Document and Entity Information - shares	6 Months Ended
Document and Entity Information - shares	Jun. 30, 2017	Jul. 31, 2017
Document and Entity Information [Abstract]
Entity Registrant Name	MGIC INVESTMENT CORP
Entity Central Index Key	0000876437
Current Fiscal Year End Date	--12-31
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		370,561,601
Document Fiscal Year Focus	2017
Document Fiscal Period Focus	Q2
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Jun. 30, 2017

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Securities, available-for-sale, at fair value:
Fixed income (amortized cost, 2017 - $4,674,965; 2016 - $4,717,211)	$ 4,701,211	$ 4,685,222
Equity securities	7,209	7,128
Total investment portfolio	4,708,420	4,692,350
Cash and cash equivalents	127,908	155,410
Accrued investment income	44,030	44,073
Reinsurance recoverable on loss reserves	44,783	50,493
Reinsurance recoverable on paid losses	6,151	4,964
Premiums receivable	51,344	52,392
Home office and equipment, net	42,212	36,088
Deferred insurance policy acquisition costs	18,677	17,759
Deferred income taxes, net	481,389	607,655
Other assets	75,254	73,345
Total assets	5,600,168	5,734,529
Liabilities:
Loss reserves	1,187,089	1,438,813
Unearned premiums	352,010	329,737
Federal Home Loan Bank advance	155,000	155,000
Senior notes	417,983	417,406
Convertible senior notes	0	349,461
Convertible junior subordinated debentures	256,872	256,872
Other liabilities	236,153	238,398
Total liabilities	2,605,107	3,185,687
Contingencies
Shareholders’ equity:
Common stock (one dollar par value, shares authorized 1,000,000; shares issued 2017 - 370,557; 2016 - 359,400; shares outstanding 2017 - 370,557; 2016 - 340,663)	370,557	359,400
Paid-in capital	1,842,601	1,782,337
Treasury stock at cost (shares 2016 - 18,737)	0	(150,359)
Accumulated other comprehensive loss, net of tax	(37,494)	(75,100)
Retained earnings	819,397	632,564
Total shareholders’ equity	2,995,061	2,548,842
Total liabilities and shareholders’ equity	$ 5,600,168	$ 5,734,529

CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Statement of Financial Position [Abstract]
Fixed maturities, amortized cost	$ 4,674,965	$ 4,717,211
Common stock, par value (in dollars per share)	$ 1	$ 1
Common stock, shares authorized (in shares)	1,000,000,000	1,000,000,000
Common stock, shares issued (in shares)	370,557,000	359,400,000
Common stock, shares outstanding (in shares)	370,557,000	340,663,000
Treasury stock, shares at cost (in shares)	0	18,737,000

CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Premiums written:
Direct	$ 275,245,000	$ 282,113,000	$ 541,068,000	$ 547,404,000
Assumed	685,000	182,000	1,973,000	390,000
Ceded	(30,096,000)	(32,280,000)	(60,505,000)	(66,498,000)
Net premiums written	245,834,000	250,015,000	482,536,000	481,296,000
Increase in unearned premiums, net	(14,698,000)	(18,559,000)	(22,297,000)	(28,499,000)
Net premiums earned	231,136,000	231,456,000	460,239,000	452,797,000
Investment income, net of expenses	29,716,000	27,248,000	59,193,000	55,057,000
Net realized investment (losses) gains	(42,000)	836,000	(164,000)	3,892,000
Other revenue	2,502,000	3,994,000	4,924,000	10,367,000
Total revenues	263,312,000	263,534,000	524,192,000	522,113,000
Losses and expenses:
Losses incurred, net	27,339,000	46,590,000	54,958,000	131,602,000
Amortization of deferred policy acquisition costs	2,584,000	2,245,000	4,814,000	4,206,000
Other underwriting and operating expenses, net	38,511,000	35,348,000	79,276,000	75,125,000
Interest expense	14,197,000	12,244,000	30,506,000	26,945,000
Loss on debt extinguishment	65,000	1,868,000	65,000	15,308,000
Total losses and expenses	82,696,000	98,295,000	169,619,000	253,186,000
Income before tax	180,616,000	165,239,000	354,573,000	268,927,000
Provision for income taxes	61,994,000	56,018,000	146,153,000	90,515,000
Net income	$ 118,622,000	$ 109,221,000	$ 208,420,000	$ 178,412,000
Earnings per share:
Basic (in dollars per share)	$ 0.32	$ 0.32	$ 0.59	$ 0.52
Diluted (in dollars per share)	$ 0.31	$ 0.26	$ 0.55	$ 0.43
Weighted average common shares outstanding - basic (in shares)	366,918	340,678	354,035	340,411
Weighted average common shares outstanding - diluted (in shares)	394,470	446,139	398,302	450,354

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Statement of Comprehensive Income [Abstract]
Net income	$ 118,622	$ 109,221	$ 208,420	$ 178,412
Other comprehensive (loss) income, net of tax:
Change in unrealized investment gains and losses	25,749	56,338	37,870	107,165
Benefit plan adjustments	(142)	(173)	(295)	(481)
Foreign currency translation adjustment	0	11	31	(964)
Other comprehensive income, net of tax	25,607	56,176	37,606	105,720
Comprehensive income	$ 144,229	$ 165,397	$ 246,026	$ 284,132

CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Common stock	Paid-in capital	Treasury stock	Accumulated other comprehensive loss	Retained earnings
Balance, beginning of period at Dec. 31, 2015		$ 340,097	$ 1,670,238	$ (3,362)	$ (60,880)	$ 290,047
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net common stock issued under share-based compensation plans		979	(5,954)
Issuance of common stock		0	0
Tax benefit from share-based compensation			115
Equity compensation			6,017
Reacquisition of convertible junior subordinated debentures-equity component			(6,337)
Reissuance of treasury stock, net				0		0
Other comprehensive income, net of tax	$ 105,720				105,720
Net income	178,412					178,412
Balance, end of period at Jun. 30, 2016	2,515,092	341,076	1,664,079	(3,362)	44,840	468,459
Balance, beginning of period at Dec. 31, 2016	2,548,842	359,400	1,782,337	(150,359)	(75,100)	632,717
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net common stock issued under share-based compensation plans		771	(7,494)
Issuance of common stock		10,386	60,903
Tax benefit from share-based compensation			0
Equity compensation			6,855
Reacquisition of convertible junior subordinated debentures-equity component			0
Reissuance of treasury stock, net				150,359		(21,740)
Other comprehensive income, net of tax	37,606				37,606
Net income	208,420					208,420
Balance, end of period at Jun. 30, 2017	$ 2,995,061	$ 370,557	$ 1,842,601	$ 0	$ (37,494)	$ 819,397

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($)	6 Months Ended
CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($)	Jun. 30, 2017	Jun. 30, 2016
Cash flows from operating activities:
Net income	$ 208,420,000	$ 178,412,000
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	33,191,000	28,477,000
Deferred tax expense	106,163,000	88,157,000
Net realized investment losses (gains)	164,000	(3,892,000)
Loss on debt extinguishment	65,000	15,308,000
Change in certain assets and liabilities:
Accrued investment income	43,000	515,000
Prepaid insurance premium	25,000	48,000
Reinsurance recoverable on loss reserves	5,710,000	(728,000)
Reinsurance recoverable on paid losses	(1,187,000)	(1,454,000)
Premium receivable	1,048,000	1,867,000
Deferred insurance policy acquisition costs	(918,000)	(1,439,000)
Profit commission receivable	(4,603,000)	(2,793,000)
Loss reserves	(251,724,000)	(261,069,000)
Unearned premiums	22,273,000	28,451,000
Return premium accrual	(11,900,000)	(7,300,000)
Income taxes payable - current	32,991,000	523,000
Other, net	(14,205,000)	(8,090,000)
Net cash provided by operating activities	125,556,000	54,993,000
Purchases of investments:
Fixed income	(545,281,000)	(723,409,000)
Equity securities	(38,000)	(3,128,000)
Proceeds from sales of fixed income	166,606,000	649,776,000
Proceeds from maturity of fixed income	390,344,000	313,484,000
Proceeds from sale of equity securities	0	2,525,000
Net increase in payable for securities	3,447,000	24,519,000
Additions to property and equipment	(9,659,000)	(2,724,000)
Net cash provided by investing activities	5,419,000	261,043,000
Cash flows from financing activities:
Proceeds from revolving credit facility	150,000,000	0
Repayment of revolving credit facility	(150,000,000)	0
Proceeds from issuance of long-term debt	0	155,000,000
Purchase or repayment of convertible senior notes	(145,620,000)	(182,846,000)
Payment of original issue discount - convertible senior notes	(4,504,000)	(5,655,000)
Purchase of convertible junior subordinated debentures	0	(100,860,000)
Payment of original issue discount - convertible junior subordinated debentures	0	(41,540,000)
Cash portion of loss on debt extinguishment	0	(15,308,000)
Payment of debt issuance costs	(1,630,000)	0
Payment of withholding taxes related to share-based compensation net share settlement	(6,723,000)	(4,973,000)
Net cash used in financing activities	(158,477,000)	(196,182,000)
Net (decrease) increase in cash and cash equivalents	(27,502,000)	119,854,000
Cash and cash equivalents at beginning of period	155,410,000	181,120,000
Cash and cash equivalents at end of period	$ 127,908,000	$ 300,974,000

Nature of Business and Basis of Presentation	6 Months Ended
Nature of Business and Basis of Presentation	Jun. 30, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Nature of Business and Basis of Presentation	Nature of Business and Basis of Presentation MGIC Investment Corporation is a holding company which, through Mortgage Guaranty Insurance Corporation (“MGIC”) is principally engaged in the mortgage insurance business. We provide mortgage insurance to lenders throughout the United States and to government sponsored entities (“GSEs”) to protect against loss from defaults on low down payment residential mortgage loans. The accompanying unaudited consolidated financial statements of MGIC Investment Corporation and its wholly-owned subsidiaries have been prepared in accordance with the instructions to Form 10-Q as prescribed by the Securities and Exchange Commission (“SEC”) for interim reporting and do not include all of the other information and disclosures required by accounting principles generally accepted in the United States of America (“GAAP”). These statements should be read in conjunction with the consolidated financial statements and notes thereto for the year ended December 31, 2016 included in our Annual Report on Form 10-K. As used below, “we,” “our” and “us” refer to MGIC Investment Corporation’s consolidated operations or to MGIC Investment Corporation, as the context requires. In the opinion of management the accompanying financial statements include all adjustments, consisting primarily of normal recurring accruals, necessary to fairly state our consolidated financial position and consolidated results of operations for the periods indicated. The consolidated results of operations for the interim period may not be indicative of the results that may be expected for the year ending December 31, 2017. Substantially all of our insurance written since 2008 has been for loans purchased by the GSEs. We operate under the Private Mortgage Insurer Eligibility Requirements ("PMIERs") of the GSEs that became effective December 31, 2015 and have been amended from time to time. The financial requirements of the PMIERs require a mortgage insurer’s "Available Assets" (generally only the most liquid assets of an insurer) to equal or exceed its "Minimum Required Assets" (which are based on an insurer's book and are calculated from tables of factors with several risk dimensions and are subject to a floor amount). Based on our interpretation of the PMIERs, as of June 30, 2017, MGIC’s Available Assets are in excess of its Minimum Required Assets; and MGIC is in compliance with the financial requirements of the PMIERs and eligible to insure loans purchased by the GSEs. Reclassifications Certain reclassifications to 2016 amounts have been made in the accompanying financial statements to conform to the 2017 presentation. Subsequent events We have considered subsequent events through the date of this filing.

New Accounting Pronouncements

6 Months Ended

Jun. 30, 2017

New Accounting Pronouncements and Changes in Accounting Principles [Abstract]

New Accounting Pronouncements

Adopted Accounting Standards

Improvements to Employee Share-Based Compensation Accounting

In March 2016, the Financial Accounting Standards Board (“FASB”) issued updated guidance that simplifies several aspects of the accounting for employee share-based compensation including the accounting for income taxes, forfeitures, and statutory tax withholding requirements, as well as classification of related amounts within the statement of cash flows. The updated guidance requires that, prospectively, all tax effects related to share-based compensation be made through the statement of operations at the time of settlement. In contrast, the previous guidance required excess tax benefits to be recognized in paid-in capital. The updated guidance also removes the requirement to delay recognition of a tax benefit until it reduces current taxes payable. This change is required to be applied on a modified retrospective basis, with a cumulative effect adjustment to opening retained earnings. Additionally, all tax related cash flows resulting from share-based compensation are to be reported as operating activities on the statement of cash flows, a change from the existing requirement to present tax benefits as an inflow from financing activities and an outflow from operating activities. Finally, for tax withholding purposes, entities will be allowed to withhold an amount of shares up to the employee’s maximum individual tax rate (as opposed to the minimum statutory tax rate) in the relevant jurisdiction without resulting in liability classification of the award. The change in tax withholding is to be applied on a modified retrospective approach. This updated guidance became effective January 1, 2017. We adopted this guidance in the first quarter of 2017 and as a result of the adoption:


•	We recognized discrete tax benefits of $1.5 million in the provision for income taxes on our statement of operations for the six months ended June 30, 2017 related to excess tax benefits upon vesting of share-based awards during the period.


•	We recognized a cumulative effect adjustment related to the recognition of a deferred tax asset related to suspended tax benefits from vesting transactions occurring in prior years and from the elimination of our forfeiture estimate on share-based awards, which was previously applied only to awards with service conditions.


•	Prior to adoption, cash flows related to excess tax benefits from share-based compensation were included in financing activities. We have reclassified excess tax benefits related to share-based compensation for the prior year period to operating activities.


•	Prior to adoption, cash flows related to employee taxes paid for withheld shares were included in operating activities. We have reclassified employee taxes paid for withheld shares for the prior year period to financing activities.

Prospective Accounting Standards

Stock Compensation - Scope of Modification Accounting

In May 2017, the FASB issued updated guidance related to a change in the terms or conditions (modification) of a share-based award. The updated guidance provides that an entity should account for the effects of a modification unless the fair value and vesting conditions of the modified award and the classification of the award (equity or liability instrument) are the same as the original award immediately before the modification. The updated guidance addresses the current diversity in practice on applying modification accounting, as some entities evaluate whether changes to awards are substantive, which is not prescribed within the current accounting guidance. The updated guidance is effective for annual periods beginning after December 15, 2017, including interim periods within those annual periods. Early adoption is permitted, including adoption in any interim period. We are currently evaluating the impacts the adoption of this guidance will have on our consolidated financial statements, but do not expect it to have a material impact on our consolidated financial statements or disclosures.

Premium Amortization on Purchased Callable Debt Securities

In March 2017, the FASB issued updated guidance to amend the amortization period for certain purchased callable debt securities held at a premium shortening the amortization period to the earliest call date. Under current GAAP, there is diversity in practice in the amortization period for premiums of callable debt securities and in how the potential for exercise of a call is factored into current impairment assessments. This updated guidance aligns with how callable debt securities, in the United States, are generally quoted, priced, and traded assuming a model that incorporates consideration of calls (also referred to as “yield-to-worst” pricing). The updated guidance is effective for annual periods beginning after December 15, 2018, including interim periods within those annual periods. We are currently evaluating the impacts the adoption of this guidance will have on our consolidated financial statements, but do not expect it to have a material impact on our consolidated financial statements or disclosures. We currently account for premium amortization on our purchased callable debt securities on a yield-to-worst basis, which generally aligns with the earliest call date.

Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost

In March 2017, the FASB issued updated guidance that improves the reporting of net benefit cost in the financial statements. The updated guidance requires that an employer report the service cost component in the same financial statement caption as other compensation costs arising from services rendered by employees during the period. The other components of net benefit cost are required to be presented in the statement of operations separately from the service cost component and outside a subtotal of income from operations, if one is presented. Current guidance does not prescribe where the amount of net benefit cost should be presented in an employer’s statement of operations and does not require entities to disclose by line item the amount of net benefit cost that is included in the statement of operations. The updated guidance is effective for annual periods beginning after December 15, 2017, including interim periods within those annual periods. We are currently evaluating the impacts the adoption of this guidance will have on our consolidated financial statements, but do not expect it to have a material impact on our consolidated financial statements or disclosures.

Measurement of Credit Losses on Financial Instruments

In June 2016, the FASB issued updated guidance that requires immediate recognition of estimated credit losses expected to occur over the remaining life of many financial instruments. Entities will be required to utilize a current expected credit losses (“CECL”) methodology that incorporates their forecasts of future economic conditions into their loss estimate unless such forecast is not reasonable and supportable, in which case the entity will revert to historical loss experience. Any allowance for CECL reduces the amortized cost basis of the financial instrument to the amount an entity expects to collect. Credit losses relating to available-for-sale fixed maturity securities are to be recorded through an allowance for credit losses, rather than a write-down of the asset, with the amount of the allowance limited to the amount by which fair value is less than amortized cost. In addition, the length of time a security has been in an unrealized loss position will no longer impact the determination of whether a credit loss exists. The updated guidance is not prescriptive about certain aspects of estimating expected credit losses, including the specific methodology to use, and therefore will require significant judgment in application. The updated guidance is effective for annual periods beginning after December 15, 2019, including interim periods within those annual periods. Early adoption is permitted for annual and interim periods in fiscal years beginning after December 15, 2018. We are currently evaluating the impacts the adoption of this guidance will have on our consolidated financial statements, but do not expect it to have a material impact on our consolidated financial statements or disclosures.

Recognition and Measurement of Financial Assets and Financial Liabilities

In January 2016, the FASB issued updated guidance to address the recognition, measurement, presentation, and disclosure of certain financial instruments. The updated guidance requires equity investments, except those accounted for under the equity method of accounting, that have a readily determinable fair value to be measured at fair value with changes in fair value recognized in net income. Equity investments that do not have readily determinable fair values may be remeasured at fair value either upon the occurrence of an observable price change or upon identification of an impairment. A qualitative assessment for impairment is required for equity investments without readily determinable fair values. The updated guidance also eliminates the requirement to disclose the method and significant assumptions used to estimate the fair value of financial instruments measured at amortized cost on the balance sheet. Further, the updated guidance clarifies that entities should evaluate the need for a valuation allowance on a deferred tax asset related to available-for-sale securities in combination with the entities other deferred tax assets. The updated guidance is effective for annual periods beginning after December 15, 2017, including interim periods within those annual periods and will require recognition of a cumulative effect adjustment at adoption. We do not currently expect the adoption of this guidance to impact our consolidated financial position or liquidity.

Debt

6 Months Ended

Jun. 30, 2017

Debt Disclosure [Abstract]

Debt

2017 debt transactions

2% Notes

On March 21, 2017, we issued an irrevocable notice of redemption in respect of our outstanding 2% Notes, with a redemption date of April 21, 2017. In April, holders of approximately $202.5 million of the outstanding principal exercised their rights to convert their notes into shares of our common stock. The remaining $5.1 million of outstanding principal was redeemed for cash. The conversions of the 2% Notes at a rate of 143.8332 shares per $1,000 principal amount resulted in the issuance of approximately 29.1 million shares of our common stock in April. The conversions and cash redemption eliminated our debt obligation. A loss on debt extinguishment of $0.07 million was recognized on the redemption of the $5.1 million of 2% Notes. No gain or loss was recognized from the conversions as the outstanding debt issuance costs associated with the conversions are included in the debt carrying value, which was credited to shareholders’ equity at the time of conversion.

Credit Facility

On March 21, 2017, we entered into a Credit Agreement with various lenders which provides for a $175 million unsecured revolving credit facility maturing on March 21, 2020. Revolving credit borrowings bear interest at a floating rate, which will be, at our option, either a eurocurrency rate or a base rate, in each case plus an applicable margin. The applicable margins are subject to adjustment based on our senior unsecured long-term debt rating, or if we do not have such a rating, our corporate or issuer rating. Amounts under the facility may be borrowed, repaid and reborrowed from time to time until the maturity of the revolving credit facility. Voluntary prepayments and commitment reductions are permitted at any time without fee subject to a minimum dollar requirement and, for outstanding eurocurrency loans, customary breakage costs.

We are required under the Credit Agreement to pay commitment fees on the average daily amount of the unused revolving commitments of the lenders, and an annual administrative fee to the administrative agent. The Credit Agreement contains affirmative, negative and financial covenants which are customary for financings of this type, including, among other things, limits on the creation of liens, limits on the incurrence of indebtedness, restrictions on dispositions, maximum debt-to-capital ratio, minimum consolidated stockholders' equity, minimum policyholder's position of MGIC, and compliance with the financial requirements of the PMIERs. The Credit Agreement includes customary events of default for facilities of this type (with customary grace periods, as applicable) and provides that, upon the occurrence of an event of default, payments of all outstanding loans may be accelerated and/or the lenders' commitments may be terminated. Upon the occurrence of certain insolvency or bankruptcy related events of default, all amounts payable under the Credit Agreements shall automatically become immediately due and payable, and the lenders' commitments will automatically terminate. In addition, upon the occurrence of certain insolvency or bankruptcy related events of default, or the failure to pay interest, principal or fees, the interest rates on all outstanding obligations will be increased.

In March, we borrowed $150 million under the revolving credit facility, to fund a portion of the redemption price of the 2% Notes if holders did not elect to convert their 2% Notes. In April, we repaid the amount borrowed under the revolving credit facility because most holders elected to convert their notes. Costs incurred to enter into the Credit Agreement have been deferred and recorded as Other assets and will be amortized over the term of the Credit Agreement.

5% Notes

On May 1, 2017, our 5% Notes due in 2017 (“5% Notes”) matured and we repaid the outstanding $145 million in aggregate par value, plus accrued interest with cash at our holding company.

First half 2016 debt transactions

5% Notes

During the first six months of 2016, we purchased $188.5 million in aggregate par value of our 5% Notes at an aggregate purchase price of $195.5 million for which we recognized losses on debt extinguishment on our consolidated statements of operations for the three and six months ended June 30, 2016.

9% Debentures

In February 2016, MGIC purchased $132.7 million in aggregate par value of our 9% Debentures at a purchase price of $150.7 million. The purchase of the 9% Debentures resulted in an $8.3 million loss on debt extinguishment on the consolidated statement of operations for the six months ended June 30, 2016, which represents the difference between the fair value and the carrying value of the liability component on the purchase date. Our shareholders’ equity was separately reduced by $6.3 million related to the reacquisition of the equity component. For GAAP accounting purposes, the 9% Debentures owned by MGIC are considered retired and are eliminated in our consolidated financial statements and the underlying common stock equivalents, approximately 9.8 million shares, are not included in the computation of diluted shares.

Debt obligations

The par value of our long-term debt obligations and their aggregate carrying values as of June 30, 2017 and December 31, 2016 were as follows.



(In millions)	June 30, 2017			December 31, 2016
FHLB Advance	$	155.0		$	155.0
5% Notes	—			145.0
2% Notes	—			207.6
5.75% Notes	425.0			425.0
9% Debentures⁽¹⁾	256.9			256.9
Long-term debt, par value	836.9			1,189.5
Debt issuance costs	(7.0		)	(10.8		)
Long-term debt, carrying value	$	829.9		$	1,178.7

⁽¹⁾

Convertible at any time prior to maturity at the holder’s option, at an initial conversion rate, which is subject to adjustment, of 74.0741 shares per $1,000 principal amount, representing an initial conversion price of approximately $13.50 per share. If a holder elects to convert their debentures, deferred interest owed on the debentures being converted is also converted into shares of our common stock. The conversion rate for any deferred interest is based on the average price that our shares traded at during a 5-day period immediately prior to the election to convert. In lieu of issuing shares of common stock upon conversion of the debentures, we may, at our option, make a cash payment to converting holders for all or some of the shares of our common stock otherwise issuable upon conversion.

The 5.75% Senior Notes due 2023 (“5.75% Notes”) and 9% Convertible Junior Subordinated Debentures due in 2063 (“9% Debentures”) are obligations of our holding company, MGIC Investment Corporation, and not of its subsidiaries. The Federal Home Loan Bank Advance (the “FHLB Advance”) is an obligation of MGIC.

Interest payments on our debt obligations appear below.



	Six Months Ended June 30,
(In millions)	2017		2016
Revolving credit facility	$	0.5	$	—
FHLB Advance	1.5		0.9
5% Notes	3.6		6.9
2% Notes	2.1		5.0
5.75% Notes	12.9		—
9% Debentures	11.6		15.9
Total interest payments	$	32.2	$	28.7

Reinsurance

6 Months Ended

Jun. 30, 2017

Reinsurance Disclosures [Abstract]

Reinsurance

The reinsurance agreements we have entered into are discussed below. The effect of all of our reinsurance agreements on premiums earned and losses incurred is as follows:



	Three Months Ended June 30,						Six Months Ended June 30,
(In thousands)	2017			2016			2017			2016
Premiums earned:
Direct	$	261,180		$	263,566		$	520,608		$	518,953
Assumed	62			182			160			390
Ceded	(30,106		)	(32,292		)	(60,529		)	(66,546		)
Net premiums earned	$	231,136		$	231,456		$	460,239		$	452,797

Losses incurred:
Direct	$	31,396		$	54,863		$	63,809		$	147,295
Assumed	61			339			166			440
Ceded	(4,118		)	(8,612		)	(9,017		)	(16,133		)
Losses incurred, net	$	27,339		$	46,590		$	54,958		$	131,602

Quota share reinsurance

In March 2017, we entered into a quota share reinsurance agreement (“2017 QSR Transaction”) with an effective date of January 1, 2017 with a group of unaffiliated reinsurers, each with a financial strength rating of A- or better by Standard and Poor’s, A.M. Best or both. We utilize quota share reinsurance to manage our exposure to losses resulting from our mortgage guaranty insurance policies and to provide reinsurance capital credit under the PMIERs. Our 2017 QSR Transaction provides coverage on new business written January 1, 2017 through December 29, 2017 that meets certain eligibility requirements. Under the agreement we cede losses incurred and premiums on or after the effective date through December 31, 2028, at which time the agreement expires. Early termination of the agreement can be elected by us effective December 31, 2021 for a fee, or under specified scenarios for no fee upon prior written notice including if we will receive less than 90% of the full credit amount under the PMIERs for the risk ceded in any required calculation period.

Our 2015 quota share reinsurance agreement (“2015 QSR Transaction”), which became effective on July 1, 2015, covers eligible risk in force written before 2017. The group of unaffiliated reinsurers under our 2015 QSR Transaction each has an insurer financial strength rating of A- or better by Standard and Poor’s Rating Services, A.M. Best or both. The 2015 QSR Transaction cedes losses incurred and premiums through December 31, 2024, at which time the agreement expires. Early termination of the agreement can be elected by us effective December 31, 2018 for a fee, or under specified scenarios for no fee upon prior written notice, including if we will receive less than 90% of the full credit amount under the PMIERs for the risk ceded in any required calculation period.

The structure of both the 2017 QSR Transaction and 2015 QSR Transaction is a 30% quota share for all policies covered, with a 20% ceding commission as well as a profit commission. Generally, under the QSR Transactions, we will receive a profit commission provided that the loss ratio on the loans covered under the agreement remains below 60%.

Following is a summary of our quota share reinsurance agreements, excluding captive agreements discussed below, for the three and six months ended June 30, 2017 and 2016.



	Three Months Ended June 30,				Six Months Ended June 30,
(In thousands)	2017		2016		2017		2016
Ceded premiums written and earned, net of profit commission ⁽¹⁾	$	28,917	$	29,961	$	57,812	$	61,627
Ceded losses incurred	4,424		6,070		9,111		14,583
Ceding commissions ⁽²⁾	12,248		11,946		24,251		23,522
Profit commission	32,325		29,767		63,442		55,982


⁽¹⁾	Under our QSR Transactions, premiums are ceded on an earned and received basis as defined in the agreements.


⁽²⁾	Ceding commissions are reported within Other underwriting and operating expenses, net on the consolidated statements of operations.

Under the terms of QSR Transactions, ceded premiums, ceding commission and profit commission are settled net on a quarterly basis. The ceded premium due after deducting the related ceding commission and profit commission is reported within “Other liabilities” on the consolidated balance sheets.

The reinsurance recoverable on loss reserves related to our QSR Transactions was $33.1 million as of June 30, 2017 and $31.8 million as of December 31, 2016. The reinsurance recoverable balance is secured by funds on deposit from the reinsurers which are based on the funding requirements of PMIERs that address ceded risk.

Captive reinsurance

In the past, MGIC also obtained captive reinsurance. In a captive reinsurance arrangement, the reinsurer is affiliated with the lender for whom MGIC provides mortgage insurance. As part of our settlement with the Consumer Financial Protection Bureau (“CFPB”) in 2013 and with the Minnesota Department of Commerce in 2015, MGIC has agreed to not enter into any new captive reinsurance agreement or reinsure any new loans under any existing captive reinsurance agreement for a period of ten years subsequent to the respective settlements. In accordance with the CFPB settlement, all of our active captive arrangements were placed into run-off. In addition, the GSEs will not approve any future reinsurance or risk sharing transaction with a mortgage enterprise or an affiliate of a mortgage enterprise.

The reinsurance recoverable on loss reserves related to captive agreements was $12.0 million as of June 30, 2017, which was supported by $86.0 million of trust assets, while as of December 31, 2016, the reinsurance recoverable on loss reserves related to captive agreements was $19.0 million, which was supported by $91.0 million of trust assets. Each captive reinsurer is required to maintain a separate trust account to support its combined reinsured risk on all annual books. MGIC is the sole beneficiary of the trusts.

Litigation and Contingencies	6 Months Ended
Litigation and Contingencies	Jun. 30, 2017
Commitments and Contingencies Disclosure [Abstract]
Litigation and Contingencies	Litigation and Contingencies Before paying an insurance claim, we review the loan and servicing files to determine the appropriateness of the claim amount. When reviewing the files, we may determine that we have the right to rescind coverage on the loan. In our SEC reports, we refer to insurance rescissions and denials of claims collectively as “rescissions” and variations of that term. In addition, all of our insurance policies provide that we can reduce or deny a claim if the servicer did not comply with its obligations under our insurance policy. We call such reduction of claims “curtailments.” In recent quarters, an immaterial percentage of claims received in a quarter have been resolved by rescissions. In each of 2016 and the first half of 2017, curtailments reduced our average claim paid by approximately 5.5%. Our loss reserving methodology incorporates our estimates of future rescissions, curtailments, and reversals of rescissions and curtailments. A variance between ultimate actual rescission, curtailment and reversal rates and our estimates, as a result of the outcome of litigation, settlements or other factors, could materially affect our losses. When the insured disputes our right to rescind coverage or curtail claims, we generally engage in discussions in an attempt to settle the dispute. If we are unable to reach a settlement, the outcome of a dispute ultimately would be determined by legal proceedings. Under ASC 450-20, until a liability associated with settlement discussions or legal proceedings becomes probable and can be reasonably estimated, we consider our claim payment or rescission resolved for financial reporting purposes and do not accrue an estimated loss. Where we have determined that a loss is probable and can be reasonably estimated, we have recorded our best estimate of our probable loss. If we are not able to implement settlements we consider probable, we intend to defend MGIC vigorously against any related legal proceedings. In addition to matters for which we have recorded a probable loss, we are involved in other discussions and/or proceedings with insureds with respect to our claims paying practices. Although it is reasonably possible that when these matters are resolved we will not prevail in all cases, we are unable to make a reasonable estimate or range of estimates of the potential liability. We estimate the maximum exposure associated with matters where a loss is reasonably possible to be approximately $291 million, although we believe (but can give no assurance that) we will ultimately resolve these matters for significantly less than this amount. This estimate of our maximum exposure does not include interest or consequential or exemplary damages. Mortgage insurers, including MGIC, have been involved in litigation and regulatory actions related to alleged violations of the anti-referral fee provisions of the Real Estate Settlement Procedures Act, which is commonly known as RESPA, and the notice provisions of the Fair Credit Reporting Act, which is commonly known as FCRA. While these proceedings in the aggregate have not resulted in material liability for MGIC, there can be no assurance that the outcome of future proceedings, if any, under these laws would not have a material adverse affect on us. In addition, various regulators, including the CFPB, state insurance commissioners and state attorneys general may bring other actions seeking various forms of relief in connection with alleged violations of RESPA. The insurance law provisions of many states prohibit paying for the referral of insurance business and provide various mechanisms to enforce this prohibition. While we believe our practices are in conformity with applicable laws and regulations, it is not possible to predict the eventual scope, duration or outcome of any such reviews or investigations nor is it possible to predict their effect on us or the mortgage insurance industry. Through a non-insurance subsidiary, we utilize our underwriting skills to provide an outsourced underwriting service to our customers known as contract underwriting. As part of the contract underwriting activities, that subsidiary is responsible for the quality of the underwriting decisions in accordance with the terms of the contract underwriting agreements with customers. That subsidiary may be required to provide certain remedies to its customers if certain standards relating to the quality of our underwriting work are not met, and we have an established reserve for such future obligations. Claims for remedies may be made a number of years after the underwriting work was performed. The underwriting remedy expense for 2016 and the first half of 2017 was immaterial to our consolidated financial statements. In addition to the matters described above, we are involved in other legal proceedings in the ordinary course of business. In our opinion, based on the facts known at this time, the ultimate resolution of these ordinary course legal proceedings will not have a material adverse effect on our financial position or results of operations. See Note 11 – “Income Taxes” for a description of federal income tax contingencies.

Earnings per Share

6 Months Ended

Jun. 30, 2017

Earnings Per Share [Abstract]

Earnings per Share

Basic earnings per share (“EPS”) is calculated by dividing net income by the weighted average number of shares of common stock outstanding. Diluted EPS includes the components of basic EPS and also gives effect to dilutive common stock equivalents. We calculate diluted EPS using the treasury stock method and if-converted method. Under the if-converted method, diluted EPS reflects the potential dilution that could occur if our convertible debt instruments result in the issuance of common stock. The determination of potentially issuable shares does not consider the satisfaction of the conversion requirements and the shares are included in the determination of diluted EPS as of the beginning of the period, if dilutive. During the quarter ended June 30, 2017, we had several debt issuances that could result in contingently issuable shares and consider each potential issuance of shares separately to reflect the maximum potential dilution. Nonetheless, our dilutive common stock equivalents may not reflect all of the contingently issuable shares that could be required to be issued upon any debt conversion. For purposes of calculating basic and diluted EPS, vested restricted stock and restricted stock units ("RSUs") are considered outstanding.

The following table reconciles the numerators and denominators used to calculate basic and diluted EPS.



	Three Months Ended June 30,				Six Months Ended June 30,
(In thousands, except per share data)	2017		2016		2017		2016
Basic earnings per share:
Net income	$	118,622	$	109,221	$	208,420	$	178,412
Weighted average common shares outstanding - basic	366,918		340,678		354,035		340,411
Basic earnings per share	$	0.32	$	0.32	$	0.59	$	0.52

Diluted earnings per share:
Net income	$	118,622	$	109,221	$	208,420	$	178,412
Interest expense, net of tax ⁽¹⁾:
2% Notes	84		1,982		907		3,964
5% Notes	427		1,728		1,709		4,406
9% Debentures	3,757		3,757		7,514		8,379
Diluted income available to common shareholders	$	122,890	$	116,688	$	218,550	$	195,161

Weighted average common shares outstanding - basic	366,918		340,678		354,035		340,411
Effect of dilutive securities:
Unvested RSUs	1,140		1,209		1,314		1,444
2% Notes	3,827		71,917		16,771		71,917
5% Notes	3,557		13,307		7,154		15,449
9% Debentures	19,028		19,028		19,028		21,133
Weighted average common shares outstanding - diluted	394,470		446,139		398,302		450,354
Diluted earnings per share	$	0.31	$	0.26	$	0.55	$	0.43


⁽¹⁾	Tax effected at a rate of 35%.

Investments

6 Months Ended

Jun. 30, 2017

Investments [Abstract]

Investments

The amortized cost, gross unrealized gains and losses and fair value of the investment portfolio at June 30, 2017 and December 31, 2016 are shown below.



June 30, 2017
(In thousands)	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses ⁽¹⁾			Fair Value
U.S. Treasury securities and obligations of U.S. government corporations and agencies	$	64,043	$	364	$	(478	)	$	63,929
Obligations of U.S. states and political subdivisions	2,131,471		42,983		(9,165		)	2,165,289
Corporate debt securities	1,823,823		12,699		(8,897		)	1,827,625
ABS	21,988		10		(11		)	21,987
RMBS	209,874		78		(7,612		)	202,340
CMBS	310,997		1,548		(5,467		)	307,078
CLOs	112,769		332		(138		)	112,963
Total debt securities	4,674,965		58,014		(31,768		)	4,701,211
Equity securities	7,183		41		(15		)	7,209
Total investment portfolio	$	4,682,148	$	58,055	$	(31,783	)	$	4,708,420



December 31, 2016
(In thousands)	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses ⁽¹⁾			Fair Value
U.S. Treasury securities and obligations of U.S. government corporations and agencies	$	73,847	$	407	$	(724	)	$	73,530
Obligations of U.S. states and political subdivisions	2,147,458		20,983		(25,425		)	2,143,016
Corporate debt securities	1,756,461		6,059		(18,610		)	1,743,910
ABS	59,519		74		(28		)	59,565
RMBS	231,733		102		(7,626		)	224,209
CMBS	327,042		769		(7,994		)	319,817
CLOs	121,151		226		(202		)	121,175
Total debt securities	4,717,211		28,620		(60,609		)	4,685,222
Equity securities	7,144		8		(24		)	7,128
Total investment portfolio	$	4,724,355	$	28,628	$	(60,633	)	$	4,692,350


⁽¹⁾	At June 30, 2017 and December 31, 2016, there were no other-than-temporary impairment losses recorded in other comprehensive income.

The FHLB Advance is secured by eligible collateral whose fair value must be maintained at 102% of the outstanding principal balance. As of June 30, 2017 that collateral is included in our total investment portfolio amount shown above with a total fair value of $165.9 million.

The amortized cost and fair values of debt securities at June 30, 2017, by contractual maturity, are shown in the following table. Expected maturities will differ from contractual maturities because borrowers may have the right to call or prepay obligations with or without call or prepayment penalties. Because most asset-backed and mortgage-backed securities and collateralized loan obligations provide for periodic payments throughout their lives, they are listed in separate categories.



June 30, 2017
(In thousands)	Amortized Cost		Fair Value
Due in one year or less	$	341,831	$	342,028
Due after one year through five years	1,356,023		1,362,799
Due after five years through ten years	1,026,851		1,030,223
Due after ten years	1,294,632		1,321,793
	$	4,019,337	$	4,056,843

ABS	21,988		21,987
RMBS	209,874		202,340
CMBS	310,997		307,078
CLOs	112,769		112,963
Total as of June 30, 2017	$	4,674,965	$	4,701,211

At June 30, 2017 and December 31, 2016, the investment portfolio had gross unrealized losses of $31.8 million and $60.6 million, respectively. For those securities in an unrealized loss position, the length of time the securities were in such a position, as measured by their month-end fair values, is as follows:



June 30, 2017	Less Than 12 Months					12 Months or Greater					Total
(In thousands)	Fair Value		Unrealized Losses			Fair Value		Unrealized Losses			Fair Value		Unrealized Losses
U.S. Treasury securities and obligations of U.S. government corporations and agencies	$	52,769	$	(471	)	$	993	$	(7	)	$	53,762	$	(478	)
Obligations of U.S. states and political subdivisions	622,767		(8,595		)	17,400		(570		)	640,167		(9,165		)
Corporate debt securities	649,134		(7,664		)	27,241		(1,233		)	676,375		(8,897		)
ABS	3,362		(11		)	—		—			3,362		(11		)
RMBS	43,815		(885		)	155,030		(6,727		)	198,845		(7,612		)
CMBS	172,505		(5,439		)	7,237		(28		)	179,742		(5,467		)
CLOs	7,275		(138		)	—		—			7,275		(138		)
Equity securities	455		(7		)	139		(8		)	594		(15		)
Total	$	1,552,082	$	(23,210	)	$	208,040	$	(8,573	)	$	1,760,122	$	(31,783	)



December 31, 2016	Less Than 12 Months					12 Months or Greater					Total
(In thousands)	Fair Value		Unrealized Losses			Fair Value		Unrealized Losses			Fair Value		Unrealized Losses
U.S. Treasury securities and obligations of U.S. government corporations and agencies	$	48,642	$	(724	)	$	—	$	—		$	48,642	$	(724	)
Obligations of U.S. states and political subdivisions	1,136,676		(24,918		)	13,681		(507		)	1,150,357		(25,425		)
Corporate debt securities	915,777		(16,771		)	35,769		(1,839		)	951,546		(18,610		)
ABS	3,366		(28		)	656		—			4,022		(28		)
RMBS	46,493		(857		)	171,326		(6,769		)	217,819		(7,626		)
CMBS	205,545		(7,529		)	38,587		(465		)	244,132		(7,994		)
CLOs	13,278		(73		)	34,760		(129		)	48,038		(202		)
Equity securities	568		(15		)	137		(9		)	705		(24		)
Total	$	2,370,345	$	(50,915	)	$	294,916	$	(9,718	)	$	2,665,261	$	(60,633	)

The unrealized losses in all categories of our investments at June 30, 2017 and December 31, 2016 were primarily caused by the difference in interest rates at each respective period, compared to interest rates at the time of purchase. There were 404 and 607 securities in an unrealized loss position at June 30, 2017 and December 31, 2016, respectively.

During each of the three and six months ended June 30, 2017 and 2016 there were no other-than-temporary impairments (“OTTI”) recognized. The net realized investment gains (losses) on the investment portfolio are as follows:



	Three Months Ended June 30,					Six Months Ended June 30,
(In thousands)	2017			2016		2017			2016
Realized investment gains (losses) on investments:
Fixed maturities	$	(52	)	$	831	$	(177	)	$	3,886
Equity securities	10			5		13			6
Net realized investments (losses) gains	$	(42	)	$	836	$	(164	)	$	3,892



	Three Months Ended June 30,						Six Months Ended June 30,
(In thousands)	2017			2016			2017			2016
Realized investment gains (losses) on investments:
Gains on sales	$	644		$	1,404		$	829		$	5,509
Losses on sales	(686		)	(568		)	(993		)	(1,617		)
Net realized investments (losses) gains	$	(42	)	$	836		$	(164	)	$	3,892

Fair Value Measurements

6 Months Ended

Jun. 30, 2017

Fair Value Disclosures [Abstract]

Fair Value Measurements

Under the authoritative guidance, fair value is disclosed using a fair value hierarchy that prioritizes the inputs to valuation techniques used to measure fair value and categorizes assets and liabilities into Levels 1, 2, and 3 based on inputs available to determine their fair values. 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. This model combines all inputs to arrive at a value assigned to each security. Quality controls are performed by the independent pricing sources throughout this process, which include reviewing tolerance reports, trading information, data changes, and directional moves compared to market moves. In addition, on a quarterly basis, we perform quality controls over values received from the pricing sources which also includes reviewing tolerance reports, trading information, data changes, and directional moves compared to market moves. We have not made any adjustments to the prices obtained from the independent pricing sources.

In accordance with fair value accounting guidance, we applied the following fair value hierarchy in order to measure fair value for assets and liabilities:

Level 1 - Quoted prices for identical instruments in active markets that we can access. Financial assets utilizing Level 1 inputs primarily include U.S. Treasury securities and equity securities.

Level 2 - Quoted prices for similar instruments in active markets that we can access; quoted prices for identical or similar instruments in markets that are not active; and inputs, other than quoted prices, that are observable in the marketplace for the instrument. The observable inputs are used in valuation models to calculate the fair value of the instruments. Financial assets utilizing Level 2 inputs primarily include obligations of U.S. government corporations and agencies, corporate bonds, mortgage-backed securities, asset-backed securities, and most municipal bonds.

The independent pricing sources utilize these approaches to determine the fair value of the instruments in Level 2 of the fair value hierarchy based on type of instrument:

Corporate Debt & U.S. Government and Agency Bonds are evaluated by surveying the dealer community, obtaining relevant trade data, benchmark quotes and spreads and incorporating this information into the evaluation process.

Obligations of U.S. States & Political Subdivisions are evaluated by tracking, capturing, and analyzing quotes for active issues and trades reported via the Municipal Securities Rulemaking Board records. Daily briefings and reviews of current economic conditions, trading levels, spread relationships, and the slope of the yield curve provide further data for evaluation.

Residential Mortgage-Backed Securities (“RMBS”) are evaluated by monitoring interest rate movements, and other pertinent data daily. Incoming market data is enriched to derive spread, yield and/or price data as appropriate, enabling known data points to be extrapolated for valuation application across a range of related securities.

Commercial Mortgage-Backed Securities (“CMBS”) are evaluated using valuation techniques that reflect market participants’ assumptions and maximize the use of relevant observable inputs including quoted prices for similar assets, benchmark yield curves and market corroborated inputs. The inputs for securities covered, including executed trades, broker quotes, credit information, collateral attributes and/or cash flow waterfall as applicable, are regularly reviewed as part of the evaluation.

Asset-Backed Securities (“ABS”) are evaluated using spreads and other information solicited from market buy- and sell-side sources, including primary and secondary dealers, portfolio managers, and research analysts. Cash flows are generated for each tranche, benchmark yields are determined, and deal collateral performance and tranche level attributes including trade activity, bids, and offer are applied, resulting in tranche-specific prices.

Collateralized loan obligations ("CLO") are evaluated by manager rating, seniority in the capital structure, assumptions about prepayment, default and recovery and their impact on cash flow generation. Loan level net asset values are determined and aggregated for tranches and as a final step, prices are checked against available recent trade activity.

Level 3 - Valuations derived from valuation techniques in which one or more significant inputs or value drivers are unobservable or from par values for equity securities restricted in their ability to be redeemed or sold. The inputs used to derive the fair value of Level 3 securities reflect our own assumptions about the assumptions a market participant would use in pricing an asset or liability. Financial assets utilizing Level 3 inputs primarily include equity securities that can only be redeemed or sold at their par value and only to the security issuer and a state premium tax credit investment. The state premium tax credit investment has a maturity of less than 2 years, a credit rating of AAA, and its balance reflects its remaining scheduled payments discounted at an average annual rate of 7.1%. Our non-financial assets that are classified as Level 3 securities consist of real estate acquired through claim settlement. The fair value of real estate acquired is the lower of our acquisition cost or a percentage of the appraised value. The percentage applied to the appraised value is based upon our historical sales experience adjusted for current trends.

_________________________________

Fair value measurements for assets measured at fair value included the following as of June 30, 2017 and December 31, 2016:

June 30, 2017

(In thousands)	Total Fair Value		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
U.S. Treasury securities and obligations of U.S. government corporations and agencies	$	63,929	$	13,342	$	50,587	$	—
Obligations of U.S. states and political subdivisions	2,165,289		—		2,164,712		577
Corporate debt securities	1,827,625		—		1,827,625		—
ABS	21,987		—		21,987		—
RMBS	202,340		—		202,340		—
CMBS	307,078		—		307,078		—
CLOs	112,963		—		112,963		—
Total debt securities	4,701,211		13,342		4,687,292		577
Equity securities ⁽¹⁾	7,209		2,941		—		4,268
Total investment portfolio	$	4,708,420	$	16,283	$	4,687,292	$	4,845
Real estate acquired ⁽²⁾	$	10,271	$	—	$	—	$	10,271


⁽¹⁾	Equity securities in Level 3 are carried at cost, which approximates fair value.


⁽²⁾	Real estate acquired through claim settlement, which is held for sale, is reported in Other assets on the consolidated balance sheets.

December 31, 2016

(In thousands)	Total Fair Value		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
U.S. Treasury securities and obligations of U.S. government corporations and agencies	$	73,530	$	30,690	$	42,840	$	—
Obligations of U.S. states and political subdivisions	2,143,016		—		2,142,325		691
Corporate debt securities	1,743,910		—		1,743,910		—
ABS	59,565		—		59,565		—
RMBS	224,209		—		224,209		—
CMBS	319,817		—		319,817		—
CLOs	121,175		—		121,175		—
Total debt securities	4,685,222		30,690		4,653,841		691
Equity securities ⁽¹⁾	7,128		2,860		—		4,268
Total investment portfolio	$	4,692,350	$	33,550	$	4,653,841	$	4,959
Real estate acquired ⁽²⁾	$	11,748	$	—	$	—	$	11,748


⁽¹⁾	Equity securities in Level 3 are carried at cost, which approximates fair value.


⁽²⁾	Real estate acquired through claim settlement, which is held for sale, is reported in Other assets on the consolidated balance sheets.

For assets measured at fair value using significant unobservable inputs (Level 3), a reconciliation of the beginning and ending balances for the three and six months ended June 30, 2017 and 2016 is shown in the following tables. There were no transfers into or out of Level 3 in those periods and there were no losses included in earnings for those periods attributable to the change in unrealized losses on assets still held at the end of the applicable period.



Three Months Ended June 30, 2017
(In thousands)	Debt Securities			Equity Securities		Total Investments			Real Estate Acquired
Balance at March 31, 2017	$	683		$	4,268	$	4,951		$	10,730
Total realized/unrealized gains (losses):
Included in earnings and reported as losses incurred, net	—			—		—			(63		)
Purchases	—			—		—			9,421
Sales	(106		)	—		(106		)	(9,817		)
Balance at June 30, 2017	$	577		$	4,268	$	4,845		$	10,271



Three Months Ended June 30, 2016
(In thousands)	Debt Securities			Equity Securities		Total Investments			Real Estate Acquired
Balance at March 31, 2016	$	1,192		$	3,421	$	4,613		$	12,849
Total realized/unrealized gains (losses):
Included in other comprehensive income	—			3,519		3,519			—
Included in earnings and reported as losses incurred, net	—			—		—			651
Purchases	—			—		—			6,748
Sales	(136		)	—		(136		)	(10,606		)
Balance at June 30, 2016	$	1,056		$	6,940	$	7,996		$	9,642



Six Months Ended June 30, 2017
(In thousands)	Debt Securities			Equity Securities		Total Investments			Real Estate Acquired
Balance at December 31, 2016	$	691		$	4,268	$	4,959		$	11,748
Total realized/unrealized gains (losses):
Included in earnings and reported as losses incurred, net	—			—		—			(226		)
Purchases	—			—		—			18,104
Sales	(114		)	—		(114		)	(19,355		)
Balance at June 30, 2017	$	577		$	4,268	$	4,845		$	10,271



Six Months Ended June 30, 2016
(In thousands)	Debt Securities			Equity Securities			Total Investments			Real Estate Acquired
Balance at December 31, 2015	$	1,228		$	2,855		$	4,083		$	12,149
Total realized/unrealized gains (losses):
Included in other comprehensive income	—			3,519			3,519			—
Included in earnings and reported as losses incurred, net	—			—			—			358
Purchases	—			3,091			3,091			19,015
Sales	(172		)	(2,525		)	(2,697		)	(21,880		)
Balance at June 30, 2016	$	1,056		$	6,940		$	7,996		$	9,642

Authoritative guidance over disclosures about the fair value of financial instruments requires additional disclosure for financial instruments not measured at fair value. Certain financial instruments, including insurance contracts, are excluded from these fair value disclosure requirements. The carrying values of cash and cash equivalents (Level 1) and accrued investment income (Level 2) approximated their fair values. Additional fair value disclosures related to our investment portfolio are included in Note 7 – “Investments.”

Financial Liabilities Not Measured at Fair Value

We incur financial liabilities in the normal course of our business. The following table presents the carrying value and fair value of our financial liabilities disclosed, but not carried, at fair value at June 30, 2017 and December 31, 2016. The fair values of our 5% Notes, 2% Notes, 5.75% Notes, and 9% Debentures were based on observable market prices. The fair value of the FHLB Advance was estimated using discounted cash flows on current incremental borrowing rates for similar borrowing arrangements. In all cases the fair values of the financial liabilities below are categorized as Level 2.



	June 30, 2017				December 31, 2016
(In thousands)	Carrying Value		Fair Value		Carrying Value		Fair Value
Financial liabilities:
FHLB Advance	155,000		154,140		$	155,000	$	151,905
5% Notes	—		—		144,789		147,679
2% Notes	—		—		204,672		308,605
5.75% Notes	417,983		457,878		417,406		445,987
9% Debentures	256,872		338,190		256,872		323,040
Total financial liabilities	$	829,855	$	950,208	$	1,178,739	$	1,377,216

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

Other Comprehensive Income

6 Months Ended

Jun. 30, 2017

Comprehensive Income (Loss), Net of Tax, Attributable to Parent [Abstract]

Other Comprehensive Income

The pretax and related income tax (expense) benefit components of our other comprehensive income (loss) for the three and six months ended June 30, 2017 and 2016 are included in the following table.



	Three Months Ended June 30,						Six Months Ended June 30,
(In thousands)	2017			2016			2017			2016
Net unrealized investment gains arising during the period	$	39,614		$	86,674		$	58,261		$	165,058
Income tax expense	(13,865		)	(30,336		)	(20,391		)	(57,893		)
Net of taxes	25,749			56,338			37,870			107,165

Net changes in benefit plan assets and obligations	(220		)	(266		)	(454		)	(740		)
Income tax benefit	78			93			159			259
Net of taxes	(142		)	(173		)	(295		)	(481		)

Net changes in unrealized foreign currency translation adjustment	—			16			45			(1,480		)
Income tax (expense) benefit	—			(5		)	(14		)	516
Net of taxes	—			11			31			(964		)

Total other comprehensive income	39,394			86,424			57,852			162,838
Total income tax expense	(13,787		)	(30,248		)	(20,246		)	(57,118		)
Total other comprehensive income, net of tax	$	25,607		$	56,176		$	37,606		$	105,720

The pretax and related income tax (expense) benefit components of the amounts reclassified from our accumulated other comprehensive loss (“AOCL”) to our consolidated statements of operations for the three and six months ended June 30, 2017 and 2016 are included in the following table.



	Three Months Ended June 30,						Six Months Ended June 30,
(In thousands)	2017			2016			2017			2016
Reclassification adjustment for net realized (losses) gains ⁽¹⁾	$	(1,392	)	$	98		$	(2,139	)	$	710
Income tax benefit (expense)	487			(34		)	748			(126		)
Net of taxes	(905		)	64			(1,391		)	584

Reclassification adjustment related to benefit plan assets and obligations ⁽²⁾	220			266			454			740
Income tax expense	(78		)	(93		)	(159		)	(259		)
Net of taxes	142			173			295			481

Reclassification adjustment related to foreign currency ⁽³⁾	—			—			—			1,467
Income tax expense	—			—			—			(513		)
Net of taxes	—			—			—			954

Total reclassifications	(1,172		)	364			(1,685		)	2,917
Total income tax benefit (expense)	409			(127		)	589			(898		)
Total reclassifications, net of tax	$	(763	)	$	237		$	(1,096	)	$	2,019


⁽¹⁾	Increases (decreases) Net realized investment (losses) gains on the consolidated statements of operations.


⁽²⁾	Decreases (increases) Other underwriting and operating expenses, net on the consolidated statements of operations.


⁽³⁾	Increases (decreases) Other revenue on the consolidated statements of operations.

__________________________

A rollforward of AOCL for the six months ended June 30, 2017, including amounts reclassified from AOCL, are included in the table below.



	Six Months Ended June 30, 2017
(In thousands)	Net unrealized gains and losses on available-for-sale securities			Net benefit plan assets and obligations recognized in shareholders' equity			Net unrealized foreign currency translation			Total AOCL
Balance, December 31, 2016, net of tax	$	(20,797	)	$	(54,272	)	$	(31	)	$	(75,100	)
Other comprehensive income before reclassifications	36,479			—			31			36,510
Less: Amounts reclassified from AOCL	(1,391		)	295			—			(1,096		)
Balance, June 30, 2017, net of tax	$	17,073		$	(54,567	)	$	—		$	(37,494	)

Benefit Plans

6 Months Ended

Jun. 30, 2017

Retirement Benefits [Abstract]

Benefit Plans

The following tables provide the components of net periodic benefit cost for our pension, supplemental executive retirement and other postretirement benefit plans for three and six months ended June 30, 2017 and 2016:



	Three Months Ended June 30,
	Pension and Supplemental Executive Retirement Plans						Other Postretirement Benefit Plans
(In thousands)	2017			2016			2017			2016
Service cost	$	2,484		$	2,402		$	220		$	201
Interest cost	3,879			4,024			186			180
Expected return on plan assets	(5,013		)	(4,865		)	(1,312		)	(1,221		)
Recognized net actuarial loss	1,549			1,567			—			—
Amortization of prior service cost	(106		)	(171		)	(1,663		)	(1,663		)
Net periodic benefit cost (benefit)	$	2,793		$	2,957		$	(2,569	)	$	(2,503	)



	Six Months Ended June 30,
	Pension and Supplemental Executive Retirement Plans						Other Postretirement Benefit Plans
(In thousands)	2017			2016			2017			2016
Service cost	$	4,778		$	4,565		$	407		$	376
Interest cost	7,737			7,953			353			352
Expected return on plan assets	(10,049		)	(9,754		)	(2,624		)	(2,443		)
Recognized net actuarial loss	3,084			2,928			—			—
Amortization of prior service cost	(213		)	(343		)	(3,325		)	(3,325		)
Net periodic benefit cost (benefit)	$	5,337		$	5,349		$	(5,189	)	$	(5,040	)

We currently intend to make contributions totaling $9.4 million to our qualified pension plan and supplemental executive retirement plan in 2017.

Income Taxes	6 Months Ended
Income Taxes	Jun. 30, 2017
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes We have approximately $1.2 billion of net operating loss (“NOL”) carryforwards on a regular tax basis and $0.3 billion of NOL carryforwards for computing the alternative minimum tax as of June 30, 2017. Any unutilized carryforwards are scheduled to expire at the end of tax years 2031 through 2033. We evaluate the realizability of our deferred tax assets including our NOL carryforwards on a quarterly basis. Based on our analysis, we have concluded that all of our deferred tax assets are fully realizable and therefore no valuation allowance existed at June 30, 2017 and December 31, 2016. Tax Contingencies As previously disclosed, the Internal Revenue Service (“IRS”) completed examinations of our federal income tax returns for the years 2000 through 2007 and issued proposed assessments for taxes, interest and penalties related to our treatment of the flow-through income and loss from an investment in a portfolio of residual interests of Real Estate Mortgage Investment Conduits (“REMICs”). The IRS indicated that it did not believe that, for various reasons, we had established sufficient tax basis in the REMIC residual interests to deduct the losses from taxable income. We appealed these assessments within the IRS and in August 2010, we reached a tentative settlement agreement with the IRS which was not finalized. In 2014, we received Notices of Deficiency (commonly referred to as “90 day letters”) covering the 2000-2007 tax years. The Notices of Deficiency reflect taxes and penalties related to the REMIC matters of $197.5 million and at June 30, 2017, there would also be interest related to these matters of approximately $195.7 million. In 2007, we made a payment of $65.2 million to the United States Department of the Treasury which will reduce any amounts we would ultimately owe. The Notices of Deficiency also reflect additional amounts due of $261.4 million, which are primarily associated with the disallowance of the carryback of the 2009 net operating loss to the 2004-2007 tax years. We believe the IRS included the carryback adjustments as a precaution to keep open the statute of limitations on collection of the tax that was refunded when this loss was carried back, and not because the IRS actually intends to disallow the carryback permanently. Depending on the outcome of this matter, additional state income taxes and state interest may become due when a final resolution is reached. As of June 30, 2017, those state taxes and interest would approximate $82.4 million. In addition, there could also be state tax penalties. Our total amount of unrecognized tax benefits as of June 30, 2017 is $140.8 million, which represents the tax benefits generated by the REMIC portfolio included in our tax returns that we have not taken benefit for in our financial statements, including any related interest. We filed a petition with the U.S. Tax Court contesting most of the IRS' proposed adjustments reflected in the Notices of Deficiency and the IRS filed an answer to our petition which continued to assert their claim. The case has twice been scheduled for trial and in each instance, the parties jointly filed, and the U.S. Tax Court approved (most recently in February 2016), motions for continuance to postpone the trial date. Also in February 2016, the U.S. Tax Court approved a joint motion to consolidate for trial, briefing and opinion, our case with similar cases of Radian Group, Inc., as successor to Enhance Financial Services Group, Inc., et al. The parties informed the Tax Court in January 2017 that they had reached a basis for settlement of the major issues in the case and in June 2017 that there was only one remaining unresolved secondary issue (a factual determination arising from the 2002-2004 audit that is unrelated to the REMIC matter which the parties continue to work toward resolving). Any agreed settlement terms will ultimately be subject to review by the Joint Committee on Taxation ("JCT") before a settlement can be completed and there is no assurance that a settlement will be completed. Based on information that we currently have regarding the status of our ongoing dispute, we recorded a provision for additional taxes and interest of $27.8 million in the first half of 2017. Should a settlement not be completed, ongoing litigation to resolve our dispute with the IRS could be lengthy and costly in terms of legal fees and related expenses. We would need to make further adjustments, which could be material, to our tax provision and liabilities if our view of the probability of success in this matter changes, and the ultimate resolution of this matter could have a material negative impact on our effective tax rate, results of operations, cash flows, available assets and statutory capital. In this regard, see Note 15 - “Statutory Information.” The total amount of the unrecognized tax benefits, related to our aforementioned REMIC issue that would affect our effective tax rate is $119.1 million. We recognize interest accrued and penalties related to unrecognized tax benefits in income taxes. As of June 30, 2017 and December 31, 2016, we had accrued $49.9 million and $28.9 million, respectively, for the payment of interest.

Loss Reserves

6 Months Ended

Jun. 30, 2017

Insurance Loss Reserves [Abstract]

Loss Reserves

We establish reserves to recognize the estimated liability for losses and loss adjustment expenses (“LAE”) related to defaults on insured mortgage loans. Loss reserves are established by estimating the number of loans in our inventory of delinquent loans that will result in a claim payment, which is referred to as the claim rate, and further estimating the amount of the claim payment, which is referred to as claim severity.

Estimation of losses is inherently judgmental. The conditions that affect the claim rate and claim severity include the current and future state of the domestic economy, including unemployment and the current and future strength of local housing markets; exposure on insured loans; the amount of time between default and claim filing; and curtailments and rescissions. The actual amount of the claim payments may be substantially different than our loss reserve estimates. Our estimates could be adversely affected by several factors, including a deterioration of regional or national economic conditions, including unemployment, leading to a reduction in borrowers’ income and thus their ability to make mortgage payments, and a drop in housing values which may affect borrower willingness to continue to make mortgage payments when the value of the home is below the mortgage balance. Changes to our estimates could result in a material impact to our results of operations and capital position, even in a stable economic environment.

The “Losses incurred” section of the table below shows losses incurred on defaults that occurred in the current year and in prior years. The amount of losses incurred relating to defaults that occurred in the current year represents the estimated amount to be ultimately paid on such defaults. The amount of losses incurred relating to defaults that occurred in prior years represents the actual claim rate and severity associated with those defaults resolved in the current year differing from the estimated liability at the prior year-end, as well as a re-estimation of amounts to be ultimately paid on defaults continuing from the end of the prior year. This re-estimation of the claim rate and severity is the result of our review of current trends in the default inventory, such as percentages of defaults that have resulted in a claim, the amount of the claims relative to the average loan exposure, changes in the relative level of defaults by geography and changes in average loan exposure.

Losses incurred on defaults that occurred in the current year decreased in the first six months of 2017 compared to the same period in 2016, primarily due to a decrease in the estimated claim rate on recently reported defaults and a decrease in the number of new defaults, net of related cures.

For the six months ended June 30, 2017 and 2016 we experienced favorable prior year loss reserve development. This development was, in part, due to the resolution of approximately 48% and 43% of the prior year default inventory during the six months ended June 30, 2017 and 2016, respectively. During the first six months of 2017 and 2016, we experienced improved cure rates on prior year defaults, which were offset in part by an increase in severity on the prior year defaults in both periods.

The “Losses paid” section of the table below shows the breakdown between claims paid on new default notices in the current year and claims paid on defaults from prior years. Until a few years ago, it took, on average, approximately twelve months for a default that is not cured to develop into a paid claim. Over the past several years, the average time it takes to receive a claim associated with a default has increased. This is, in part, due to new loss mitigation protocols established by servicers and to changes in some state foreclosure laws that may include, for example, a requirement for additional review and/or mediation processes. It is difficult to estimate how long it may take for current and future defaults that do not cure to develop into paid claims.

During the first six months of 2017 and 2016, our losses paid included amounts paid in connection with disputes concerning our claims paying practices and settlements of coverage on pools of non-performing loans (“NPLs”). The impacts of the settlements were as follows:


•	2017 - Items removed from inventory totaled 1,128 notices with an amount paid of $45 million.


•	2016 - Items removed from inventory totaled 1,273 notices with an amount paid of $51 million.

The liability associated with our estimate of premiums to be refunded on expected claim payments is accrued for separately at June 30, 2017 and December 31, 2016 and approximated $74 million and $85 million, respectively. This liability was included in “Other liabilities” on our consolidated balance sheets.

The following table provides a reconciliation of beginning and ending loss reserves as of and for the six months ended June 30, 2017 and 2016:



	Six months ended June 30,
(In thousands)	2017			2016
Reserve at beginning of period	$	1,438,813		$	1,893,402
Less reinsurance recoverable	50,493			44,487
Net reserve at beginning of period	1,388,320			1,848,915

Losses incurred:
Losses and LAE incurred in respect of default notices received in:
Current year	158,906			196,543
Prior years ⁽¹⁾	(103,948		)	(64,941		)
Total losses incurred	54,958			131,602

Losses paid:
Losses and LAE paid in respect of default notices received in:
Current year	2,125			1,396
Prior years	298,847			392,007
Reinsurance terminations	—			(4		)
Total losses paid	300,972			393,399
Net reserve at end of period	1,142,306			1,587,118
Plus reinsurance recoverables	44,783			45,215
Reserve at end of period	$	1,187,089		$	1,632,333


⁽¹⁾	A negative number for prior year losses incurred indicates a redundancy of prior year loss reserves. See the following table for more information about prior year loss development.

The prior year development of the reserves in the first six months of 2017 and 2016 is reflected in the following table.



	Six months ended June 30,
(In millions)	2017			2016
Decrease in estimated claim rate on primary defaults	$	(104	)	$	(76	)
Increase in estimated severity on primary defaults	2			17
Change in estimates related to pool reserves, LAE reserves and reinsurance	(2		)	(6		)
Total prior year loss development ⁽¹⁾	$	(104	)	$	(65	)


⁽¹⁾	A negative number for prior year loss development indicates a redundancy of prior year loss reserves.

Default inventory

A rollforward of our primary default inventory for the three and six months ended June 30, 2017 and 2016 appears in the following table. The information concerning new notices and cures is compiled from monthly reports received from loan servicers. The level of new notice and cure activity reported in a particular month can be influenced by, among other things, the date on which a servicer generates its report, the accuracy of the data provided by servicers, the number of business days in a month, transfers of servicing between loan servicers and whether all servicers have provided the reports in a given month.



	Three months ended June 30,				Six Months Ended June 30,
	2017		2016		2017		2016
Default inventory at beginning of period	45,349		55,590		50,282		62,633
New notices	14,463		16,080		29,402		32,811
Cures	(14,708	)	(15,640	)	(31,836	)	(34,693	)
Paids (including those charged to a deductible or captive)	(2,573	)	(3,195	)	(5,208	)	(6,568	)
Rescissions and denials	(100	)	(142	)	(195	)	(352	)
Other items removed from inventory	(1,114	)	(135	)	(1,128	)	(1,273	)
Default inventory at end of period	41,317		52,558		41,317		52,558

The decrease in the primary default inventory experienced during 2017 and 2016 was generally across all markets and primarily in book years 2008 and prior. Historically as a default ages it becomes more likely to result in a claim.

Consecutive months in default

	June 30, 2017			December 31, 2016			June 30, 2016
3 months or less	10,299	25	%	12,194	24	%	11,547	22	%
4 - 11 months	11,018	27	%	13,450	27	%	12,680	24	%
12 months or more ^{(1) (2)}	20,000	48	%	24,638	49	%	28,331	54	%
Total primary default inventory	41,317	100	%	50,282	100	%	52,558	100	%

Primary claims received inventory included in ending default inventory:
	1,258	3	%	1,385	3	%	1,829	3	%


⁽¹⁾	Approximately 46%, 47%, and 49% of the primary default inventory in default for 12 consecutive months or more has been in default for at least 36 consecutive months as of June 30, 2017, December 31, 2016, and June 30, 2016, respectively.


⁽²⁾	The majority of items removed from our default inventory under NPL settlements during the six months ended June 30, 2017 were in default for 12 consecutive months or more as of December 31, 2016.

The number of months a loan is in the default inventory can differ from the number of payments that the borrower has not made or is considered delinquent. These differences typically result from a borrower making monthly payments that do not result in the loan becoming fully current. The number of payments that a borrower is delinquent is shown in the table below.

Number of payments delinquent

	June 30, 2017			December 31, 2016			June 30, 2016
3 payments or less	15,858	38	%	18,419	36	%	17,299	33	%
4 - 11 payments	10,560	26	%	12,892	26	%	12,746	24	%
12 payments or more ⁽¹⁾	14,899	36	%	18,971	38	%	22,513	43	%
Total primary default inventory	41,317	100	%	50,282	100	%	52,558	100	%


⁽¹⁾	The majority of items removed from our default inventory under NPL settlements during the six months ended June 30, 2017 had 12 or more payments delinquent as of December 31, 2016.

Pool insurance default inventory decreased to 1,511 at June 30, 2017 from 1,883 at December 31, 2016, and 2,024 at June 30, 2016.

Claims paying practices

Our loss reserving methodology incorporates our estimates of future rescissions. A variance between ultimate actual rescission rates and our estimates, as a result of the outcome of litigation, settlements or other factors, could materially affect our losses.

The liability associated with our estimate of premiums to be refunded on expected future rescissions is accrued for separately and is included in “Other liabilities” on our consolidated balance sheets.

For information about discussions and legal proceedings with customers with respect to our claims paying practices see Note 5 – “Litigation and Contingencies.”

Shareholders' Equity	6 Months Ended
Shareholders' Equity	Jun. 30, 2017
Stockholders' Equity Note [Abstract]
Shareholders' Equity	Shareholders’ Equity Change in accounting principle As described in Note 2 - “New Accounting Pronouncements,” during the first quarter of 2017 we adopted the updated guidance of “Improvements to Employee Share-Based Compensation Accounting.” The adoption of this guidance resulted in an immaterial cumulative effect adjustment to our 2017 beginning retained earnings. 2% Notes As described in Note 3 - “Debt,” on March 21, 2017, we issued an irrevocable notice of redemption in respect of our outstanding 2% Notes, with a redemption date of April 21, 2017. Subsequent to our notice of redemption, in April, holders of approximately $202.5 million of the outstanding principal amount exercised their rights to convert their notes into shares of our common stock. As a result, we issued approximately 29.1 million shares of our common stock, of which 18.7 million shares were reissued from our treasury stock and 10.4 million were newly issued shares. The conversions of the notes increased our shareholders’ equity by the carrying value of the notes, which included outstanding debt issuance costs, at the time of conversion. Shareholders Rights Agreement Our Amended and Restated Rights Agreement dated July 23, 2015 seeks to diminish the risk that our ability to use our NOLs to reduce potential future federal income tax obligations may become substantially limited and to deter certain abusive takeover practices. The benefit of the NOLs would be substantially limited, and the timing of the usage of the NOLs could be substantially delayed, if we were to experience an “ownership change” as defined by Section 382 of the Internal Revenue Code. Under the Agreement each outstanding share of our Common Stock is accompanied by one Right. The “Distribution Date” occurs on the earlier of ten days after a public announcement that a person has become an “Acquiring Person,” or ten business days after a person announces or begins a tender offer in which consummation of such offer would result in a person becoming an “Acquiring Person.” An “Acquiring Person” is any person that becomes, by itself or together with its affiliates and associates, a beneficial owner of 5% or more of the shares of our Common Stock then outstanding, but excludes, among others, certain exempt and grandfathered persons as defined in the Agreement. The Rights are not exercisable until the Distribution Date. Each Right will initially entitle shareholders to buy one-tenth of one share of our Common Stock at a Purchase Price of $45 per full share (equivalent to $4.50 for each one-tenth share), subject to adjustment. Each exercisable Right (subject to certain limitations) will entitle its holder to purchase, at the Rights’ then-current Purchase Price, a number of our shares of Common Stock (or if after the Shares Acquisition Date, we are acquired in a business combination, common shares of the acquiror) having a market value at the time equal to twice the Purchase Price. The Rights will expire on August 1, 2018, or earlier as described in the Agreement. The Rights are redeemable at a price of $0.001 per Right at any time prior to the time a person becomes an Acquiring Person. Other than certain amendments, the Board of Directors may amend the Rights in any respect without the consent of the holders of the Rights.

Share-Based Compensation

6 Months Ended

Jun. 30, 2017

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Share-Based Compensation

We have certain share-based compensation plans. Under the fair value method, compensation cost is measured at the grant date based on the fair value of the award and is recognized over the service period which generally corresponds to the vesting period. Awards under our plans generally vest over periods ranging from one to three years.

The number of shares granted to employees and the weighted average fair value per share during the periods presented were (shares in thousands):



	Six months ended June 30,
	2017			2016
	Shares Granted	Weighted Average Share Fair Value		Shares Granted	Weighted Average Share Fair Value
RSUs subject to performance conditions	1,237	$	10.41	1,257	$	5.66
RSUs subject only to service conditions	395	10.41		433	5.67

Statutory Information	6 Months Ended
Statutory Information	Jun. 30, 2017
Statutory Capital [Abstract]
Statutory Information	Statutory Information Statutory Capital Requirements The insurance laws of 16 jurisdictions, including Wisconsin, our domiciliary state, require a mortgage insurer to maintain a minimum amount of statutory capital relative to the risk in force (or a similar measure) in order for the mortgage insurer to continue to write new business. We refer to these requirements as the “State Capital Requirements.” While they vary among jurisdictions, the most common State Capital Requirements allow for a maximum risk-to-capital ratio of 25 to 1. A risk-to-capital ratio will increase if (i) the percentage decrease in capital exceeds the percentage decrease in insured risk, or (ii) the percentage increase in capital is less than the percentage increase in insured risk. Wisconsin does not regulate capital by using a risk-to-capital measure but instead requires a minimum policyholder position (“MPP”). The “policyholder position” of a mortgage insurer is its net worth or surplus, contingency reserve and a portion of the reserves for unearned premiums. At June 30, 2017, MGIC’s risk-to-capital ratio was 10.2 to 1, below the maximum allowed by the jurisdictions with State Capital Requirements, and its policyholder position was $1.8 billion above the required MPP of $1.1 billion. In calculating our risk-to-capital ratio and MPP, we are allowed full credit for the risk ceded under our reinsurance transactions with a group of unaffiliated reinsurers. It is possible that under the revised State Capital Requirements discussed below, MGIC will not be allowed full credit for the risk ceded to the reinsurers. If MGIC is not allowed an agreed level of credit under either the State Capital Requirements or the financial requirements of the PMIERs, MGIC may terminate the reinsurance transactions, without penalty. At this time, we expect MGIC to continue to comply with the current State Capital Requirements; however, you should read the rest of these financial statement footnotes for information about matters that could negatively affect such compliance. At June 30, 2017, the risk-to-capital ratio of our combined insurance operations (which includes a reinsurance affiliate) was 11.3 to 1. Reinsurance agreements with an affiliate permit MGIC to write insurance with a higher coverage percentage than it could on its own under certain state-specific requirements. A higher risk-to-capital ratio on a combined basis may indicate that, in order for MGIC to continue to utilize reinsurance agreements with its affiliate, additional capital contributions to the reinsurance affiliate could be needed. We ask the Commissioner of Insurance of the State of Wisconsin (the “OCI”) not to object before MGIC pays dividends. In the second quarter of 2017, MGIC paid a $30 million dividend to our holding company. MGIC is subject to statutory regulations as to payment of dividends. The maximum amount of dividends that MGIC may pay in any twelve-month period without regulatory approval by the OCI 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. The 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. The OCI has adopted certain prescribed accounting practices that differ from those found in other states. Specifically, Wisconsin domiciled companies record changes in the contingency reserves through the income statement as changes in underwriting deductions. As a result, in periods in which MGIC is increasing contingency reserves, statutory net income is lowered. For the year ended December 31, 2016, MGIC’s statutory net income was reduced by $490 million to account for the increase in contingency reserves. The NAIC previously announced that it plans to revise the minimum capital and surplus requirements for mortgage insurers that are provided for in its Mortgage Guaranty Insurance Model Act. In May 2016, a working group of state regulators released an exposure draft of a risk-based capital framework to establish capital requirements for mortgage insurers, although no date has been established by which the NAIC must propose revisions to the capital requirements. We are currently evaluating the impact of the framework contained in the exposure draft, including the potential impact of certain items that have not yet been completely addressed by the framework which include: the treatment of ceded risk, minimum capital floors, and action level triggers. While MGIC currently meets the State Capital Requirements of Wisconsin and all other jurisdictions, it could be prevented from writing new business in the future in all jurisdictions if it fails to meet the State Capital Requirements of Wisconsin, or it could be prevented from writing new business in another jurisdiction if it fails to meet the State Capital Requirements of that jurisdiction, and in each case MGIC does not obtain a waiver of such requirements. It is possible that regulatory action by one or more jurisdictions, including those that do not have specific State Capital Requirements, may prevent MGIC from continuing to write new insurance in such jurisdictions. If we are unable to write business in all jurisdictions, lenders may be unwilling to procure insurance from us anywhere. In addition, a lender’s assessment of the future ability of our insurance operations to meet the State Capital Requirements or the PMIERs may affect its willingness to procure insurance from us. A possible future failure by MGIC to meet the State Capital Requirements or the PMIERs will not necessarily mean that MGIC lacks sufficient resources to pay claims on its insurance liabilities. While we believe MGIC has sufficient claims paying resources to meet its claim obligations on its insurance in force on a timely basis, you should read the rest of these financial statement footnotes for information about matters that could negatively affect MGIC’s claims paying resources.

New Accounting Pronouncements (Policies)

6 Months Ended

Jun. 30, 2017

New Accounting Pronouncements and Changes in Accounting Principles [Abstract]

Adopted Accounting Standards and Prospective Accounting Standards

Adopted Accounting Standards

Improvements to Employee Share-Based Compensation Accounting


•	We recognized discrete tax benefits of $1.5 million in the provision for income taxes on our statement of operations for the six months ended June 30, 2017 related to excess tax benefits upon vesting of share-based awards during the period.


•	We recognized a cumulative effect adjustment related to the recognition of a deferred tax asset related to suspended tax benefits from vesting transactions occurring in prior years and from the elimination of our forfeiture estimate on share-based awards, which was previously applied only to awards with service conditions.


•	Prior to adoption, cash flows related to excess tax benefits from share-based compensation were included in financing activities. We have reclassified excess tax benefits related to share-based compensation for the prior year period to operating activities.


•	Prior to adoption, cash flows related to employee taxes paid for withheld shares were included in operating activities. We have reclassified employee taxes paid for withheld shares for the prior year period to financing activities.

Prospective Accounting Standards

Stock Compensation - Scope of Modification Accounting

Premium Amortization on Purchased Callable Debt Securities

Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost

Measurement of Credit Losses on Financial Instruments

Recognition and Measurement of Financial Assets and Financial Liabilities

Debt (Tables)

6 Months Ended

Jun. 30, 2017

Debt Disclosure [Abstract]

Long-term debt

The par value of our long-term debt obligations and their aggregate carrying values as of June 30, 2017 and December 31, 2016 were as follows.



(In millions)	June 30, 2017			December 31, 2016
FHLB Advance	$	155.0		$	155.0
5% Notes	—			145.0
2% Notes	—			207.6
5.75% Notes	425.0			425.0
9% Debentures⁽¹⁾	256.9			256.9
Long-term debt, par value	836.9			1,189.5
Debt issuance costs	(7.0		)	(10.8		)
Long-term debt, carrying value	$	829.9		$	1,178.7

⁽¹⁾

Interest payments made

Interest payments on our debt obligations appear below.



	Six Months Ended June 30,
(In millions)	2017		2016
Revolving credit facility	$	0.5	$	—
FHLB Advance	1.5		0.9
5% Notes	3.6		6.9
2% Notes	2.1		5.0
5.75% Notes	12.9		—
9% Debentures	11.6		15.9
Total interest payments	$	32.2	$	28.7

Reinsurance (Tables)

6 Months Ended

Jun. 30, 2017

Reinsurance Disclosures [Abstract]

Effect of reinsurance agreement

The effect of all of our reinsurance agreements on premiums earned and losses incurred is as follows:



	Three Months Ended June 30,						Six Months Ended June 30,
(In thousands)	2017			2016			2017			2016
Premiums earned:
Direct	$	261,180		$	263,566		$	520,608		$	518,953
Assumed	62			182			160			390
Ceded	(30,106		)	(32,292		)	(60,529		)	(66,546		)
Net premiums earned	$	231,136		$	231,456		$	460,239		$	452,797

Losses incurred:
Direct	$	31,396		$	54,863		$	63,809		$	147,295
Assumed	61			339			166			440
Ceded	(4,118		)	(8,612		)	(9,017		)	(16,133		)
Losses incurred, net	$	27,339		$	46,590		$	54,958		$	131,602

Effect of quota share reinsurance agreements on premiums earned and losses incurred

Following is a summary of our quota share reinsurance agreements, excluding captive agreements discussed below, for the three and six months ended June 30, 2017 and 2016.



	Three Months Ended June 30,				Six Months Ended June 30,
(In thousands)	2017		2016		2017		2016
Ceded premiums written and earned, net of profit commission ⁽¹⁾	$	28,917	$	29,961	$	57,812	$	61,627
Ceded losses incurred	4,424		6,070		9,111		14,583
Ceding commissions ⁽²⁾	12,248		11,946		24,251		23,522
Profit commission	32,325		29,767		63,442		55,982


⁽¹⁾	Under our QSR Transactions, premiums are ceded on an earned and received basis as defined in the agreements.


⁽²⁾	Ceding commissions are reported within Other underwriting and operating expenses, net on the consolidated statements of operations.

Earnings per Share (Tables)

6 Months Ended

Jun. 30, 2017

Earnings Per Share [Abstract]

Calculation of earnings (loss) per share

The following table reconciles the numerators and denominators used to calculate basic and diluted EPS.



	Three Months Ended June 30,				Six Months Ended June 30,
(In thousands, except per share data)	2017		2016		2017		2016
Basic earnings per share:
Net income	$	118,622	$	109,221	$	208,420	$	178,412
Weighted average common shares outstanding - basic	366,918		340,678		354,035		340,411
Basic earnings per share	$	0.32	$	0.32	$	0.59	$	0.52

Diluted earnings per share:
Net income	$	118,622	$	109,221	$	208,420	$	178,412
Interest expense, net of tax ⁽¹⁾:
2% Notes	84		1,982		907		3,964
5% Notes	427		1,728		1,709		4,406
9% Debentures	3,757		3,757		7,514		8,379
Diluted income available to common shareholders	$	122,890	$	116,688	$	218,550	$	195,161

Weighted average common shares outstanding - basic	366,918		340,678		354,035		340,411
Effect of dilutive securities:
Unvested RSUs	1,140		1,209		1,314		1,444
2% Notes	3,827		71,917		16,771		71,917
5% Notes	3,557		13,307		7,154		15,449
9% Debentures	19,028		19,028		19,028		21,133
Weighted average common shares outstanding - diluted	394,470		446,139		398,302		450,354
Diluted earnings per share	$	0.31	$	0.26	$	0.55	$	0.43


⁽¹⁾	Tax effected at a rate of 35%.

Investments (Tables)

6 Months Ended

Jun. 30, 2017

Investments [Abstract]

Amortized cost, gross unrealized gains and losses and fair value of investments portfolio

The amortized cost, gross unrealized gains and losses and fair value of the investment portfolio at June 30, 2017 and December 31, 2016 are shown below.



June 30, 2017
(In thousands)	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses ⁽¹⁾			Fair Value
U.S. Treasury securities and obligations of U.S. government corporations and agencies	$	64,043	$	364	$	(478	)	$	63,929
Obligations of U.S. states and political subdivisions	2,131,471		42,983		(9,165		)	2,165,289
Corporate debt securities	1,823,823		12,699		(8,897		)	1,827,625
ABS	21,988		10		(11		)	21,987
RMBS	209,874		78		(7,612		)	202,340
CMBS	310,997		1,548		(5,467		)	307,078
CLOs	112,769		332		(138		)	112,963
Total debt securities	4,674,965		58,014		(31,768		)	4,701,211
Equity securities	7,183		41		(15		)	7,209
Total investment portfolio	$	4,682,148	$	58,055	$	(31,783	)	$	4,708,420



December 31, 2016
(In thousands)	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses ⁽¹⁾			Fair Value
U.S. Treasury securities and obligations of U.S. government corporations and agencies	$	73,847	$	407	$	(724	)	$	73,530
Obligations of U.S. states and political subdivisions	2,147,458		20,983		(25,425		)	2,143,016
Corporate debt securities	1,756,461		6,059		(18,610		)	1,743,910
ABS	59,519		74		(28		)	59,565
RMBS	231,733		102		(7,626		)	224,209
CMBS	327,042		769		(7,994		)	319,817
CLOs	121,151		226		(202		)	121,175
Total debt securities	4,717,211		28,620		(60,609		)	4,685,222
Equity securities	7,144		8		(24		)	7,128
Total investment portfolio	$	4,724,355	$	28,628	$	(60,633	)	$	4,692,350


⁽¹⁾	At June 30, 2017 and December 31, 2016, there were no other-than-temporary impairment losses recorded in other comprehensive income.

Amortized cost and fair values of debt securities by contractual maturity



June 30, 2017
(In thousands)	Amortized Cost		Fair Value
Due in one year or less	$	341,831	$	342,028
Due after one year through five years	1,356,023		1,362,799
Due after five years through ten years	1,026,851		1,030,223
Due after ten years	1,294,632		1,321,793
	$	4,019,337	$	4,056,843

ABS	21,988		21,987
RMBS	209,874		202,340
CMBS	310,997		307,078
CLOs	112,769		112,963
Total as of June 30, 2017	$	4,674,965	$	4,701,211

Aging of the fair values of securities in an unrealized loss position

For those securities in an unrealized loss position, the length of time the securities were in such a position, as measured by their month-end fair values, is as follows:



June 30, 2017	Less Than 12 Months					12 Months or Greater					Total
(In thousands)	Fair Value		Unrealized Losses			Fair Value		Unrealized Losses			Fair Value		Unrealized Losses
U.S. Treasury securities and obligations of U.S. government corporations and agencies	$	52,769	$	(471	)	$	993	$	(7	)	$	53,762	$	(478	)
Obligations of U.S. states and political subdivisions	622,767		(8,595		)	17,400		(570		)	640,167		(9,165		)
Corporate debt securities	649,134		(7,664		)	27,241		(1,233		)	676,375		(8,897		)
ABS	3,362		(11		)	—		—			3,362		(11		)
RMBS	43,815		(885		)	155,030		(6,727		)	198,845		(7,612		)
CMBS	172,505		(5,439		)	7,237		(28		)	179,742		(5,467		)
CLOs	7,275		(138		)	—		—			7,275		(138		)
Equity securities	455		(7		)	139		(8		)	594		(15		)
Total	$	1,552,082	$	(23,210	)	$	208,040	$	(8,573	)	$	1,760,122	$	(31,783	)



December 31, 2016	Less Than 12 Months					12 Months or Greater					Total
(In thousands)	Fair Value		Unrealized Losses			Fair Value		Unrealized Losses			Fair Value		Unrealized Losses
U.S. Treasury securities and obligations of U.S. government corporations and agencies	$	48,642	$	(724	)	$	—	$	—		$	48,642	$	(724	)
Obligations of U.S. states and political subdivisions	1,136,676		(24,918		)	13,681		(507		)	1,150,357		(25,425		)
Corporate debt securities	915,777		(16,771		)	35,769		(1,839		)	951,546		(18,610		)
ABS	3,366		(28		)	656		—			4,022		(28		)
RMBS	46,493		(857		)	171,326		(6,769		)	217,819		(7,626		)
CMBS	205,545		(7,529		)	38,587		(465		)	244,132		(7,994		)
CLOs	13,278		(73		)	34,760		(129		)	48,038		(202		)
Equity securities	568		(15		)	137		(9		)	705		(24		)
Total	$	2,370,345	$	(50,915	)	$	294,916	$	(9,718	)	$	2,665,261	$	(60,633	)

Net realized investment gains (losses) and OTTI on investments

The net realized investment gains (losses) on the investment portfolio are as follows:



	Three Months Ended June 30,					Six Months Ended June 30,
(In thousands)	2017			2016		2017			2016
Realized investment gains (losses) on investments:
Fixed maturities	$	(52	)	$	831	$	(177	)	$	3,886
Equity securities	10			5		13			6
Net realized investments (losses) gains	$	(42	)	$	836	$	(164	)	$	3,892



	Three Months Ended June 30,						Six Months Ended June 30,
(In thousands)	2017			2016			2017			2016
Realized investment gains (losses) on investments:
Gains on sales	$	644		$	1,404		$	829		$	5,509
Losses on sales	(686		)	(568		)	(993		)	(1,617		)
Net realized investments (losses) gains	$	(42	)	$	836		$	(164	)	$	3,892

Fair Value Measurements (Tables)

6 Months Ended

Jun. 30, 2017

Fair Value Disclosures [Abstract]

Fair value measurements for items measured at fair value

Fair value measurements for assets measured at fair value included the following as of June 30, 2017 and December 31, 2016:

June 30, 2017

(In thousands)	Total Fair Value		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
U.S. Treasury securities and obligations of U.S. government corporations and agencies	$	63,929	$	13,342	$	50,587	$	—
Obligations of U.S. states and political subdivisions	2,165,289		—		2,164,712		577
Corporate debt securities	1,827,625		—		1,827,625		—
ABS	21,987		—		21,987		—
RMBS	202,340		—		202,340		—
CMBS	307,078		—		307,078		—
CLOs	112,963		—		112,963		—
Total debt securities	4,701,211		13,342		4,687,292		577
Equity securities ⁽¹⁾	7,209		2,941		—		4,268
Total investment portfolio	$	4,708,420	$	16,283	$	4,687,292	$	4,845
Real estate acquired ⁽²⁾	$	10,271	$	—	$	—	$	10,271


⁽¹⁾	Equity securities in Level 3 are carried at cost, which approximates fair value.


⁽²⁾	Real estate acquired through claim settlement, which is held for sale, is reported in Other assets on the consolidated balance sheets.

December 31, 2016

(In thousands)	Total Fair Value		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
U.S. Treasury securities and obligations of U.S. government corporations and agencies	$	73,530	$	30,690	$	42,840	$	—
Obligations of U.S. states and political subdivisions	2,143,016		—		2,142,325		691
Corporate debt securities	1,743,910		—		1,743,910		—
ABS	59,565		—		59,565		—
RMBS	224,209		—		224,209		—
CMBS	319,817		—		319,817		—
CLOs	121,175		—		121,175		—
Total debt securities	4,685,222		30,690		4,653,841		691
Equity securities ⁽¹⁾	7,128		2,860		—		4,268
Total investment portfolio	$	4,692,350	$	33,550	$	4,653,841	$	4,959
Real estate acquired ⁽²⁾	$	11,748	$	—	$	—	$	11,748


⁽¹⁾	Equity securities in Level 3 are carried at cost, which approximates fair value.


⁽²⁾	Real estate acquired through claim settlement, which is held for sale, is reported in Other assets on the consolidated balance sheets.

Reconciliation of beginning and ending balance for assets and liabilities measured at fair value with significant unobservable inputs (level 3)



Three Months Ended June 30, 2017
(In thousands)	Debt Securities			Equity Securities		Total Investments			Real Estate Acquired
Balance at March 31, 2017	$	683		$	4,268	$	4,951		$	10,730
Total realized/unrealized gains (losses):
Included in earnings and reported as losses incurred, net	—			—		—			(63		)
Purchases	—			—		—			9,421
Sales	(106		)	—		(106		)	(9,817		)
Balance at June 30, 2017	$	577		$	4,268	$	4,845		$	10,271



Three Months Ended June 30, 2016
(In thousands)	Debt Securities			Equity Securities		Total Investments			Real Estate Acquired
Balance at March 31, 2016	$	1,192		$	3,421	$	4,613		$	12,849
Total realized/unrealized gains (losses):
Included in other comprehensive income	—			3,519		3,519			—
Included in earnings and reported as losses incurred, net	—			—		—			651
Purchases	—			—		—			6,748
Sales	(136		)	—		(136		)	(10,606		)
Balance at June 30, 2016	$	1,056		$	6,940	$	7,996		$	9,642



Six Months Ended June 30, 2017
(In thousands)	Debt Securities			Equity Securities		Total Investments			Real Estate Acquired
Balance at December 31, 2016	$	691		$	4,268	$	4,959		$	11,748
Total realized/unrealized gains (losses):
Included in earnings and reported as losses incurred, net	—			—		—			(226		)
Purchases	—			—		—			18,104
Sales	(114		)	—		(114		)	(19,355		)
Balance at June 30, 2017	$	577		$	4,268	$	4,845		$	10,271



Six Months Ended June 30, 2016
(In thousands)	Debt Securities			Equity Securities			Total Investments			Real Estate Acquired
Balance at December 31, 2015	$	1,228		$	2,855		$	4,083		$	12,149
Total realized/unrealized gains (losses):
Included in other comprehensive income	—			3,519			3,519			—
Included in earnings and reported as losses incurred, net	—			—			—			358
Purchases	—			3,091			3,091			19,015
Sales	(172		)	(2,525		)	(2,697		)	(21,880		)
Balance at June 30, 2016	$	1,056		$	6,940		$	7,996		$	9,642

Carrying value and fair value of debt

The following table presents the carrying value and fair value of our financial liabilities disclosed, but not carried, at fair value at June 30, 2017 and December 31, 2016. The fair values of our 5% Notes, 2% Notes, 5.75% Notes, and 9% Debentures were based on observable market prices. The fair value of the FHLB Advance was estimated using discounted cash flows on current incremental borrowing rates for similar borrowing arrangements. In all cases the fair values of the financial liabilities below are categorized as Level 2.



	June 30, 2017				December 31, 2016
(In thousands)	Carrying Value		Fair Value		Carrying Value		Fair Value
Financial liabilities:
FHLB Advance	155,000		154,140		$	155,000	$	151,905
5% Notes	—		—		144,789		147,679
2% Notes	—		—		204,672		308,605
5.75% Notes	417,983		457,878		417,406		445,987
9% Debentures	256,872		338,190		256,872		323,040
Total financial liabilities	$	829,855	$	950,208	$	1,178,739	$	1,377,216

Other Comprehensive Income (Tables)

6 Months Ended

Jun. 30, 2017

Comprehensive Income (Loss), Net of Tax, Attributable to Parent [Abstract]

Other comprehensive income

The pretax and related income tax (expense) benefit components of our other comprehensive income (loss) for the three and six months ended June 30, 2017 and 2016 are included in the following table.



	Three Months Ended June 30,						Six Months Ended June 30,
(In thousands)	2017			2016			2017			2016
Net unrealized investment gains arising during the period	$	39,614		$	86,674		$	58,261		$	165,058
Income tax expense	(13,865		)	(30,336		)	(20,391		)	(57,893		)
Net of taxes	25,749			56,338			37,870			107,165

Net changes in benefit plan assets and obligations	(220		)	(266		)	(454		)	(740		)
Income tax benefit	78			93			159			259
Net of taxes	(142		)	(173		)	(295		)	(481		)

Net changes in unrealized foreign currency translation adjustment	—			16			45			(1,480		)
Income tax (expense) benefit	—			(5		)	(14		)	516
Net of taxes	—			11			31			(964		)

Total other comprehensive income	39,394			86,424			57,852			162,838
Total income tax expense	(13,787		)	(30,248		)	(20,246		)	(57,118		)
Total other comprehensive income, net of tax	$	25,607		$	56,176		$	37,606		$	105,720

Reclassification out of accumulated other comprehensive income



	Three Months Ended June 30,						Six Months Ended June 30,
(In thousands)	2017			2016			2017			2016
Reclassification adjustment for net realized (losses) gains ⁽¹⁾	$	(1,392	)	$	98		$	(2,139	)	$	710
Income tax benefit (expense)	487			(34		)	748			(126		)
Net of taxes	(905		)	64			(1,391		)	584

Reclassification adjustment related to benefit plan assets and obligations ⁽²⁾	220			266			454			740
Income tax expense	(78		)	(93		)	(159		)	(259		)
Net of taxes	142			173			295			481

Reclassification adjustment related to foreign currency ⁽³⁾	—			—			—			1,467
Income tax expense	—			—			—			(513		)
Net of taxes	—			—			—			954

Total reclassifications	(1,172		)	364			(1,685		)	2,917
Total income tax benefit (expense)	409			(127		)	589			(898		)
Total reclassifications, net of tax	$	(763	)	$	237		$	(1,096	)	$	2,019


⁽¹⁾	Increases (decreases) Net realized investment (losses) gains on the consolidated statements of operations.


⁽²⁾	Decreases (increases) Other underwriting and operating expenses, net on the consolidated statements of operations.


⁽³⁾	Increases (decreases) Other revenue on the consolidated statements of operations.

Accumulated other comprehensive income (loss)

A rollforward of AOCL for the six months ended June 30, 2017, including amounts reclassified from AOCL, are included in the table below.



	Six Months Ended June 30, 2017
(In thousands)	Net unrealized gains and losses on available-for-sale securities			Net benefit plan assets and obligations recognized in shareholders' equity			Net unrealized foreign currency translation			Total AOCL
Balance, December 31, 2016, net of tax	$	(20,797	)	$	(54,272	)	$	(31	)	$	(75,100	)
Other comprehensive income before reclassifications	36,479			—			31			36,510
Less: Amounts reclassified from AOCL	(1,391		)	295			—			(1,096		)
Balance, June 30, 2017, net of tax	$	17,073		$	(54,567	)	$	—		$	(37,494	)

Benefit Plans (Tables)

6 Months Ended

Jun. 30, 2017

Retirement Benefits [Abstract]

Components of net periodic benefit cost



	Three Months Ended June 30,
	Pension and Supplemental Executive Retirement Plans						Other Postretirement Benefit Plans
(In thousands)	2017			2016			2017			2016
Service cost	$	2,484		$	2,402		$	220		$	201
Interest cost	3,879			4,024			186			180
Expected return on plan assets	(5,013		)	(4,865		)	(1,312		)	(1,221		)
Recognized net actuarial loss	1,549			1,567			—			—
Amortization of prior service cost	(106		)	(171		)	(1,663		)	(1,663		)
Net periodic benefit cost (benefit)	$	2,793		$	2,957		$	(2,569	)	$	(2,503	)



	Six Months Ended June 30,
	Pension and Supplemental Executive Retirement Plans						Other Postretirement Benefit Plans
(In thousands)	2017			2016			2017			2016
Service cost	$	4,778		$	4,565		$	407		$	376
Interest cost	7,737			7,953			353			352
Expected return on plan assets	(10,049		)	(9,754		)	(2,624		)	(2,443		)
Recognized net actuarial loss	3,084			2,928			—			—
Amortization of prior service cost	(213		)	(343		)	(3,325		)	(3,325		)
Net periodic benefit cost (benefit)	$	5,337		$	5,349		$	(5,189	)	$	(5,040	)

Loss Reserves (Tables)

6 Months Ended

Jun. 30, 2017

Insurance Loss Reserves [Abstract]

Reconciliation of beginning and ending loss reserves

The following table provides a reconciliation of beginning and ending loss reserves as of and for the six months ended June 30, 2017 and 2016:



	Six months ended June 30,
(In thousands)	2017			2016
Reserve at beginning of period	$	1,438,813		$	1,893,402
Less reinsurance recoverable	50,493			44,487
Net reserve at beginning of period	1,388,320			1,848,915

Losses incurred:
Losses and LAE incurred in respect of default notices received in:
Current year	158,906			196,543
Prior years ⁽¹⁾	(103,948		)	(64,941		)
Total losses incurred	54,958			131,602

Losses paid:
Losses and LAE paid in respect of default notices received in:
Current year	2,125			1,396
Prior years	298,847			392,007
Reinsurance terminations	—			(4		)
Total losses paid	300,972			393,399
Net reserve at end of period	1,142,306			1,587,118
Plus reinsurance recoverables	44,783			45,215
Reserve at end of period	$	1,187,089		$	1,632,333


⁽¹⁾	A negative number for prior year losses incurred indicates a redundancy of prior year loss reserves. See the following table for more information about prior year loss development.

Prior year development of the reserves

The prior year development of the reserves in the first six months of 2017 and 2016 is reflected in the following table.



	Six months ended June 30,
(In millions)	2017			2016
Decrease in estimated claim rate on primary defaults	$	(104	)	$	(76	)
Increase in estimated severity on primary defaults	2			17
Change in estimates related to pool reserves, LAE reserves and reinsurance	(2		)	(6		)
Total prior year loss development ⁽¹⁾	$	(104	)	$	(65	)


⁽¹⁾	A negative number for prior year loss development indicates a redundancy of prior year loss reserves.

Rollforward of primary default inventory



	Three months ended June 30,				Six Months Ended June 30,
	2017		2016		2017		2016
Default inventory at beginning of period	45,349		55,590		50,282		62,633
New notices	14,463		16,080		29,402		32,811
Cures	(14,708	)	(15,640	)	(31,836	)	(34,693	)
Paids (including those charged to a deductible or captive)	(2,573	)	(3,195	)	(5,208	)	(6,568	)
Rescissions and denials	(100	)	(142	)	(195	)	(352	)
Other items removed from inventory	(1,114	)	(135	)	(1,128	)	(1,273	)
Default inventory at end of period	41,317		52,558		41,317		52,558

Aging of the primary default inventory

Historically as a default ages it becomes more likely to result in a claim.

Consecutive months in default

	June 30, 2017			December 31, 2016			June 30, 2016
3 months or less	10,299	25	%	12,194	24	%	11,547	22	%
4 - 11 months	11,018	27	%	13,450	27	%	12,680	24	%
12 months or more ^{(1) (2)}	20,000	48	%	24,638	49	%	28,331	54	%
Total primary default inventory	41,317	100	%	50,282	100	%	52,558	100	%

Primary claims received inventory included in ending default inventory:
	1,258	3	%	1,385	3	%	1,829	3	%


⁽¹⁾	Approximately 46%, 47%, and 49% of the primary default inventory in default for 12 consecutive months or more has been in default for at least 36 consecutive months as of June 30, 2017, December 31, 2016, and June 30, 2016, respectively.


⁽²⁾	The majority of items removed from our default inventory under NPL settlements during the six months ended June 30, 2017 were in default for 12 consecutive months or more as of December 31, 2016.

Number of payments delinquent

The number of payments that a borrower is delinquent is shown in the table below.

Number of payments delinquent

	June 30, 2017			December 31, 2016			June 30, 2016
3 payments or less	15,858	38	%	18,419	36	%	17,299	33	%
4 - 11 payments	10,560	26	%	12,892	26	%	12,746	24	%
12 payments or more ⁽¹⁾	14,899	36	%	18,971	38	%	22,513	43	%
Total primary default inventory	41,317	100	%	50,282	100	%	52,558	100	%


⁽¹⁾	The majority of items removed from our default inventory under NPL settlements during the six months ended June 30, 2017 had 12 or more payments delinquent as of December 31, 2016.

Share-Based Compensation (Tables)

6 Months Ended

Jun. 30, 2017

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Schedule of stock-based compensation, activity

The number of shares granted to employees and the weighted average fair value per share during the periods presented were (shares in thousands):



	Six months ended June 30,
	2017			2016
	Shares Granted	Weighted Average Share Fair Value		Shares Granted	Weighted Average Share Fair Value
RSUs subject to performance conditions	1,237	$	10.41	1,257	$	5.66
RSUs subject only to service conditions	395	10.41		433	5.67

Debt - Narrative (Details) shares in Millions		1 Months Ended		3 Months Ended		6 Months Ended
Debt - Narrative (Details) shares in Millions	May 01, 2017 USD ($)	Apr. 30, 2017 USD ($) shares	Feb. 29, 2016 USD ($)	Jun. 30, 2017 USD ($)	Jun. 30, 2016 USD ($)	Jun. 30, 2017 USD ($)	Jun. 30, 2016 USD ($) shares	Mar. 31, 2017 USD ($)	Mar. 21, 2017 USD ($)
Debt Instrument [Line Items]
Loss on debt extinguishment				$ 65,000	$ 1,868,000	$ 65,000	$ 15,308,000
Repayments of convertible debt						$ 145,620,000	182,846,000
2% Notes
Debt Instrument [Line Items]
Stated interest rate (in hundredths)				2.00%		2.00%
Principal amount of notes converted into shares		$ 202,500,000
Principal amount of notes redeemed for cash		$ 5,100,000
Conversion rate (in shares per $1,000 note)		0.1438332
Loss on debt extinguishment		$ 70,000
Convertible Senior Notes
Debt Instrument [Line Items]
Stated interest rate (in hundredths)				5.00%		5.00%
Repayments of convertible debt	$ 145,000,000						195,500,000
Extinguishment of debt, amount							188,500,000
Convertible Senior Notes \| 2% Convertible Senior Notes
Debt Instrument [Line Items]
Shares issued during period upon conversion of convertible debt (in shares) \| shares		29.1
Line of Credit \| Revolving Credit Facility
Debt Instrument [Line Items]
Maximum borrowing capacity									$ 175,000,000
Revolving credit facility								$ 150,000,000
9% Debentures
Debt Instrument [Line Items]
Stated interest rate (in hundredths)				9.00%		9.00%
Conversion rate (in shares per $1,000 note)						0.0740741
Loss on debt extinguishment			$ 8,300,000
Repayments of convertible debt			150,700,000
Extinguishment of debt, amount			$ 132,700,000
Reacquisition of convertible junior subordinated debentures-equity component							$ 6,300,000
Reduction in shares for computation of earnings per share \| shares							9.8

Debt - Summary of Debt Obligations (Details) $ / shares in Units, $ in Millions	1 Months Ended	6 Months Ended
	Apr. 30, 2017	Jun. 30, 2017 USD ($) $ / shares	Dec. 31, 2016 USD ($)
Debt Instrument [Line Items]
Long-term debt, par value		$ 836.9	$ 1,189.5
Debt issuance costs		(7.0)	(10.8)
Long-term debt, carrying value		829.9	1,178.7
FHLB Advance
Debt Instrument [Line Items]
Long-term debt, par value		155.0	155.0
5% Convertible Senior Notes due 2017
Debt Instrument [Line Items]
Long-term debt, par value		$ 0.0	145.0
Stated interest rate (in hundredths)		5.00%
2% Notes
Debt Instrument [Line Items]
Long-term debt, par value		$ 0.0	207.6
Stated interest rate (in hundredths)		2.00%
Conversion rate (in shares per $1,000 note)	0.1438332
5.75% Notes \| 5.75% Notes
Debt Instrument [Line Items]
Long-term debt, par value		$ 425.0	425.0
Stated interest rate (in hundredths)		5.75%
9% Debentures
Debt Instrument [Line Items]
Long-term debt, par value		$ 256.9	$ 256.9
Stated interest rate (in hundredths)		9.00%
Conversion rate (in shares per $1,000 note)		0.0740741
Convertible debt, conversion price (in dollars per share) \| $ / shares		$ 13.50
Period preceding election to convert (in days)		5 days

Debt - Summary of Interest Paid (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
Debt Instrument [Line Items]
Total interest payments	$ 32.2	$ 28.7
Line of Credit \| Revolving Credit Facility
Debt Instrument [Line Items]
Total interest payments	0.5	0.0
FHLB Advance
Debt Instrument [Line Items]
Total interest payments	1.5	0.9
5% Convertible Senior Notes due 2017
Debt Instrument [Line Items]
Total interest payments	$ 3.6	6.9
Stated interest rate (in hundredths)	5.00%
2% Notes
Debt Instrument [Line Items]
Total interest payments	$ 2.1	5.0
Stated interest rate (in hundredths)	2.00%
5.75% Notes \| 5.75% Notes
Debt Instrument [Line Items]
Total interest payments	$ 12.9	0.0
Stated interest rate (in hundredths)	5.75%
9% Debentures
Debt Instrument [Line Items]
Total interest payments	$ 11.6	$ 15.9
Stated interest rate (in hundredths)	9.00%

Reinsurance - Summary of Premiums Earned and Losses Incurred (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Premiums earned:
Direct	$ 261,180	$ 263,566	$ 520,608	$ 518,953
Assumed	62	182	160	390
Ceded	(30,106)	(32,292)	(60,529)	(66,546)
Net premiums earned	231,136	231,456	460,239	452,797
Losses incurred:
Direct	31,396	54,863	63,809	147,295
Assumed	61	339	166	440
Ceded	(4,118)	(8,612)	(9,017)	(16,133)
Losses incurred, net	$ 27,339	$ 46,590	$ 54,958	$ 131,602

Reinsurance - Narrative (Details) - USD ($)	6 Months Ended
Reinsurance - Narrative (Details) - USD ($)	Jun. 30, 2017	Dec. 31, 2016	Jun. 30, 2016	Dec. 31, 2015
Effects of Reinsurance [Line Items]
Reinsurance recoverable on loss reserves	$ 44,783,000	$ 50,493,000	$ 45,215,000	$ 44,487,000
Period of existing captive reinsurance agreement	10 years
Fair value of trust fund assets under captive agreements	$ 86,000,000	91,000,000
Quota Share Reinsurance Agreement, 2017
Effects of Reinsurance [Line Items]
Contingent termination fee	$ 0
Threshold for private mortgage insurer eligibility requirements for termination election (less than) (as a percent)	90.00%
Quota share for all policies covered (as a percent)	30.00%
Ceding commission, percentage (as a percent)	20.00%
Loss ratio threshold for profit commissions (as a percent)	60.00%
Quota Share Reinsurance Agreement, 2015
Effects of Reinsurance [Line Items]
Contingent termination fee	$ 0
Threshold for private mortgage insurer eligibility requirements for termination election (less than) (as a percent)	90.00%
Quota share for all policies covered (as a percent)	30.00%
Ceding commission, percentage (as a percent)	20.00%
Loss ratio threshold for profit commissions (as a percent)	60.00%
Quota Share Reinsurance Agreements, Excluding Captive Agreements
Effects of Reinsurance [Line Items]
Reinsurance recoverable on loss reserves	$ 33,100,000	31,800,000
Reinsurance Agreements, Captive Agreements
Effects of Reinsurance [Line Items]
Reinsurance recoverable on loss reserves related to captive agreements	$ 12,000,000	$ 19,000,000

Reinsurance - Summary of Quota Reinsurance Arrangements (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Effects of Reinsurance [Line Items]
Ceded losses incurred	$ 4,118	$ 8,612	$ 9,017	$ 16,133
Quota Share Reinsurance Agreements, Excluding Captive Agreements
Effects of Reinsurance [Line Items]
Ceded premiums written and earned, net of profit commission	28,917	29,961	57,812	61,627
Ceded losses incurred	4,424	6,070	9,111	14,583
Ceding commissions	12,248	11,946	24,251	23,522
Profit commission	$ 32,325	$ 29,767	$ 63,442	$ 55,982

Litigation and Contingencies (Details) - USD ($) $ in Millions	6 Months Ended	12 Months Ended
	Jun. 30, 2017	Dec. 31, 2016
Commitments and Contingencies Disclosure [Abstract]
Average paid claim reduction due to curtailments (as a percent)	5.50%	5.50%
Maximum exposure associated with other discussions and legal proceedings	$ 291

Earnings per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Basic earnings per share:
Net income	$ 118,622	$ 109,221	$ 208,420	$ 178,412
Weighted average common shares outstanding - basic (in shares)	366,918	340,678	354,035	340,411
Basic earnings per share (in dollars per share)	$ 0.32	$ 0.32	$ 0.59	$ 0.52
Diluted earnings per share:
Net income	$ 118,622	$ 109,221	$ 208,420	$ 178,412
Diluted income available to common shareholders	$ 122,890	$ 116,688	$ 218,550	$ 195,161
Weighted average common shares outstanding - basic (in shares)	366,918	340,678	354,035	340,411
Effect of dilutive securities:
Weighted average common shares outstanding - diluted (in shares)	394,470	446,139	398,302	450,354
Diluted earnings per share (in dollars per share)	$ 0.31	$ 0.26	$ 0.55	$ 0.43
Effective income tax rate (in hundredths)	35.00%	35.00%	35.00%	35.00%
Unvested RSUs
Effect of dilutive securities:
Unvested RSUs (in shares)	1,140	1,209	1,314	1,444
2% Notes
Diluted earnings per share:
Dilutive securities	$ 84	$ 1,982	$ 907	$ 3,964
Effect of dilutive securities:
Dilutive securities (in shares)	3,827	71,917	16,771	71,917
Stated interest rate (in hundredths)	2.00%		2.00%
5% Notes
Diluted earnings per share:
Dilutive securities	$ 427	$ 1,728	$ 1,709	$ 4,406
Effect of dilutive securities:
Dilutive securities (in shares)	3,557	13,307	7,154	15,449
Stated interest rate (in hundredths)	5.00%		5.00%
9% Debentures
Diluted earnings per share:
Dilutive securities	$ 3,757	$ 3,757	$ 7,514	$ 8,379
Effect of dilutive securities:
Dilutive securities (in shares)	19,028	19,028	19,028	21,133
Stated interest rate (in hundredths)	9.00%		9.00%

Investments (Details)	3 Months Ended		6 Months Ended		12 Months Ended
Investments (Details)	Jun. 30, 2017 USD ($) security	Jun. 30, 2016 USD ($)	Jun. 30, 2017 USD ($) security	Jun. 30, 2016 USD ($)	Dec. 31, 2016 USD ($) security
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 4,682,148,000		$ 4,682,148,000		$ 4,724,355,000
Gross Unrealized Gains	58,055,000		58,055,000		28,628,000
Gross Unrealized Losses	(31,783,000)		(31,783,000)		(60,633,000)
Fair Value	4,708,420,000		4,708,420,000		4,692,350,000
Other than Temporary Impairment Losses, Portion in Other Comprehensive Income			$ 0		0
Federal Home Loan Bank advances, collateral, value of principal, percent (as a percent)			102.00%
FHLB advance collateral	165,900,000		$ 165,900,000
Gross accumulated unrealized gain (losses) on available-for-sale securities	$ (31,800,000)		$ (31,800,000)		$ (60,600,000)
Number of securities in unrealized loss position (in securities) \| security	404		404		607
Net impairment losses recognized in earnings	$ 0	$ 0	$ 0	$ 0
Total debt securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	4,674,965,000		4,674,965,000		$ 4,717,211,000
Gross Unrealized Gains	58,014,000		58,014,000		28,620,000
Gross Unrealized Losses	(31,768,000)		(31,768,000)		(60,609,000)
Fair Value	4,701,211,000		4,701,211,000		4,685,222,000
U.S. Treasury securities and obligations of U.S. government corporations and agencies
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	64,043,000		64,043,000		73,847,000
Gross Unrealized Gains	364,000		364,000		407,000
Gross Unrealized Losses	(478,000)		(478,000)		(724,000)
Fair Value	63,929,000		63,929,000		73,530,000
Obligations of U.S. states and political subdivisions
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	2,131,471,000		2,131,471,000		2,147,458,000
Gross Unrealized Gains	42,983,000		42,983,000		20,983,000
Gross Unrealized Losses	(9,165,000)		(9,165,000)		(25,425,000)
Fair Value	2,165,289,000		2,165,289,000		2,143,016,000
Corporate debt securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	1,823,823,000		1,823,823,000		1,756,461,000
Gross Unrealized Gains	12,699,000		12,699,000		6,059,000
Gross Unrealized Losses	(8,897,000)		(8,897,000)		(18,610,000)
Fair Value	1,827,625,000		1,827,625,000		1,743,910,000
ABS
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	21,988,000		21,988,000		59,519,000
Gross Unrealized Gains	10,000		10,000		74,000
Gross Unrealized Losses	(11,000)		(11,000)		(28,000)
Fair Value	21,987,000		21,987,000		59,565,000
RMBS
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	209,874,000		209,874,000		231,733,000
Gross Unrealized Gains	78,000		78,000		102,000
Gross Unrealized Losses	(7,612,000)		(7,612,000)		(7,626,000)
Fair Value	202,340,000		202,340,000		224,209,000
CMBS
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	310,997,000		310,997,000		327,042,000
Gross Unrealized Gains	1,548,000		1,548,000		769,000
Gross Unrealized Losses	(5,467,000)		(5,467,000)		(7,994,000)
Fair Value	307,078,000		307,078,000		319,817,000
CLOs
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	112,769,000		112,769,000		121,151,000
Gross Unrealized Gains	332,000		332,000		226,000
Gross Unrealized Losses	(138,000)		(138,000)		(202,000)
Fair Value	112,963,000		112,963,000		121,175,000
Equity securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	7,183,000		7,183,000		7,144,000
Gross Unrealized Gains	41,000		41,000		8,000
Gross Unrealized Losses	(15,000)		(15,000)		(24,000)
Fair Value	$ 7,209,000		$ 7,209,000		$ 7,128,000

Investments - Amortized Cost and Fair Values of Debt Securities (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Amortized Cost
Due in one year or less	$ 341,831
Due after one year through five years	1,356,023
Due after five years through ten years	1,026,851
Due after ten years	1,294,632
Total debt securities with single maturity date, amortized cost	4,019,337
Total at end of period	4,674,965	$ 4,717,211
Fair Value
Due in one year or less	342,028
Due after one year through five years	1,362,799
Due after five years through ten years	1,030,223
Due after ten years	1,321,793
Total debt securities with single maturity date, fair value	4,056,843
Total at end of period	4,701,211	$ 4,685,222
ABS
Amortized Cost
Total debt securities without single maturity date, amortized cost	21,988
Fair Value
Total debt securities without single maturity date, fair value	21,987
RMBS
Amortized Cost
Total debt securities without single maturity date, amortized cost	209,874
Fair Value
Total debt securities without single maturity date, fair value	202,340
CMBS
Amortized Cost
Total debt securities without single maturity date, amortized cost	310,997
Fair Value
Total debt securities without single maturity date, fair value	307,078
CLOs
Amortized Cost
Total debt securities without single maturity date, amortized cost	112,769
Fair Value
Total debt securities without single maturity date, fair value	$ 112,963

Investments - Securities In Unrealized Loss Position (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Continuous Unrealized Loss Portion, Fair Value [Abstract]
Less than 12 months	$ 1,552,082	$ 2,370,345
12 months or greater	208,040	294,916
Total investment portfolio	1,760,122	2,665,261
Continuous Unrealized Loss Portion, Unrealized Loses [Abstract]
Less than 12 months	(23,210)	(50,915)
12 months or greater	(8,573)	(9,718)
Total investment portfolio	(31,783)	(60,633)
U.S. Treasury securities and obligations of U.S. government corporations and agencies
Continuous Unrealized Loss Portion, Fair Value [Abstract]
Less than 12 months	52,769	48,642
12 months or greater	993	0
Total investment portfolio	53,762	48,642
Continuous Unrealized Loss Portion, Unrealized Loses [Abstract]
Less than 12 months	(471)	(724)
12 months or greater	(7)	0
Total investment portfolio	(478)	(724)
Obligations of U.S. states and political subdivisions
Continuous Unrealized Loss Portion, Fair Value [Abstract]
Less than 12 months	622,767	1,136,676
12 months or greater	17,400	13,681
Total investment portfolio	640,167	1,150,357
Continuous Unrealized Loss Portion, Unrealized Loses [Abstract]
Less than 12 months	(8,595)	(24,918)
12 months or greater	(570)	(507)
Total investment portfolio	(9,165)	(25,425)
Corporate debt securities
Continuous Unrealized Loss Portion, Fair Value [Abstract]
Less than 12 months	649,134	915,777
12 months or greater	27,241	35,769
Total investment portfolio	676,375	951,546
Continuous Unrealized Loss Portion, Unrealized Loses [Abstract]
Less than 12 months	(7,664)	(16,771)
12 months or greater	(1,233)	(1,839)
Total investment portfolio	(8,897)	(18,610)
ABS
Continuous Unrealized Loss Portion, Fair Value [Abstract]
Less than 12 months	3,362	3,366
12 months or greater	0	656
Total investment portfolio	3,362	4,022
Continuous Unrealized Loss Portion, Unrealized Loses [Abstract]
Less than 12 months	(11)	(28)
12 months or greater	0	0
Total investment portfolio	(11)	(28)
RMBS
Continuous Unrealized Loss Portion, Fair Value [Abstract]
Less than 12 months	43,815	46,493
12 months or greater	155,030	171,326
Total investment portfolio	198,845	217,819
Continuous Unrealized Loss Portion, Unrealized Loses [Abstract]
Less than 12 months	(885)	(857)
12 months or greater	(6,727)	(6,769)
Total investment portfolio	(7,612)	(7,626)
CMBS
Continuous Unrealized Loss Portion, Fair Value [Abstract]
Less than 12 months	172,505	205,545
12 months or greater	7,237	38,587
Total investment portfolio	179,742	244,132
Continuous Unrealized Loss Portion, Unrealized Loses [Abstract]
Less than 12 months	(5,439)	(7,529)
12 months or greater	(28)	(465)
Total investment portfolio	(5,467)	(7,994)
CLOs
Continuous Unrealized Loss Portion, Fair Value [Abstract]
Less than 12 months	7,275	13,278
12 months or greater	0	34,760
Total investment portfolio	7,275	48,038
Continuous Unrealized Loss Portion, Unrealized Loses [Abstract]
Less than 12 months	(138)	(73)
12 months or greater	0	(129)
Total investment portfolio	(138)	(202)
Equity securities
Continuous Unrealized Loss Portion, Fair Value [Abstract]
Less than 12 months	455	568
12 months or greater	139	137
Total investment portfolio	594	705
Continuous Unrealized Loss Portion, Unrealized Loses [Abstract]
Less than 12 months	(7)	(15)
12 months or greater	(8)	(9)
Total investment portfolio	$ (15)	$ (24)

Investments - Gain (Loss) on Investments (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Gain (Loss) on Investments [Line Items]
Realized investment gains (losses) on investments:	$ (42)	$ 836	$ (164)	$ 3,892
Realized investment gains (losses) on investments:
Gains on sales	644	1,404	829	5,509
Losses on sales	(686)	(568)	(993)	(1,617)
Net realized investment (losses) gains	(42)	836	(164)	3,892
Fixed maturities
Gain (Loss) on Investments [Line Items]
Realized investment gains (losses) on investments:	(52)	831	(177)	3,886
Realized investment gains (losses) on investments:
Net realized investment (losses) gains	(52)	831	(177)	3,886
Equity securities
Gain (Loss) on Investments [Line Items]
Realized investment gains (losses) on investments:	10	5	13	6
Realized investment gains (losses) on investments:
Net realized investment (losses) gains	$ 10	$ 5	$ 13	$ 6

- Definition

This item represents the net total realized and unrealized gain (loss) included in earnings for the period as a result of selling or holding marketable securities categorized as trading, available-for-sale, or held-to-maturity, including the unrealized holding gain (loss) of held-to-maturity securities transferred to the trading security category and the cumulative unrealized gain (loss) which was included in other comprehensive income (a separate component of shareholders' equity) for available-for-sale securities transferred to trading securities during the period. Additionally, this item would include any gains (losses) realized during the period from the sale of investments accounted for under the cost method of accounting and losses recognized for other than temporary impairments (OTTI) of the subject investments.

+ References + Details

Fair Value Measurements (Details) - USD ($) $ in Thousands	6 Months Ended
Fair Value Measurements (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Fair Value Disclosures [Abstract]
State premium tax credit investments, maturity (in years)	2 years
Annual average discount rate (as a percent)	7.10%
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
U.S. Treasury securities and obligations of U.S. government corporations and agencies	$ 63,929	$ 73,530
Obligations of U.S. states and political subdivisions	2,165,289	2,143,016
Corporate debt securities	1,827,625	1,743,910
ABS	21,987	59,565
RMBS	202,340	224,209
CMBS	307,078	319,817
CLOs	112,963	121,175
Total debt securities	4,701,211	4,685,222
Equity securities	7,209	7,128
Total investment portfolio	4,708,420	4,692,350
Real estate acquired	10,271	11,748
Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
U.S. Treasury securities and obligations of U.S. government corporations and agencies	13,342	30,690
Obligations of U.S. states and political subdivisions	0	0
Corporate debt securities	0	0
ABS	0	0
RMBS	0	0
CMBS	0	0
CLOs	0	0
Total debt securities	13,342	30,690
Equity securities	2,941	2,860
Total investment portfolio	16,283	33,550
Real estate acquired	0	0
Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
U.S. Treasury securities and obligations of U.S. government corporations and agencies	50,587	42,840
Obligations of U.S. states and political subdivisions	2,164,712	2,142,325
Corporate debt securities	1,827,625	1,743,910
ABS	21,987	59,565
RMBS	202,340	224,209
CMBS	307,078	319,817
CLOs	112,963	121,175
Total debt securities	4,687,292	4,653,841
Equity securities	0	0
Total investment portfolio	4,687,292	4,653,841
Real estate acquired	0	0
Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
U.S. Treasury securities and obligations of U.S. government corporations and agencies	0	0
Obligations of U.S. states and political subdivisions	577	691
Corporate debt securities	0	0
ABS	0	0
RMBS	0	0
CMBS	0	0
CLOs	0	0
Total debt securities	577	691
Equity securities	4,268	4,268
Total investment portfolio	4,845	4,959
Real estate acquired	$ 10,271	$ 11,748

Fair Value Measurements - Unobservable Input Reconciliation (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Total Investments
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at beginning of period	$ 4,951	$ 4,613	$ 4,959	$ 4,083
Total realized/unrealized gains (losses):
Included in other comprehensive income		3,519		3,519
Included in earnings and reported as losses incurred, net	0	0	0	0
Purchases	0	0	0	3,091
Sales	(106)	(136)	(114)	(2,697)
Balance at end of period	4,845	7,996	4,845	7,996
Debt Securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at beginning of period	683	1,192	691	1,228
Total realized/unrealized gains (losses):
Included in other comprehensive income		0		0
Included in earnings and reported as losses incurred, net	0	0	0	0
Purchases	0	0	0	0
Sales	(106)	(136)	(114)	(172)
Balance at end of period	577	1,056	577	1,056
Equity securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at beginning of period	4,268	3,421	4,268	2,855
Total realized/unrealized gains (losses):
Included in other comprehensive income		3,519		3,519
Included in earnings and reported as losses incurred, net	0	0	0	0
Purchases	0	0	0	3,091
Sales	0	0	0	(2,525)
Balance at end of period	4,268	6,940	4,268	6,940
Real Estate Acquired
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at beginning of period	10,730	12,849	11,748	12,149
Total realized/unrealized gains (losses):
Included in other comprehensive income		0		0
Included in earnings and reported as losses incurred, net	(63)	651	(226)	358
Purchases	9,421	6,748	18,104	19,015
Sales	(9,817)	(10,606)	(19,355)	(21,880)
Balance at end of period	$ 10,271	$ 9,642	$ 10,271	$ 9,642

Fair Value Measurements - Liabilities Not Measured at Fair Value (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
5% Convertible Senior Notes due 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Stated interest rate (in hundredths)	5.00%
2% Notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Stated interest rate (in hundredths)	2.00%
Senior Notes \| 5.75% Notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Stated interest rate (in hundredths)	5.75%
9% Debentures
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Stated interest rate (in hundredths)	9.00%
Carrying Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
FHLB Advance	$ 155,000	$ 155,000
5% Notes	0	144,789
2% Notes	0	204,672
5.75% Notes	417,983	417,406
9% Debentures	256,872	256,872
Total financial liabilities	829,855	1,178,739
Fair Value \| Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
FHLB Advance	154,140	151,905
5% Notes	0	147,679
2% Notes	0	308,605
5.75% Notes	457,878	445,987
9% Debentures	338,190	323,040
Total financial liabilities	$ 950,208	$ 1,377,216

Other Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Total other comprehensive income	$ 39,394	$ 86,424	$ 57,852	$ 162,838
Income tax (benefit)	(13,787)	(30,248)	(20,246)	(57,118)
Other comprehensive income, net of tax	25,607	56,176	37,606	105,720
Amounts Reclassified From Accumulated Other Comprehensive Income [Abstract]
Net realized investment (losses) gains	(42)	836	(164)	3,892
Other underwriting and operating expenses, net	(38,511)	(35,348)	(79,276)	(75,125)
Other revenue	2,502	3,994	4,924	10,367
Income before tax	180,616	165,239	354,573	268,927
Income tax benefit (expense)	(61,994)	(56,018)	(146,153)	(90,515)
Net income	118,622	109,221	208,420	178,412
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance, beginning of period			2,548,842
Other comprehensive income before reclassifications			36,510
Less: Amounts reclassified from AOCL			(1,096)
Balance, end of period	2,995,061	2,515,092	2,995,061	2,515,092
Reclassification from Accumulated Other Comprehensive Income
Amounts Reclassified From Accumulated Other Comprehensive Income [Abstract]
Income before tax	(1,172)	364	(1,685)	2,917
Income tax benefit (expense)	409	(127)	589	(898)
Net income	(763)	237	(1,096)	2,019
Accumulated other comprehensive loss
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other comprehensive income, net of tax			37,606	105,720
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance, beginning of period			(75,100)	(60,880)
Balance, end of period	(37,494)	44,840	(37,494)	44,840
Net unrealized gains and losses on available-for-sale securities
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Total other comprehensive income	39,614	86,674	58,261	165,058
Income tax (benefit)	(13,865)	(30,336)	(20,391)	(57,893)
Other comprehensive income, net of tax	25,749	56,338	37,870	107,165
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance, beginning of period			(20,797)
Other comprehensive income before reclassifications			36,479
Less: Amounts reclassified from AOCL			(1,391)
Balance, end of period	17,073		17,073
Net unrealized gains and losses on available-for-sale securities \| Reclassification from Accumulated Other Comprehensive Income
Amounts Reclassified From Accumulated Other Comprehensive Income [Abstract]
Net realized investment (losses) gains	(1,392)	98	(2,139)	710
Income tax benefit (expense)	487	(34)	748	(126)
Net income	(905)	64	(1,391)	584
Net benefit plan assets and obligations recognized in shareholders' equity
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Total other comprehensive income	(220)	(266)	(454)	(740)
Income tax (benefit)	78	93	159	259
Other comprehensive income, net of tax	(142)	(173)	(295)	(481)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance, beginning of period			(54,272)
Other comprehensive income before reclassifications			0
Less: Amounts reclassified from AOCL			295
Balance, end of period	(54,567)		(54,567)
Net benefit plan assets and obligations recognized in shareholders' equity \| Reclassification from Accumulated Other Comprehensive Income
Amounts Reclassified From Accumulated Other Comprehensive Income [Abstract]
Other underwriting and operating expenses, net	220	266	454	740
Income tax benefit (expense)	(78)	(93)	(159)	(259)
Net income	142	173	295	481
Net unrealized foreign currency translation
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Total other comprehensive income	0	16	45	(1,480)
Income tax (benefit)	0	(5)	(14)	516
Other comprehensive income, net of tax	0	11	31	(964)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance, beginning of period			(31)
Other comprehensive income before reclassifications			31
Less: Amounts reclassified from AOCL			0
Balance, end of period	0		0
Net unrealized foreign currency translation \| Reclassification from Accumulated Other Comprehensive Income
Amounts Reclassified From Accumulated Other Comprehensive Income [Abstract]
Other revenue	0	0	0	1,467
Income tax benefit (expense)	0	0	0	(513)
Net income	$ 0	$ 0	$ 0	$ 954

Benefit Plans (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
Benefit Plans (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Pension and Supplemental Executive Retirement Plans
Components of Net Periodic Benefit Cost [Abstract]
Service cost	$ 2,484	$ 2,402	$ 4,778	$ 4,565
Interest cost	3,879	4,024	7,737	7,953
Expected return on plan assets	(5,013)	(4,865)	(10,049)	(9,754)
Recognized net actuarial loss	1,549	1,567	3,084	2,928
Amortization of prior service cost	(106)	(171)	(213)	(343)
Net periodic benefit cost (benefit)	2,793	2,957	5,337	5,349
Estimated future employer contributions in current fiscal year	9,400		9,400
Other Postretirement Benefit Plans
Components of Net Periodic Benefit Cost [Abstract]
Service cost	220	201	407	376
Interest cost	186	180	353	352
Expected return on plan assets	(1,312)	(1,221)	(2,624)	(2,443)
Recognized net actuarial loss	0	0	0	0
Amortization of prior service cost	(1,663)	(1,663)	(3,325)	(3,325)
Net periodic benefit cost (benefit)	$ (2,569)	$ (2,503)	$ (5,189)	$ (5,040)

Income Taxes (Details) - USD ($)	6 Months Ended	12 Months Ended
Income Taxes (Details) - USD ($)	Jun. 30, 2017	Dec. 31, 2007	Dec. 31, 2016	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Net operating loss carryforwards, regular tax basis	$ 1,200,000,000
Net operating loss carryforwards for computing the alternative minimum tax	300,000,000
Valuation allowance	0		$ 0
Information regarding income tax examinations [Abstract]
Amount of IRS assessment for unpaid taxes and penalties related to REMIC issue				$ 197,500,000
Estimate of federal interest that may be due	195,700,000
Amount of payment made related to the IRS assessment on the REMIC issue		$ 65,200,000
Amount of IRS assessment for unpaid taxes and penalties related to disallowance of carryback of 2009 net operating loss				$ 261,400,000
Estimate of additional state income taxes and interest that may be due	82,400,000
Total amount of unrecognized tax benefits	140,800,000
Provision for additional taxes and interest recorded	27,800,000
Total amount of the unrecognized tax benefits that would affect our effective tax rate	119,100,000
Unrecognized tax benefits, accrued interest	$ 49,900,000		$ 28,900,000

Loss Reserves - Reconciliation of Beginning and Ending Balances (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
Loss Reserve [Roll Forward]
Reserve at beginning of period	$ 1,438,813	$ 1,893,402
Less reinsurance recoverable	50,493	44,487
Net reserve at beginning of period	1,388,320	1,848,915
Losses and LAE incurred in respect of default notices received in:
Current year	158,906	196,543
Prior years	(103,948)	(64,941)
Total losses incurred	54,958	131,602
Losses and LAE paid in respect of default notices received in:
Current year	2,125	1,396
Prior years	298,847	392,007
Reinsurance terminations	0	(4)
Total losses paid	300,972	393,399
Net reserve at end of period	1,142,306	1,587,118
Plus reinsurance recoverables	44,783	45,215
Reserve at end of period	$ 1,187,089	$ 1,632,333

Loss Reserves (Details) $ in Thousands	3 Months Ended		6 Months Ended
Loss Reserves (Details) $ in Thousands	Jun. 30, 2017 USD ($) loan	Jun. 30, 2016 loan	Jun. 30, 2017 USD ($) loan	Jun. 30, 2016 USD ($) loan	Dec. 31, 2016 USD ($)
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Other items removed from inventory (in loans)	(1,114)	(135)	(1,128)	(1,273)
Prior years \| $			$ 298,847	$ 392,007
Premium refund liability, expected claim payments \| $	$ 74,000		74,000		$ 85,000
Prior years \| $			$ (103,948)	$ (64,941)
Primary Default Inventory [Roll Forward]
Default inventory at the beginning of period (in loans)	45,349	55,590	50,282	62,633
New notices (in loans)	14,463	16,080	29,402	32,811
Cures (in loans)	(14,708)	(15,640)	(31,836)	(34,693)
Paids (including those charged to a deductible or captive) (in loans)	(2,573)	(3,195)	(5,208)	(6,568)
Rescissions and denials (in loans)	(100)	(142)	(195)	(352)
Other items removed from inventory (in loans)	(1,114)	(135)	(1,128)	(1,273)
Default inventory at end of period (in loans)	41,317	52,558	41,317	52,558
Decrease in estimated claim rate on primary defaults
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Percentage of prior year default inventory resolved (as a percent)			48.00%	43.00%
Prior years \| $			$ (104,000)	$ (76,000)
Increase in estimated severity on primary defaults
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Prior years \| $			2,000	17,000
Change in estimates related to pool reserves, LAE reserves and reinsurance
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Prior years \| $			(2,000)	(6,000)
Settlements for claims paying practices and nonperforming loan sale
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Prior years \| $			$ 45,000	$ 51,000

Loss Reserves - Delinquent Items (Details) - loan	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015
Aging of the Primary Default Inventory [Abstract]
3 months or less (in loans)	10,299		12,194	11,547
3 months or less (as a percent)	25.00%		24.00%	22.00%
4 - 11 months (in loans)	11,018		13,450	12,680
4 - 11 months (as a percent)	27.00%		27.00%	24.00%
12 months or more (in loans)	20,000		24,638	28,331
12 months or more (as a percent)	48.00%		49.00%	54.00%
Total primary default inventory (in loans)	41,317	45,349	50,282	52,558	55,590	62,633
Total primary default inventory (as a percent)	100.00%		100.00%	100.00%
Primary claims received inventory included in ending default inventory (in loans)	1,258		1,385	1,829
Primary claims received inventory included in ending default inventory (as a percent)	3.00%		3.00%	3.00%
Percent of default inventory in default for more than 36 months (as a percent)	46.00%		47.00%	49.00%
Number of payments delinquent [Abstract]
3 payments or less (in loans)	15,858		18,419	17,299
3 payments or less (as a percent)	38.00%		36.00%	33.00%
4 - 11 payments (in loans)	10,560		12,892	12,746
4 - 11 payments (as a percent)	26.00%		26.00%	24.00%
12 payments or more (in loans)	14,899		18,971	22,513
12 payments or more (as a percent)	36.00%		38.00%	43.00%
Total primary default inventory (in loans)	41,317	45,349	50,282	52,558	55,590	62,633
Total primary default inventory (as a percent)	100.00%		100.00%	100.00%
Pool insurance notice inventory (in number of loans)	1,511		1,883	2,024

Shareholders' Equity (Details) - USD ($) $ / shares in Units, $ in Millions		1 Months Ended
	Jul. 23, 2015	Apr. 30, 2017	Jun. 30, 2017
Class of Warrant or Right [Line Items]
Common stock, beneficial ownership threshold to be considered an Acquiring Person (as a percent)	5.00%
Common shares purchasable per Right (in shares)	0.1
Shareholder rights accompanying each outstanding share of the company's common stock (in number of Rights)	1
Purchase price (in dollars per share)	$ 45
Purchase price (in dollars per share)	4.50
Redemption price (in dollars per Right)	$ 0.001
Rights
Class of Warrant or Right [Line Items]
Number of rights per outstanding share of common stock (in shares)	1
Period after public announcement that a person has become an acquirer (in days)	10 days
Period after a person announces a tender offer which would make them an acquirer (in days)	10 days
2% Notes
Class of Warrant or Right [Line Items]
Stated interest rate (in hundredths)			2.00%
Principal amount of notes converted into shares		$ 202.5
Convertible Senior Notes
Class of Warrant or Right [Line Items]
Stated interest rate (in hundredths)			5.00%
Convertible Senior Notes \| 2% Convertible Senior Notes
Class of Warrant or Right [Line Items]
Shares issued during period upon conversion of convertible debt (in shares)		29,100,000
Treasury stock reissued during period upon conversion of notes (in shares)		18,700,000
Stock issued during period upon conversion of notes (in shares)		10,400,000

Share-Based Compensation (Details) - $ / shares shares in Thousands	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
RSUs subject to performance conditions
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in shares)	1,237	1,257
Weighted Average Share Fair Value (in dollars per share)	$ 10.41	$ 5.66
RSUs subject only to service conditions
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in shares)	395	433
Weighted Average Share Fair Value (in dollars per share)	$ 10.41	$ 5.67
Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period (in years)	1 year
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period (in years)	3 years

Statutory Information (Details) $ in Millions	3 Months Ended	6 Months Ended	12 Months Ended
Statutory Information (Details) $ in Millions	Jun. 30, 2017 USD ($) jurisdiction	Jun. 30, 2017 USD ($) jurisdiction	Dec. 31, 2016 USD ($)
Statutory capital requirements [Abstract]
Number of jurisdictions with risk-to-capital requirements (in jurisdictions) \| jurisdiction	16	16
Maximum permitted risk-to-capital ratio commonly applied		25 to 1
Risk to capital ratio of combined insurance operations, including reinsurance affiliates, at end of period		11.3 to 1
Risk-to-capital ratio for combined insurance operations	11.3	11.3
Percentage of statutory policyholders surplus used to determine maximum allowable dividends (as a percent)	10.00%	10.00%
Mortgage Guaranty Insurance Corporation
Statutory capital requirements [Abstract]
Maximum risk-to-capital ratio		25
Risk to capital ratio at end of period		10.2 to 1
Risk-to-capital ratio	10.2	10.2
Amount of policyholders position above or below required MPP	$ 1,800	$ 1,800
Amount of required MPP	1,100	$ 1,100
Cash dividends paid	$ 30
Adjusted statutory net income measurement period (in years)		3 years
Adjusted statutory net income dividend payment measurement period (in years)		2 years
Reduction in statutory net income due to increase in contingency reserve			$ 490

New Accounting Pronouncements (Details) $ in Millions	6 Months Ended
New Accounting Pronouncements (Details) $ in Millions	Jun. 30, 2017 USD ($)
New Accounting Pronouncements and Changes in Accounting Principles [Abstract]
Discrete tax benefits realized upon adoption of ASU	$ 1.5