,000	-14,596,000
Cash flows from investing activities
Purchase of short-term investments	0	-510,000	-4,862,000
Purchase of fixed-maturity investments, available-for-sale	-60,462,000	-559,875,000	0
Proceeds from maturity of short-term investments	0	5,374,000	0
Proceeds from redemptions, maturities and sale of fixed-maturity investments, available-for-sale	136,764,000	141,754,000	0
Purchase of software and equipment	-8,220,000	-6,692,000	-2,447,000
Acquisition of subsidiaries	0	0	-2,500,000
Net cash provided by (used in) investing activities	68,082,000	-419,949,000	-9,809,000
Cash flows from financing activities
Payments on line of credit	0	0	-205,000
Taxes paid related to net share settlement of equity awards	-1,083,000	-1,578,000	0
Issuance of common stock	1,097,000	27,912,000	510,465,000
Net cash provided by financing activities	14,000	26,334,000	510,260,000
Net increase (decrease) in cash and cash equivalents	47,092,000	-429,926,000	485,855,000
Cash and cash equivalents, beginning of period	55,929,000	485,855,000	0
Cash and cash equivalents, end of period	103,021,000	55,929,000	485,855,000
Supplemental disclosures of cash flow information
Restricted cash	0	0	40,338,000
Noncash financing activities
Conversion of class B shares of common stock into class A shares of common stock	$0	$2,000	$0
Acquisition of subsidiaries
Warrants issued in connection with acquisition of subsidiaries	0	0	3,500
Common stock issued in connection with acquisition of subsidiaries	0	0	2,500

Organization_and_Basis_of_Pres

Organization and Basis of Presentation	12 Months Ended
	Dec. 31, 2014
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization and Basis of Presentation	Organization and Basis of Presentation
	NMIH is a Delaware corporation, formed in May 2011, to provide mortgage insurance through its wholly owned insurance subsidiaries, NMIC and 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 shares 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 April 2013, NMIC, our primary insurance subsidiary, wrote our first mortgage insurance policy.
	Under the terms of the Private Placement, we were required to obtain approvals from the GSEs by January 17, 2013. Freddie Mac and Fannie Mae approved NMIC as an eligible mortgage insurer, on January 15, 2013 and January 16, 2013, respectively, which approvals are conditioned upon NMIC maintaining certain conditions (the "GSE Approval"). For a further discussion of these conditions, see "Note 11, Commitments and Contingencies."
	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 on November 8, 2013, under the symbol "NMIH." For a further discussion, see "Note 12, Common Stock Offerings."
	Basis of Presentation
	The accompanying consolidated financial statements include the results of NMIH and its wholly owned subsidiaries. All inter-company transactions have been eliminated. These financial statements have been prepared in accordance with accounting principles generally accepted in the U.S. ("GAAP") and our accounts are maintained in US dollars. The preparation of financial statements in accordance with GAAP requires management to make estimates and assumptions that affect reported amounts of assets and liabilities, as well as disclosure of contingent assets and liabilities as of the balance sheet date. Estimates also affect the reported amounts of income and expenses for the reporting period. Actual results could differ from those estimates.

Summary_of_Accounting_Policies

Summary of Accounting Policies	12 Months Ended
	Dec. 31, 2014
Accounting Policies [Abstract]
Summary of Accounting Principles	Summary of Accounting Principles
	Revenue Recognition
	In the mortgage insurance industry, a "book" is a group of loans that an MI company insures in a particular period, normally a calendar year. We set premiums at the time a policy is issued based on our expectations regarding likely performance over the term of coverage. The policies we write are guaranteed renewable contracts at the policyholder's option. Premiums may be paid to us on a single, annual or monthly basis. Premiums written on a single premium basis and an annual premium basis are initially deferred as unearned premium reserve and earned over the policy term commencing in the month coverage is effective.  Premiums written on policies covering more than one year are amortized over the policy life in accordance with the expiration of risk, which is the anticipated claim payment pattern based on industry experience.  Premiums written on annual policies are earned on a monthly pro rata basis.  Premiums written on monthly policies are earned as coverage is provided. Premiums written on pool transactions are earned over the period that coverage is provided.  Upon cancellation of a policy, all premium that is non-refundable is immediately earned and any refundable premium is returned to the policyholder. Premiums returned to policyholders are recorded as a reduction of written and earned premiums in the current period. The actual return of premium for all periods affects premiums written and earned in those periods.
	For the year ended December 31, 2014, two customers represented a material portion of our revenues. At December 31, 2014, approximately 18% of our total RIF was concentrated in California. Our RIF and customer concentrations are not representative of those concentrations that we believe will exist when our insurance portfolio is more mature.
	Reserves for Insurance Claims and Claims Expenses
	Consistent with industry accounting practices, for purposes of establishing claim reserves, we adhere to the general claim reserving principles contained in Financial Accounting Standards Board Accounting Standards Codification ("ASC") Topic 944, Financial Services - Insurance ("ASC 944"), even though that standard expressly excludes mortgage insurance from its guidance. However, and consistent with our industry, we do not establish claim reserves for anticipated future claims on insured loans that are not currently in default. We do not consider a loan to be in default for claim reserve purposes until we receive notice from the servicer that a borrower has failed to make two consecutive regularly scheduled payments and is at least 60 days in default. In addition to reserves on reported defaults, we establish reserves 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.
	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 as a component of accumulated other comprehensive (loss) income in shareholders' equity. Net realized investment gains and losses are reported in income based upon specific identification of securities sold.
	Purchases and sales of investments are recorded on a trade date basis. Net investment income is recognized when earned and includes interest and dividend income together with amortization of market premiums and discounts using the effective yield method and is net of investment management fees and other investment related expenses. For asset-backed securities and any other holdings for which there is a prepayment risk, prepayment assumptions are evaluated and revised as necessary. Any adjustments required due to the change in effective yields and maturities are recognized on a prospective basis through yield adjustments.
	Each quarter, we evaluate our investments in order to determine whether declines in fair value below amortized cost were considered other-than-temporary in accordance with applicable guidance. Under the current guidance, a debt security impairment is deemed other-than-temporary if (i) we either intend to sell the security or it is more likely than not that we will be required to sell the security before recovery or (ii) we do not expect to collect cash flows sufficient to recover the amortized cost basis of the security. In evaluating whether a decline in fair value is other-than-temporary, we consider several factors including, but not limited to:
	•	our intent to sell the security or whether it is more likely than not that we will be required to sell the security before recovery;
	•	severity and duration of the decline in fair value;
	•	the financial condition of the issuer;
	•	the failure of the issuer to make scheduled interest or principal payments;
	•	recent credit downgrades of the applicable security or the issuer below investment grade; and
	•	adverse conditions specifically related to the security, an industry, or a geographic area.
	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"). For each book year of business, these costs are amortized to expense in relation to the anticipated recognition of premiums.
	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 each of the years in the three-year period ended December 31, 2014.
	Income Taxes
	We account for income taxes using the liability method in accordance with ASC Topic 740, Income Taxes. The liability method measures the expected future tax effects of temporary differences at the enacted tax rates applicable for the period in which the deferred asset or liability is expected to be realized or settled. Temporary differences are differences between the tax basis of an asset or liability and its reported amount in the consolidated financial statements that would result in future increases or decreases in taxes owed on a cash basis compared to amounts already recognized as tax expense in the consolidated statement of operations.
	Warrants
	We account for 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. Our outstanding warrants may be settled by us using either (i) physical settlement method or (ii) cashless exercise, where shares that are issued upon exercise of the warrants are reduced, to cover the cost of the exercise, in lieu of the holder remitting a cash payment of the exercise price. The warrants expire and are not exercisable after the 10th anniversary of the date the warrant was issued. The exercise price and the number of warrants are subject to anti-dilution provisions whereby the existing exercise price is adjusted downward, and the number of warrants increased, for events that may not be dilutive. The adjustment may be in excess of any dilution suffered. As a result, the warrants are classified as a liability. We revalue the warrants at the end of each reporting period, and any change in fair value is reported in the statements of operations in the period in which the change occurred. We calculate the fair value of the warrants using a Black-Scholes option-pricing model in combination with a binomial model, and we value the pricing protection features of the warrants using a Monte Carlo simulation model.
	Share-Based Compensation
	We account for stock compensation in accordance with ASC 718, Compensation - Stock Compensation. This addresses accounting for share-based awards and recognition of compensation expense, measured using grant date fair value, over the requisite service or performance period of the award. Share-based payments include restricted stock units ("RSUs") and stock option grants under the 2012 Stock Incentive Plan. We determine the fair value of issued stock option grants using an option pricing model, which takes into account various assumptions that are subjective. Key assumptions used in the stock option valuation include the expected term of the equity award, taking into account the contractual term of the award, the effects of expected exercise and post-vesting termination behavior, expected volatility, expected dividends and the risk-free interest rate for the expected term of the award. RSU grants to employees contain a market condition and/or service condition. The fair value of RSU grants to employees with a market condition is determined based on a Monte Carlo simulation model at the date of grant. RSU grants to employees with a service condition and RSU grants to non-employee directors are valued at our stock price on the date of grant less the present value of anticipated dividends.
	Earnings per Share
	Basic net loss per share is based on the weighted-average number of common shares outstanding, while diluted net loss per share is based on the weighted-average number of common shares outstanding and common stock equivalents that would be issuable upon the exercise of stock options, other stock-based compensation arrangements, and the dilutive effect of outstanding warrants. As a result of our net losses for the each of the years in the three-year period ended December 31, 2014, 5,839,909 shares, 5,303,394 shares, and 4,414,165 shares of our common stock equivalents issued under stock-based compensation arrangements and warrants, respectively, were not included in the calculation of diluted net loss per share as of such dates because they were anti-dilutive.
	Cash and Cash Equivalents
	We consider items such as certificates of deposit and money market funds with original maturities of 90 days or less to be cash equivalents. The Company did not have any restricted cash as of December 31, 2014 and 2013.
	Software and Equipment
	Certain costs associated with the development of internal-use software are capitalized. Software and equipment are stated at cost, less accumulated amortization and depreciation. Once the software is ready for its intended use, amortization and depreciation are calculated using the straight-line method over the estimated useful lives of the respective assets ranging typically from 3 to 7 years, unless factors indicate a shorter useful life. Amortization of software and depreciation of equipment commences at the beginning of the month following our placement of the assets into use. For further detail, see "Note 9, Software and Equipment."
	Business Combinations, Goodwill and Intangible Assets
	Goodwill represents the excess of the purchase price over the estimated fair value of net assets acquired from a business combination. In accordance with ASC 350, Intangibles - Goodwill and Other, we test goodwill for impairment during the third quarter each year, or more frequently if we believe indicators of impairment exist. We have not identified any impairments of goodwill through December 31, 2014.
	Our intangible assets consist of state licenses and GSE applications which have indefinite lives. We test indefinite-lived intangible assets for impairment during the fourth quarter of each year or more frequently if we believe indicators of impairment exist. We do not believe that the indefinite-lived intangible assets were impaired as of December 31, 2014.
	Premiums receivable
	Premiums receivable consist of premiums due on our mortgage insurance policies. If mortgage insurance premiums are unpaid for more than 120 days, the receivable is written off against earned premium and the related insurance policy is canceled.
	Recent Accounting Standards Updates Adopted
	In August 2014, the FASB issued an update that requires an entity's management to evaluate whether there is substantial doubt about that entity's ability to continue as a going concern and, if so, disclose that fact. An entity's management will also be required to evaluate and disclose whether its plans alleviate that doubt. The guidance is effective for annual periods ending after December 15, 2016 and for interim and annual periods thereafter. We do not expect the adoption of this update to have a material effect on the presentation of our financial statements and notes therein.
	Reclassifications
	Certain items in the financial statements as of December 31, 2014 and for the periods ending December 31, 2013 and December 31, 2012 have been reclassified to conform to the current period's presentation. There was no effect on net income or shareholders' equity previously reported.
	Subsequent Events
	We have considered subsequent events through the date of this filing.

Investments

Investments	12 Months Ended
	Dec. 31, 2014
Investments, Debt and Equity Securities [Abstract]
Investments	Investments
	Fair Values and Gross Unrealized Gains and Losses on Investments
		Amortized				Gross Unrealized								Fair
		Cost				Gains				Losses				Value
	As of December 31, 2014	(In Thousands)
	U.S. Treasury securities and obligations of U.S. government agencies	$	68,911			$	7			$	(573	)		$	68,345
	Municipal debt securities	12,009				27				(73		)		11,963
	Corporate debt securities	200,358				883				(1,456		)		199,785
	Asset-backed securities	56,440				222				(254		)		56,408
	Total investments	$	337,718			$	1,139			$	(2,356	)		$	336,501
		Amortized				Gross Unrealized								Fair
		Cost				Gains				Losses				Value
	As of December 31, 2013	(In Thousands)
	U.S. Treasury securities and obligations of U.S. government agencies	$	108,067			$	—			$	(1,461	)		$	106,606
	Municipal debt securities	12,017				1				(85		)		11,933
	Corporate debt securities	221,899				157				(4,799		)		217,257
	Asset-backed securities	74,152				114				(974		)		73,292
	Total investments	$	416,135			$	272			$	(7,319	)		$	409,088
	Scheduled Maturities
	The amortized cost and fair values of available for sale securities at December 31, 2014, 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 separate categories.
	As of December 31, 2014	Amortized				Fair
		Cost				Value
		(In Thousands)
	Due in one year or less	$	6,110			$	6,125
	Due after one through five years	195,492				194,472
	Due after five through ten years	54,360				53,891
	Due after ten years	25,316				25,605
	Asset-backed securities	56,440				56,408
	Total investments	$	337,718			$	336,501
	As of December 31, 2013	Amortized				Fair
		Cost				Value
		(In Thousands)
	Due in one year or less	$	—			$	—
	Due after one through five years	260,855				257,501
	Due after five through ten years	65,687				63,440
	Due after ten years	15,441				14,855
	Asset-backed securities	74,152				73,292
	Total investments	$	416,135			$	409,088
	Aging of Unrealized Losses
	At December 31, 2014, the investment portfolio had gross unrealized losses of $2.4 million, $1.7 million of which has been in an unrealized loss position for a period of twelve months or greater. We did not consider these securities to be other-than-temporarily impaired as of December 31, 2014. We based our conclusion that these investments were not other-than-temporarily impaired at December 31, 2014 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 December 31, 2014			(Dollars in Thousands)
	U.S. Treasury securities and obligations of U.S. government agencies	4		$	7,228		$	(33	)		10		$	49,884		$	(540	)	14	$	57,112	$	(573	)
	Municipal debt securities	1		3,232			(18		)		1		1,695			(55		)	2	4,927		(73		)
	Corporate debt securities	26		60,334			(559		)		22		65,806			(897		)	48	126,140		(1,456		)
	Assets-backed securities	3		10,614			(57		)		4		20,047			(197		)	7	30,661		(254		)
	Total investments	34		$	81,408		$	(667	)		37		$	137,432		$	(1,689	)	71	$	218,840	$	(2,356	)
		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, 2013			(Dollars in Thousands)
	U.S. Treasury securities and obligations of U.S. government agencies	19		$	106,606		$	(1,461	)		—		$	—		$	—		19	$	106,606	$	(1,461	)
	Municipal debt securities	2		4,915			(85		)		—		—			—			2	4,915		(85		)
	Corporate debt securities	47		187,714			(4,799		)		—		—			—			47	187,714		(4,799		)
	Assets-backed securities	11		58,225			(974		)		—		—			—			11	58,225		(974		)
	Total investments	79		$	357,460		$	(7,319	)		—		$	—		$	—		79	$	357,460	$	(7,319	)
	Net Investment Income
	Net investment income is comprised of the following:
		For the Year Ended December 31,
		2014				2013				2012
		(In Thousands)
	Fixed maturities	$	6,127			$	5,289			$	4
	Cash equivalents	—				—				2
	Other	8				2				—
Investment income	6,135				5,291				6
Investment expenses	(517		)		(483		)		—
Net investment income	$	5,618			$	4,808			$	6
Gross realized gains were $0.7 million and $0.6 million for the years ended December 31, 2014 and 2013, respectively. Gross realized losses were $0.5 million and $0.4 million for the years ended December 31, 2014 and 2013, respectively. There were no realized investment gains or losses for the year ended December 31, 2012.
As of December 31, 2014 and December 31, 2013, there were approximately $7.0 million of cash and investments in the form of U.S. Treasury securities on deposit with various state insurance departments to satisfy regulatory requirements.

Fair_Value_of_Financial_Instru

Fair Value of Financial Instruments	12 Months Ended
	Dec. 31, 2014
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 financial instruments held at December 31, 2014 and December 31, 2013:
	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 - Unadjusted quoted prices for identical assets or liabilities in active markets that are accessible at the measurement date for identical assets or liabilities. Financial assets utilizing Level 1 inputs are U.S. Treasury securities;
	Level 2 - Prices or valuations based on observable inputs other than quoted prices in active markets for identical assets and liabilities. Financial assets utilizing Level 2 inputs include certain obligations of U.S. government agencies, municipal and corporate debt securities and asset-backed securities; and
	Level 3 - Unobservable inputs that are significant to the fair value of the assets or liabilities. Level 3 assets and liabilities include financial instruments whose value is determined using pricing models, discounted cash flow methodologies, or similar techniques, as well as instruments for which the determination of fair value requires significant management judgment or estimation. We value our warrant liability utilizing Level 3 inputs.
	The level of market activity used to determine the fair value hierarchy is based on the availability of observable inputs market participants would use to price an asset or a liability, including market value price observations.
	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 year ended December 31, 2014.
	Liabilities classified as Level 3
	We calculate the fair value of outstanding warrants 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. Variables in the model include the risk-free rate of return, dividend yield, expected life and expected volatility of our stock price.
	ASC 825, Disclosures about Fair Value of Financial Instruments, requires all entities to disclose the fair value of their financial instruments, both assets and liabilities recognized and not recognized in the balance sheet, for which it is practicable to estimate fair value.
	The following is a list of those assets and liabilities that are measured at fair value by hierarchy level as of December 31, 2014 and December 31, 2013:
		Fair Value Measurements Using
		Quoted Prices in			Significant Other		Significant		Fair Value
		Active Markets for			Observable Inputs		Unobservable
		Identical Assets			(Level 2)		Inputs
		(Level 1)					(Level 3)
	As of December 31, 2014	(In Thousands)
	U.S. Treasury securities and obligations of U.S. government agencies	$	39,176		$	29,169	$	—	$	68,345
	Municipal debt securities	—			11,963		—		11,963
	Corporate debt securities	—			199,785		—		199,785
	Asset-backed securities	—			56,408		—		56,408
	Cash and cash equivalents	103,021			—		—		103,021
	Total assets	$	142,197		$	297,325	$	—	$	439,522
	Warrant liability	$	—		$	—	$	3,372	$	3,372
	Total liabilities	$	—		$	—	$	3,372	$	3,372
		Fair Value Measurements Using
		Quoted Prices in			Significant Other		Significant		Fair Value
		Active Markets for			Observable Inputs		Unobservable
		Identical Assets			(Level 2)		Inputs
		(Level 1)					(Level 3)
	As of December 31, 2013	(In Thousands)
	U.S. Treasury securities and obligations of U.S. government agencies	$	49,484		$	57,122	$	—	$	106,606
	Municipal debt securities	—			11,933		—		11,933
	Corporate debt securities	—			217,257		—		217,257
	Asset-backed securities	—			73,292		—		73,292
	Cash and cash equivalents	55,929			—		—		55,929
	Total assets	$	105,413		$	359,604	$	—	$	465,017
	Warrant liability	$	—		$	—	$	6,371	$	6,371
	Total liabilities	$	—		$	—	$	6,371	$	6,371
	The following is a roll-forward of Level 3 liabilities measured at fair value for the year ended December 31, 2014:
		Warrant Liability
	For the Year Ended December 31, 2014	(In Thousands)
	Balance, January 1, 2014	$	6,371
	Change in fair value of warrant liability included in earnings	(2,949		)
	Gain on settlement of warrants	(37		)
	Issuance of common stock on warrant exercise	(13		)
	Balance, December 31, 2014	$	3,372
		Warrant Liability
	For the Year Ended December 31, 2013	(In Thousands)
	Balance, January 1, 2013	$	4,842
	Change in fair value of warrant liability included in earnings	1,529
	Balance, December 31, 2013	$	6,371
	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 December 31, 2014, the assumptions used in the option pricing model were as follows: a common stock price as of December 31, 2014 of $9.13, risk free interest rate of 1.88%, expected life of 6.44 years, expected volatility of 37.4% and a dividend yield of 0%. The change in fair value is primarily attributable to a decline in the price of our common stock from December 31, 2013 to December 31, 2014.
	There were no transfers in or out of Level 3 of the fair value hierarchy during the year ended December 31, 2014.

Reserves_for_Insurance_Claims_

Reserves for Insurance Claims and Claims Expenses	12 Months Ended
	Dec. 31, 2014
Insurance [Abstract]
Reserves for Insurance Claims and Claims Expenses	Reserves for Insurance Claims and Claims Expenses
	We establish claim 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 claim reserves only for loans in default. Our claim reserves also include amounts for IBNR. We received our first primary NOD in the second quarter of 2014. For the year ended December 31, 2013, we had no claim or IBNR reserves.
	Additionally, we entered into a pool insurance transaction with Fannie Mae, effective September 1, 2013. We would only establish claim or IBNR reserves for this pool transaction, if we expect claims to exceed the transaction's deductible, which represents the amount of claims absorbed by Fannie Mae before we are obligated to pay any claims under the policy. At December 31, 2014, thirty loans in the pool were past due by sixty days or more. These thirty loans represent approximately $1.7 million in RIF. Due to the size of the deductible ($10.3 million), the low level of NODs reported through December 31, 2014 and the high quality of the loans (all loans are less than 80% LTV), we have not established any pool reserves for claims or IBNR for the years ended December 31, 2014 and December 31, 2013.
	The following table provides a reconciliation of the beginning and ending reserve balances for insurance claims and claims expenses for the year ended December 31, 2014 and 2013:
		For the Year Ended December 31,
		2014		2013
		(In Thousands)
	Reserve at beginning of period	$	—	$	—
	Claims incurred:
	Claims and claim expenses incurred:
	Current year	83		—
	Prior years	—		—
	Total claims incurred	83		—
	Claims paid:
	Claims and claim expenses paid:
	Current year	—		—
	Prior years	—		—
	Total claims paid	—		—
	Reserve at end of period	$	83	$	—

Warrants

Warrants	12 Months Ended
	Dec. 31, 2014
Debt Disclosure [Abstract]
Warrants	Warrants
	We issued 992,000 warrants in connection with our Private Placement. Each warrant gave 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. During the first quarter of 2014, 7,790 warrants were exercised and we issued 1,115 Class A common shares via a cashless exercise. Upon exercise, we reclassified the fair value of the warrants from warrant liability to additional paid in capital and recognized a gain of approximately $37 thousand. No other warrants were exercised during 2014.

ShareBased_Compensation

Share-Based Compensation	12 Months Ended
	Dec. 31, 2014
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Share-Based Compensation	Share-Based Compensation
	The 2012 Stock Incentive Plan (the "Plan") was approved by the Board on April 16, 2012 and authorized 5.5 million shares to be reserved for issuance under the Plan, with 3.85 million shares available for stock options and 1.65 million shares available for RSUs. Options granted under the Plan are non-qualified stock options and may be granted to employees, directors and other key persons. The exercise price per share for the common stock covered by this Plan shall be determined by the Board at the time of grant, but shall not be less than the fair market value, defined as the closing price of our common stock, on the date of the grant. The term of the stock option grants will be established by the Board, but no stock option shall be exercisable more than ten years after the date the stock option is granted. The vesting period of the stock option grants will also be established by the Board at the time of grant and generally is for a three-year period. Upon the exercise of stock options, we issue shares from the authorized, unissued share reserve.
	On May 8, 2014, NMIH held its annual shareholder meeting, at which our shareholders voted to approve the NMIH 2014 Omnibus Incentive Plan, which authorizes us to make 4 million shares of NMIH's class A common stock available to be granted. These shares may be either authorized but unissued shares or treasury shares.
	A summary of option activity in the plan during the years ended December 31, 2014 and December 31, 2013 is as follows:
	For the Year Ended December 31, 2014	Shares		Weighted Average Grant Date Fair Value per Share		Weighted Average Exercise Price
		(Shares in Thousands)
	Options outstanding at December 31, 2013	3,062		$	3.98	$	10.31
	Options granted	780		4.85		12.03
	Options exercised	(109	)	3.85		10
	Options forfeited	(87	)	4.47		11.35
	Options expired	(16	)	4.25		10.93
	Options outstanding at December 31, 2014	3,630		$	4.16	$	10.66
	For the Year Ended December 31, 2013	Shares		Weighted Average Grant Date Fair Value per Share		Weighted Average Exercise Price
		(Shares in Thousands)
	Options outstanding at December 31, 2012	2,547		$	3.86	$	10
	Options granted	532		4.57		11.78
	Options forfeited	(15	)	3.84		10
	Options canceled	(2	)	3.84		10
	Options outstanding at December 31, 2013	3,062		$	3.98	$	10.31
	As of December 31, 2014, there were 108,606 exercises and approximately 1,742,822 options were fully vested and exercisable. The weighted average exercise price for the fully vested and exercisable options was $10.20. The remaining weighted average contractual life of options fully vested and exercisable as of December 31, 2014 was 7.5 years. The aggregate intrinsic value for fully vested and exercisable options was $0 as of December 31, 2014.
	The remaining weighted average contractual life of options outstanding as of December 31, 2014 was 7.9 years. As of December 31, 2014, there was $2.4 million of total unrecognized compensation cost related to non-vested stock options. The weighted-average period over which total compensation related to non-vested stock options will be recognized is 1.28 years.
	We account for stock options under ASC 718, which requires all share-based payments to be recognized in the financial statements at their fair values. To measure the fair value of stock options granted, we utilize the Black-Scholes options pricing model. Expense is recognized over the required service period, which is generally the three-year vesting period of the options (vesting in one-third increments per year).
	The estimated grant date fair values of the stock options granted during 2014 and 2013 were calculated using the Black-Scholes valuation model based on the following assumptions:
		2014		2013
	Expected life	6 years		6 years
	Risk free interest rate	1.90% - 2.01%		0.98% - 1.12%
	Dividend yield	0	%	0	%
	Expected stock price volatility	39	%	39	%
	Projected forfeiture rate	5	%	1	%
	Expected Life - is the period of time over which the options granted are expected to remain outstanding giving consideration to vesting schedules, historical exercise and forfeiture patterns. We use the simplified method outlined in SEC Staff Accounting Bulletin No. 107 to estimate expected lives for options granted during the period as historical exercise data is not available and the options meet the requirements set out in the Bulletin. Options granted have a maximum term of ten years.
	Risk-Free Interest Rate - is the U.S. Treasury rate for the date of the grant having a term approximating the expected life of the option.
	Dividend Yield - is calculated by dividing the expected annual dividend by our stock price at the valuation date.
	Expected Price Volatility - is a measure of the amount by which a price has fluctuated or is expected to fluctuate. At the time of grant, our common shares trading history was not sufficient to calculate an expected volatility representative of the volatility over the expected lives of the options. As a substitute for such estimate, we used historical volatilities of a set of comparable companies in the industry in which we operate.
	Projected Forfeiture Rate - is the estimated percentage of options granted that are expected to be forfeited or canceled before becoming fully vested. An increase in the forfeiture rate will decrease compensation expense.
	A summary of RSU activity in the plan during the years ended December 31, 2014 and December 31, 2013 is as follows:
	For the Year Ended December 31, 2014	Shares		Weighted Average Grant Date Fair Value per Share
		(Shares in Thousands)
	Non-vested restricted stock units at December 31, 2013	1,242		$	7.75
	Restricted stock units granted	373		11.52
	Restricted stock units vested	(360	)	9.53
	Restricted stock units forfeited	(46	)	10.14
	Non-vested restricted stock units at December 31, 2014	1,209		$	8.9
	For the Year Ended December 31, 2013	Shares		Weighted Average Grant Date Fair Value per Share
		(Shares in Thousands)
	Non-vested restricted stock units at December 31, 2012	1,429		$	7.35
	Restricted stock units granted	76		12.03
	Restricted stock units vested	(263	)	6.79
	Restricted stock units forfeited	—		—
	Non-vested restricted stock units at December 31, 2013	1,242		$	7.75
	In February 2013, the Board approved a modification to the vesting terms of approximately 400,000 granted and non-vested RSUs held by our employees. The modification to the vesting terms removed the market condition leaving the RSUs subject to a service condition only. The modification resulted in a change in the period over which compensation costs are recognized and prospective recognition of incremental compensation cost. Incremental compensation cost is measured as the excess of the fair value of the modified award over the fair value of the original award immediately before its terms are modified using relevant valuation inputs as of the modification date.
	At December 31, 2014, the 1.2 million shares of granted and non-vested RSUs consisted of 0.5 million shares that are subject to both a market and service condition and 0.7 million shares that are subject only to service conditions. The non-vested RSUs subject to both a market and service condition vest in one-half increments upon the achievement of certain market price goals and continued service. Non-vested RSUs subject only to a service condition vest over a service period ranging from one to three years. The fair value of RSUs subject to market and service conditions is determined based on a Monte Carlo simulation model at the date of grant. The fair value of RSUs subject only to service conditions are valued at our stock price on the date of grant less the present value of anticipated dividends.
	The estimated grant date fair values of the RSUs granted in 2012 that are subject to both a market and service condition were calculated using a Monte Carlo simulation model based on the average outcome of 150,000 simulations using the following assumption:
		2012
	Expected life	5 years
	Risk free interest rate	0.86	%
	Dividend yield	0	%
	Expected stock price volatility	39	%
	Projected forfeiture rate	1	%
	There were no RSUs granted in 2014 or 2013 that were subject to a market condition, therefore the Monte Carlo simulation was not used.
	The remaining weighted average contractual life of non-vested RSUs as of December 31, 2014 was 7.9 years. The weighted-average period over which total compensation related to non-vested RSUs will be recognized is 1.18 years.
	The RSUs granted in 2014 were valued at our stock price on the date of grant less the present value of anticipated dividends, which is $0. As of December 31, 2014, there was $3.0 million of total unrecognized compensation cost related to non-vested RSUs compared to $4.3 million as of December 31, 2013.
	401(k) Savings Plan
	Beginning on January 1, 2014, we offered to our employees a 401(k) Savings Plan ("401(k) Plan") that qualifies as a deferred salary arrangement under Section 401(k) of the Internal Revenue Code. Under the 401(k) Plan, we match up to 100% of eligible employees' pre-tax contributions up to 4% of eligible compensation. We contributed approximately $0.9 million for the year ended December 31, 2014.

Income_Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes
	The provision (benefit) for income taxes consists of:
		For the Year Ended December 31,
		2014				2013				2012
		(In Thousands
	Current	$	(2,390	)		$	—			$	—
	Deferred	4				—				—
	Total income tax benefit	$	(2,386	)		$	—			$	—
	The income tax benefit of $2.4 million for the year ended December 31, 2014 is related to the tax effects of unrealized gains credited to OCI. Generally, the amount of tax expense or benefit allocated to continuing operations is determined without regard to the tax effects of other categories of income or loss, such as OCI. However, an exception to the general rule is provided in ASC 740-20-45-7 when there is a pre-tax loss from continuing operations and there are items charged or credited to other categories, including OCI, in the current year. The intraperiod tax allocation rules related to items charged or credited directly to OCI can result in disproportionate tax effects that remain in OCI until certain events occur. As a result of a reduction in unrealized losses credited directly to OCI, approximately $2.4 million of tax provision expense has been netted with current year unrealized gains in OCI, and $2.4 million of tax provision benefit was allocated to the income tax provision for continuing operations.
	Reconciliation of the federal statutory income tax (benefit) rate to the effective income tax (benefit) rate is as follows:
		For the Year Ended December 31,
		2014			2013			2012
	Federal statutory income tax rate	35	%		35	%		35	%
	Loss on impairment	—			—			(1.48	)
	Prior year adjustment	—			3.52			1.66
	Other	1.07			1.66			(1.00	)
	Valuation allowance	(31.42	)		(40.18	)		(28.00	)
	Purchase accounting adjustment	—			—			(6.18	)
	Effective income tax rate	4.65	%		—	%		—	%
	Following is a reconciliation of our net deferred income tax asset (liability) as of December 31, 2014 and December 31, 2013:
		December 31, 2014
		Gross				Tax Effected
	Deferred tax asset	(In Thousands)
	Capitalized start-up costs	$	2,403			$	985
	Share-based compensation	20,030				8,212
	Unrealized loss on investments	1,217				499
	Net operating loss carry forwards	114,548				43,198
	Unearned premium reserve	4,414				1,810
	Other	8,785				3,602
	Total gross deferred tax assets	151,397				58,306
	Less: valuation allowance	(140,236		)		(53,730		)
	Total deferred tax assets	11,161				4,576
	Deferred tax liability
	Capitalized software	(7,967		)		(3,266		)
	Intangible assets	(390		)		(137		)
	Deferred acquisition costs	(2,985		)		(1,224		)
	Other	(209		)		(86		)
	Total deferred tax liabilities	(11,551		)		(4,713		)
	Net deferred income tax liability	$	(390	)		$	(137	)
		December 31, 2013
		Gross				Tax Effected
	Deferred tax asset	(In Thousands)
	Capitalized start-up costs	$	2,579			$	903
	Share-based compensation	14,701				5,990
	Unrealized loss on investments	7,047				2,694
	Net operating loss carry forwards	65,276				24,602
	Other	10,118				3,760
	Total gross deferred tax assets	99,721				37,949
	Less: valuation allowance	(94,497		)		(35,778		)
	Total deferred tax assets	5,224				2,171
	Deferred tax liability
	Capitalized software	(5,008		)		(2,095		)
	Intangible assets	(390		)		(133		)
	Other	(216		)		(76		)
	Total deferred tax liabilities	(5,614		)		(2,304		)
	Net deferred income tax liability	$	(390	)		$	(133	)
	At December 31, 2014 and 2013, we had a net deferred tax liability of $0.1 million as a result of the acquisition of indefinite-lived intangibles from the acquisition of our insurance subsidiaries for which no benefit had been reflected in the acquired net operating loss carry forwards. The tax liability incurred at the acquisition was recorded as an increase in goodwill.
	Excluded from deferred tax assets were $2.1 million and $1.5 million of excess stock compensation as of December 31, 2014 and December 31, 2013, respectively, for which any benefit realized will be recorded to stockholders' equity.
	As of December 31, 2014, the Company had federal net operating loss carryforwards of $114.5 million, which expire from 2029 to 2034 and state net operating loss carryforwards of $36.0 million, which expire from 2031 to 2034. Section 382 of the Internal Revenue Code imposes annual limitations on a corporation's ability to utilize its net operating loss carryforwards if it experiences an "ownership change." As a result of the acquisition of our insurance subsidiaries, $7.3 million of NOLs are subject to annual limitations of $0.8 million through 2016, then $0.3 million through 2029.
	As we have just recently begun insurance operations and have no history to provide a basis for reliable future net income projections, a valuation allowance of $53.7 million and $35.8 million was recorded at December 31, 2014 and December 31, 2013, respectively, to reflect the amount of the deferred tax asset that may not be realized.
	As of December 31, 2014 and 2013, we have no reserve for unrecognized tax benefits, and have taken no material uncertain positions in its tax returns that would require measurement and recognition.
	We file income tax returns with the U.S. federal government and various state jurisdictions which are subject to potential examination by tax authorities. We are not currently under examination, and federal and state tax years remain open by statute.

Software_and_Equipment

Software and Equipment	12 Months Ended
	Dec. 31, 2014
Property, Plant and Equipment [Abstract]
Software and Equipment	Software and Equipment
	Software and equipment consist largely of capitalized software developed to support our MI operations. Software and equipment, net of accumulated amortization and depreciation, as of December 31, 2014 and December 31, 2013, consists of the following:
		31-Dec-14			31-Dec-13
		(In Thousands)
	Software	$	11,608		$	14,140
	Equipment	1,175			542
	Leasehold improvements	973			141
	Subtotal	13,756			14,823
	Accumulated amortization and depreciation	(1,950		)	(5,947		)
	Software and equipment, net	$	11,806		$	8,876
	Amortization and depreciation expense for software and equipment for the years ended December 31, 2014 and 2013 was $5.8 million and $5.9 million, respectively. In the second quarter of 2013, we reduced the useful life and shortened the amortization period of some of the software we purchased in connection with the acquisition of our insurance subsidiaries. This software was completely amortized by November 2014, and the original cost and accumulated amortization of $9.8 million were written off at that time.

Intangible_Assets_and_Goodwill

Intangible Assets and Goodwill	12 Months Ended
	Dec. 31, 2014
Goodwill and Intangible Assets Disclosure [Abstract]
Intangible Assets and Goodwill	Intangible Assets and Goodwill
	Intangible assets and goodwill consist of identifiable intangible assets and goodwill we purchased in connection with the acquisition of our insurance subsidiaries, and at December 31, 2014 and December 31, 2013, were as follows for both years:
				Expected Lives
	Goodwill	$	3,244	Indefinite
	State licenses	260		Indefinite
	GSE applications	130		Indefinite
	Total intangible assets and goodwill	$	3,634
	We test goodwill and intangibles for impairment in the third and fourth quarter, respectively, of every year, or more frequently if we believe indicators of impairment exist. As of December 31, 2012, we determined the carrying value of operational manuals acquired with NMIC and Re One would not be recovered, and the manuals could not be sold and would be disposed; as a result, we assessed the fair value at zero and recognized a loss on impairment of $1.2 million. No impairments of indefinite-lived intangibles or goodwill were identified as of December 31, 2014 and 2013.

Commitments_and_Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2014
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies
	GSE Approval
	In January 2013, the GSEs approved NMIC as a qualified mortgage insurer, and with their approvals, imposed certain capitalization, operational and reporting conditions on NMIC, most of which remain in effect for a three-year period from the date of GSE Approval. As a GSE qualified mortgage insurer, NMIC is subject to ongoing compliance with the conditions in the GSE Approval as well as the GSEs' Eligibility Requirements.
	The conditions in the GSE Approval require, among other things, that NMIC:
	•	maintain minimum capital of $150 million;
	•	operate at a risk-to-capital ratio not to exceed 15:1 for its first three years and then pursuant to the GSE Eligibility Requirements then in effect;
	•	not declare or pay dividends to affiliates or to NMIH for its first three years, then pursuant to the Eligibility Requirements;
	•	not enter into capital support agreements or guarantees for the benefit of, or purchase or otherwise invest in the debt of, affiliates without the prior written approval of the GSEs for its first three years, then pursuant to the Eligibility Requirements; and
	•	not enter into reinsurance or other risk share arrangements without the GSEs' prior written approval for its first three years, then pursuant to the Eligibility Requirements.
	The GSE Approvals also include other conditions, limitations and reporting requirements, including, among others, limits on costs allocated to NMIC under affiliate expense sharing arrangements; conditions related to risk concentration and rates of return; requirements to obtain a financial strength rating; restrictions on provision of ancillary services (i.e., non-insurance) to customers and transfers of underwriting to affiliates; notification requirements regarding change of ownership and new five percent shareholders; requirement to, at the direction of one or both of the GSEs, re-domicile from Wisconsin to another state; and provisions regarding underwriting policies and claims processing.
	Office Lease
	We entered into an office facility lease effective July 1, 2012 for a term of two years. In October 2013, we amended our facility's lease to (i) add 23,000 square feet of furnished office space, and (ii) extend the facility's lease period through October 31, 2017.
	Management expects that, in the normal course of business, as of December 31, 2014, future minimum lease payments under this lease will be as follows:
	Years ending December 31,	(In Thousands)
	2015	$	1,690
	2016	1,741
	2017	1,488
	Totals	$	4,919
	We incurred rent expense related to this lease of $1.6 million for the year ended December 31, 2014. Rent expense for the year ended December 31, 2013 was $0.8 million.

Common_Stock_Offerings

Common Stock Offerings	12 Months Ended
	Dec. 31, 2014
Equity [Abstract]
Common Stock Offerings	Common Stock Offerings
	On April 17, 2012, we completed the Private Placement, through which we offered and sold an aggregate of 55,000,000 of our Class A common shares resulting in net proceeds of approximately $510 million.
	On November 8, 2013, we filed a final prospectus announcing the sale of 2.1 million shares of common stock through an initial public offering. The underwriters of the offering were granted a 30-day option to purchase up to an additional 315,000 shares of common stock from us at an initial public offering price of $13.00, which they exercised on November 12, 2013. The offering closed on November 14, 2013. Gross proceeds to us were $31.4 million. Net proceeds from the offering were approximately $28 million.

Statutory_Information

Statutory Information	12 Months Ended
	Dec. 31, 2014
Insurance [Abstract]
Statutory Information	Statutory Information
	Our insurance subsidiaries, NMIC and Re One, file financial statements in conformity with statutory basis accounting principles ("SAP") prescribed or permitted by the Wisconsin OCI. NMIC's principal regulator is the Wisconsin OCI. Prescribed SAP includes state laws, regulations and general administrative rules, as well as a variety of publications of the NAIC. The Wisconsin OCI recognizes only statutory accounting practices prescribed or permitted by the state of Wisconsin for determining and reporting the financial condition and results of operations of an insurance company and for determining its solvency under Wisconsin insurance laws.
	NMIC and Re One's combined statutory net income, statutory surplus and contingency reserve as of and for each of the years in the three-year period ended December 31, 2014 were as follows:
		December 31,
		2014			2013			2012
		(In Thousands)
	Statutory net loss	$	(47,961	)	$	(33,307	)	$	(18	)
	Statutory surplus	236,738			189,698			220,004
	Contingency reserve	9,401			2,314			—
	Under applicable Wisconsin law and 15 other states, a mortgage insurer must maintain a minimum amount of statutory capital relative to its risk-in-force (risk-to-capital ratio or "RTC ratio") in order for the mortgage insurer to continue to write new business. While formulations of minimum capital may vary in each jurisdiction that has such a requirement, the most common measure applied allows for a maximum permitted RTC ratio of 25 to 1. Wisconsin and certain other states, including California and Illinois, apply a substantially similar requirement referred to as minimum policyholders' position. Our operation plan filed with the Wisconsin OCI and other state insurance departments in connection with NMIC's applications for licensure includes the expectation that NMIH will downstream additional capital if needed so that NMIC does not exceed risk-to-capital ratios agreed to with those states. NMIC may in the future seek state insurance department approvals, as needed, of an amendment to our business plan to increase this ratio to the Wisconsin regulatory minimum of 25 to 1. In addition, under the terms of our conditional approvals from the GSEs we are required to operate at a risk-to-capital ratio not to exceed 15:1 for our first three years of operations.
	Certain states limit the amount of risk a mortgage insurer may retain on a single loan to 25% of the indebtedness to the insured and, as a result, the portion of such insurance in excess of 25% must be reinsured. NMIC and Re One have entered into a primary excess share reinsurance agreement, effective August 1, 2012, and a facultative pool reinsurance agreement, effective September 1, 2013, under which NMIC cedes premiums, loss reserves and claims to Re One on an excess share basis for any primary or pool policy which offers coverage greater than 25% on any loan insured thereunder. NMIC will use reinsurance provided by Re One solely for purposes of compliance with these state statutory coverage limits. Currently, NMIC has no other reinsurance agreements. During April 2013, NMIC began writing its first mortgage insurance policies and ceding premium and risk to Re One the following month.
	As of December 31, 2013, NMIC had 22 policies in force totaling approximately $36.5 million of RIF, resulting in a RTC ratio of 0.5:1. As of December 31, 2014, NMIC had $800 million in total RIF (1) with a RTC ratio of 3.5:1, significantly below the GSE and state imposed financial requirements. The risk-to-capital calculation for each of our insurance subsidiaries, as well as our combined risk-to-capital calculation, as of December 31, 2014, is presented below.
	As of December 31, 2014	NMIC			Re One			Combined
		(In Thousands)
	Primary risk-in-force (1)
	Direct	$	801,353		$	—		$	801,353
	Assumed	—			69,396			69,396
	Ceded	(69,396		)	—			(69,396		)
	Total primary risk-in-force	731,957			69,396			801,353
	Pool risk-in-force (2)
	Direct	93,090			—			93,090
	Assumed	—			24,705			24,705
	Ceded	(24,705		)	—			(24,705		)
	Total pool risk-in-force	68,385			24,705			93,090
	Total risk-in-force	800,342			94,101			894,443
	Statutory policyholders' surplus	223,119			13,619			236,738
	Statutory contingency reserve	7,945			1,456			9,401
	Total statutory policyholders' position	231,064			15,075			246,139
	Risk-to-Capital (3)	3.5:1			6.2:1			3.6:1
	(1)	Our net risk in force includes both primary and pool risk in force, and excludes risk on policies that are currently in default and for which loss reserves have been established.
	(2)	Pool risk-in-force as shown in the table above is equal to the aggregate stop loss less a deductible.
	(3)	Represents total risk-in-force divided by statutory policyholders' position which is the metric by which the majority of state insurance regulators will assess our capital adequacy. Additionally, pursuant to the 2013 Fannie Mae pool agreement, we are required to maintain the greater of (a) the risk-to-capital requirements outlined in Fannie Mae's January 2013 approval letter or (b) a risk-to-capital ratio of 18:1 on primary business plus statutory capital equal to the amount of net risk-in-force of the pool.
	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 capital surplus or (subject to certain limitations) recent net profits. As of December 31, 2014, NMIH's capital surplus was approximately $427 million. NMIH's assets, excluding investment in NMIC and Re One, were approximately $179 million at December 31, 2014, and were unencumbered by any debt or other subsidiary commitments or obligations. The insurance subsidiaries are both mono-line mortgage insurance companies, and the assets of each are dedicated only to the support of direct risk and obligations of each mortgage insurance entity. NMIC only writes direct mortgage insurance business and assumes no business from any other entity. Re One only assumes business from NMIC to allow NMIC to comply with statutory risk requirements. Neither NMIC nor Re One have subsidiaries, and therefore do not have subsidiary risks and obligations that compete for its resources.
	The GSEs and state insurance regulators may restrict our insurance subsidiaries' ability to pay dividends to NMIH. In addition to the restrictions imposed during the GSE Approval and state licensing processes, the ability of our insurance subsidiaries to pay dividends to NMIH is limited by insurance laws of the State of Wisconsin and certain other states. Wisconsin law provides that an insurance company may pay out dividends without the prior approval of the Wisconsin OCI ("ordinary dividends") in an amount, when added to other shareholder distributions made in the prior 12 months, not to exceed the lesser of (a) 10% of the insurer's surplus as regards to policyholders as of the prior December 31 or (b) its net income (excluding realized capital gains) for the twelve month period ending December 31 of the immediately preceding calendar year. In determining net income, an insurer may carry forward net income from the previous calendar years that has not already been paid out as a dividend. Dividends that exceed this amount are "extraordinary dividends," which require prior approval of the Wisconsin OCI. As of December 31, 2014, the amount of restricted net assets held by our consolidated insurance subsidiaries totaled approximately $252 million of NMIH's consolidated net assets of $427 million. The amount of restricted assets used to determine any dividend to NMIH, once all restrictions expire, would be computed under SAP which may differ from the amount of restricted assets computed under GAAP. Since inception, NMIC has not paid any dividends to NMIH. As NMIC had a statutory net loss for the year ended December 31, 2013, NMIC cannot pay any dividends to NMIH through December 31, 2014, without the prior approval of the Wisconsin OCI. Additionally, NMIC will not be permitted to pay dividends to NMIH until after December 31, 2015 as a condition of GSE Approval or until January 2016 under agreements with various state insurance regulators.

Quarterly_Financial_Data_Unaud

Quarterly Financial Data (Unaudited)	12 Months Ended
	Dec. 31, 2014
Quarterly Financial Information Disclosure [Abstract]
Quarterly Financial Data (Unaudited)	Quarterly Financial Data (Unaudited)
		2014 Quarters												2014
		First			Second			Third			Fourth			Year
		(In Thousands, except share data)
	Net premiums written	$	5,178		$	5,051		$	9,661		$	14,139		$	34,029
	Net premiums earned	1,904			2,093			3,900			5,510			13,407
	Net investment income	1,489			1,468			1,342			1,319			5,618
	Net realized investment gains (losses)	—			—			134			63			197
	Gain (loss) from change in fair value of warrant liability	817			952			1,240			(60		)	2,949
	Gain from settlement of warrants	37			—			—			—			37
	Insurance claims and claims expenses	—			28			(26		)	81			83
	Amortization of deferred policy acquisition costs	19			42			47			265			373
	Underwriting and operating expenses	19,283			18,595			17,848			17,318			73,044
	Net loss	(15,055		)	(12,855		)	(10,976		)	(10,020		)	(48,906		)
	Loss per share (1)
	Basic and diluted loss per share	$	(0.26	)	$	(0.22	)	$	(0.19	)	$	(0.17	)	$	(0.84	)
	Weighted average common shares outstanding	58,061,299			58,289,801			58,363,334			58,406,574			58,281,425
		2013 Quarters												2013
		First			Second			Third			Fourth			Year
		(In Thousands, except share data)
	Net premiums written	$	—		$	1		$	482		$	3,058		$	3,541
	Net premiums earned	—			1			482			1,612			2,095
	Net investment income	410			1,407			1,519			1,472			4,808
	Net realized investment gains (losses)	28			452			(308		)	14			186
	Gain (loss) from change in fair value of warrant liability	35			(1,115		)	469			(918		)	(1,529		)
	Insurance claims and claims expenses	—			—			—			—			—
	Amortization of deferred policy acquisition costs	—			—			—			1			1
	Underwriting and operating expenses	12,426			17,019			16,035			15,263			60,743
	Net loss	(11,953		)	(16,274		)	(13,873		)	(13,084		)	(55,184		)
	Loss per share (1)
	Basic and diluted loss per share	$	(0.22	)	$	(0.29	)	$	(0.25	)	$	(0.23	)	$	(0.99	)
	Weighted average common shares outstanding	55,500,100			55,629,932			55,637,480			57,238,730			56,005,326
	-1	Due to the use of weighted average shares outstanding when calculating earnings per share, the sum of quarterly per share data may not equal the per share data for the year.

SCHEDULE_I_SUMMARY_OF_INVESTME

SCHEDULE I - SUMMARY OF INVESTMENTS- OTHER THAN INVESTMENTS IN RELATED PARTIES	12 Months Ended
	Dec. 31, 2014
Summary of Investments, Other than Investments in Related Parties [Abstract]
Summary of Investments - Other than Investments in Related Parties
	December 31, 2014	Amortized Cost		Fair Value		Amount Reflected on Balance Sheet
		(In Thousands)
	Fixed maturities
	U.S. Treasury securities and obligations of U.S. government agencies	$	68,911	$	68,345	$	68,345
	Municipal debt securities	12,009		11,963		11,963
	Corporate debt securities	200,358		199,785		199,785
	Asset-backed securities	56,440		56,408		56,408
	Total investments other than investments in related parties	$	337,718	$	336,501	$	336,501

SCHEDULE_II_FINANCIAL_INFORMAT

SCHEDULE II - FINANCIAL INFORMATION OF REGISTRANT- PARENT COMPANY ONLY	12 Months Ended
	Dec. 31, 2014
Condensed Financial Information of Parent Company Only Disclosure [Abstract]
Financial Information of Registrant Parent Company Only
		31-Dec-14			31-Dec-13
		(In Thousands, except for share data)
	Assets
	Fixed maturities, available-for-sale, at fair value	$	134,199		$	229,064
	Cash and cash equivalents	29,925			36,433
	Investment in subsidiaries, at equity in net assets	251,880			193,242
	Accrued investment income	629			1,038
	Prepaid expenses	2,054			1,519
	Due from affiliates, net	9,949			10,565
	Software and equipment, net	11,806			7,574
	Other assets	509			61
	Total assets	$	440,951		$	479,496
	Liabilities
	Accounts payable and accrued expenses	$	10,621		$	9,908
	Warrant liability, at fair value	3,372			6,371
	Total liabilities	13,993			16,279
	Shareholders' equity
	Common stock - class A shares, $0.01 par value;	584			581
	58,428,548 and 58,052,480 shares issued and outstanding as of December 31, 2014 and December 31, 2013, respectively (250,000,000 shares authorized)
	Additional paid-in capital	562,911			553,707
	Accumulated other comprehensive loss, net of tax	(3,607		)	(7,047		)
	Accumulated deficit	(132,930		)	(84,024		)
	Total shareholders' equity	426,958			463,217
	Total liabilities and shareholders' equity	$	440,951		$	479,496
		For the Year Ended December 31,
		2014			2013			2012
		(In Thousands)
	Revenues
	Net investment income	$	2,937		$	2,758		$	2
	Net realized investment gains	67			188			—
	Gain (loss) from change in fair value of warrant liability	2,949			(1,529		)	278
	Gain from settlement of warrants	37			—			—
	Total revenues	5,990			1,417			280
	Expenses
	Other operating expenses	18,817			24,319			26,575
	Total expenses	18,817			24,319			26,575
	Equity in net loss of subsidiaries	(38,710		)	(32,282		)	(1,196		)
	Loss before income taxes	(51,537		)	(55,184		)	(27,491		)
	Income tax benefit	(2,631		)	—			—
	Net loss	$	(48,906	)	$	(55,184	)	$	(27,491	)
		For the Year Ended December 31,
		2014			2013			2012
	Cash flows from operating activities	(In Thousands)
	Net loss	$	(48,906	)	$	(55,184	)	$	(27,491	)
	Adjustments to reconcile net loss to net cash used in operating activities:
	Share-based compensation expense	9,180			10,367			6,115
	Warrants issued in connection with line of credit	—			—			1,620
	(Gain) loss from change in fair value of warrant liability	(2,949		)	1,529			(278		)
	Gain from settlement of warrants	(37		)	—			—
	Net realized investment gains	(67		)	(188		)	—
	Depreciation and other amortization	5,618			3,325			3
	Noncash intraperiod tax allocation	(2,390		)	—			—
	Changes in operating assets and liabilities:
	Equity in net loss of subsidiaries	38,710			35,371			1,196
	Accrued investment income	409			(1,038		)	(2		)
	Receivable from affiliates	616			(10,565		)	—
	Prepaid expenses	(535		)	(1,102		)	(234		)
	Other assets	(445		)	(3,045		)	(78		)
	Accounts payable and accrued expenses	233			623			4,550
	Net cash used in operating activities	(563		)	(19,907		)	(14,599		)
	Cash flows from investing activities
	Capitalization of subsidiaries	(95,000		)	—			(220,000		)
	Purchase of fixed-maturity investments, available-for-sale	(23,552		)	(293,470		)	—
Proceeds from redemptions, maturities and sale of fixed-maturity investments, available-for-sale	120,813			59,454			—
Purchase of software and equipment	(8,220		)	(6,695		)	(2,444		)
Acquisition of subsidiaries	—			—			(2,500		)
Net cash used in investing activities	(5,959		)	(240,711		)	(224,944		)
Cash flows from financing activities
Payments on line of credit	—			—			(205		)
Issuance of common stock	1,097			27,912			510,465
Taxes paid related to net share settlement of equity awards	(1,083		)	(1,578		)	—
Net cash provided by financing activities	14			26,334			510,260
Net (decrease) increase in cash and cash equivalents	(6,508		)	(234,284		)	270,717
Cash and cash equivalents, beginning of period	36,433			270,717			—
Cash and cash equivalents, end of period	$	29,925		$	36,433		$	270,717
Note A
The NMI Holdings, Inc. (the "Parent Company") financial statements represent the stand-alone financial statements of the Parent Company. These financial statements have been prepared on the same basis and using the same accounting policies as described in the consolidated financial statements included herein. Refer to the Parent Company's consolidated financial statements for additional information.
Revisions to Prior Periods
Certain other prior balances have been reclassified to conform to the current period presentation.
Note B
Our insurance subsidiaries are subject to statutory regulations as to maintenance of policyholders' surplus and payment of dividends. The maximum amount of dividends that the insurance subsidiaries may pay in any twelve-month period without regulatory approval by the Office of the Commissioner of Insurance of the State of Wisconsin is the lesser of adjusted statutory net income or 10% of statutory policyholders' surplus as of the preceding calendar year end. Adjusted statutory net income is defined for this purpose to be the greater of statutory net income, net of realized investment gains, for the calendar year preceding the date of the dividend or statutory net income, net of realized investment gains, for the three calendar years preceding the date of the dividend less dividends paid within the first two of the preceding three calendar years.
Note C
The Parent Company provides certain services to its subsidiaries. The Parent Company allocates to its subsidiaries corporate expense it incurs in the capacity of supporting those subsidiaries, based on either an allocated percentage of time spent or internally allocated capital. Total operating expenses allocated to subsidiaries for each of the years in the three year period ended December 31, 2014 were $55.7 million, $32.5 million and $0. Amounts charged to the subsidiaries for operating expenses are based on actual cost, without any mark-up. The Parent Company considers these charges fair and reasonable. The subsidiaries reimburse the Parent Company for these costs in a timely manner, which has the impact of improving the cash flows of the Parent Company.

SCHEDULE_IV_FINANCIAL_INFORMAT

SCHEDULE IV - FINANCIAL INFORMATION OF REGISTRANT REINSURANCE PARENT COMPANY ONLY	12 Months Ended
	Dec. 31, 2014
Supplemental Schedule of Reinsurance Premiums for Insurance Companies [Abstract]
Financial Information of Registrant Reinsurance Parent Company Only	The Parent Company has no reinsurance agreements. The insurance subsidiaries are both mono-line mortgage insurance companies and the assets of each are dedicated only to the support of our mortgage insurance operations. NMIC only writes direct mortgage insurance business and assumes no business from any other entity. Re One only assumes business from NMIC to allow NMIC to comply with statutory risk requirements. Neither NMIC nor Re One count any subsidiary of any kind in their admitted statutory assets.

Summary_of_Accounting_Policies1

Summary of Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2014
Accounting Policies [Abstract]
Revenue Recognition	Revenue Recognition
	In the mortgage insurance industry, a "book" is a group of loans that an MI company insures in a particular period, normally a calendar year. We set premiums at the time a policy is issued based on our expectations regarding likely performance over the term of coverage. The policies we write are guaranteed renewable contracts at the policyholder's option. Premiums may be paid to us on a single, annual or monthly basis. Premiums written on a single premium basis and an annual premium basis are initially deferred as unearned premium reserve and earned over the policy term commencing in the month coverage is effective.  Premiums written on policies covering more than one year are amortized over the policy life in accordance with the expiration of risk, which is the anticipated claim payment pattern based on industry experience.  Premiums written on annual policies are earned on a monthly pro rata basis.  Premiums written on monthly policies are earned as coverage is provided. Premiums written on pool transactions are earned over the period that coverage is provided.  Upon cancellation of a policy, all premium that is non-refundable is immediately earned and any refundable premium is returned to the policyholder. Premiums returned to policyholders are recorded as a reduction of written and earned premiums in the current period. The actual return of premium for all periods affects premiums written and earned in those periods.
Reserve for Insurance Claims and Claims Expenses	Reserves for Insurance Claims and Claims Expenses
	Consistent with industry accounting practices, for purposes of establishing claim reserves, we adhere to the general claim reserving principles contained in Financial Accounting Standards Board Accounting Standards Codification ("ASC") Topic 944, Financial Services - Insurance ("ASC 944"), even though that standard expressly excludes mortgage insurance from its guidance. However, and consistent with our industry, we do not establish claim reserves for anticipated future claims on insured loans that are not currently in default. We do not consider a loan to be in default for claim reserve purposes until we receive notice from the servicer that a borrower has failed to make two consecutive regularly scheduled payments and is at least 60 days in default. In addition to reserves on reported defaults, we establish reserves 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.
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 as a component of accumulated other comprehensive (loss) income in shareholders' equity. Net realized investment gains and losses are reported in income based upon specific identification of securities sold.
	Purchases and sales of investments are recorded on a trade date basis. Net investment income is recognized when earned and includes interest and dividend income together with amortization of market premiums and discounts using the effective yield method and is net of investment management fees and other investment related expenses. For asset-backed securities and any other holdings for which there is a prepayment risk, prepayment assumptions are evaluated and revised as necessary. Any adjustments required due to the change in effective yields and maturities are recognized on a prospective basis through yield adjustments.
	Each quarter, we evaluate our investments in order to determine whether declines in fair value below amortized cost were considered other-than-temporary in accordance with applicable guidance. Under the current guidance, a debt security impairment is deemed other-than-temporary if (i) we either intend to sell the security or it is more likely than not that we will be required to sell the security before recovery or (ii) we do not expect to collect cash flows sufficient to recover the amortized cost basis of the security. In evaluating whether a decline in fair value is other-than-temporary, we consider several factors including, but not limited to:
	•	our intent to sell the security or whether it is more likely than not that we will be required to sell the security before recovery;
	•	severity and duration of the decline in fair value;
	•	the financial condition of the issuer;
	•	the failure of the issuer to make scheduled interest or principal payments;
	•	recent credit downgrades of the applicable security or the issuer below investment grade; and
	•	adverse conditions specifically related to the security, an industry, or a geographic area.
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"). For each book year of business, these costs are amortized to expense in relation to the anticipated recognition of premiums.
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. We have determined that no premium deficiency reserves were necessary for each of the years in the three-year period ended December 31, 2014.
Income Taxes	Income Taxes
	We account for income taxes using the liability method in accordance with ASC Topic 740, Income Taxes. The liability method measures the expected future tax effects of temporary differences at the enacted tax rates applicable for the period in which the deferred asset or liability is expected to be realized or settled. Temporary differences are differences between the tax basis of an asset or liability and its reported amount in the consolidated financial statements that would result in future increases or decreases in taxes owed on a cash basis compared to amounts already recognized as tax expense in the consolidated statement of operations.
Warrants	Warrants
	We account for 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. Our outstanding warrants may be settled by us using either (i) physical settlement method or (ii) cashless exercise, where shares that are issued upon exercise of the warrants are reduced, to cover the cost of the exercise, in lieu of the holder remitting a cash payment of the exercise price. The warrants expire and are not exercisable after the 10th anniversary of the date the warrant was issued. The exercise price and the number of warrants are subject to anti-dilution provisions whereby the existing exercise price is adjusted downward, and the number of warrants increased, for events that may not be dilutive. The adjustment may be in excess of any dilution suffered. As a result, the warrants are classified as a liability. We revalue the warrants at the end of each reporting period, and any change in fair value is reported in the statements of operations in the period in which the change occurred. We calculate the fair value of the warrants using a Black-Scholes option-pricing model in combination with a binomial model, and we value the pricing protection features of the warrants using a Monte Carlo simulation model.
Share-based Compensation	Share-Based Compensation
	We account for stock compensation in accordance with ASC 718, Compensation - Stock Compensation. This addresses accounting for share-based awards and recognition of compensation expense, measured using grant date fair value, over the requisite service or performance period of the award. Share-based payments include restricted stock units ("RSUs") and stock option grants under the 2012 Stock Incentive Plan. We determine the fair value of issued stock option grants using an option pricing model, which takes into account various assumptions that are subjective. Key assumptions used in the stock option valuation include the expected term of the equity award, taking into account the contractual term of the award, the effects of expected exercise and post-vesting termination behavior, expected volatility, expected dividends and the risk-free interest rate for the expected term of the award. RSU grants to employees contain a market condition and/or service condition. The fair value of RSU grants to employees with a market condition is determined based on a Monte Carlo simulation model at the date of grant. RSU grants to employees with a service condition and RSU grants to non-employee directors are valued at our stock price on the date of grant less the present value of anticipated dividends.
Earnings per Share	Earnings per Share
	Basic net loss per share is based on the weighted-average number of common shares outstanding, while diluted net loss per share is based on the weighted-average number of common shares outstanding and common stock equivalents that would be issuable upon the exercise of stock options, other stock-based compensation arrangements, and the dilutive effect of outstanding warrants. As a result of our net losses for the each of the years in the three-year period ended December 31, 2014, 5,839,909 shares, 5,303,394 shares, and 4,414,165 shares of our common stock equivalents issued under stock-based compensation arrangements and warrants, respectively, were not included in the calculation of diluted net loss per share as of such dates because they were anti-dilutive.
Cash and Cash Equivalents	Cash and Cash Equivalents
	We consider items such as certificates of deposit and money market funds with original maturities of 90 days or less to be cash equivalents. The Company did not have any restricted cash as of December 31, 2014 and 2013.
Software and Equipment	Software and Equipment
	Certain costs associated with the development of internal-use software are capitalized. Software and equipment are stated at cost, less accumulated amortization and depreciation. Once the software is ready for its intended use, amortization and depreciation are calculated using the straight-line method over the estimated useful lives of the respective assets ranging typically from 3 to 7 years, unless factors indicate a shorter useful life. Amortization of software and depreciation of equipment commences at the beginning of the month following our placement of the assets into use. For further detail, see "Note 9, Software and Equipment.
Business Combinations, Goodwill and Intangible Assets	Business Combinations, Goodwill and Intangible Assets
	Goodwill represents the excess of the purchase price over the estimated fair value of net assets acquired from a business combination. In accordance with ASC 350, Intangibles - Goodwill and Other, we test goodwill for impairment during the third quarter each year, or more frequently if we believe indicators of impairment exist. We have not identified any impairments of goodwill through December 31, 2014.
	Our intangible assets consist of state licenses and GSE applications which have indefinite lives. We test indefinite-lived intangible assets for impairment during the fourth quarter of each year or more frequently if we believe indicators of impairment exist. We do not believe that the indefinite-lived intangible assets were impaired as of December 31, 2014.
Premiums receivable	Premiums receivable
	Premiums receivable consist of premiums due on our mortgage insurance policies. If mortgage insurance premiums are unpaid for more than 120 days, the receivable is written off against earned premium and the related insurance policy is canceled.
Recent Accounting Standards Updates Adopted	Recent Accounting Standards Updates Adopted
	In August 2014, the FASB issued an update that requires an entity's management to evaluate whether there is substantial doubt about that entity's ability to continue as a going concern and, if so, disclose that fact. An entity's management will also be required to evaluate and disclose whether its plans alleviate that doubt. The guidance is effective for annual periods ending after December 15, 2016 and for interim and annual periods thereafter. We do not expect the adoption of this update to have a material effect on the presentation of our financial statements and notes therein.
Reclassifications	Reclassifications
	Certain items in the financial statements as of December 31, 2014 and for the periods ending December 31, 2013 and December 31, 2012 have been reclassified to conform to the current period's presentation. There was no effect on net income or shareholders' equity previously reported.
Subsequent Events	Subsequent Events
	We have considered subsequent events through the date of this filing.

Investments_Tables

Investments (Tables)	12 Months Ended
	Dec. 31, 2014
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
		Cost				Gains				Losses				Value
	As of December 31, 2014	(In Thousands)
	U.S. Treasury securities and obligations of U.S. government agencies	$	68,911			$	7			$	(573	)		$	68,345
	Municipal debt securities	12,009				27				(73		)		11,963
	Corporate debt securities	200,358				883				(1,456		)		199,785
	Asset-backed securities	56,440				222				(254		)		56,408
	Total investments	$	337,718			$	1,139			$	(2,356	)		$	336,501
		Amortized				Gross Unrealized								Fair
		Cost				Gains				Losses				Value
	As of December 31, 2013	(In Thousands)
	U.S. Treasury securities and obligations of U.S. government agencies	$	108,067			$	—			$	(1,461	)		$	106,606
	Municipal debt securities	12,017				1				(85		)		11,933
	Corporate debt securities	221,899				157				(4,799		)		217,257
	Asset-backed securities	74,152				114				(974		)		73,292
	Total investments	$	416,135			$	272			$	(7,319	)		$	409,088
Schedule of Investments by Maturity	The amortized cost and fair values of available for sale securities at December 31, 2014, 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 separate categories.
	As of December 31, 2014	Amortized				Fair
		Cost				Value
		(In Thousands)
	Due in one year or less	$	6,110			$	6,125
	Due after one through five years	195,492				194,472
	Due after five through ten years	54,360				53,891
	Due after ten years	25,316				25,605
	Asset-backed securities	56,440				56,408
	Total investments	$	337,718			$	336,501
	As of December 31, 2013	Amortized				Fair
		Cost				Value
		(In Thousands)
	Due in one year or less	$	—			$	—
	Due after one through five years	260,855				257,501
	Due after five through ten years	65,687				63,440
	Due after ten years	15,441				14,855
	Asset-backed securities	74,152				73,292
	Total investments	$	416,135			$	409,088
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 December 31, 2014			(Dollars in Thousands)
	U.S. Treasury securities and obligations of U.S. government agencies	4		$	7,228		$	(33	)		10		$	49,884		$	(540	)	14	$	57,112	$	(573	)
	Municipal debt securities	1		3,232			(18		)		1		1,695			(55		)	2	4,927		(73		)
	Corporate debt securities	26		60,334			(559		)		22		65,806			(897		)	48	126,140		(1,456		)
	Assets-backed securities	3		10,614			(57		)		4		20,047			(197		)	7	30,661		(254		)
	Total investments	34		$	81,408		$	(667	)		37		$	137,432		$	(1,689	)	71	$	218,840	$	(2,356	)
		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, 2013			(Dollars in Thousands)
	U.S. Treasury securities and obligations of U.S. government agencies	19		$	106,606		$	(1,461	)		—		$	—		$	—		19	$	106,606	$	(1,461	)
	Municipal debt securities	2		4,915			(85		)		—		—			—			2	4,915		(85		)
	Corporate debt securities	47		187,714			(4,799		)		—		—			—			47	187,714		(4,799		)
	Assets-backed securities	11		58,225			(974		)		—		—			—			11	58,225		(974		)
	Total investments	79		$	357,460		$	(7,319	)		—		$	—		$	—		79	$	357,460	$	(7,319	)
Schedule of Net Investment Income	Net investment income is comprised of the following:
		For the Year Ended December 31,
		2014				2013				2012
		(In Thousands)
	Fixed maturities	$	6,127			$	5,289			$	4
	Cash equivalents	—				—				2
	Other	8				2				—
	Investment income	6,135				5,291				6
	Investment expenses	(517		)		(483		)		—
	Net investment income	$	5,618			$	4,808			$	6

Fair_Value_of_Financial_Instru1

Fair Value of Financial Instruments (Tables)	12 Months Ended
	Dec. 31, 2014
Fair Value Disclosures [Abstract]
Fair Value Measurements, Recurring and Nonrecurring	The following is a list of those assets and liabilities that are measured at fair value by hierarchy level as of December 31, 2014 and December 31, 2013:
		Fair Value Measurements Using
		Quoted Prices in			Significant Other		Significant		Fair Value
		Active Markets for			Observable Inputs		Unobservable
		Identical Assets			(Level 2)		Inputs
		(Level 1)					(Level 3)
	As of December 31, 2014	(In Thousands)
	U.S. Treasury securities and obligations of U.S. government agencies	$	39,176		$	29,169	$	—	$	68,345
	Municipal debt securities	—			11,963		—		11,963
	Corporate debt securities	—			199,785		—		199,785
	Asset-backed securities	—			56,408		—		56,408
	Cash and cash equivalents	103,021			—		—		103,021
	Total assets	$	142,197		$	297,325	$	—	$	439,522
	Warrant liability	$	—		$	—	$	3,372	$	3,372
	Total liabilities	$	—		$	—	$	3,372	$	3,372
		Fair Value Measurements Using
		Quoted Prices in			Significant Other		Significant		Fair Value
		Active Markets for			Observable Inputs		Unobservable
		Identical Assets			(Level 2)		Inputs
		(Level 1)					(Level 3)
	As of December 31, 2013	(In Thousands)
	U.S. Treasury securities and obligations of U.S. government agencies	$	49,484		$	57,122	$	—	$	106,606
	Municipal debt securities	—			11,933		—		11,933
	Corporate debt securities	—			217,257		—		217,257
	Asset-backed securities	—			73,292		—		73,292
	Cash and cash equivalents	55,929			—		—		55,929
	Total assets	$	105,413		$	359,604	$	—	$	465,017
	Warrant liability	$	—		$	—	$	6,371	$	6,371
	Total liabilities	$	—		$	—	$	6,371	$	6,371
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation	The following is a roll-forward of Level 3 liabilities measured at fair value for the year ended December 31, 2014:
		Warrant Liability
	For the Year Ended December 31, 2014	(In Thousands)
	Balance, January 1, 2014	$	6,371
	Change in fair value of warrant liability included in earnings	(2,949		)
	Gain on settlement of warrants	(37		)
	Issuance of common stock on warrant exercise	(13		)
	Balance, December 31, 2014	$	3,372
		Warrant Liability
	For the Year Ended December 31, 2013	(In Thousands)
	Balance, January 1, 2013	$	4,842
	Change in fair value of warrant liability included in earnings	1,529
	Balance, December 31, 2013	$	6,371

Reserves_for_Insurance_Claims_1

Reserves for Insurance Claims and Claims Expenses (Tables)	12 Months Ended
	Dec. 31, 2014
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 insurance claims and claims expenses for the year ended December 31, 2014 and 2013:
		For the Year Ended December 31,
		2014		2013
		(In Thousands)
	Reserve at beginning of period	$	—	$	—
	Claims incurred:
	Claims and claim expenses incurred:
	Current year	83		—
	Prior years	—		—
	Total claims incurred	83		—
	Claims paid:
	Claims and claim expenses paid:
	Current year	—		—
	Prior years	—		—
	Total claims paid	—		—
	Reserve at end of period	$	83	$	—

ShareBased_Compensation_Tables

Share-Based Compensation (Tables)	12 Months Ended
	Dec. 31, 2014
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Schedule of Stock Option Activity	A summary of option activity in the plan during the years ended December 31, 2014 and December 31, 2013 is as follows:
	For the Year Ended December 31, 2014	Shares		Weighted Average Grant Date Fair Value per Share		Weighted Average Exercise Price
		(Shares in Thousands)
	Options outstanding at December 31, 2013	3,062		$	3.98	$	10.31
	Options granted	780		4.85		12.03
	Options exercised	(109	)	3.85		10
	Options forfeited	(87	)	4.47		11.35
	Options expired	(16	)	4.25		10.93
	Options outstanding at December 31, 2014	3,630		$	4.16	$	10.66
	For the Year Ended December 31, 2013	Shares		Weighted Average Grant Date Fair Value per Share		Weighted Average Exercise Price
		(Shares in Thousands)
	Options outstanding at December 31, 2012	2,547		$	3.86	$	10
	Options granted	532		4.57		11.78
	Options forfeited	(15	)	3.84		10
	Options canceled	(2	)	3.84		10
	Options outstanding at December 31, 2013	3,062		$	3.98	$	10.31
Schedule of Grant Date Fair Values of Stock Options, Valuation Assumptions	The estimated grant date fair values of the stock options granted during 2014 and 2013 were calculated using the Black-Scholes valuation model based on the following assumptions:
		2014		2013
	Expected life	6 years		6 years
	Risk free interest rate	1.90% - 2.01%		0.98% - 1.12%
	Dividend yield	0	%	0	%
	Expected stock price volatility	39	%	39	%
	Projected forfeiture rate	5	%	1	%
Schedule of Restricted Stock Units Activity	A summary of RSU activity in the plan during the years ended December 31, 2014 and December 31, 2013 is as follows:
	For the Year Ended December 31, 2014	Shares		Weighted Average Grant Date Fair Value per Share
		(Shares in Thousands)
	Non-vested restricted stock units at December 31, 2013	1,242		$	7.75
	Restricted stock units granted	373		11.52
	Restricted stock units vested	(360	)	9.53
	Restricted stock units forfeited	(46	)	10.14
	Non-vested restricted stock units at December 31, 2014	1,209		$	8.9
	For the Year Ended December 31, 2013	Shares		Weighted Average Grant Date Fair Value per Share
		(Shares in Thousands)
	Non-vested restricted stock units at December 31, 2012	1,429		$	7.35
	Restricted stock units granted	76		12.03
	Restricted stock units vested	(263	)	6.79
	Restricted stock units forfeited	—		—
	Non-vested restricted stock units at December 31, 2013	1,242		$	7.75
Schedule of Grant Date Fair Value of Restricted Stock Units, Valuation Assumptions	The estimated grant date fair values of the RSUs granted in 2012 that are subject to both a market and service condition were calculated using a Monte Carlo simulation model based on the average outcome of 150,000 simulations using the following assumption:
		2012
	Expected life	5 years
	Risk free interest rate	0.86	%
	Dividend yield	0	%
	Expected stock price volatility	39	%
	Projected forfeiture rate	1	%

Income_Taxes_Tables

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Schedule of Components of Income Tax Expense (Benefit)	The provision (benefit) for income taxes consists of:
		For the Year Ended December 31,
		2014				2013				2012
		(In Thousands
	Current	$	(2,390	)		$	—			$	—
	Deferred	4				—				—
	Total income tax benefit	$	(2,386	)		$	—			$	—
Schedule of Effective Income Tax Rate Reconciliation	Reconciliation of the federal statutory income tax (benefit) rate to the effective income tax (benefit) rate is as follows:
		For the Year Ended December 31,
		2014			2013			2012
	Federal statutory income tax rate	35	%		35	%		35	%
	Loss on impairment	—			—			(1.48	)
	Prior year adjustment	—			3.52			1.66
	Other	1.07			1.66			(1.00	)
	Valuation allowance	(31.42	)		(40.18	)		(28.00	)
	Purchase accounting adjustment	—			—			(6.18	)
	Effective income tax rate	4.65	%		—	%		—	%
Schedule of Deferred Tax Assets and Liabilities	Following is a reconciliation of our net deferred income tax asset (liability) as of December 31, 2014 and December 31, 2013:
		December 31, 2014
		Gross				Tax Effected
	Deferred tax asset	(In Thousands)
	Capitalized start-up costs	$	2,403			$	985
	Share-based compensation	20,030				8,212
	Unrealized loss on investments	1,217				499
	Net operating loss carry forwards	114,548				43,198
	Unearned premium reserve	4,414				1,810
	Other	8,785				3,602
	Total gross deferred tax assets	151,397				58,306
	Less: valuation allowance	(140,236		)		(53,730		)
	Total deferred tax assets	11,161				4,576
	Deferred tax liability
	Capitalized software	(7,967		)		(3,266		)
	Intangible assets	(390		)		(137		)
	Deferred acquisition costs	(2,985		)		(1,224		)
	Other	(209		)		(86		)
	Total deferred tax liabilities	(11,551		)		(4,713		)
	Net deferred income tax liability	$	(390	)		$	(137	)
		December 31, 2013
		Gross				Tax Effected
	Deferred tax asset	(In Thousands)
	Capitalized start-up costs	$	2,579			$	903
	Share-based compensation	14,701				5,990
	Unrealized loss on investments	7,047				2,694
	Net operating loss carry forwards	65,276				24,602
	Other	10,118				3,760
	Total gross deferred tax assets	99,721				37,949
	Less: valuation allowance	(94,497		)		(35,778		)
	Total deferred tax assets	5,224				2,171
	Deferred tax liability
	Capitalized software	(5,008		)		(2,095		)
	Intangible assets	(390		)		(133		)
	Other	(216		)		(76		)
	Total deferred tax liabilities	(5,614		)		(2,304		)
	Net deferred income tax liability	$	(390	)		$	(133	)

Software_and_Equipment_Tables

Software and Equipment (Tables)	12 Months Ended
	Dec. 31, 2014
Property, Plant and Equipment [Abstract]
Schedule of Equipment and Software	Software and equipment, net of accumulated amortization and depreciation, as of December 31, 2014 and December 31, 2013, consists of the following:
		31-Dec-14			31-Dec-13
		(In Thousands)
	Software	$	11,608		$	14,140
	Equipment	1,175			542
	Leasehold improvements	973			141
	Subtotal	13,756			14,823
	Accumulated amortization and depreciation	(1,950		)	(5,947		)
	Software and equipment, net	$	11,806		$	8,876

Intangible_Assets_and_Goodwill1

Intangible Assets and Goodwill (Tables)	12 Months Ended
	Dec. 31, 2014
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of Indefinite-Lived Intangible Assets	Intangible assets and goodwill consist of identifiable intangible assets and goodwill we purchased in connection with the acquisition of our insurance subsidiaries, and at December 31, 2014 and December 31, 2013, were as follows for both years:
				Expected Lives
	Goodwill	$	3,244	Indefinite
	State licenses	260		Indefinite
	GSE applications	130		Indefinite
	Total intangible assets and goodwill	$	3,634

Commitments_and_Contingencies_

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2014
Commitments and Contingencies Disclosure [Abstract]
Schedule of Future Minimum Lease Payments	Management expects that, in the normal course of business, as of December 31, 2014, future minimum lease payments under this lease will be as follows:
	Years ending December 31,	(In Thousands)
	2015	$	1,690
	2016	1,741
	2017	1,488
	Totals	$	4,919

Statutory_Information_Tables

Statutory Information (Tables)	12 Months Ended
	Dec. 31, 2014
Insurance [Abstract]
Schedule of Risk to Capital	The risk-to-capital calculation for each of our insurance subsidiaries, as well as our combined risk-to-capital calculation, as of December 31, 2014, is presented below.
	As of December 31, 2014	NMIC			Re One			Combined
		(In Thousands)
	Primary risk-in-force (1)
	Direct	$	801,353		$	—		$	801,353
	Assumed	—			69,396			69,396
	Ceded	(69,396		)	—			(69,396		)
	Total primary risk-in-force	731,957			69,396			801,353
	Pool risk-in-force (2)
	Direct	93,090			—			93,090
	Assumed	—			24,705			24,705
	Ceded	(24,705		)	—			(24,705		)
	Total pool risk-in-force	68,385			24,705			93,090
	Total risk-in-force	800,342			94,101			894,443
	Statutory policyholders' surplus	223,119			13,619			236,738
	Statutory contingency reserve	7,945			1,456			9,401
	Total statutory policyholders' position	231,064			15,075			246,139
	Risk-to-Capital (3)	3.5:1			6.2:1			3.6:1
	(1)	Our net risk in force includes both primary and pool risk in force, and excludes risk on policies that are currently in default and for which loss reserves have been established.
	(2)	Pool risk-in-force as shown in the table above is equal to the aggregate stop loss less a deductible.
	(3)	Represents total risk-in-force divided by statutory policyholders' position which is the metric by which the majority of state insurance regulators will assess our capital adequacy. Additionally, pursuant to the 2013 Fannie Mae pool agreement, we are required to maintain the greater of (a) the risk-to-capital requirements outlined in Fannie Mae's January 2013 approval letter or (b) a risk-to-capital ratio of 18:1 on primary business plus statutory capital equal to the amount of net risk-in-force of the pool.
	NMIC and Re One's combined statutory net income, statutory surplus and contingency reserve as of and for each of the years in the three-year period ended December 31, 2014 were as follows:
		December 31,
		2014			2013			2012
		(In Thousands)
	Statutory net loss	$	(47,961	)	$	(33,307	)	$	(18	)
	Statutory surplus	236,738			189,698			220,004
	Contingency reserve	9,401			2,314			—

Quarterly_Financial_Data_Unaud1

Quarterly Financial Data (Unaudited) (Tables)	12 Months Ended
	Dec. 31, 2014
Quarterly Financial Information Disclosure [Abstract]
Schedule of Quarterly Financial Information
		2014 Quarters												2014
		First			Second			Third			Fourth			Year
		(In Thousands, except share data)
	Net premiums written	$	5,178		$	5,051		$	9,661		$	14,139		$	34,029
	Net premiums earned	1,904			2,093			3,900			5,510			13,407
	Net investment income	1,489			1,468			1,342			1,319			5,618
	Net realized investment gains (losses)	—			—			134			63			197
	Gain (loss) from change in fair value of warrant liability	817			952			1,240			(60		)	2,949
	Gain from settlement of warrants	37			—			—			—			37
	Insurance claims and claims expenses	—			28			(26		)	81			83
	Amortization of deferred policy acquisition costs	19			42			47			265			373
	Underwriting and operating expenses	19,283			18,595			17,848			17,318			73,044
	Net loss	(15,055		)	(12,855		)	(10,976		)	(10,020		)	(48,906		)
	Loss per share (1)
	Basic and diluted loss per share	$	(0.26	)	$	(0.22	)	$	(0.19	)	$	(0.17	)	$	(0.84	)
	Weighted average common shares outstanding	58,061,299			58,289,801			58,363,334			58,406,574			58,281,425
		2013 Quarters												2013
		First			Second			Third			Fourth			Year
		(In Thousands, except share data)
	Net premiums written	$	—		$	1		$	482		$	3,058		$	3,541
	Net premiums earned	—			1			482			1,612			2,095
	Net investment income	410			1,407			1,519			1,472			4,808
	Net realized investment gains (losses)	28			452			(308		)	14			186
	Gain (loss) from change in fair value of warrant liability	35			(1,115		)	469			(918		)	(1,529		)
	Insurance claims and claims expenses	—			—			—			—			—
	Amortization of deferred policy acquisition costs	—			—			—			1			1
	Underwriting and operating expenses	12,426			17,019			16,035			15,263			60,743
	Net loss	(11,953		)	(16,274		)	(13,873		)	(13,084		)	(55,184		)
	Loss per share (1)
	Basic and diluted loss per share	$	(0.22	)	$	(0.29	)	$	(0.25	)	$	(0.23	)	$	(0.99	)
	Weighted average common shares outstanding	55,500,100			55,629,932			55,637,480			57,238,730			56,005,326
	-1	Due to the use of weighted average shares outstanding when calculating earnings per share, the sum of quarterly per share data may not equal the per share data for the year.

Organization_and_Basis_of_Pres1

Organization and Basis of Presentation (Details) (USD $)	0 Months Ended	1 Months Ended	0 Months Ended	1 Months Ended
In Millions, except Share data, unless otherwise specified	Apr. 17, 2012	Apr. 30, 2012	Nov. 08, 2013	Nov. 30, 2013
Business Acquisition [Line Items]
Proceeds from issuance of common stock, net of stock issuance costs	$510
MAC Financial Holding Corporation and Subsidiaries [Member]
Business Acquisition [Line Items]
Cash, common stock and warrants issued for acquisition		8.5
Liabilities assumed in acquisition		$1.30
Common Class A [Member]
Business Acquisition [Line Items]
Common stock offered and sold, (in shares)	55,000,000
IPO [Member]
Business Acquisition [Line Items]
Common stock offered and sold, (in shares)			2,100,000	2,400,000

Summary_of_Accounting_Policies2

Summary of Accounting Policies (Details)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
	customer
Finite-Lived Intangible Assets [Line Items]
Number of customers	2
Antidilutive securities excluded from computation of earnings per share (in shares)	5,839,909	5,303,394	4,414,165
Minimum [Member] | Software [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated useful life	3 years
Minimum [Member] | Equipment [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated useful life	3 years
Maximum [Member] | Software [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated useful life	7 years
Maximum [Member] | Equipment [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated useful life	7 years
Geographic Concentration Risk [Member] | Sales Revenue, Net [Member]
Finite-Lived Intangible Assets [Line Items]
Concentration risk	18.00%

Investments_Fair_Values_and_Gr

Investments - Fair Values and Gross Unrealized Gains and Losses on Investments (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$337,718	$416,135
Gross Unrealized Gains	1,139	272
Gross Unrealized (Losses)	-2,356	-7,319
Fair Value	336,501	409,088
U.S. Treasury securities and obligations of U.S. government agencies [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	68,911	108,067
Gross Unrealized Gains	7	0
Gross Unrealized (Losses)	-573	-1,461
Fair Value	68,345	106,606
Municipal debt securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	12,009	12,017
Gross Unrealized Gains	27	1
Gross Unrealized (Losses)	-73	-85
Fair Value	11,963	11,933
Corporate debt securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	200,358	221,899
Gross Unrealized Gains	883	157
Gross Unrealized (Losses)	-1,456	-4,799
Fair Value	199,785	217,257
Asset-backed securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	56,440	74,152
Gross Unrealized Gains	222	114
Gross Unrealized (Losses)	-254	-974
Fair Value	$56,408	$73,292

Investments_Scheduled_Maturiti

Investments - Scheduled Maturities (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Available-for-sale Securities, Debt Maturities, Single Maturity Date, Amortized Cost Basis [Abstract]
Amortized Cost, Due in one year or less	$6,110	$0
Amortized Cost, Due after one through five years	195,492	260,855
Amortized Cost, Due after five through ten years	54,360	65,687
Amortized Cost, Due after ten years	25,316	15,441
Amortized Cost, Total Investments	337,718	416,135
Available-for-sale Securities, Debt Maturities, Single Maturity Date [Abstract]
Fair Value, Due in one year or less	6,125	0
Fair Value, Due after one through five years	194,472	257,501
Fair Value, Due after five through ten years	53,891	63,440
Fair Value Due after ten years	25,605	14,855
Fair Value	336,501	409,088
Asset-backed securities [Member]
Available-for-sale Securities, Debt Maturities, Single Maturity Date, Amortized Cost Basis [Abstract]
Amortized Cost, Total Investments	56,440	74,152
Available-for-sale Securities, Debt Maturities, Single Maturity Date [Abstract]
Fair Value	56,408	73,292
Total bonds [Member]
Available-for-sale Securities, Debt Maturities, Single Maturity Date, Amortized Cost Basis [Abstract]
Amortized Cost, Total Investments	337,718	416,135
Available-for-sale Securities, Debt Maturities, Single Maturity Date [Abstract]
Fair Value	$336,501	$409,088

Investments_Narrative_Details

Investments - Narrative (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Schedule of Available-for-sale Securities [Line Items]
Gross unrealized losses	$2,356,000	$7,319,000
Unrealized losses for a period of 12 months or greater	1,689,000	0
Gross realized gains	700,000	600,000	0
Gross realized losses	500,000	400,000	0
U.S. Treasury securities and obligations of U.S. government agencies [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross unrealized losses	573,000	1,461,000
Unrealized losses for a period of 12 months or greater	540,000	0
Cash and investments held with various state insurance departments	$7,000,000	$7,000,000

Investments_Unrealized_Losses_

Investments - Unrealized Losses (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified	security	security
Schedule of Available-for-sale Securities [Line Items]
Number of Securities, Less than 12 Months	34	79
Fair Value, Less than 12 Months	$81,408	$357,460
Unrealized Losses, Less than 12 Months	-667	-7,319
Number of Securities, 12 Months or Greater	37	0
Fair Value, 12 Months or Greater	137,432	0
Unrealized Losses, 12 Months or Greater	-1,689	0
Number of Securities, Total	71	79
Fair Value, Total	218,840	357,460
Unrealized Losses, Total	-2,356	-7,319
U.S. Treasury securities and obligations of U.S. government agencies [Member]
Schedule of Available-for-sale Securities [Line Items]
Number of Securities, Less than 12 Months	4	19
Fair Value, Less than 12 Months	7,228	106,606
Unrealized Losses, Less than 12 Months	-33	-1,461
Number of Securities, 12 Months or Greater	10	0
Fair Value, 12 Months or Greater	49,884	0
Unrealized Losses, 12 Months or Greater	-540	0
Number of Securities, Total	14	19
Fair Value, Total	57,112	106,606
Unrealized Losses, Total	-573	-1,461
Municipal debt securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Number of Securities, Less than 12 Months	1	2
Fair Value, Less than 12 Months	3,232	4,915
Unrealized Losses, Less than 12 Months	-18	-85
Number of Securities, 12 Months or Greater	1	0
Fair Value, 12 Months or Greater	1,695	0
Unrealized Losses, 12 Months or Greater	-55	0
Number of Securities, Total	2	2
Fair Value, Total	4,927	4,915
Unrealized Losses, Total	-73	-85
Corporate debt securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Number of Securities, Less than 12 Months	26	47
Fair Value, Less than 12 Months	60,334	187,714
Unrealized Losses, Less than 12 Months	-559	-4,799
Number of Securities, 12 Months or Greater	22	0
Fair Value, 12 Months or Greater	65,806	0
Unrealized Losses, 12 Months or Greater	-897	0
Number of Securities, Total	48	47
Fair Value, Total	126,140	187,714
Unrealized Losses, Total	-1,456	-4,799
Asset-backed securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Number of Securities, Less than 12 Months	3	11
Fair Value, Less than 12 Months	10,614	58,225
Unrealized Losses, Less than 12 Months	-57	-974
Number of Securities, 12 Months or Greater	4	0
Fair Value, 12 Months or Greater	20,047	0
Unrealized Losses, 12 Months or Greater	-197	0
Number of Securities, Total	7	11
Fair Value, Total	30,661	58,225
Unrealized Losses, Total	($254)	($974)

Investments_Net_Investment_Inc

Investments - Net Investment Income (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Schedule of Available-for-sale Securities [Line Items]
Investment income	$6,135	$5,291	$6
Investment expenses	-517	-483	0
Net investment income	5,618	4,808	6
Fixed maturities [Member]
Schedule of Available-for-sale Securities [Line Items]
Investment income	6,127	5,289	4
Cash equivalents [Member]
Schedule of Available-for-sale Securities [Line Items]
Investment income	0	0	2
Other [Member]
Schedule of Available-for-sale Securities [Line Items]
Investment income	$8	$2	$0

Fair_Value_of_Financial_Instru2

Fair Value of Financial Instruments - Assets and Liabilities at Fair Value (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	$336,501	$409,088
Warrant liability	3,372	6,371
Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	103,021	55,929
Total assets	439,522	465,017
Warrant liability	3,372	6,371
Total liabilities	3,372	6,371
Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	103,021	55,929
Total assets	142,197	105,413
Warrant liability	0	0
Total liabilities	0	0
Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	0	0
Total assets	297,325	359,604
Warrant liability	0	0
Total liabilities	0	0
Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	0	0
Total assets	0	0
Warrant liability	3,372	6,371
Total liabilities	3,372	6,371
U.S. Treasury securities and obligations of U.S. government agencies [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	68,345	106,606
U.S. Treasury securities and obligations of U.S. government agencies [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	68,345	106,606
U.S. Treasury securities and obligations of U.S. government agencies [Member] | Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	39,176	49,484
U.S. Treasury securities and obligations of U.S. government agencies [Member] | Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	29,169	57,122
U.S. Treasury securities and obligations of U.S. government agencies [Member] | Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	0	0
Municipal debt securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	11,963	11,933
Municipal debt securities [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	11,963	11,933
Municipal debt securities [Member] | Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	0	0
Municipal debt securities [Member] | Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	11,963	11,933
Municipal debt securities [Member] | Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	0	0
Corporate debt securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	199,785	217,257
Corporate debt securities [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	199,785	217,257
Corporate debt securities [Member] | Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	0	0
Corporate debt securities [Member] | Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	199,785	217,257
Corporate debt securities [Member] | Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	0	0
Asset-backed securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	56,408	73,292
Asset-backed securities [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	56,408	73,292
Asset-backed securities [Member] | Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	0	0
Asset-backed securities [Member] | Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	56,408	73,292
Asset-backed securities [Member] | Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	$0	$0

Fair_Value_of_Financial_Instru3

Fair Value of Financial Instruments - Rollforward of Level 3 (Details) (Significant Unobservable Inputs (Level 3) [Member], Warrant Liability [Member], USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Significant Unobservable Inputs (Level 3) [Member] | Warrant Liability [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	$6,371	$4,842
Change in fair value of warrant liability included in earnings	-2,949	1,529
Gain on settlement of warrants	-37
Issuance of common stock on warrant exercise	-13
Ending balance	$3,372	$6,371

Fair_Value_of_Financial_Instru4

Fair Value of Financial Instruments - Narrative (Details) (Significant Unobservable Inputs (Level 3) [Member], USD $)	12 Months Ended
	Dec. 31, 2014
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Volatility Assumption	37.40%
Warrant Liability [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Share price (in dollars per share)	9.13
Risk free rate	1.88%
Expected term	6 years 5 months 10 days
Expected dividend rate	0.00%

Reserves_for_Insurance_Claims_2

Reserves for Insurance Claims and Claims Expenses Narrative (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014
	loan
Insurance [Abstract]
Number of loans in pool past due 60 days or more	30
Risk in Force of loans in pool past due 60 days or more	$1.70
Deductible on policy	$10.30
Less than, LTV ratio	0.8

Reserves_for_Insurance_Claims_3

Reserves for Insurance Claims and Claims Expenses Reconciliation of Reserve Balances for Insurance Claims Expenses (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Reserve at beginning of period	$0	$0
Claims and claim expenses incurred:
Current year	83	0
Prior years	0	0
Total claims incurred	83	0
Claims and claim expenses paid:
Current year	0	0
Prior years	0	0
Total claims paid	0	0
Reserve at end of period	$83	$0

Warrants_Details

Warrants (Details) (USD $)	3 Months Ended				12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Apr. 30, 2012
Line of Credit Facility [Line Items]
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								$5,100,000
Warrants exercised				7,790
Gain from settlement of warrants	$0	$0	$0	$37,000	$37,000	$0	$0
Common Class A [Member]
Line of Credit Facility [Line Items]
Common stock, shares issued	58,428,548			1,115	58,428,548	58,052,480

ShareBased_Compensation_Stock_

Share-Based Compensation - Stock Option Activity (Details) (The 2012 Stock Incentive Plan [Member], USD $)	12 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
The 2012 Stock Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Options beginning balance (in shares)	3,062	2,547
Options granted (in shares)	780	532
Less: Options exercised (in shares)	-109
Less: Options forfeited (in shares)	-87	-15
Less: Options canceled (in shares)		-2
Less: Options expired (in shares)	-16
Options ending balance (in shares)	3,630	3,062
Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested, Number of Shares [Roll Forward]
Options beginning balance (in dollars per share)	$3.98	$3.86
Options granted (in dollars per share)	$4.85	$4.57
Less: Options exercised	$3.85
Less: Options forfeited (in dollars per share)	$4.47	$3.84
Less: Options expired (in dollars per share)	$4.25
Less: Options canceled (in dollars per share)		$3.84
Options ending balance (in dollars per share)	$4.16	$3.98
Weighted Average Grant Date Fair Value per Share
Options beginning balance (in dollars per share)	$10.31	$10
Options granted (in dollars per share)	$12.03	$11.78
Less: Options exercised	$10
Less: Options forfeited (in dollars per share)	$11.35	$10
Less: Options canceled (in dollars per share)		$10
Less: Options expired (in dollars per share)	$10.93
Options beginning balance (in dollars per share)	$10.66	$10.31

ShareBased_Compensation_Stock_1

Share-Based Compensation - Stock Options, Valuation Assumptions (Details) (The 2012 Stock Incentive Plan [Member], Stock Options [Member])	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected life	6 years	6 years
Dividend yield	0.00%	0.00%
Expected stock price volatility	39.00%	39.00%
Projected forfeiture rate	5.00%	1.00%
Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk free interest rate	1.90%	0.98%
Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk free interest rate	2.01%	1.12%

ShareBased_Compensation_Restri

Share-Based Compensation - Restricted Stock Units Activity (Details) (The 2012 Stock Incentive Plan [Member], Restricted Stock Units [Member], USD $)	12 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
The 2012 Stock Incentive Plan [Member] | Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Restricted Stock beginning balance (in shares)	1,242	1,429
Restricted stock units granted (in shares)	373	76
Less: Restricted stock units vested (in shares)	-360	-263
Less: Restricted stock units forfeited (in shares)	-46	0
Restricted Stock beginning balance (in shares)	1,209	1,242
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Restricted Stock beginning balance (in dollars per share)	$7.75	$7.35
Restricted Stock Units Granted (in dollars per share)	$11.52	$12.03
Less: Restricted Stock Units Vested (in dollars per share)	$9.53	$6.79
Less: Restricted Stock Units Forfeited (in dollars per share)	$10.14	$0
Restricted Stock ending balance (in dollars per share)	$8.90	$7.75

ShareBased_Compensation_Restri1

Share-Based Compensation - Restricted Stock Units, Valuation Assumptions (Details) (The 2012 Stock Incentive Plan [Member], Restricted Stock Units [Member])	12 Months Ended
	Dec. 31, 2012
The 2012 Stock Incentive Plan [Member] | Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected life	5 years
Risk free interest rate	0.86%
Dividend yield	0.00%
Expected stock price volatility	39.00%
Projected forfeiture rate	1.00%

ShareBased_Compensation_Narrat

Share-Based Compensation - Narrative (Details) (USD $)	12 Months Ended	1 Months Ended
	Dec. 31, 2014	Feb. 28, 2013	Apr. 16, 2012	Dec. 31, 2013	Dec. 31, 2012	8-May-14
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Dividends	$0
Employer matching contribution, percent of match	100.00%
Employer matching contribution, percent of employees' gross pay	4.00%
Contribution amount	900,000
The 2012 Stock Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized to be reserved for issuance (in shares)			5,500,000
Number of exercises	109,000
Number of options vested (in shares)	1,742,822
Weighted average exercise price for options vested (in dollars per share)	$10.20
Weighted average remaining contractual term	7 years 5 months 25 days
Options vested aggregate value	0
Weighted average remaining contractual life of options outstanding	7 years 10 months 17 days
Total unrecognized compensation cost related to non-vested stock options	2,400,000
Compensation related to non-vested awards, weighted-average period for recognition	1 year 3 months 10 days
The 2012 Stock Incentive Plan [Member] | Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized to be reserved for issuance (in shares)			3,850,000
Expiration period	10 years
Vesting period	3 years
The 2012 Stock Incentive Plan [Member] | Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized to be reserved for issuance (in shares)			1,650,000
Expiration period	10 years
Compensation related to non-vested awards, weighted-average period for recognition	1 year 2 months 5 days
Modification to vesting terms, number of restricted stock units affected (in shares)		400,000
Restricted stock units outstanding (in shares)	1,209,000			1,242,000	1,429,000
Vesting percentage subject to both market and service conditions, annual vesting percentage	50.00%
Number of simulations	150,000
Weighted average remaining contractual life of RSUs outstanding	7 years 11 months
Total unrecognized compensation cost related to non-vested restricted stock units	$3,000,000			$4,300,000
NMIH 2014 Omnibus Incentive Plan [Member] | Common Class A [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized to be reserved for issuance (in shares)						4,000,000
Subject to Market and Service Conditions [Member] | The 2012 Stock Incentive Plan [Member] | Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock units outstanding (in shares)	500,000
Subject to Service Conditions [Member] | The 2012 Stock Incentive Plan [Member] | Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock units outstanding (in shares)	700,000

Income_Taxes_Components_of_Pro

Income Taxes - Components of Provision for Income Taxes (Benefits) (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income Tax Disclosure [Abstract]
Current	($2,390)	$0	$0
Deferred	4	0	0
Total income tax benefit	($2,386)	$0	$0

Income_Taxes_Income_Tax_Reconc

Income Taxes - Income Tax Reconciliation (Details)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income Tax Disclosure [Abstract]
Federal statutory income tax rate	35.00%	35.00%	35.00%
Loss on impairment	0.00%	0.00%	-1.48%
Prior year adjustment	0.00%	3.52%	1.66%
Other	1.07%	1.66%	-1.00%
Valuation allowance	-31.42%	-40.18%	-28.00%
Purchase accounting adjustment	0.00%	0.00%	-6.18%
Effective income tax rate	4.65%	0.00%	0.00%

Income_Taxes_Deferred_Tax_Asse

Income Taxes - Deferred Tax Asset (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Deferred Tax Asset, Gross [Abstract]
Capitalized start-up costs	$2,403	$2,579
Share-based compensation	20,030	14,701
Unrealized loss on investments	1,217	7,047
Net operating loss carry forwards	114,548	65,276
Unearned premium reserve	4,414
Other	8,785	10,118
Total gross deferred tax assets	151,397	99,721
Less: valuation allowance	-140,236	-94,497
Total deferred tax assets	11,161	5,224
Deferred tax asset
Capitalized start-up costs	985	903
Share-based compensation	8,212	5,990
Unrealized loss on investments	499	2,694
Net operating loss carry forwards	43,198	24,602
Unearned premium reserve	1,810
Other	3,602	3,760
Total gross deferred tax assets	58,306	37,949
Less: valuation allowance	-53,730	-35,778
Total deferred tax assets	4,576	2,171
Deferred Tax Liability, Gross [Abstract]
Capitalized software	-7,967	-5,008
Intangible assets	-390	-390
Deferred acquisition costs	-2,985
Other	-209	-216
Total deferred tax liabilities	-11,551	-5,614
Net deferred income tax liability	-390	-390
Deferred tax liability
Capitalized software	-3,266	-2,095
Intangible assets	-137	-133
Deferred acquisition costs	-1,224
Other	-86	-76
Total deferred tax liabilities	-4,713	-2,304
Net deferred income tax liability	($137)	($133)

Income_Taxes_Narrative_Details

Income Taxes - Narrative (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income Tax Contingency [Line Items]
Income tax benefit	($2,386,000)	$0	$0
Federal statutory income tax rate	35.00%	35.00%	35.00%
Effective income tax rate	4.65%	0.00%	0.00%
Income tax expense (benefit)	-2,390,000	0	0
Deferred tax liabilities, gross	137,000	133,000
Taxes paid related to net share settlement of equity awards	2,100,000	1,500,000
Loss carry forwards subject to expiration	7,300,000
Valuation allowance	53,730,000	35,778,000
Annual Limitation Through Year Two [Member]
Income Tax Contingency [Line Items]
Loss carry forwards subject to expiration	800,000
Annual Limitations After Year Two [Member]
Income Tax Contingency [Line Items]
Loss carry forwards subject to expiration	300,000
Domestic Tax Authority [Member]
Income Tax Contingency [Line Items]
Operating loss carryforwards	114,500,000
State and Local Jurisdiction [Member]
Income Tax Contingency [Line Items]
Operating loss carryforwards	$36,000,000

Software_and_Equipment_Details

Software and Equipment (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Property, Plant and Equipment [Line Items]
Property plant and equipment	$13,756	$14,823
Accumulated amortization and depreciation	-1,950	-5,947
Software and equipment, net	11,806	8,876
Software [Member]
Property, Plant and Equipment [Line Items]
Property plant and equipment	11,608	14,140
Equipment [Member]
Property, Plant and Equipment [Line Items]
Property plant and equipment	1,175	542
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Property plant and equipment	$973	$141

Software_and_Equipment_Narrati

Software and Equipment - Narrative (Details) (USD $)	12 Months Ended		1 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Nov. 30, 2014
Property, Plant and Equipment [Line Items]
Depreciation and amortization	$5.80	$5.90
Software [Member]
Property, Plant and Equipment [Line Items]
Software acquired, written off			$9.80

Intangible_Assets_and_Goodwill2

Intangible Assets and Goodwill (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Indefinite-lived Intangible Assets [Line Items]
Goodwill	$3,244,000	$3,244,000
Intangible assets and goodwill	3,634,000	3,634,000
Loss on impairment	0	0	1,200,000
State licenses [Member]
Indefinite-lived Intangible Assets [Line Items]
Intangible assets	260,000	260,000
GSE Approvals [Member]
Indefinite-lived Intangible Assets [Line Items]
Intangible assets	$130,000	$130,000

Commitments_and_Contingencies_1

Commitments and Contingencies - Narrative (Details) (USD $)	0 Months Ended	12 Months Ended
	Jul. 01, 2012	Dec. 31, 2014	Dec. 31, 2013	Oct. 31, 2013
				sqft
Compliance with Regulatory Capital Requirements for Mortgage Companies [Line Items]
Maximum risk to capital ratio		25
Office facility lease, term of contract	2 years
Additional square feet of furnished office space under amended lease terms				23,000
Rent expense		$1,600,000	$800,000
Fannie Mae and Freddie Mac [Member]
Compliance with Regulatory Capital Requirements for Mortgage Companies [Line Items]
Capital required to be capitalized		$150,000,000
Maximum risk to capital ratio		15
Minimum capitalization requirement period		3 years

Commitments_and_Contingencies_2

Commitments and Contingencies - Future Minimum Lease Payments (Details) (USD $)	Dec. 31, 2014
In Thousands, unless otherwise specified
Commitments and Contingencies Disclosure [Abstract]
2015	$1,690
2016	1,741
2017	1,488
Totals	$4,919

Common_Stock_Offerings_Details

Common Stock Offerings (Details) (USD $)	0 Months Ended			1 Months Ended
In Millions, except Share data, unless otherwise specified	Apr. 17, 2012	Nov. 08, 2013	Nov. 14, 2013	Nov. 30, 2013
Class of Stock [Line Items]
Proceeds from issuance of common stock, net of stock issuance costs	$510
Common Class A [Member]
Class of Stock [Line Items]
Common stock offered and sold, (in shares)	55,000,000
IPO [Member]
Class of Stock [Line Items]
Common stock offered and sold, (in shares)		2,100,000		2,400,000
Maximum number of common stock shares granted to underwriters of IPO (in shares)		315,000
Maximum number of common stock shares granted to underwriters of IPO, exercise price (in dollars per share)		$13
Proceeds from issuance initial public offering			31.4
Underwriting fee and other offering expense			$28

Statutory_Information_Statutor

Statutory Information - Statutory Income (Details) (NMic and Re one Combined [Member], USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
NMic and Re one Combined [Member]
Statutory Accounting Practices [Line Items]
Statutory net loss	($47,961)	($33,307)	($18)
Statutory surplus	236,738	189,698	220,004
Contingency reserve	$9,401	$2,314	$0

Statutory_Information_Narrativ

Statutory Information - Narrative (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
In Thousands, unless otherwise specified	state	policy
Statutory Accounting Practices [Line Items]
Number of states which require minimum amount of statutory capital relative to risk in force	15
Risk-to-capital	25
Required risk-to-capital ratio on agreements per GSE approval	15
Mortgage insurance, percentage of indebtedness on single loan	25.00%
Number of Policies in Force		22
Shareholders' equity	$426,958	$463,217	$488,748	($1,349)	[1]
Investment in subsidiaries, at equity in net assets	179,000
Ordinary dividends, restriction with regards to capital surplus	10.00%
NMIC [Member]
Statutory Accounting Practices [Line Items]
Risk-to-capital	3.5	0.5
Mortgage Insurance Risk in Force	800,342	36,500
Subsidiaries [Member]
Statutory Accounting Practices [Line Items]
Shareholders' equity	$252,000
WISCONSIN [Member]
Statutory Accounting Practices [Line Items]
Risk-to-capital	25
[1]	At inception, we issued 100 common shares with a par value of $0.01 to FBR & Co. in consideration of their investment of $1 in the Company, which are not visible in this schedule due to rounding.

Statutory_Information_Risk_to_

Statutory Information - Risk to Capital (Details) (USD $)	Dec. 31, 2014		Dec. 31, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
NMIC [Member]
Primary risk-in-force
Direct	$801,353	[1]
Assumed	0	[1]
Ceded	-69,396	[1]
Total primary risk-in-force	731,957	[1]
Pool risk-in-force
Direct	93,090	[2]
Assumed	0	[2]
Ceded	-24,705	[2]
Total pool risk-in-force	68,385	[2]
Total risk-in-force	800,342		36,500
Total statutory policyholders' position	223,119
Statutory contingency reserve	7,945
Total statutory policyholders' position	231,064
Risk-to-Capital	3.5	[3]
NMI Re One [Member]
Primary risk-in-force
Direct	0	[1]
Assumed	69,396	[1]
Ceded	0	[1]
Total primary risk-in-force	69,396	[1]
Pool risk-in-force
Direct	0	[2]
Assumed	24,705	[2]
Ceded	0	[2]
Total pool risk-in-force	24,705	[2]
Total risk-in-force	94,101
Total statutory policyholders' position	13,619
Statutory contingency reserve	1,456
Total statutory policyholders' position	15,075
Risk-to-Capital	6.2	[3]
NMic and Re one Combined [Member]
Primary risk-in-force
Direct	801,353	[1]
Assumed	69,396	[1]
Ceded	-69,396	[1]
Total primary risk-in-force	801,353	[1]
Pool risk-in-force
Direct	93,090	[2]
Assumed	24,705	[2]
Ceded	-24,705	[2]
Total pool risk-in-force	93,090	[2]
Total risk-in-force	894,443
Total statutory policyholders' position	236,738		189,698	220,004
Statutory contingency reserve	9,401
Total statutory policyholders' position	$246,139
Risk-to-Capital	3.6	[3]
[1]	Our net risk in force includes both primary and pool risk in force, and excludes risk on policies that are currently in default and for which loss reserves have been established.
[2]	Pool risk-in-force as shown in the table above is equal to the aggregate stop loss less a deductible.
[3]	Represents total risk-in-force divided by statutory policyholders' position which is the metric by which the majority of state insurance regulators will assess our capital adequacy. Additionally, pursuant to the 2013 Fannie Mae pool agreement, we are required to maintain the greater of (a) the risk-to-capital requirements outlined in Fannie Mae's January 2013 approval letter or (b) a risk-to-capital ratio of 18:1 on primary business plus statutory capital equal to the amount of net risk-in-force of the pool.

Quarterly_Financial_Data_Unaud2

Quarterly Financial Data (Unaudited) (Details) (USD $)	3 Months Ended												12 Months Ended
In Thousands, except Share data, unless otherwise specified	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013		Sep. 30, 2013		Jun. 30, 2013		Mar. 31, 2013		Dec. 31, 2014	Dec. 31, 2013		Dec. 31, 2012
Quarterly Financial Information Disclosure [Abstract]
Net premiums written	$14,139	$9,661	$5,051	$5,178	$3,058		$482		$1		$0		$34,029	$3,541		$0
Net premiums earned	5,510	3,900	2,093	1,904	1,612		482		1		0		13,407	2,095		0
Net investment income	1,319	1,342	1,468	1,489	1,472		1,519		1,407		410		5,618	4,808		6
Net realized investment gains (losses)	63	134	0	0	14		-308		452		28		197	186		0
Gain (loss) from change in fair value of warrant liability	-60	1,240	952	817	-918		469		-1,115		35		2,949	-1,529		278
Gain from settlement of warrants	0	0	0	37									37	0		0
Insurance claims and claims expenses	81	-26	28	0	0		0		0		0		83	0		0
Amortization of deferred policy acquisition costs	265	47	42	19	1		0		0		0		373	1		0
Underwriting and operating expenses	17,318	17,848	18,595	19,283	15,263		16,035		17,019		12,426		73,044	60,743
Net loss	($10,020)	($10,976)	($12,855)	($15,055)	($13,084)		($13,873)		($16,274)		($11,953)		($48,906)	($55,184)		($27,491)
Loss per share
Basic and diluted loss per share (in dollars per share)	($0.17)	($0.19)	($0.22)	($0.26)	($0.23)	[1]	($0.25)	[1]	($0.29)	[1]	($0.22)	[1]	($0.84)	($0.99)	[1]	($0.73)
Weighted average common shares outstanding (in shares)	58,406,574	58,363,334	58,289,801	58,061,299	57,238,730	[1]	55,637,480	[1]	55,629,932	[1]	55,500,100	[1]	58,281,425	56,005,326	[1]	37,909,936
[1]	Due to the use of weighted average shares outstanding when calculating earnings per share, the sum of quarterly per share data may not equal the per share data for the year.

SCHEDULE_I_SUMMARY_OF_INVESTME1

SCHEDULE I - SUMMARY OF INVESTMENTS- OTHER THAN INVESTMENTS IN RELATED PARTIES (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Amortized Cost	$337,718	$416,135
Fair Value	336,501	409,088
Amount Reflected on Balance Sheet	336,501
U.S. Treasury securities and obligations of U.S. government agencies [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Amortized Cost	68,911	108,067
Fair Value	68,345	106,606
Amount Reflected on Balance Sheet	68,345
Municipal debt securities [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Amortized Cost	12,009	12,017
Fair Value	11,963	11,933
Amount Reflected on Balance Sheet	11,963
Corporate debt securities [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Amortized Cost	200,358	221,899
Fair Value	199,785	217,257
Amount Reflected on Balance Sheet	199,785
Asset-backed securities [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Amortized Cost	56,440	74,152
Fair Value	56,408	73,292
Amount Reflected on Balance Sheet	$56,408

SCHEDULE_II_FINANCIAL_INFORMAT1

SCHEDULE II - FINANCIAL INFORMATION OF REGISTRANT- PARENT COMPANY ONLY - Balance Sheet (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
In Thousands, unless otherwise specified
Assets
Cash and cash equivalents	$103,021	$55,929	$485,855	$0
Investment in subsidiaries, at equity in net assets	179,000
Accrued investment income	1,707	2,001
Prepaid expenses	2,054	1,519
Software and equipment, net	11,806	8,876
Other assets	509	63
Total assets	463,265	481,219
Liabilities
Accounts payable and accrued expenses	10,646	10,052
Warrant liability, at fair value	3,372	6,371
Total liabilities	36,307	18,002
Equity [Abstract]
Additional paid-in capital	562,911	553,707
Accumulated other comprehensive loss, net of tax	-3,607	-7,047
Accumulated deficit	-132,930	-84,024
Total shareholders' equity	426,958	463,217	488,748	-1,349	[1]
Total liabilities and shareholders' equity	463,265	481,219
Parent [Member]
Assets
Fixed maturities, available-for-sale, at fair value	134,199	229,064
Cash and cash equivalents	29,925	36,433	270,717	0
Investment in subsidiaries, at equity in net assets	251,880	193,242
Accrued investment income	629	1,038
Prepaid expenses	2,054	1,519
Due from affiliates, net	9,949	10,565
Software and equipment, net	11,806	7,574
Other assets	509	61
Total assets	440,951	479,496
Liabilities
Accounts payable and accrued expenses	10,621	9,908
Warrant liability, at fair value	3,372	6,371
Total liabilities	13,993	16,279
Equity [Abstract]
Total liabilities and shareholders' equity	440,951	479,496
Common Class A [Member]
Equity [Abstract]
Common stock - class A shares, $0.01 par value; 58,428,548 and 58,052,480 shares issued and outstanding as of December 31, 2014 and December 31, 2013, respectively (250,000,000 shares authorized)	$584	$581
[1]	At inception, we issued 100 common shares with a par value of $0.01 to FBR & Co. in consideration of their investment of $1 in the Company, which are not visible in this schedule due to rounding.

SCHEDULE_II_FINANCIAL_INFORMAT2

SCHEDULE II - FINANCIAL INFORMATION OF REGISTRANT- PARENT COMPANY ONLY - Balance Sheet Additional Information (Details) (Common Class A [Member], USD $)	Dec. 31, 2014	Mar. 31, 2014	Dec. 31, 2013
Common stock, par value (in dollars per share)	$0.01		$0.01
Common stock, shares issued	58,428,548	1,115	58,052,480
Common stock, shares outstanding	58,428,548		58,052,480
Common stock, shares authorized	250,000,000		250,000,000
Parent [Member]
Common stock, par value (in dollars per share)	$0.01		$0.01
Common stock, shares issued	58,428,548		58,052,480
Common stock, shares outstanding	58,428,548		58,052,480
Common stock, shares authorized	250,000,000		250,000,000

SCHEDULE_II_FINANCIAL_INFORMAT3

SCHEDULE II - FINANCIAL INFORMATION OF REGISTRANT- PARENT COMPANY ONLY - Income Statement (Details) (USD $)	3 Months Ended								12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Assets
Net investment income	$1,319	$1,342	$1,468	$1,489	$1,472	$1,519	$1,407	$410	$5,618	$4,808	$6
Net realized investment gains	63	134	0	0	14	-308	452	28	197	186	0
Gain (loss) from change in fair value of warrant liability	-60	1,240	952	817	-918	469	-1,115	35	2,949	-1,529	278
Gain from settlement of warrants	0	0	0	37					37	0	0
Total revenues									22,208	5,560	284
Expenses
Other operating expenses	17,318	17,848	18,595	19,283	15,263	16,035	17,019	12,426	73,044	60,743
Total expenses									73,500	60,744	27,775
Loss before income taxes									-51,292	-55,184	-27,491
Income tax benefit									-2,386	0	0
Net loss	-10,020	-10,976	-12,855	-15,055	-13,084	-13,873	-16,274	-11,953	-48,906	-55,184	-27,491
Parent [Member]
Assets
Net investment income									2,937	2,758	2
Net realized investment gains									67	188	0
Gain (loss) from change in fair value of warrant liability									2,949	-1,529	278
Gain from settlement of warrants									37	0	0
Total revenues									5,990	1,417	280
Expenses
Other operating expenses									18,817	24,319	26,575
Total expenses									18,817	24,319	26,575
Equity in net loss of subsidiaries									-38,710	-32,282	-1,196
Loss before income taxes									-51,537	-55,184	-27,491
Income tax benefit									-2,631	0	0
Net loss									($48,906)	($55,184)	($27,491)

SCHEDULE_II_FINANCIAL_INFORMAT4

SCHEDULE II - FINANCIAL INFORMATION OF REGISTRANT- PARENT COMPANY ONLY - Cash Flow Statement (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Cash flows from operating activities
Net loss	($48,906)	($55,184)	($27,491)
Adjustments to reconcile net loss to net cash used in operating activities:
Share-based compensation expense	9,180	10,367	6,115
Warrants issued in connection with line of credit	0	0	1,620
(Gain) loss from change in fair value of warrant liability	-2,949	1,529	-278
Gain from settlement of warrants	-37	0	0
Net realized investment gains	-197	-186	0
Depreciation and other amortization	8,080	8,116	3
Noncash intraperiod tax allocation	-2,386	0	0
Changes in operating assets and liabilities:
Accrued investment income	294	-2,001	-6
Prepaid expenses	-535	-1,102	-234
Other assets	-446	46	-78
Accounts payable and accrued expenses	117	767	4,553
Net cash used in operating activities	-21,004	-36,311	-14,596
Cash flows from investing activities
Purchase of fixed-maturity investments, available-for-sale	-60,462	-559,875	0
Proceeds from redemptions, maturities and sale of fixed-maturity investments, available-for-sale	136,764	141,754	0
Purchase of software and equipment	-8,220	-6,692	-2,447
Acquisition of subsidiaries	0	0	-2,500
Net cash provided by (used in) investing activities	68,082	-419,949	-9,809
Cash flows from financing activities
Payments on line of credit	0	0	-205
Issuance of common stock	1,097	27,912	510,465
Taxes paid related to net share settlement of equity awards	-1,083	-1,578	0
Net cash provided by financing activities	14	26,334	510,260
Net increase (decrease) in cash and cash equivalents	47,092	-429,926	485,855
Cash and cash equivalents, beginning of period	55,929	485,855	0
Cash and cash equivalents, end of period	103,021	55,929	485,855
Parent [Member]
Cash flows from operating activities
Net loss	-48,906	-55,184	-27,491
Adjustments to reconcile net loss to net cash used in operating activities:
Share-based compensation expense	9,180	10,367	6,115
Warrants issued in connection with line of credit	0	0	1,620
(Gain) loss from change in fair value of warrant liability	-2,949	1,529	-278
Gain from settlement of warrants	-37	0	0
Net realized investment gains	-67	-188	0
Depreciation and other amortization	5,618	3,325	3
Noncash intraperiod tax allocation	-2,390	0	0
Changes in operating assets and liabilities:
Equity in net loss of subsidiaries	38,710	35,371	1,196
Accrued investment income	409	-1,038	-2
Receivable from affiliates	616	-10,565	0
Prepaid expenses	-535	-1,102	-234
Other assets	-445	-3,045	-78
Accounts payable and accrued expenses	233	623	4,550
Net cash used in operating activities	-563	-19,907	-14,599
Cash flows from investing activities
Capitalization of subsidiaries	-95,000	0	-220,000
Purchase of fixed-maturity investments, available-for-sale	-23,552	-293,470	0
Proceeds from redemptions, maturities and sale of fixed-maturity investments, available-for-sale	120,813	59,454	0
Purchase of software and equipment	-8,220	-6,695	-2,444
Acquisition of subsidiaries	0	0	-2,500
Net cash provided by (used in) investing activities	-5,959	-240,711	-224,944
Cash flows from financing activities
Payments on line of credit	0	0	-205
Issuance of common stock	1,097	27,912	510,465
Taxes paid related to net share settlement of equity awards	-1,083	-1,578	0
Net cash provided by financing activities	14	26,334	510,260
Net increase (decrease) in cash and cash equivalents	-6,508	-234,284	270,717
Cash and cash equivalents, beginning of period	36,433	270,717	0
Cash and cash equivalents, end of period	$29,925	$36,433	$270,717

SCHEDULE_II_FINANCIAL_INFORMAT5

SCHEDULE II - FINANCIAL INFORMATION OF REGISTRANT- PARENT COMPANY ONLY - Supplemental Notes (Details) (Subsidiaries [Member], USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Other underwriting and operating expenses	$55,700,000	$32,500,000	$0