NMI (NMIH) 10-Q 14 May 14 2014 Q1 Quarterly report Financial data

Document_and_Entity_Informatio

Document and Entity Information	3 Months Ended
	Mar. 31, 2014	9-May-14
Document and Entity Information [Abstract]	'	'
Entity Registrant Name	'NMI HOLDINGS, INC.	'
Entity Central Index Key	'0001547903	'
Document Type	'10-Q	'
Document Period End Date	31-Mar-14	'
Amendment Flag	'false	'
Document Fiscal Year Focus	'2014	'
Document Fiscal Period Focus	'Q1	'
Current Fiscal Year End Date	'--12-31	'
Entity Current Reporting Status	'Yes	'
Entity Filer Category	'Non-accelerated Filer	'
Entity Common Stock, Shares Outstanding	'	58,230,104

CONDENSED_CONSOLIDATED_BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS (USD $)	Mar. 31, 2014	Dec. 31, 2013
Investments, available-for-sale, at fair value:	'	'
Fixed maturities (amortized cost of $414,888 and $416,135 as of March 31, 2014 and December 31, 2013, respectively)	$410,876,000	$409,088,000
Total investments	410,876,000	409,088,000
Cash and cash equivalents	42,792,000	55,929,000
Accrued investment income	1,791,000	2,001,000
Premiums receivable	129,000	19,000
Prepaid expenses	1,702,000	1,519,000
Deferred policy acquisition costs, net	976,600	90,200
Goodwill and other indefinite lived intangible assets	3,634,000	3,634,000
Software and equipment, net	9,226,000	8,876,000
Other assets	57,000	63,000
Total Assets	471,184,000	481,219,000
Liabilities	'	'
Unearned premiums	4,721,000	1,446,000
Reserve for insurance claims and claims expenses	0	0
Accounts payable and accrued expenses	7,373,000	10,052,000
Warrant liability, at fair value	5,504,000	6,371,000
Deferred tax liability	133,000	133,000
Total Liabilities	17,731,000	18,002,000
Commitments and Contingencies	'	'
Shareholders' Equity	'	'
Additional paid-in capital	555,963,000	553,707,000
Accumulated other comprehensive loss	-4,012,000	-7,047,000
Accumulated deficit	-99,079,000	-84,024,000
Total Shareholders' Equity	453,453,000	463,217,000
Total Liabilities and Shareholders' Equity	471,184,000	481,219,000
Class A	'	'
Shareholders' Equity	'	'
Common stock - Class A shares, $0.01 par value, 58,067,326 and 58,052,480 shares issued and outstanding as of March 31, 2014 and December 31, 2013, respectively (250,000,000 shares authorized)	$581,000	$581,000

CONDENSED_CONSOLIDATED_BALANCE1

CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) (USD $)	Mar. 31, 2014	Dec. 31, 2013
In Thousands, except Share data, unless otherwise specified
Fixed maturity, amortized cost	$414,888	$416,135
Class A	'	'
Common stock, par value (in dollars per share)	$0.01	$0.01
Common stock, shares issued	58,067,326	58,052,480
Common stock, shares outstanding	58,067,326	58,052,480
Common stock, shares authorized	250,000,000	250,000,000

CONDENSED_CONSOLIDATED_STATEME

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS (USD $)	3 Months Ended
In Thousands, except Share data, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Premiums written	'	'
Direct	$5,178	$0
Net premiums written	5,178	0
Increase in unearned premiums	-3,274	0
Net premiums earned	1,904	0
Net investment income	1,489	410
Net realized investment gains	0	28
Gain from change in fair value of warrant liability	817	35
Gain from settlement of warrants	37	0
Total Revenues	4,247	473
Expenses	'	'
Insurance claims and claims expenses	0	0
Amortization of deferred policy acquisition costs	19	0
Other underwriting and operating expenses	19,283	12,426
Total Expenses	19,302	12,426
Net Loss	-15,055	-11,953
Other Comprehensive Income (net of tax)	'	'
Net unrealized holding gains for the period included in accumulated other comprehensive loss	3,035	888
Other Comprehensive Income (net of tax)	3,035	888
Total Comprehensive Loss	($12,020)	($11,065)
Loss per share	'	'
Basic and Diluted loss per share (in dollars per share)	($0.26)	($0.22)
Weighted average common shares outstanding (in shares)	58,061,299	55,500,100

CONDENSED_CONSOLIDATED_STATEME1

CONDENSED CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY (USD $)	Total	Common stock	Common stock	Additional Paid-in Capital	Accumulated Other Comprehensive Loss	Accumulated Deficit
In Thousands, unless otherwise specified		Class A	Class B
Beginning Balance at Dec. 31, 2012	$488,748	$553	$2	$517,032	$1	($28,840)
Increase (Decrease) in Stockholders' Equity [Roll Forward]	'	'	'	'	'	'
Common stock Class A share issuance related to restricted stock units	-1,578	1	'	-1,579	'	'
Issuance of shares of common stock	27,912	25	0	27,887	'	'
Conversion of Class B shares of common stock into Class A shares of common stock	0	2	-2	'	'	'
Share-based compensation expense	10,367	'	'	10,367	'	'
Change in unrealized investment gains/losses	-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 share issuance related to restricted stock units	13	'	'	13	'	'
Issuance of shares of common stock	-90	'	'	-90	'	'
Share-based compensation expense	2,333	'	'	2,333	'	'
Change in unrealized investment gains/losses	3,035	'	'	'	3,035	'
Net loss	-15,055	'	'	'	'	-15,055
Ending Balance at Mar. 31, 2014	$453,453	$581	$0	$555,963	($4,012)	($99,079)

CONDENSED_CONSOLIDATED_STATEME2

CONDENSED CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY (Parenthetical) (USD $)	12 Months Ended	3 Months Ended
In Thousands, except Share data, unless otherwise specified	Dec. 31, 2013	Mar. 31, 2014
		Class A
		Common stock
Issuance of Class A shares of common stock as part of cashless exercise of warrants, shares	'	1,115
Issuance of shares of common stock, shares	'	13,731
Payments of stock issuance costs	$3,483	'
Common stock, par value (in dollars per share)	'	$0.01

CONDENSED_CONSOLIDATED_STATEME3

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Cash Flows From Operating Activities	'	'
Net loss	($15,055)	($11,953)
Adjustments to reconcile net loss to net cash used in operating activities:	'	'
Share-based compensation expense	2,333	3,013
Gain from change in fair value of warrant liability	-817	-35
Gain from settlement of warrants	-37	0
Net realized investment gains	0	-28
Depreciation and other amortization	1,952	59
Changes in operating assets and liabilities:	'	'
Accrued investment income	210	-1,134
Unearned premiums	3,274	0
Prepaid expenses	-183	-116
Deferred policy acquisition costs, net	-887	0
Premiums receivable	-110	0
Other assets	7	54
Accounts payable and accrued expenses	-2,678	-3,104
Net Cash Used in Operating Activities	-11,991	-13,244
Cash Flows From Investing Activities	'	'
Purchase of short-term investments	0	-510
Purchase of fixed-maturity investments, available-for-sale	-110	-338,329
Proceeds from redemptions, maturities and sale of fixed-maturity investments, available-for-sale	718	15,352
Purchase of software and equipment	-1,664	-1,722
Net Cash Used in Investing Activities	-1,056	-325,209
Cash Flows From Financing Activities	'	'
Taxes paid related to net share settlement of equity awards	-90	0
Net Cash Used in Financing Activities	-90	0
Net Decrease in Cash and Cash Equivalents	-13,137	-338,453
Cash and Cash Equivalents, beginning of period	55,929	485,855
Cash and Cash Equivalents, end of period	$42,792	$147,402

Organization_and_Basis_of_Pres

Organization and Basis of Presentation	3 Months Ended
	Mar. 31, 2014
Organization, Consolidation and Presentation of Financial Statements [Abstract]	'
Organization and Basis of Presentation	'
	Organization and Basis of Presentation
	NMI Holdings, Inc. ("NMIH"), a Delaware corporation, was formed in May 2011 with the intention of providing private mortgage guaranty insurance through a wholly owned insurance subsidiary. From May 2011 through March 2013, our activities were limited to raising capital, seeking to acquire the assets and approvals necessary to become a private mortgage guaranty insurance provider and hiring personnel. In April 2013, we, through our primary insurance subsidiary, National Mortgage Insurance Corporation ("NMIC"), wrote our first mortgage guaranty insurance policy. As of March 31, 2014, we had $514.8 million primary insurance in force ("IIF") and $5.0 billion pool IIF, with $115.5 million of primary risk-in-force ("RIF") and $93.1 million of pool RIF.
	The accompanying consolidated financial statements include the accounts of NMIH and its wholly owned subsidiaries, NMIC, National Mortgage Reinsurance Inc One ("Re One"), and National Mortgage Reinsurance Inc Two ("Re Two"). On September 30, 2013, we merged Re Two into NMIC with NMIC surviving the merger.
	On November 30, 2011, we entered into an agreement with MAC Financial Ltd. to acquire MAC Financial Holding Corporation and its subsidiaries, which were renamed NMIC, Re One and Re Two, for $8.5 million in cash, common stock and warrants plus the assumption of $1.3 million in liabilities ("MAC Acquisition"). In addition, we incurred $0.1 million in deferred tax liabilities as a result of the acquisition of certain indefinite-lived intangibles. The MAC Acquisition was completed in April 2012. On September 30, 2013, we merged MAC Financial Holding Corporation into NMIH, with NMIH surviving the merger.
	In April 2012, we offered and sold 55.0 million shares of common stock at an issue price of $10.00 per share in a private placement ("Private Placement"). Gross proceeds from the Private Placement were $550.0 million. Net proceeds from the Private Placement, after an approximate 7% underwriting fee and other offering expenses, were approximately $510 million. The fee was escrowed for the benefit of FBR Capital Markets and Co. ("FBR") and was released to FBR upon our receipt of approval from Federal National Home Mortgage Association ("Fannie Mae") and Federal Home Loan Mortgage Corporation ("Freddie Mac") ("GSE Approval").
	Under the terms of the Private Placement, we had until January 17, 2013 to obtain GSE Approval. NMIC was approved as an eligible mortgage guaranty insurer by Freddie Mac and Fannie Mae on January 15, 2013 and January 16, 2013, respectively, which approvals require NMIC to continue meeting certain conditions.
	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 2, Common Stock Offerings."
	Basis of Presentation
	The accompanying unaudited condensed consolidated financial statements, which include the results of NMIH and its wholly owned subsidiaries, have been prepared in accordance with the instructions to Form 10-Q as prescribed by the United States ("U.S.") Securities and Exchange Commission for interim reporting and include all of the other information and disclosures required by accounting principles generally accepted in the U.S. ("GAAP"). Our accounts are maintained in U.S. dollars. These statements should be read in conjunction with our consolidated financial statements and notes thereto for the year ended December 31, 2013 included in our Annual Report on Form 10-K. All intercompany transactions have been eliminated. The preparation of financial statements in accordance with GAAP requires management to make estimates and assumptions that affect reported amounts of assets and liabilities, as well as disclosure of contingent assets and liabilities as of the balance sheet date. Estimates also affect the reported amounts of income and expenses for the reporting period. Actual results could differ from those estimates. The results of operations for the interim period may not be indicative of the results that may be expected for the full year ending December 31, 2014.
	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 quarters ended March 31, 2014 and March 31, 2013, 6.2 million and 6.5 million 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.
	Deferred Policy Acquisition Costs
	Costs directly associated with the successful acquisition of mortgage guaranty 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 income in proportion to estimated gross profits over the estimated life of the policies.  We recorded net DAC of $976.6 thousand at March 31, 2014 and $90.2 thousand at December 31, 2013.
	Reserve for Insurance Claims and Claims Expenses
	We establish reserves to recognize the estimated liability for insurance claims and claim expenses related to defaults on insured mortgage loans. Our method, consistent with industry practice, is to establish claims reserves only for loans in default. We are a new company and recently began transacting mortgage guaranty insurance. We have not received any primary notices of default ("NOD"), and thus have not established any primary reserves for claims or claims that we believe have been incurred but not reported ("IBNR") for the three months ended March 31, 2014 or for the year ended December 31, 2013. Additionally, we entered into a pool insurance transaction with Fannie Mae, effective September 1, 2013. For this pool transaction, any claims reserve potentially established would be in excess of 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. Due to the size of the deductible ($10.3 million), the low level of NODs reported through March 31, 2014 and the high quality of the loans, we have not established any pool reserves for claims or IBNR for the three months ended March 31, 2014 or for the year ended December 31, 2013.
	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. We have determined that no premium deficiency reserves were necessary for the quarter ended March 31, 2014 or for the year ended December 31, 2013.
	Reclassifications
	Certain items in the financial statements as of December 31, 2013 and for the quarter ended March 31, 2013 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
	On April 7, 2014, we received our final certificate of authority (our insurance license permitting us to write mortgage guaranty insurance in that state) from the state of Wyoming. With Wyoming, we are now licensed in all 50 states and Washington D.C.
	On May 8, 2014 we held our annual shareholder meeting. Our shareholders voted to approve several items, including our 2014 Omnibus Incentive Plan, which authorizes us to make 4 million shares of our class A common stock available to be granted. These shares may be either authorized but unissued shares or treasury shares.
	We have considered subsequent events through the date of this filing.

Common_Stock_Offering

Common Stock Offering	3 Months Ended
	Mar. 31, 2014
Equity [Abstract]	'
Common Stock Offering	'
	Common Stock Offerings
	We entered into a purchase/placement agreement that closed in April 2012, pursuant to 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 after an approximate 7% underwriting fee and other offering expenses. On November 8, 2013, we completed an initial public offering of 2.4 million shares of common stock, and our common stock began trading on the NASDAQ under the symbol "NMIH". Net proceeds from the offering were approximately $28 million, after an approximate 6% underwriting fee and other offering expenses and reimbursements pursuant to the underwriting agreement.

Investments

Investments	3 Months Ended
	Mar. 31, 2014
Investments, Debt and Equity Securities [Abstract]	'
Investments	'
	Investments
	We have designated our investment portfolio as available-for-sale and report it at fair value. The related unrealized gains and losses are, after considering the related tax expense or benefit, recognized as a component of accumulated other comprehensive loss in shareholders' equity. Net realized investment gains and losses are reported in income based upon specific identification of securities sold.
	Fair Values and Gross Unrealized Gains and Losses on Investments
		Amortized				Gross Unrealized								Fair
		Cost				Gains				Losses				Value
	As of March 31, 2014	(In Thousands)
	U.S. Treasury securities and obligations of U.S. government agencies	$	108,053			$	12			$	(1,224	)		$	106,841
	Municipal bonds	12,015				28				(35		)		12,008
	Corporate debt securities	221,506				351				(2,888		)		218,969
	Asset-backed securities	73,314				296				(552		)		73,058
	Total Investments	$	414,888			$	687			$	(4,699	)		$	410,876
		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 bonds	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 March 31, 2014 and December 31, 2013, 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 March 31, 2014	Amortized				Fair
		Cost				Value
		(In Thousands)
	Due in one year or less	$	2,674			$	2,675
	Due after one through five years	264,257				261,989
	Due after five through ten years	59,222				57,975
	Due after ten years	15,421				15,179
	Asset-backed securities	73,314				73,058
	Total Investments	$	414,888			$	410,876
	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
	Net Realized Investment Gains (Losses) on Investments
	We had no net realized gains or losses for the three months ended March 31, 2014. For the three months ended March 31, 2013, we had net realized gains on corporate bonds of $28 thousand.
	Aging of Unrealized Losses
	At March 31, 2014, the investment portfolio had gross unrealized losses of $4.7 million, $347 thousand of which has been in an unrealized loss position for a period of 12 months or greater. We did not consider these securities to be other-than-temporarily impaired as of March 31, 2014. We based our conclusion that these investments were not other-than-temporarily impaired at March 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 March 31, 2014			(Dollars in Thousands)
	U.S. Treasury securities and obligations of U.S. government agencies	41		$	87,817		$	(1,224	)		—		$	—		$	—		41	$	87,817	$	(1,224	)
	Municipal bonds	1		1,715			(35		)		—		—			—			1	1,715		(35		)
	Corporate debt securities	93		152,174			(2,668		)		4		10,928			(220		)	97	163,102		(2,888		)
	Assets-backed securities	26		37,101			(425		)		2		5,669			(127		)	28	42,770		(552		)
	Total Investments	161		$	278,807		$	(4,352	)		6		$	16,597		$	(347	)	167	$	295,404	$	(4,699	)
		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 bonds	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 is comprised of the following:
		For the Three Months Ended March 31,
		2014				2013
		(In Thousands)
Fixed maturities	$	1,626			$	566
Cash equivalents	—				1
Investment income	1,626				567
Investment expenses	(137		)		(157		)
Net Investment Income	$	1,489			$	410
As of March 31, 2014 and December 31, 2013, there were approximately $7.1 million and $7.0 million, respectively, 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	3 Months Ended
	Mar. 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 March 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;
	Level 2 - Prices or valuations based on observable inputs other than quoted prices in active markets for identical assets and liabilities; 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.
	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.
	Liabilities classified as Level 3
	The warrants outstanding are valued using a Black-Scholes option-pricing model in combination with a binomial model and Monte Carlo simulation used to value the pricing protection features within the warrants. 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 March 31, 2014 and December 31, 2013:
		Fair Value Measurements Using
	Assets and Liabilities at Fair Value	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 March 31, 2014	(In Thousands)
	U.S. Treasury securities and obligations of U.S. government agencies	$	49,675		$	57,166	$	—	$	106,841
	Municipal bonds	—			12,008		—		12,008
	Corporate debt securities	—			218,969		—		218,969
	Asset-backed securities	—			73,058		—		73,058
	Cash and cash equivalents	42,792			—		—		42,792
	Total Assets	$	92,467		$	361,201	$	—	$	453,668
	Warrant liability	$	—		$	—	$	5,504	$	5,504
	Total Liabilities	$	—		$	—	$	5,504	$	5,504
		Fair Value Measurements Using
	Assets and Liabilities at Fair Value	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 bonds	—			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 three months ended March 31, 2014 and the year ended December 31, 2013:
	Level 3 Instruments Only	Warrant Liability
	Three Months Ended March 31, 2014	(In Thousands)
	Balance, January 1, 2014	$	6,371
	Change in fair value of warrant liability included in earnings	(817		)
	Gain on settlement of warrants	(37		)
	Issuance of common stock on warrant exercise	(13		)
	Balance, March 31, 2014	$	5,504
	Level 3 Instruments Only	Warrant Liability
	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 a Monte-Carlo simulation model used to value the pricing protection features within the warrant. As of March 31, 2014 the assumptions used in the option pricing model were as follows: a common stock price as of March 31, 2014 of $11.72, risk free interest rate of 2.18%, expected life of 6.57 years, expected volatility of 39.0%, 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 March 31, 2014.
	The carrying value of other selected assets on our consolidated balance sheet approximates fair value.

Software_and_Equipment

Software and Equipment	3 Months Ended
	Mar. 31, 2014
Property, Plant and Equipment [Abstract]	'
Software and Equipment	'
	Software and Equipment
	Software and equipment consist of capitalized software purchased in connection with the MAC Acquisition which had a fair value of $5.0 million at the date of acquisition, as well as software we have developed. Software and equipment, net of accumulated amortization and depreciation, as of March 31, 2014 and December 31, 2013 consist of the following:
		As of March 31,			As of December 31,
		2014			2013
		(In Thousands)
	Software	$	15,726		$	14,140
	Equipment	544			542
	Leasehold improvements	217			141
	Subtotal	16,487			14,823
	Accumulated amortization and depreciation	(7,261		)	(5,947		)
	Software and equipment, net	$	9,226		$	8,876
	Amortization and depreciation expense for the three months ended March 31, 2014 and for the year ended December 31, 2013 was $1.3 million and $59 thousand, respectively.

Intangible_Assets_and_Goodwill

Intangible Assets and Goodwill	3 Months Ended
	Mar. 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 purchased in connection with the MAC Acquisition. Intangible assets and goodwill, net, as of March 31, 2014 and December 31, 2013, consist of the following:
	As of March 31, 2014 and December 31, 2013	(In Thousands)		Expected Lives
	Goodwill	$	3,244	Indefinite
	State licenses	260		Indefinite
	GSE approvals	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. We have not identified any impairments of goodwill or impairments of indefinite-lived intangibles as of March 31, 2014.

Income_Taxes

Income Taxes	3 Months Ended
	Mar. 31, 2014
Income Tax Disclosure [Abstract]	'
Income Taxes	'
	Income Taxes
	We are a U.S. taxpayer and are subject to a statutory U.S. federal corporate income tax rate of 35%. Our holding company files a consolidated U.S. federal and various state income tax returns on behalf of itself and its subsidiaries. Our effective income tax rate on our pre-tax loss was 0% for the three months ended March 31, 2014, which was the same for the comparable 2013 period. During those periods, the benefit from income taxes was eliminated or reduced by the recognition of a full valuation allowance which was recorded to reflect the amount of the deferred taxes that may not be realized.
	As of March 31, 2014 and December 31, 2013, we have a net deferred tax liability of $0.1 million as a result of the acquisition of indefinite-lived intangibles in the MAC Acquisition for which no benefit has been reflected in the acquired net operating loss carry forwards. The tax liability incurred at the acquisition is recorded as an increase in goodwill.

ShareBased_Compensation

Share-Based Compensation	3 Months Ended
	Mar. 31, 2014
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]	'
Share-Based Compensation	'
	Share Based Compensation
	A summary of option activity under our 2012 Stock Incentive Plan during the quarters ending March 31, 2014 and March 31, 2013 is as follows:
		Shares		Weighted Average Exercise Price		Weighted Average Grant Date Fair Value per Share
		(Shares in Thousands)
	Options outstanding at December 31, 2013	3,063		$	10.31	$	3.98
	Options granted	693		12.32		4.97
	Options exercised	(2	)	10		3.84
	Options forfeited	(28	)	10.71		4.15
	Options outstanding at March 31, 2014	3,726		$	10.68	$	4.17
		Shares		Weighted Average Exercise Price		Weighted Average Grant Date Fair Value per Share
		(Shares in Thousands)
	Options outstanding at December 31, 2012	2,547		$	10	$	3.86
	Options granted	514		11.75		4.56
	Options forfeited	(10	)	10		3.84
	Options outstanding at March 31, 2013	3,051		$	10.27	$	3.98
	As of March 31, 2014, there were 2,000 options exercised and 989,000 options were fully vested and exercisable. The weighted average exercise price for the fully vested and exercisable options was $10.32. The remaining weighted average contractual life of options fully vested and exercisable as of March 31, 2014 was 7.2 years. The aggregate intrinsic value for fully vested and exercisable options was $1.4 million as of March 31, 2014. The fair value of option grants to employees is determined based on a Black-Scholes simulation model at the date of grant.
	A summary of RSU activity in the plan during the quarters ending March 31, 2014 and March 31, 2013 is as follows:
		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	239		12.32
	Restricted stock units vested	(19	)	11.31
	Restricted stock units forfeited	(14	)	6.98
	Non-vested restricted stock units at March 31, 2014	1,448		$	8.46
		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	82		11.75
	Restricted stock units forfeited	—		—
	Non-vested restricted stock units at March 31, 2013	1,511		$	7.59
	At March 31, 2014, the 1.4 million shares of non-vested RSUs consisted of 0.5 million shares that are subject to both a market and service condition and 0.9 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 1 to 3 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.

Warrants

Warrants	3 Months Ended
	Mar. 31, 2014
Debt Disclosure [Abstract]	'
Warrants	'
	Warrants
	We issued 992,000 warrants, to FBR and the former stockholders of MAC Financial Ltd., upon the completion of our Private Placement and in conjunction with the MAC Acquisition, respectively. 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 reclassified from warrant liability to 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.
	We account for these warrants to purchase our common shares in accordance with ASC 470-20, Debt with Conversion and Other Options and ASC 815-40, Derivatives and Hedging - Contracts in Entity's Own Equity.

Litigation

Litigation	3 Months Ended
	Mar. 31, 2014
Commitments and Contingencies Disclosure [Abstract]	'
Litigation	'
	Litigation
	On August 8, 2012, Germaine Marks, as Receiver, and Truitte Todd, as Special Deputy Receiver, of PMI Mortgage Insurance Co. (“PMI”), an Arizona insurance company in receivership, filed a complaint (the “PMI Complaint”) against NMIH, NMIC and certain named individuals, in California Superior Court, Alameda County (the "Court"). The PMI Complaint, as amended, alleges breach of fiduciary duty, breach of loyalty, aiding and abetting breach of fiduciary duty and loyalty, misappropriation of trade secrets, conversion, breach of proprietary information agreement, breach of separation agreement, intentional interference with contractual relations and unfair competition. The lawsuit seeks injunctive relief as well as unspecified monetary damages. We and the individual defendants believe these claims are without merit and have filed answers denying all allegations. We and the individual defendants intend to defend ourselves vigorously.
	On January 30, 2014, Arch announced the closing of its acquisition of CMG and certain assets of PMI. The terms of the February 7, 2013 Asset Purchase Agreement ("APA") between Arch and PMI provide that effective as of the closing of that transaction, PMI shall transfer and assign to Arch all causes of action being pursued by PMI in the PMI Complaint. The APA further provides that within thirty (30) days after the closing of the transaction, Arch shall have its attorney file appropriate pleadings and other documents and instruments with the court requesting that PMI be removed as a party plaintiff in the PMI Complaint and that Arch be substituted as the real party in interest. Although Arch has not yet filed any such request with the Court, the plaintiff is now described in pleadings as “Plaintiff and Real Party in Interest Arch U.S. MI Services, Inc.”
	The parties are now engaged in discovery and the court has set a trial date for September 29, 2014. Because the litigation and related discovery are ongoing, we do not have sufficient information to determine or predict the ultimate outcome or estimate the range of possible losses, if any. Accordingly, no provision for litigation losses has been included in the financial statements.

Statutory_Information

Statutory Information	3 Months Ended
	Mar. 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 Office of the Commissioner of Insurance ("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 National Association of Insurance Commissioners ("NAIC"). The Wisconsin OCI recognizes only statutory accounting practices prescribed or permitted by the state of Wisconsin for determining and reporting the financial condition and results of operations of an insurance company and for determining its solvency under Wisconsin insurance laws.
	NMIC and Re One's combined statutory net income, statutory surplus and contingency reserve as of March 31, 2014 and for the year ended December 31, 2013 were as follows:
		March 31, 2014			December 31, 2013
		(In Thousands)
	Statutory net loss	$	(12,750	)	$	(33,307	)
	Statutory surplus	196,948			189,698
	Contingency reserve	3,265			2,314
	Under applicable Wisconsin law, as well as that of 15 other states, a mortgage guaranty insurer must maintain a minimum amount of statutory capital relative to the risk-in-force (Risk to Capital ratio or “RTC ratio”) in order for the mortgage guaranty insurer to continue to write new business. We refer to these requirements as the “RTC requirement.” 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.
	As part of the NMIC's approval by the GSEs, we agreed to maintain minimum capital of $150 million at NMIC and not exceed a risk-to-capital of 15:1. At March 31, 2014, NMIH had sufficient resources to downstream cash to either insurance subsidiary, as necessary, to comply with all commitments.
	Certain states limit the amount of risk a mortgage guaranty 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 has entered into a primary excess share reinsurance agreement effective August 1, 2012 and a facultative pool reinsurance agreement effective September 1, 2013, both with Re One. NMIC cedes premiums and claims to Re One on an excess share basis for any primary or pool policy which offers coverage greater than 25%. NMIC will use reinsurance provided by Re One solely for purposes of compliance with statutory coverage limits. During April 2013, NMIC wrote its first mortgage insurance policies and ceded premium and risk to Re One the following month.
	As of March 31, 2013, none of our insurance subsidiaries had written any business, had no risk-in-force and therefore had no RTC ratios. As of March 31, 2014, NMIC's RTC ratio is less than 1:1, significantly below the limits established with the GSEs and state insurance departments. The risk-to-capital calculation for each of our insurance subsidiaries, as well as our combined risk-to-capital calculation, as of March 31, 2014, is presented below.
	As of March 31, 2014	NMIC			Re One			Combined
		(In Thousands)
	Primary risk-in-force
	Direct	$	115,467		$	—		$	115,467
	Assumed	—			8,172			8,172
	Ceded	(8,172		)	—			(8,172		)
	Total primary risk-in-force	107,295			8,172			115,467
	Pool risk-in-force (1)
	Direct	93,090			—			93,090
	Assumed	—			25,163			25,163
	Ceded	(25,163		)	—			(25,163		)
	Total pool risk-in-force	67,927			25,163			93,090
	Total risk-in-force	175,222			33,335			208,557
	Statutory policyholders' surplus	187,593			9,355			196,948
	Statutory contingency reserve	2,631			634			3,265
	Total statutory policyholders' position	$	190,224		$	9,989		$	200,213
	Risk-to-Capital (2)	0.9:1			3.3:1			1:01
	(1)	Pool risk-in-force as shown in the table above is equal to the aggregate stop loss less a deductible.
	(2)	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, Fannie Mae requires us to maintain the greater of (a) the risk-to-capital requirements outlined in the 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, 2013, NMIH's capital surplus was approximately $463 million. NMIH assets, excluding investment in NMIC and Re One, were approximately $276 million at December 31, 2013 and were unencumbered by any debt or other subsidiary commitments or obligations. The insurance subsidiaries are both mono-line mortgage guaranty 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 guaranty 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 risks and obligations that compete for its resources, and neither entity counts a subsidiary's asset in their admitted statutory assets.
	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, 2013, the amount of restricted net assets held by our consolidated insurance subsidiaries totaled approximately $193 million of NMIH's consolidated net assets of $463 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.

Investments_Tables

Investments (Tables)	3 Months Ended
	Mar. 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 March 31, 2014	(In Thousands)
	U.S. Treasury securities and obligations of U.S. government agencies	$	108,053			$	12			$	(1,224	)		$	106,841
	Municipal bonds	12,015				28				(35		)		12,008
	Corporate debt securities	221,506				351				(2,888		)		218,969
	Asset-backed securities	73,314				296				(552		)		73,058
	Total Investments	$	414,888			$	687			$	(4,699	)		$	410,876
		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 bonds	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 March 31, 2014 and December 31, 2013, 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 March 31, 2014	Amortized				Fair
		Cost				Value
		(In Thousands)
	Due in one year or less	$	2,674			$	2,675
	Due after one through five years	264,257				261,989
	Due after five through ten years	59,222				57,975
	Due after ten years	15,421				15,179
	Asset-backed securities	73,314				73,058
	Total Investments	$	414,888			$	410,876
	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 March 31, 2014			(Dollars in Thousands)
	U.S. Treasury securities and obligations of U.S. government agencies	41		$	87,817		$	(1,224	)		—		$	—		$	—		41	$	87,817	$	(1,224	)
	Municipal bonds	1		1,715			(35		)		—		—			—			1	1,715		(35		)
	Corporate debt securities	93		152,174			(2,668		)		4		10,928			(220		)	97	163,102		(2,888		)
	Assets-backed securities	26		37,101			(425		)		2		5,669			(127		)	28	42,770		(552		)
	Total Investments	161		$	278,807		$	(4,352	)		6		$	16,597		$	(347	)	167	$	295,404	$	(4,699	)
		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 bonds	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 Three Months Ended March 31,
		2014				2013
		(In Thousands)
	Fixed maturities	$	1,626			$	566
	Cash equivalents	—				1
	Investment income	1,626				567
	Investment expenses	(137		)		(157		)
	Net Investment Income	$	1,489			$	410

Fair_Value_of_Financial_Instru1

Fair Value of Financial Instruments (Tables)	3 Months Ended
	Mar. 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 March 31, 2014 and December 31, 2013:
		Fair Value Measurements Using
	Assets and Liabilities at Fair Value	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 March 31, 2014	(In Thousands)
	U.S. Treasury securities and obligations of U.S. government agencies	$	49,675		$	57,166	$	—	$	106,841
	Municipal bonds	—			12,008		—		12,008
	Corporate debt securities	—			218,969		—		218,969
	Asset-backed securities	—			73,058		—		73,058
	Cash and cash equivalents	42,792			—		—		42,792
	Total Assets	$	92,467		$	361,201	$	—	$	453,668
	Warrant liability	$	—		$	—	$	5,504	$	5,504
	Total Liabilities	$	—		$	—	$	5,504	$	5,504
		Fair Value Measurements Using
	Assets and Liabilities at Fair Value	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 bonds	—			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 three months ended March 31, 2014 and the year ended December 31, 2013:
	Level 3 Instruments Only	Warrant Liability
	Three Months Ended March 31, 2014	(In Thousands)
	Balance, January 1, 2014	$	6,371
	Change in fair value of warrant liability included in earnings	(817		)
	Gain on settlement of warrants	(37		)
	Issuance of common stock on warrant exercise	(13		)
	Balance, March 31, 2014	$	5,504
	Level 3 Instruments Only	Warrant Liability
	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

Software_and_Equipment_Tables

Software and Equipment (Tables)	3 Months Ended
	Mar. 31, 2014
Property, Plant and Equipment [Abstract]	'
Schedule of Equipment and Software	'
	Software and equipment, net of accumulated amortization and depreciation, as of March 31, 2014 and December 31, 2013 consist of the following:
		As of March 31,			As of December 31,
		2014			2013
		(In Thousands)
	Software	$	15,726		$	14,140
	Equipment	544			542
	Leasehold improvements	217			141
	Subtotal	16,487			14,823
	Accumulated amortization and depreciation	(7,261		)	(5,947		)
	Software and equipment, net	$	9,226		$	8,876

Intangible_Assets_and_Goodwill1

Intangible Assets and Goodwill (Tables)	3 Months Ended
	Mar. 31, 2014
Goodwill and Intangible Assets Disclosure [Abstract]	'
Schedule of Indefinite-Lived Intangible Assets	'
	Intangible assets and goodwill, net, as of March 31, 2014 and December 31, 2013, consist of the following:
	As of March 31, 2014 and December 31, 2013	(In Thousands)		Expected Lives
	Goodwill	$	3,244	Indefinite
	State licenses	260		Indefinite
	GSE approvals	130		Indefinite
	Total Intangible Assets and Goodwill	$	3,634

ShareBased_Compensation_Tables

Share-Based Compensation (Tables)	3 Months Ended
	Mar. 31, 2014
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]	'
Schedule of Stock Option Activity	'
	A summary of option activity under our 2012 Stock Incentive Plan during the quarters ending March 31, 2014 and March 31, 2013 is as follows:
		Shares		Weighted Average Exercise Price		Weighted Average Grant Date Fair Value per Share
		(Shares in Thousands)
	Options outstanding at December 31, 2013	3,063		$	10.31	$	3.98
	Options granted	693		12.32		4.97
	Options exercised	(2	)	10		3.84
	Options forfeited	(28	)	10.71		4.15
	Options outstanding at March 31, 2014	3,726		$	10.68	$	4.17
		Shares		Weighted Average Exercise Price		Weighted Average Grant Date Fair Value per Share
		(Shares in Thousands)
	Options outstanding at December 31, 2012	2,547		$	10	$	3.86
	Options granted	514		11.75		4.56
	Options forfeited	(10	)	10		3.84
	Options outstanding at March 31, 2013	3,051		$	10.27	$	3.98
Schedule of Restricted Stock Units Activity	'
	A summary of RSU activity in the plan during the quarters ending March 31, 2014 and March 31, 2013 is as follows:
		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	239		12.32
	Restricted stock units vested	(19	)	11.31
	Restricted stock units forfeited	(14	)	6.98
	Non-vested restricted stock units at March 31, 2014	1,448		$	8.46
		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	82		11.75
	Restricted stock units forfeited	—		—
	Non-vested restricted stock units at March 31, 2013	1,511		$	7.59

Statutory_Information_Tables

Statutory Information (Tables)	3 Months Ended
	Mar. 31, 2014
Insurance [Abstract]	'
Schedule of Risk to Capital	'
	NMIC and Re One's combined statutory net income, statutory surplus and contingency reserve as of March 31, 2014 and for the year ended December 31, 2013 were as follows:
		March 31, 2014			December 31, 2013
		(In Thousands)
	Statutory net loss	$	(12,750	)	$	(33,307	)
	Statutory surplus	196,948			189,698
	Contingency reserve	3,265			2,314
	The risk-to-capital calculation for each of our insurance subsidiaries, as well as our combined risk-to-capital calculation, as of March 31, 2014, is presented below.
	As of March 31, 2014	NMIC			Re One			Combined
		(In Thousands)
	Primary risk-in-force
	Direct	$	115,467		$	—		$	115,467
	Assumed	—			8,172			8,172
	Ceded	(8,172		)	—			(8,172		)
	Total primary risk-in-force	107,295			8,172			115,467
	Pool risk-in-force (1)
	Direct	93,090			—			93,090
	Assumed	—			25,163			25,163
	Ceded	(25,163		)	—			(25,163		)
	Total pool risk-in-force	67,927			25,163			93,090
	Total risk-in-force	175,222			33,335			208,557
	Statutory policyholders' surplus	187,593			9,355			196,948
	Statutory contingency reserve	2,631			634			3,265
	Total statutory policyholders' position	$	190,224		$	9,989		$	200,213
	Risk-to-Capital (2)	0.9:1			3.3:1			1:01
	(1)	Pool risk-in-force as shown in the table above is equal to the aggregate stop loss less a deductible.
	(2)	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, Fannie Mae requires us to maintain the greater of (a) the risk-to-capital requirements outlined in the 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.

Organization_and_Basis_of_Pres1

Organization and Basis of Presentation (Details) (USD $)	1 Months Ended	3 Months Ended			0 Months Ended	1 Months Ended	0 Months Ended
	Apr. 30, 2012	Mar. 31, 2014	Mar. 31, 2013	Dec. 31, 2013	Nov. 30, 2011	Apr. 30, 2012	Nov. 08, 2013	Apr. 07, 2014	8-May-14
					MAC Financial Holding Corporation and Subsidiaries [Member]	Class A	IPO [Member]	Subsequent Event [Member]	2014 Omnibus Incentive Plan [Member]
								state	Subsequent Event [Member]
Business Acquisition [Line Items]	'	'	'	'	'	'	'	'	'
Primary insurance in force	'	$514,800,000	'	'	'	'	'	'	'
Pool insurance in force	'	5,000,000,000	'	'	'	'	'	'	'
Cash, common stock and warrants issued for acquisition	'	'	'	'	8,500,000	'	'	'	'
Liabilities assumed in acquisition	'	'	'	'	1,300,000	'	'	'	'
Tax liabilities assumed in acquisition	'	'	'	'	100,000	'	'	'	'
Common stock offered and sold, (in shares)	'	'	'	'	'	55,000,000	2,400,000	'	'
Common stock issue price (usd per share)	'	'	'	'	'	$10	'	'	'
Issuance of common stock	'	'	'	'	'	550,000,000	'	'	'
Underwriting fee and other offering expense (percent)	7.00%	'	'	'	'	'	6.00%	'	'
Underwriting fee and other offering expense	510,000,000	'	'	'	'	'	28,000,000	'	'
Antidilutive securities excluded from computation of earnings per share (in shares)	'	6,200,000	6,500,000	'	'	'	'	'	'
Deferred policy acquisition costs, net	'	976,600	'	90,200	'	'	'	'	'
Mortgage pool insurance deductible	'	10,300,000	'	'	'	'	'	'	'
Reserve for primary insurance claims and claims IBNR	'	'	0	0	'	'	'	'	'
Reserve for pool insurance claims and claims IBNR	'	'	$0	$0	'	'	'	'	'
Number of States in which Entity Operates	'	'	'	'	'	'	'	50	'
Number of shares authorized to be reserved for issuance (in shares)	'	'	'	'	'	'	'	'	4,000,000

Common_Stock_Offering_Details

Common Stock Offering (Details) (USD $)	1 Months Ended		0 Months Ended
In Millions, except Share data, unless otherwise specified	Apr. 30, 2012	Apr. 30, 2012	Nov. 08, 2013
		Class A	IPO [Member]
Class of Stock [Line Items]	'	'	'
Common stock offered and sold, (in shares)	'	55,000,000	2,400,000
Underwriting fee and other offering expense	$510	'	$28
Underwriting fee and other offering expense (percent)	7.00%	'	6.00%

Investments_Narrative_Details

Investments - Narrative (Details) (USD $)	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Dec. 31, 2013
Schedule of Available-for-sale Securities [Line Items]	'	'	'
Net realized investment gains	$0	$28,000	'
Unrealized losses	-4,699,000	'	-7,319,000
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Loss, Accumulated in Investments	347,000	'	0
Bonds [Member]	'	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'	'
Net realized investment gains	0	28,000	'
U.S. Treasury securities and obligations of U.S. government agencies [Member]	'	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'	'
Unrealized losses	-1,224,000	'	-1,461,000
Cash and investments held with various state insurance departments	7,100,000	'	7,000,000
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Loss, Accumulated in Investments	$0	'	$0

Investments_Fair_Values_and_Gr

Investments - Fair Values and Gross Unrealized Gains and Losses on Investments (Details) (USD $)	Mar. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Schedule of Available-for-sale Securities [Line Items]	'	'
Amortized Cost	$414,888	$416,135
Gross Unrealized Gains	687	272
Gross Unrealized (Losses)	-4,699	-7,319
Fair Value	410,876	409,088
U.S. Treasury securities and obligations of U.S. government agencies [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Amortized Cost	108,053	108,067
Gross Unrealized Gains	12	0
Gross Unrealized (Losses)	-1,224	-1,461
Fair Value	106,841	106,606
Municipal bonds [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Amortized Cost	12,015	12,017
Gross Unrealized Gains	28	1
Gross Unrealized (Losses)	-35	-85
Fair Value	12,008	11,933
Corporate debt securities [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Amortized Cost	221,506	221,899
Gross Unrealized Gains	351	157
Gross Unrealized (Losses)	-2,888	-4,799
Fair Value	218,969	217,257
Asset-backed securities [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Amortized Cost	73,314	74,152
Gross Unrealized Gains	296	114
Gross Unrealized (Losses)	-552	-974
Fair Value	73,058	73,292
Total bonds [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Amortized Cost	414,888	416,135
Fair Value	$410,876	$409,088

Investments_Scheduled_Maturiti

Investments - Scheduled Maturities (Details) (USD $)	Mar. 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	$2,674	$0
Amortized Cost, Due after one through five years	264,257	260,855
Amortized Cost, Due after five through ten years	59,222	65,687
Amortized Cost, Due after ten years	15,421	15,441
Amortized Cost, Total Investments	414,888	416,135
Available-for-sale Securities, Debt Maturities, Single Maturity Date [Abstract]	'	'
Fair Value, Due in one year or less	2,675	0
Fair Value, Due after one through five years	261,989	257,501
Fair Value, Due after five through ten years	57,975	63,440
Fair Value Due after ten years	15,179	14,855
Fair Value, Total Investments	410,876	409,088
Asset-backed securities [Member]	'	'
Available-for-sale Securities, Debt Maturities, Single Maturity Date, Amortized Cost Basis [Abstract]	'	'
Amortized Cost, Total Investments	73,314	74,152
Available-for-sale Securities, Debt Maturities, Single Maturity Date [Abstract]	'	'
Fair Value, Total Investments	73,058	73,292
Total bonds [Member]	'	'
Available-for-sale Securities, Debt Maturities, Single Maturity Date, Amortized Cost Basis [Abstract]	'	'
Amortized Cost, Total Investments	414,888	416,135
Available-for-sale Securities, Debt Maturities, Single Maturity Date [Abstract]	'	'
Fair Value, Total Investments	$410,876	$409,088

Investments_Net_Realized_Inves

Investments - Net Realized Investment (Losses) Gains on Investments (Details) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Schedule of Available-for-sale Securities [Line Items]	'	'
Net realized investment gains	$0	$28

Investments_Unrealized_Losses_

Investments - Unrealized Losses (Details) (USD $)	Mar. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified	securities	securities
Schedule of Available-for-sale Securities [Line Items]	'	'
Number of securities, less than 12 months	161	79
Fair Value, Less than 12 Months	$278,807	$357,460
Unrealized Losses, Less than 12 Months	-4,352	-7,319
Number of securities,12 months or greater	6	0
Fair Value, 12 Months or Greater	16,597	0
Unrealized Losses, 12 Months or Greater	-347	0
Number of securities, Total	167	79
Fair Value, Total	295,404	357,460
Unrealized Losses	-4,699	-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	41	19
Fair Value, Less than 12 Months	87,817	106,606
Unrealized Losses, Less than 12 Months	-1,224	-1,461
Number of securities,12 months or greater	0	0
Fair Value, 12 Months or Greater	0	0
Unrealized Losses, 12 Months or Greater	0	0
Number of securities, Total	41	19
Fair Value, Total	87,817	106,606
Unrealized Losses	-1,224	-1,461
Municipal bonds [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Number of securities, less than 12 months	1	2
Fair Value, Less than 12 Months	1,715	4,915
Unrealized Losses, Less than 12 Months	-35	-85
Number of securities,12 months or greater	0	0
Fair Value, 12 Months or Greater	0	0
Unrealized Losses, 12 Months or Greater	0	0
Number of securities, Total	1	2
Fair Value, Total	1,715	4,915
Unrealized Losses	-35	-85
Corporate debt securities [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Number of securities, less than 12 months	93	47
Fair Value, Less than 12 Months	152,174	187,714
Unrealized Losses, Less than 12 Months	-2,668	-4,799
Number of securities,12 months or greater	4	0
Fair Value, 12 Months or Greater	10,928	0
Unrealized Losses, 12 Months or Greater	-220	0
Number of securities, Total	97	47
Fair Value, Total	163,102	187,714
Unrealized Losses	-2,888	-4,799
Asset-backed securities [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Number of securities, less than 12 months	26	11
Fair Value, Less than 12 Months	37,101	58,225
Unrealized Losses, Less than 12 Months	-425	-974
Number of securities,12 months or greater	2	0
Fair Value, 12 Months or Greater	5,669	0
Unrealized Losses, 12 Months or Greater	-127	0
Number of securities, Total	28	11
Fair Value, Total	42,770	58,225
Unrealized Losses	($552)	($974)

Investments_Net_Investment_Inc

Investments - Net Investment Income (Details) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Schedule of Available-for-sale Securities [Line Items]	'	'
Investment income	$1,626	$567
Investment expenses	-137	-157
Net Investment Income	1,489	410
Fixed maturities [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Investment income	1,626	566
Cash equivalents [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Investment income	$0	$1

Fair_Value_of_Financial_Instru2

Fair Value of Financial Instruments - Narrative (Details) (Significant Unobservable Inputs (Level 3) [Member], USD $)	3 Months Ended
	Mar. 31, 2014
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'
Volatility Assumption	39.00%
Warrant Liability [Member]	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'
Share Price (in dollars per share)	11.72
Risk free rate	2.18%
Expected term	'6 years 6 months 25 days
Expected dividend rate	0.00%

Fair_Value_of_Financial_Instru3

Fair Value of Financial Instruments - Assets and Liabilities at Fair Value (Details) (USD $)	Mar. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Available-for-sale Securities	$410,876	$409,088
Warrant liability, at fair value	5,504	6,371
Fair Value, Measurements, Recurring [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Cash and cash equivalents	42,792	55,929
Total Assets	453,668	465,017
Warrant liability, at fair value	5,504	6,371
Financial and Nonfinancial Liabilities, Fair Value Disclosure	5,504	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	42,792	55,929
Total Assets	92,467	105,413
Warrant liability, at fair value	0	0
Financial and Nonfinancial Liabilities, Fair Value Disclosure	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	361,201	359,604
Warrant liability, at fair value	0	0
Financial and Nonfinancial Liabilities, Fair Value Disclosure	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, at fair value	5,504	6,371
Financial and Nonfinancial Liabilities, Fair Value Disclosure	5,504	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]	'	'
Available-for-sale Securities	106,841	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]	'	'
Available-for-sale Securities	106,841	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]	'	'
Available-for-sale Securities	49,675	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]	'	'
Available-for-sale Securities	57,166	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]	'	'
Available-for-sale Securities	0	0
Municipal bonds [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Available-for-sale Securities	12,008	11,933
Municipal bonds [Member] | Fair Value, Measurements, Recurring [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Available-for-sale Securities	12,008	11,933
Municipal bonds [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]	'	'
Available-for-sale Securities	0	0
Municipal bonds [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]	'	'
Available-for-sale Securities	12,008	11,933
Municipal bonds [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]	'	'
Available-for-sale Securities	0	0
Corporate debt securities [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Available-for-sale Securities	218,969	217,257
Corporate debt securities [Member] | Fair Value, Measurements, Recurring [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Available-for-sale Securities	218,969	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]	'	'
Available-for-sale Securities	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]	'	'
Available-for-sale Securities	218,969	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]	'	'
Available-for-sale Securities	0	0
Asset-backed securities [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Available-for-sale Securities	73,058	73,292
Asset-backed securities [Member] | Fair Value, Measurements, Recurring [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Available-for-sale Securities	73,058	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]	'	'
Available-for-sale Securities	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]	'	'
Available-for-sale Securities	73,058	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]	'	'
Available-for-sale Securities	$0	$0

Fair_Value_of_Financial_Instru4

Fair Value of Financial Instruments - Rollforward of Level 3 (Details) (Significant Unobservable Inputs (Level 3) [Member], Warrant Liability [Member], USD $)	3 Months Ended	12 Months Ended
In Thousands, unless otherwise specified	Mar. 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	-817	1,529
Gain on settlement of warrants	-37	'
Issuance of common stock on warrant exercise	-13	'
Ending balance	$5,504	$6,371

Software_and_Equipment_Details

Software and Equipment (Details) (USD $)	Mar. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Property, Plant and Equipment [Line Items]	'	'
Property plant and equipment	$16,487	$14,823
Accumulated amortization and depreciation	-7,261	-5,947
Software and equipment, net	9,226	8,876
Software	'	'
Property, Plant and Equipment [Line Items]	'	'
Property plant and equipment	15,726	14,140
Equipment	'	'
Property, Plant and Equipment [Line Items]	'	'
Property plant and equipment	544	542
Leasehold improvements	'	'
Property, Plant and Equipment [Line Items]	'	'
Property plant and equipment	$217	$141

Software_and_Equipment_Narrati

Software and Equipment - Narrative (Details) (USD $)	3 Months Ended	12 Months Ended
	Mar. 31, 2014	Dec. 31, 2013
Property, Plant and Equipment [Line Items]	'	'
Depreciation and amortization	$1,300,000	$59,000
MAC Financial Holding Corporation and Subsidiaries [Member]	'	'
Property, Plant and Equipment [Line Items]	'	'
Capitalized software	$5,000,000	'

Intangible_Assets_and_Goodwill2

Intangible Assets and Goodwill (Details) (USD $)	Mar. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Indefinite-lived Intangible Assets [Line Items]	'	'
Goodwill and other indefinite lived intangible assets	$3,634	$3,634
Goodwill impairment	0	'
MAC Financial Holding Corporation and Subsidiaries [Member]	'	'
Indefinite-lived Intangible Assets [Line Items]	'	'
Goodwill	3,244	3,244
Goodwill and other indefinite lived intangible assets	3,634	390
MAC Financial Holding Corporation and Subsidiaries [Member] | State licenses [Member]	'	'
Indefinite-lived Intangible Assets [Line Items]	'	'
Intangible assets	260	260
MAC Financial Holding Corporation and Subsidiaries [Member] | GSE Approvals [Member]	'	'
Indefinite-lived Intangible Assets [Line Items]	'	'
Intangible assets	$130	$130

Income_Taxes_Narrative_Details

Income Taxes - Narrative (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013	Dec. 31, 2013
Income Tax Disclosure [Abstract]	'	'	'
Federal statutory income tax rate	35.00%	'	'
Effective Income Tax Rate Reconciliation, Percent	0.00%	0.00%	'
Deferred tax liabilities, gross	$0.10	'	$0.10

ShareBased_Compensation_Stock_

Share-Based Compensation - Stock Option Activity (Details) (The 2012 Stock Incentive Plan [Member], USD $)	3 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Mar. 31, 2014	Mar. 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)	3,063	2,547
Options granted (in shares)	693	514
Less: Options exercised (in shares)	-2	'
Less: Options forfeited (in shares)	-28	-10
Options ending balance (in shares)	3,726	3,051
Weighted Average Grant Date Fair Value per Share	'	'
Options beginning balance (in dollars per share)	$10.31	$10
Options granted (in dollars per share)	$12.32	$11.75
Less: Options exercised (in dollars per share)	$10	'
Less: Options forfeited (in dollars per share)	$10.71	$10
Options ending balance (in dollars per share)	$10.68	$10.27
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)	$4.97	$4.56
Less: Options exercised (in dollars per share)	$3.84	'
Less: Options forfeited (in dollars per share)	$4.15	$3.84
Options ending balance (in dollars per share)	$4.17	$3.98

ShareBased_Compensation_Restri

Share-Based Compensation - Restricted Stock Units Activity (Details) (The 2012 Stock Incentive Plan [Member], Restricted Stock Units [Member], USD $)	3 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Mar. 31, 2014	Mar. 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)	239	82
Less: Restricted stock units vested (in shares)	-19	'
Less: Restricted stock units forfeited (in shares)	-14	0
Restricted Stock ending balance (in shares)	1,448	1,511
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)	$12.32	$11.75
Less: Restricted Stock Units Vested (in dollars per share)	$11.31	'
Less: Restricted Stock Units Forfeited (in dollars per share)	$6.98	$0
Restricted Stock ending balance (in dollars per share)	$8.46	$7.59

ShareBased_Compensation_Narrat

Share-Based Compensation - Narrative (Details) (USD $)	3 Months Ended							3 Months Ended
In Millions, except Share data in Thousands, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2014	Dec. 31, 2013	Mar. 31, 2013	Dec. 31, 2012	Mar. 31, 2014	Mar. 31, 2014	Mar. 31, 2014	Mar. 31, 2014
	The 2012 Stock Incentive Plan [Member]	The 2012 Stock Incentive Plan [Member]	The 2012 Stock Incentive Plan [Member]	The 2012 Stock Incentive Plan [Member]	The 2012 Stock Incentive Plan [Member]	Subject to Market and Service Conditions [Member]	Subject to Service Conditions [Member]	Subject to Service Conditions [Member]	Subject to Service Conditions [Member]
		Restricted Stock Units [Member]	Restricted Stock Units [Member]	Restricted Stock Units [Member]	Restricted Stock Units [Member]	The 2012 Stock Incentive Plan [Member]	The 2012 Stock Incentive Plan [Member]	Minimum [Member]	Maximum [Member]
						Restricted Stock Units [Member]	Restricted Stock Units [Member]	Restricted Stock Units [Member]	Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'	'	'	'	'	'	'
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period	2	'	'	'	'	'	'	'	'
Restricted stock vesting period	'	'	'	'	'	'	'	'1 year	'3 years
Number of options vested (in shares)	989	'	'	'	'	'	'	'	'
Weighted average exercise price for options vested (in dollars per share)	$10.32	'	'	'	'	'	'	'	'
Weighted average remaining contractual term	'7 years 2 months	'	'	'	'	'	'	'	'
Options vested aggregate value	$1.40	'	'	'	'	'	'	'	'
Restricted stock units outstanding (in shares)	'	1,448	1,242	1,511	1,429	500	900	'	'

Warrants_Details

Warrants (Details) (USD $)	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Apr. 24, 2012
Line of Credit Facility [Line Items]	'	'	'
Exercise price of warrants (in dollars per warrant)	'	'	10
Warrants issued (in shares)	'	'	992,000
Warrants value	'	'	$5,100,000
Class of Warrant or Right, Number of Warrants Exercised During Period	7,790	'	'
Gain from settlement of warrants	$37,000	$0	'

Statutory_Information_Statutor

Statutory Information - Statutory Income (Details) (Combined [Member], USD $)	3 Months Ended	12 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Combined [Member]	'	'
Statutory Accounting Practices [Line Items]	'	'
Statutory net loss	($12,750)	($33,307)
Statutory surplus	196,948	189,698
Contingency reserve	$3,265	$2,314

Statutory_Information_Narrativ

Statutory Information - Narrative (Details) (USD $)	Mar. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
	state
Statutory Accounting Practices [Line Items]	'	'	'
Number of states which require minimum amount of statutory capital relative to risk in force	15	'	'
Statutory capital and surplus required	$150,000,000	'	'
Required Risk-to-Capital Ratio on Agreements Per GSE Approval, Maximum	15	'	'
Mortgage insurance, percentage of indebtedness on single loan	25.00%	'	'
Shareholders' equity	453,453,000	463,217,000	488,748,000
Investment in subsidiaries, at equity in net assets	'	276,000,000	'
Ordinary dividends, restriction with regards to capital surplus	10.00%	'	'
Subsidiaries [Member]	'	'	'
Statutory Accounting Practices [Line Items]	'	'	'
Shareholders' equity	'	$193,000,000	'
Maximum [Member]	'	'	'
Statutory Accounting Practices [Line Items]	'	'	'
Risk-to-capital	25	'	'
WISCONSIN [Member] | Maximum [Member]	'	'	'
Statutory Accounting Practices [Line Items]	'	'	'
Potential risk In force to capital, ratio	25	'	'
Fannie Mae [Member]	'	'	'
Statutory Accounting Practices [Line Items]	'	'	'
Risk-to-capital	18	'	'

Statutory_Information_Risk_to_

Statutory Information - Risk to Capital (Details) (USD $)	Mar. 31, 2014		Dec. 31, 2013
In Thousands, unless otherwise specified
NMIC [Member]	'		'
Primary risk-in-force	'		'
Direct	$115,467		'
Assumed	0		'
Ceded	-8,172		'
Total primary risk-in-force	107,295		'
Pool risk-in-force	'		'
Direct	93,090	[1]	'
Assumed	0	[1]	'
Ceded	-25,163	[1]	'
Total pool risk-in-force	67,927	[1]	'
Total risk-in-force	175,222		'
Statutory policyholders' surplus	187,593		'
Statutory contingency reserve	2,631		'
Total statutory policyholders' position	190,224		'
Risk to capital ratio	0.9	[2]	'
NMI Re One [Member]	'		'
Primary risk-in-force	'		'
Direct	0		'
Assumed	8,172		'
Ceded	0		'
Total primary risk-in-force	8,172		'
Pool risk-in-force	'		'
Direct	0	[1]	'
Assumed	25,163	[1]	'
Ceded	0	[1]	'
Total pool risk-in-force	25,163	[1]	'
Total risk-in-force	33,335		'
Statutory policyholders' surplus	9,355		'
Statutory contingency reserve	634		'
Total statutory policyholders' position	9,989		'
Risk to capital ratio	3.3	[2]	'
Combined [Member]	'		'
Primary risk-in-force	'		'
Direct	115,467		'
Assumed	8,172		'
Ceded	-8,172		'
Total primary risk-in-force	115,467		'
Pool risk-in-force	'		'
Direct	93,090	[1]	'
Assumed	25,163	[1]	'
Ceded	-25,163	[1]	'
Total pool risk-in-force	93,090	[1]	'
Total risk-in-force	208,557		'
Statutory policyholders' surplus	196,948		189,698
Statutory contingency reserve	3,265		'
Total statutory policyholders' position	$200,213		'
Risk to capital ratio	1.1	[2]	'
[1]	Pool risk-in-force as shown in the table above is equal to the aggregate stop loss less a deductible.
[2]	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, Fannie Mae requires us to maintain the greater of (a) the risk-to-capital requirements outlined in the 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.