MGIC Investment (MTG) 10-K 23 Feb 21 2020 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($) $ in Billions	12 Months Ended
	Dec. 31, 2020	Feb. 19, 2021	Jun. 30, 2020
Cover [Abstract]
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2020
Document Transition Report	false
Entity File Number	1-10816
Entity Registrant Name	MGIC Investment Corp
Entity Incorporation, State or Country Code	WI
Entity Tax Identification Number	39-1486475
Entity Address, Address Line One	250 E. Kilbourn Avenue
Entity Address, Postal Zip Code	53202
Entity Address, City or Town	Milwaukee,
Entity Address, State or Province	WI
City Area Code	(414)
Local Phone Number	347-6480
Title of 12(b) Security	Common stock, par value $1 per share
Trading Symbol	MTG
Security Exchange Name	NYSE
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
ICFR Auditor Attestation Flag	true
Entity Shell Company	false
Entity Public Float			$ 2.8
Entity Common Stock, Shares Outstanding		338,779,666
Documents Incorporated by Reference	The following documents have been incorporated by reference in this Form 10-K, as indicated: Document Part and Item Number of Form 10-K Into Which Incorporated* Proxy Statement for the 2021 Annual Meeting of Shareholders, provided such Proxy Statement is filed within 120 days after December 31, 2020. If not so filed, the information provided in Items 10 through 14 of Part III will be included in an amended Form 10-K filed within such 120 day period. Items 10 through 14 of Part III * In each case, to the extent provided in the Items listed.
Entity Central Index Key	0000876437
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	FY
Amendment Flag	false

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Investment portfolio:
Fixed income, available-for-sale, at fair value (amortized cost, 2020 - $6,317,164; 2019 - $5,562,550)	$ 6,661,596	$ 5,737,892
Equity securities, at fair value (cost, 2020 - $17,522; 2019 - $17,188)	18,215	17,328
Other invested assets, at cost	3,100	3,100
Total investment portfolio	6,682,911	5,758,320
Cash and cash equivalents	287,953	161,847
Restricted cash and cash equivalents	8,727	7,209
Accrued investment income	49,997	49,705
Reinsurance recoverable on loss reserves	95,042	21,641
Reinsurance recoverable on paid losses	669	1,521
Premiums receivable	56,044	55,587
Home office and equipment, net	47,144	50,121
Deferred insurance policy acquisition costs	21,561	18,531
Other assets	104,478	105,089
Total assets	7,354,526	6,229,571
Liabilities:
Loss reserves	880,537	555,334
Unearned premiums	287,099	380,302
Federal Home Loan Bank Advance	155,000	155,000
Senior notes	879,379	420,867
Convertible junior subordinated debentures	208,814	256,872
Other liabilities	244,711	151,962
Total liabilities	2,655,540	1,920,337
Contingencies
Shareholders' equity:
Common stock (one dollar par value, shares authorized 1,000,000; shares issued 2020 - 371,353; 2019 - 371,353; outstanding 2020 - 338,573; 2019 - 347,308)	371,353	371,353
Paid-in capital	1,862,042	1,869,719
Treasury stock (shares at cost 2020 - 32,779; 2019 - 24,045)	(393,326)	(283,196)
Accumulated other comprehensive income, net of tax	216,821	72,708
Retained earnings	2,642,096	2,278,650
Total shareholders' equity	4,698,986	4,309,234
Total liabilities and shareholders' equity	$ 7,354,526	$ 6,229,571

CONSOLIDATED BALANCE SHEETS (Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Statement of Financial Position [Abstract]
Fixed income, amortized cost	$ 6,317,164	$ 5,562,550
Equity securities, cost	$ 17,522	$ 17,188
Shareholders' equity:
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)	371,353,000	371,353,000
Common stock, shares outstanding (in shares)	338,573,000	347,308,000
Treasury stock, shares at cost (in shares)	32,779,000	24,045,000

CONSOLIDATED STATEMENTS OF OPER

CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Premiums written:
Direct	$ 1,106,632	$ 1,124,196	$ 1,103,332
Assumed	10,837	6,446	271
Ceded	(188,727)	(129,334)	(111,341)
Net premiums written	928,742	1,001,308	992,262
Decrease (increase) in unearned premiums	93,201	29,680	(17,100)
Net premiums earned	1,021,943	1,030,988	975,162
Investment income, net of expenses	154,396	167,045	141,331
Net realized investment gains (losses)	13,752	5,306	(1,353)
Other revenue	9,055	10,638	8,708
Total revenues	1,199,146	1,213,977	1,123,848
Losses and expenses:
Losses incurred, net	364,774	118,575	36,562
Amortization of deferred policy acquisition costs	12,380	12,001	11,932
Other underwriting and operating expenses, net	176,398	182,768	178,211
Loss on debt extinguishment	26,736	0	0
Interest expense	59,595	52,656	52,993
Total losses and expenses	639,883	366,000	279,698
Income before tax	559,263	847,977	844,150
Provision for income taxes	113,170	174,214	174,053
Net income	$ 446,093	$ 673,763	$ 670,097
Earnings per share:
Basic (in dollars per share)	$ 1.31	$ 1.91	$ 1.83
Diluted (in dollars per share)	$ 1.29	$ 1.85	$ 1.78
Weighted average common shares outstanding - basic (in shares)	339,953	352,827	365,406
Weighted average common shares outstanding - diluted (in shares)	359,293	373,924	386,078

CONSOLIDATED STATEMENTS OF COMP

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Statement of Comprehensive Income [Abstract]
Net income	$ 151,430	$ 130,811	$ 14,047	$ 149,805	$ 177,110	$ 176,934	$ 167,778	$ 151,941	$ 446,093	$ 673,763	$ 670,097
Other comprehensive income (loss), net of tax:
Change in unrealized investment gains and losses									133,616	173,910	(64,646)
Benefit plans adjustment									10,497	23,012	(15,767)
Other comprehensive income (loss), net of tax									144,113	196,922	(80,413)
Comprehensive income									$ 590,206	$ 870,685	$ 589,684

CONSOLIDATED STATEMENTS OF SHAR

CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Common stock	Paid-in capital	Treasury stock	Accumulated other comprehensive income (loss)	Retained earnings	ASU 2016-01Accumulated other comprehensive income (loss)	ASU 2016-01Retained earnings
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect of accounting standard update							$ (18)	$ 18
Balance, beginning of year at Dec. 31, 2017		$ 370,567	$ 1,850,582	$ 0	$ (43,783)	$ 977,160
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net common stock issued under share-based compensation plans		786	(8,917)
Reacquisition of convertible junior subordinated debentures-equity component			0
Reissuance of treasury stock, net under share-based compensation plans			0	0
Equity compensation			20,871
Purchases of common stock				(175,059)
Other comprehensive income (loss)	$ (80,413)				(80,413)
Net income	670,097					670,097
Cash dividends						0
Balance, end of year at Dec. 31, 2018	3,581,891	371,353	1,862,536	(175,059)	(124,214)	1,647,275
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect of accounting standard update					(18)
Net common stock issued under share-based compensation plans		0	0
Reacquisition of convertible junior subordinated debentures-equity component			0
Reissuance of treasury stock, net under share-based compensation plans			(11,715)	5,989
Equity compensation			18,898
Purchases of common stock				(114,126)
Other comprehensive income (loss)	196,922				196,922
Net income	673,763					673,763
Cash dividends						(42,388)
Balance, end of year at Dec. 31, 2019	4,309,234	371,353	1,869,719	(283,196)	72,708	2,278,650
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net common stock issued under share-based compensation plans		0	0
Reacquisition of convertible junior subordinated debentures-equity component			(2,673)
Reissuance of treasury stock, net under share-based compensation plans			(18,807)	9,867
Equity compensation			13,803
Purchases of common stock				(119,997)
Other comprehensive income (loss)	144,113				144,113
Net income	446,093					446,093
Cash dividends	(82,600)					(82,647)
Balance, end of year at Dec. 31, 2020	$ 4,698,986	$ 371,353	$ 1,862,042	$ (393,326)	$ 216,821	$ 2,642,096

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Cash flows from operating activities:
Net income	$ 446,093	$ 673,763	$ 670,097
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and other amortization	57,812	48,784	58,215
Deferred tax expense	27,475	11,096	186,572
Loss on debt extinguishment	26,736	0	0
Net realized investment (gains) losses	(13,752)	(5,306)	1,353
Change in certain assets and liabilities:
Accrued investment income	(292)	(1,704)	(1,941)
Reinsurance recoverable on loss reserves	(73,401)	11,687	15,146
Reinsurance recoverable on paid losses	852	1,427	924
Premiums receivable	(457)	(497)	(1,045)
Deferred insurance policy acquisition costs	(3,030)	(643)	953
Profit commission receivable	4,586	4,945	(5,479)
Loss reserves	325,203	(118,685)	(311,616)
Unearned premiums	(93,203)	(29,683)	17,051
Return premium accrual	(500)	(11,500)	(22,900)
Current income taxes	6,271	1,057	(77,551)
Other, net	21,916	24,791	14,738
Net cash provided by operating activities	732,309	609,532	544,517
Cash flows from investing activities:
Purchases of investments	(2,636,972)	(1,394,126)	(1,459,473)
Proceeds from sales of investments	836,851	229,796	370,449
Proceeds from maturity of fixed income securities	1,030,926	748,165	785,175
Net decrease in payables for securities	0	(307)	307
Additions to property and equipment	(3,311)	(5,636)	(14,238)
Net cash used in investing activities	(772,506)	(422,108)	(317,780)
Cash flows from financing activities:
Proceeds from issuance of senior notes	640,250	0	0
Purchase of senior notes	(179,735)	0	0
Payment of original issue discount - senior notes	(2,969)	0	0
Purchase of convertible junior subordinated debentures	(36,392)	0	0
Payment of original issue discount- convertible junior subordinated debentures	(15,049)	0	0
Cash portion of loss on debt extinguishment	(25,266)	0	0
Repurchase of common stock	(119,997)	(125,766)	(163,419)
Dividends paid	(82,061)	(41,914)	0
Payment of debt issuance costs	(2,020)	0	0
Payment of withholding taxes related to share-based compensation net share settlement	(8,940)	(5,726)	(8,131)
Net cash provided by (used in) financing activities	167,821	(173,406)	(171,550)
Net increase in cash and cash equivalents and restricted cash and cash equivalents	127,624	14,018	55,187
Cash and cash equivalents and restricted cash and cash equivalents at beginning of year	169,056	155,038	99,851
Cash and cash equivalents and restricted cash and cash equivalents at end of year	$ 296,680	$ 169,056	$ 155,038

Nature of Business

Nature of Business	12 Months Ended
	Dec. 31, 2020
Nature of Business [Abstract]
Nature of Business	NOTE 1 Nature of Business 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 to protect against loss from defaults on low down payment residential mortgage loans. Primary mortgage insurance provides mortgage default protection on individual loans and covers a percentage of the unpaid loan principal, delinquent interest and certain expenses associated with the default and subsequent foreclosure or sale approved by us, of the underlying property. MGIC Assurance Corporation ("MAC") and MGIC Indemnity Corporation ("MIC"), insurance subsidiaries of MGIC, provide insurance for certain mortgages under Fannie Mae and Freddie Mac (the "GSEs") credit risk transfer programs. Through certain non-insurance subsidiaries, we also provide various services for the mortgage finance industry, such as contract underwriting, analysis of loan originations and portfolios, and mortgage lead generation. At December 31, 2020, our direct primary insurance in force ("IIF") was $246.6 billion, which represents the principal balance in our records of all mortgage loans that we insure, and our direct primary risk in force ("RIF") was $61.8 billion, which represents the IIF multiplied by the insurance coverage percentage. The substantial majority of our NIW has been for loans purchased by the GSEs. The current private mortgage insurer eligibility requirements ("PMIERs") of the GSEs include financial requirements, as well as business, quality control and certain transactional approval requirements. 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 of risk in force, calculated from tables of factors with several risk dimensions). Based on our application of the PMIERs, as of December 31, 2020, MGIC’s Available Assets are in excess of its Minimum Required Assets; and MGIC is in compliance with the PMIERs and eligible to insure loans purchased by the GSEs.

Basis of Presentation

Basis of Presentation	12 Months Ended
	Dec. 31, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	NOTE 2 Basis of Presentation BASIS OF PRESENTATION The accompanying consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America ("GAAP"), as codified in the Accounting Standards Codification ("ASC"). Our consolidated financial statements include the accounts of MGIC Investment Corporation and its majority-owned subsidiaries. Intercompany transactions and balances have been eliminated. In accordance with GAAP, we are required to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the consolidated financial statements and the reported amounts of revenues and expenses during the reporting periods. Actual results could differ from those estimates. RECLASSIFICATIONS Certain reclassifications to 2019 and 2018 amounts have been made in the accompanying consolidated financial statements to conform to the 2020 presentation. RECENT DEVELOPMENTS The COVID-19 pandemic had a material impact on our 2020 financial results. Among other things, the COVID-19 pandemic led to an increase in delinquencies, which increased our capital requirements under PMIERs on those delinquent loans and increased our losses incurred. While uncertain, the future impact of the COVID-19 pandemic on the Company’s business, financial results, liquidity and/or financial condition may also be material. The magnitude of the impact will be influenced by various factors, including the length and severity of the pandemic in the United States, the length of time that measures intended to reduce the transmission of COVID-19 remain in place, the level of unemployment, and the impact of government initiatives and actions taken by Fannie Mae and Freddie Mac (the "GSEs") (including mortgage forbearance and modification programs) to mitigate the economic harm caused by COVID-19. SUBSEQUENT EVENTS

Significant Accounting Policies

Significant Accounting Policies	12 Months Ended
	Dec. 31, 2019
Accounting Policies [Abstract]
Significant Accounting Policies	NOTE 3 Significant Accounting Policies CASH AND CASH EQUIVALENTS We consider money market funds and investments with original maturities of three months or less to be cash equivalents. RESTRICTED CASH AND CASH EQUIVALENTS Restricted cash and cash equivalents consists of cash and money market funds held in trusts for the benefit of contractual counterparties under reinsurance agreements. FAIR VALUE MEASUREMENTS We carry certain financial instruments at fair value and disclose the fair value of all financial instruments. Our financial instruments carried at fair value are predominantly measured on a recurring basis. Financial instruments measured on a nonrecurring basis are subject to fair value adjustments only in certain circumstances (for example, when there is evidence of impairment). The fair value of an asset or liability is defined as the price that would be received upon a sale of an asset, or paid to transfer a liability, in an orderly transaction between market participants at the measurement date. Fair value is based on quoted market prices or inputs, where available. If prices or quotes are not available, fair value is based on valuation models or other valuation techniques that consider relevant transaction characteristics (such as maturity) and use as inputs observable or unobservable market parameters including yield curves, interest rates, volatilities, equity or debt prices, and credit curves. Valuation adjustments may be made to ensure that financial instruments are recorded at fair value, as described below. Valuation process We use independent pricing sources to determine the fair value of a substantial majority of our financial instruments, which primarily consist of assets in our investment portfolio, but also includes cash and cash equivalents and restricted cash and cash equivalents. A variety of inputs are used; in approximate order of priority, they are: benchmark yields, reported trades, broker/dealer quotes, issuer spreads, two-sided markets, benchmark securities, bids, offers, and reference data including market research publications. 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. On a quarterly basis, we perform quality controls over values received from the pricing sources which also include reviewing tolerance reports, data changes, and directional moves compared to market moves. We have not made any adjustments to the prices obtained from the independent pricing sources. Valuation hierarchy A three-level valuation hierarchy has been established under GAAP for disclosure of fair value measurements. The valuation hierarchy is based on the transparency of inputs to the valuation of a financial instrument as of the measurement date. To determine the fair value of securities available-for-sale in Level 1 and Level 2 of the fair value hierarchy, independent pricing sources, as described in " Valuation process, " 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. The three levels are defined as follows: è Level 1 Quoted prices for identical instruments in active markets that we can access. Financial assets using Level 1 inputs primarily include U.S. Treasury securities, money market funds, treasury bills, and certain equity securities. è 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 using Level 2 inputs primarily include obligations of U.S. government corporations and agencies, corporate bonds, mortgage-backed securities, asset-backed securities, most municipal bonds, and commercial paper. è Level 3 Valuations derived from valuation techniques in which one or more significant inputs or value drivers are unobservable or, from par values due to restrictions on certain securities that require them to be redeemed or sold only to the security issuer at par value. 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. 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. INVESTMENTS Fixed income securities. Our fixed income securities are classified as available-for-sale and are reported at fair value. The related unrealized investment gains or losses are, after considering the related tax expense or benefit, recognized as a component of accumulated other comprehensive income (loss) in shareholders' equity. Realized investment gains and losses on fixed income securities are reported in income based upon specific identification of securities sold as well as any credit allowance (2020), and any "other than temporary" impairments ("OTTI") (2019). Equity securities. Equity securities are reported at fair value, except for certain securities that are carried at cost. Equity securities carried at cost are reported as Other invested assets. Realized investment gains and losses on equity securities are reported in income based upon specific identification of securities sold, as well as any change in fair value of equity securities. Other invested assets. Other invested assets are carried at cost. These assets represent our investment in Federal Home Loan Bank of Chicago ("FHLB") stock, which due to restrictions, is required to be redeemed or sold only to the security issuer at par value. Unrealized losses and allowance for credit losses Effective January 1, 2020, each quarter we perform reviews of our investments to assess if declines in fair value of available-for-sale securities are impaired. In evaluating the decline in fair value, we consider several factors including, but not limited to: è our intent to sell the security or whether it is more likely than not that we will be required to sell the security before recovery of its amortized cost basis; è the present value of the discounted cash flows we expect to collect compared to the amortized cost basis of the security; è failure of the issuer to make scheduled interest or principal payments; è change in rating below investment grade; and è adverse conditions specifically related to the security, an industry, or a geographic area. Based on our evaluation, we will record a realized loss on a security if we intend to sell the impaired security, if it is more likely than not that we will be required to sell the impaired security prior to recovery of its amortized cost basis, or if the present value of the discounted cash flows we expect to collect is less than the amortized cost basis of the security. When a security is considered to be impaired, the losses are separated into the portion of the loss that represents the credit loss and the portion that is due to other factors. An allowance for credit losses is recorded, subject to reversal, for the credit loss portion in the statement of operations, while the loss due to other factors is recognized in accumulated other comprehensive loss, net of taxes. A credit loss is determined to exist if the present value of the discounted cash flows, using the security’s original yield, expected to be collected from the security is less than the cost basis of the security. For 2019, our evaluation of whether a decline in fair values is other-than-temporary also includes reviewing the extent and duration of the decline. Based on our evaluation, if the fair value of a security is below its amortized cost at the time of our intent to sell, the security is classified as other-than-temporarily impaired and the full amount of the impairment is recognized as a loss in the statement of operations. Otherwise, when a security is considered to be other-than-temporarily impaired, the losses are separated into the portion of the loss that represents the credit loss and the portion that is due to other factors. The credit loss portion is recognized as a loss in the statement of operations, while the loss due to other factors is recognized in accumulated other comprehensive loss, net of taxes. A credit loss is determined to exist if the present value of the discounted cash flows, using the security’s original yield, expected to be collected from the security is less than the cost basis of the security. If the security is determined to be other-than-temporary-impaired the security is classified as other-than-temporarily impaired and the full amount of the impairment is recognized as a loss in the statement of operations. HOME OFFICE AND EQUIPMENT Home office and equipment is carried at cost net of depreciation. For financial reporting purposes, depreciation is determined on a straight-line basis for the home office and equipment over estimated lives ranging from 3 to 45 years. For income tax purposes, we use accelerated depreciation methods. Home office and equipment is shown net of accumulated depreciation of $51.2 million, $43.0 million and $38.1 million as of December 31, 2020, 2019 and 2018, respectively. Depreciation expense for the years ended December 31, 2020, 2019 and 2018 was $6.3 million, $6.5 million and $6.0 million, respectively. DEFERRED INSURANCE POLICY ACQUISITION COSTS Costs directly associated with the successful acquisition of mortgage insurance business, consisting of employee compensation and other policy issuance and underwriting expenses, are initially deferred and reported as deferred insurance policy acquisition costs ("DAC"). The deferred costs are net of any ceding commissions received associated with our reinsurance agreements. For each underwriting year of business, these costs are amortized to income in proportion to estimated gross profits over the estimated life of the policies. We utilize anticipated investment income in our calculation. This includes accruing interest on the unamortized balance of DAC. The estimates for each underwriting year are reviewed quarterly and updated when necessary to reflect actual experience and any changes to key variables such as persistency or loss development. LOSS RESERVES Case reserves and loss adjustment expenses ("LAE") reserves are established when notices of delinquency on insured mortgage loans are received. Such loans are referred to as being in our delinquency inventory. For reporting purposes, we consider a loan delinquent when it is two or more payments past due and has not become current or resulted in a claim payment. Even though the accounting standard, ASC 944, regarding accounting and reporting by insurance entities specifically excludes mortgage insurance from its guidance relating to loss reserves, we establish loss reserves using the general principles contained in the insurance standard. However, consistent with industry standards for mortgage insurers, we do not establish case reserves for future claims on insured loans which are not currently delinquent. Case 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. Our case reserve estimates are established based upon historical experience, including rescissions of policies, curtailments of claims, and loan modification activity. Adjustments to reserve estimates are reflected in the financial statements in the years in which the adjustments are made. The liability for reinsurance assumed is based on information provided by the ceding companies. Incurred but not reported ("IBNR") reserves are established for delinquencies estimated to have occurred prior to the close of an accounting period, but not yet reported to us. Consistent with reserves for reported delinquencies, IBNR reserves are also established using estimated claim rates and claim severities. LAE reserves are established for the estimated costs of settling claims, including legal and other expenses, and general expenses of administering the claims settlement process. Loss reserves are ceded to reinsurers under our reinsurance agreements. (See Note 8 – “Loss Reserves” and Note 9 – “Reinsurance.” ) PREMIUM DEFICIENCY RESERVE After our loss reserves are initially established, we perform premium deficiency tests using our best estimate assumptions as of the testing date. Premium deficiency reserves are established, if necessary, when the present value of expected future losses and expenses exceeds the present value of expected future premium and already established reserves. Products are grouped for premium deficiency testing purposes based on similarities in the way the products are acquired, serviced and measured for profitability. REVENUE RECOGNITION We write policies which are guaranteed renewable contracts at the insured's option on a monthly, single, or annual premium basis. We have no ability to re-underwrite or reprice these contracts. Premiums written on monthly premium policies are earned as coverage is provided. Premiums written on single premium policies and annual premium policies are initially deferred as unearned premium reserve and earned over the estimated policy life. Premiums written on policies covering more than one year are amortized over the estimated policy life based on historical experience, which includes the anticipated incurred loss pattern. Premiums written on annual premium policies are earned on a monthly pro rata basis. When a policy is cancelled for a reason other than rescission or claim payment, all premium that is non-refundable is immediately earned. Any refundable premium is returned to the servicer or borrower. When a policy is cancelled due to rescission, all previously collected premium is returned to the servicer and when a policy is cancelled because a claim is paid, premium collected since the date of delinquency is returned. The liability associated with our estimate of premium to be returned is accrued for separately and included in "Other liabilities" on our consolidated balance sheets. Changes in this liability, and the actual return of premiums for all periods, affects premiums written and earned. Effective, January 1, 2020, we assess whether a credit loss exists for our premium receivable. In determining if a credit loss allowance is required for premium receivable, consideration is given to the life of the premium receivable asset, areas of potential credit loss, and forward-looking predictive indicators. Any estimated credit loss would be immediately recognized. Fee income of our non-insurance subsidiaries is earned and recognized as the services are provided and the customer is obligated to pay. Fee income consists primarily of contract underwriting and related fee-based services provided to lenders and is included in “Other revenue” on the consolidated statements of operations. INCOME TAXES Deferred income taxes are provided under the liability method, which recognizes the future tax effects of temporary differences between amounts reported in the consolidated financial statements and the tax bases of these items. The estimated tax effects are computed at the enacted federal statutory income tax rate. Changes in tax laws, rates, regulations, and policies or the final determination of tax audits or examinations, could materially affect our estimates and can be significant to our operating results. We evaluate the realizability of the deferred tax assets based on the weight of all available positive and negative evidence. Deferred tax assets are reduced by a valuation allowance if it is more likely than not that all or some portion of the deferred tax assets will not be realized. The recognition of a tax position is determined using a two-step approach. The first step applies a more-likely-than-not threshold for recognition and derecognition. The second step measures the tax position as the greatest amount of benefit that is cumulatively greater than 50% likely to be realized. When evaluating a tax position for recognition and measurement, we presume that the tax position will be examined by the relevant taxing authority that has full knowledge of all relevant information. We recognize interest accrued and penalties related to unrecognized tax benefits in our provision for income taxes. Federal tax law permits mortgage guaranty insurance companies to deduct from taxable income, subject to certain limitations, the amounts added to contingency loss reserves that are recorded for regulatory purposes. The amounts we deduct must generally be included in taxable income in the tenth subsequent year. The deduction is allowed only to the extent that we purchase and hold U.S. government non-interest-bearing tax and loss bonds in an amount equal to the tax benefit attributable to the deduction. We account for these purchases as a payment of current federal income tax. (See "Note 12 - Income Taxes." ) BENEFIT PLANS We have a non-contributory defined benefit pension plan covering substantially all domestic employees, as well as a supplemental executive retirement plan. Retirement benefits are based on compensation and years of service. Effective January 1, 2019, all participants, regardless of hire or rehire date, earn benefits using a cash balance formula. Participants hired or rehired prior to January 1, 2014, earned benefits under a traditional formula through December 31, 2018. which calculated a pension credit for each year of eligible service. Under the cash balance formula, participants’ accounts are credited each year with an employer contribution and interest. The employer contribution is a percentage of eligible earnings based on the participant’s age on January 1, 2019. We recognize these retirement benefit costs over the period during which employees render the service that qualifies them for benefits. Our policy is to fund pension cost as required under the Employee Retirement Income Security Act of 1974. We offer both medical and dental benefits for retired domestic employees, their eligible spouses and dependents until the retiree reaches the age of 65. Under the plan retirees pay a premium for these benefits. We accrue the estimated costs of retiree medical and dental benefits over the period during which employees render the service that qualifies them for benefits. (See Note 11 – “Benefit Plans.” ) REINSURANCE Loss reserves are reported before taking credit for amounts ceded under reinsurance agreements. Ceded loss reserves are reflected as "Reinsurance recoverable on loss reserves." Amounts due from reinsurers on paid claims are reflected as “Reinsurance recoverable on paid losses.” Ceded premiums payable are included in “Other liabilities.” Profit commissions are included with “Premiums written – Ceded” and ceding commissions are included with “Other underwriting and operating expenses, net.” We remain liable for all insurance ceded. (See Note 9 – “Reinsurance.” ) Quarterly, we assess the credit risk associated with our reinsurance recoverable. Effective January 1, 2020 if an estimated credit loss is expected to occur over the remaining life of reinsurance recoverable, it is immediately recorded to income. In assessing whether a credit allowance should be established, we consider several factors including, but not limited to the credit ratings of individual reinsurers, investor reports for our Home Re Transactions, collateral held in trust accounts in which MGIC is the sole beneficiary, and aging of outstanding reinsurance recoverable balances. Assumed reinsurance is based on information received from the ceding company. 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. (See Note 15 – “Share-based Compensation Plans.” ) 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. The computation of basic EPS includes as "participating securities" an immaterial number of unvested share-based compensation awards that contain non-forfeitable rights to dividends or dividend equivalents, whether paid or unpaid, under the "two-class" method. Our participating securities are composed of vested restricted stock and restricted stock units ("RSUs") with non-forfeitable rights to dividends. 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 treasury stock method, diluted EPS reflects the potential dilution that could occur if our unvested restricted stock units result in the issuance of common stock. Under the if-converted method, diluted EPS reflects the potential dilution that could occur if our 9% Debentures 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. For purposes of calculating basic and diluted EPS, vested restricted stock and RSUs are considered outstanding. RELATED PARTY TRANSACTIONS In 2020, MGIC Reinsurance Corporation of Wisconsin, a subsidiary of MGIC, merged with MGIC. There were no related party transactions during 2019 or 2018. RECENT ACCOUNTING AND REPORTING DEVELOPMENTS Accounting standards effective in 2020, or early adopted, and relevant to our financial statements Measurement of Credit Losses on Financial Instruments: ASU 2016-13 Effective January 1, 2020, we adopted ASC 326, Financial Instruments - Credit Losses (“CECL”). This new standard replaced the incurred loss impairment methodology with a methodology that reflects lifetime expected credit losses and requires consideration of a broader range of reasonable and supportable information to inform credit loss estimates. Under CECL, allowances are established by incorporating the forecast of future economic conditions into our loss estimate unless such forecast is not reasonable and supportable, in which case we revert to historical loss experience. Application of the CECL model impacts our reinsurance recoverables and premium receivable. ASC 326 also replaced the OTTI model with an impairment allowance model, subject to reversal, for available-for-sale investments, which are measured at fair value. Our mortgage insurance policies are outside the scope of ASC 326. The new guidance is not prescriptive about certain aspects of estimating expected credit losses, including the specific methodology to use, and therefore requires significant judgment in application. Applying ASC 326, we have determined that an allowance for credit losses related to our premium receivables and reinsurance recoverables was not necessary as of December 31, 2020. At December 31, 2020, we established an allowance for credit losses for available-for-sale securities of $49 thousand. We continue to apply the previous guidance to 2019 and prior periods. Changes to the Disclosure Requirements for Fair Value Measurement: ASU 2018-13 Effective January 1, 2020, we adopted FASB guidance that changes the disclosure requirements for fair value measurements. The updated guidance removed the requirement to disclose the amount and reasons for transfers between Level 1 and Level 2 of the fair value hierarchy; the policy for timing of transfers between levels; and the valuation processes for Level 3 fair value measurements. The updated guidance requires disclosure of changes in unrealized gains and losses for the period included in other comprehensive income for recurring Level 3 fair value measurements held at the end of the reporting period; and the range and weighted average of significant unobservable inputs used to develop Level 3 fair value measurements. The adoption of the updated guidance did not have a material effect on our consolidated financial statement disclosures. Changes to the Disclosure Requirements for Defined Benefit Plans: ASU 2018-14 In August 2018, the FASB issued amendments to modify the disclosure requirements for defined benefit plans. The updated guidance removed the requirements to identify amounts that are expected to be reclassified out of accumulated other comprehensive income and recognized as components of net periodic benefit cost in the coming year and the effects of a one-percentage-point change in assumed health care cost trend rates on service and interest cost and on the postretirement benefit obligation. The updated guidance added disclosures for the weighted-average interest crediting rates for cash balance plans and other plans with interest crediting rates and explanations for significant gains and losses related to changes in the benefit obligation for the period. Early adoption is permitted. An entity should apply the amendments on a retrospective basis to all periods presented. The adoption of this guidance did not have a material impact to our consolidated financial statement disclosures. Prospective Accounting Standards Table 2.1 shows the relevant new amendments to accounting standards, which are not yet effective or adopted. Standard / Interpretation Table 2.1 Amended Standards Effective date ASC 321, 323, 815 Investments • ASU 2020-01 - Investments-Equity Securities (Topic 321), Investments-Equity Method and Joint Ventures (Topic 323), and Derivatives and Hedging (Topic 815) January 1, 2021 ASC 740 Income Taxes • ASU 2019-12 - Simplifying the Accounting for Income Taxes January 1, 2021 ASC 310-20 Receivables • ASU 2020-08 - Codification Improvements to Subtopic 310-20, Receivables - Nonrefundable Fees and Other Costs January 1, 2021 ASC 470, 815 Debt • ASU 2020-06 - Debt with conversion and other options (Topic 470), derivatives and hedging - contracts in entity’s own equity (Topic 815) January 1, 2022 Clarification of Accounting for Equity Securities: ASU 2020-01 In January 2020, the FASB issued guidance which clarifies certain interactions of accounting for equity securities under Topic 321, under the equity method of accounting in Topic 323, and accounting for certain forward contracts and purchased options in Topic 815. The amendment clarifies the consideration of observable transactions before applying or discounting the equity method of accounting. The updated guidance is effective for annual periods beginning after December 15, 2020, including interim periods within those annual periods. We have evaluated the impacts the adoption of this guidance will have on our consolidated financial statements, and determined it will not have a material impact. Simplifying the Accounting for Income Taxes : ASU 2019-12 In December 2019, the FASB issued guidance which simplifies Accounting for Income Taxes (Topic 740). The ASU intends to reduce complexity through clarification and amendments of existing guidance. The updated guidance is effective for annual periods beginning after December 15, 2020, including interim periods within those annual periods. We have evaluated the impacts the adoption of this guidance will have on our consolidated financial statements, and determined it will not have a material impact. Codification Improvements to Subtopic 310-20, Receivables - Nonrefundable Fees and Other Costs: ASU 2020-08 In October 2020, the FASB issued amendments to the codification that clarifies the accounting guidance for Accounting Standards Update No. 2017-08, Receivables—Nonrefundable Fees and Other Costs (Subtopic 310-20): Premium Amortization on Purchased Callable Debt Securities. FASB standard 2017-08 shortened the amortization period for certain purchased callable debt securities held at a premium by requiring that entities amortize the premium associated with those callable debt securities within the scope of paragraph 310-20-25-33 to the earliest call date and clarified the FASB’s intent that an entity should reevaluate whether a callable debt security that has multiple call dates is within the scope of paragraph 310-20-35-33 for each reporting period. This guidance clarifies the issuer of a callable debt security should utilize the next call date versus the earliest call date in amortizing premium. The updated guidance is effective for annual periods beginning after December 15, 2020, including interim periods within those annual periods. We have evaluated the impacts the adoption of this guidance will have on our consolidated financial statements, and determined it will not have a material impact. Accounting for Convertible Instruments and Contracts in an Entity’s Own Equity: ASU 2020-06 In August 2020, the FASB issued guidance that simplifies the accounting for certain financial instruments with characteristics of liabilities and equity. It also includes amendments to EPS guidance. The updated guidance reduces the number of accounting models for convertible debt instruments and convertible preferred stock. This ASU eliminates the cash conversion and the beneficial conversion models, which will make more instruments eligible for the fair value option. As a result of these changes, more convertible instruments will be reported as a single unit on the balance sheet. The updated guidance also includes updates to the EPS calculation. The ASU requires companies to use the if-converted method, assume share settlement when settlement can be in cash or in shares, use an average market price for the period if the number of shares is based on an entity’s share price, and use the weighted average shares from each quarter to calculate the year to date weighted average shares. The ASU also includes improvements to the disclosures for convertible instruments and EPS. The updated guidance is effective for annual periods beginning after December 15, 2021. Early adoption is permitted for fiscal years beginning after December 15, 2020. The ASU requires adoption to be applied retrospectively or using a modified retrospective basis. We are currently evaluating the impacts the adoption of this guidance will have on our consolidated financial statement disclosures and whether we would early adopt.

Earnings per Share

Earnings per Share	12 Months Ended
	Dec. 31, 2020
Earnings Per Share [Abstract]
Earnings per Share	NOTE 4 Earnings Per Share Table 4.1 reconciles basic and diluted EPS amounts: Earnings per share Table 4.1 Years Ended December 31, (In thousands, except per share data) 2020 2019 2018 Basic earnings per share: Net income $ 446,093 $ 673,763 $ 670,097 Weighted average common shares outstanding - basic 339,953 352,827 365,406 Basic earnings per share $ 1.31 $ 1.91 $ 1.83 Diluted earnings per share: Net income $ 446,093 $ 673,763 $ 670,097 Interest expense, net of tax (1) : 9% Debentures 17,004 18,264 18,264 Diluted income available to common shareholders $ 463,097 $ 692,027 $ 688,361 Weighted-average shares - basic 339,953 352,827 365,406 Effect of dilutive securities: Unvested restricted stock units 1,589 2,069 1,644 9% Debentures 17,751 19,028 19,028 Weighted average common shares outstanding - diluted 359,293 373,924 386,078 Diluted income per share $ 1.29 $ 1.85 $ 1.78 (1) Interest expense for the years ended December 31, 2020, 2019 and 2018 has been tax effected at a rate of 21%.

Investments

Investments	12 Months Ended
	Dec. 31, 2020
Investments [Abstract]
Investments	NOTE 5 Investments FIXED INCOME SECURITIES Our fixed income securities consisted of the following as of December 31, 2020 and 2019: Details of fixed income investment securities by category as of December 31, 2020 Table 5.1a (In thousands) Amortized Cost Allowance for Expected Credit Loss Gross Unrealized Gains Gross Unrealized Losses Fair Value U.S. Treasury securities and obligations of U.S. government corporations and agencies $ 264,531 $ — $ 1,164 $ (2) $ 265,693 Obligations of U.S. states and political subdivisions 2,083,568 — 166,557 (256) 2,249,869 Corporate debt securities 2,690,860 — 155,156 (1,728) 2,844,288 ABS 203,807 (49) 2,946 (18) 206,686 RMBS 425,532 — 6,472 (838) 431,166 CMBS 312,572 — 16,055 (1,125) 327,502 CLOs 310,616 — 566 (692) 310,490 Debt securities issued by foreign sovereign governments 4,485 — 224 — 4,709 Other Investments (1) 21,193 — — — 21,193 Total fixed income securities $ 6,317,164 $ (49) $ 349,140 $ (4,659) $ 6,661,596 Details of fixed income investment securities by category as of December 31, 2019 Table 5.1b (In thousands) Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value U.S. Treasury securities and obligations of U.S. government corporations and agencies $ 195,176 $ 1,237 $ (210) $ 196,203 Obligations of U.S. states and political subdivisions 1,555,394 99,328 (857) 1,653,865 Corporate debt securities 2,711,910 76,220 (3,008) 2,785,122 ABS 227,376 2,466 (178) 229,664 RMBS 271,384 429 (3,227) 268,586 CMBS 274,234 5,531 (779) 278,986 CLOs 327,076 33 (1,643) 325,466 Total fixed income securities $ 5,562,550 $ 185,244 $ (9,902) $ 5,737,892 (1) Consists of short-term commercial paper with original maturities greater than ninety days. The increase in gross unrealized gains and the decrease in gross unrealized losses in our fixed income securities from December 31, 2019 to December 31, 2020 were primarily caused by declines in interest rates during that period. We had $14.1 million and $13.9 million of investments at fair value on deposit with various states as of December 31, 2020 and 2019, respectively, due to regulatory requirements of those states' insurance departments. In connection with our insurance and reinsurance activities, we are required to maintain assets in trusts for the benefit of contractual counterparties. The fair value of the investments on deposit in these trusts was $165.9 million and $88.9 million at December 31, 2020 and 2019, respectively. Table 5.2 compares the amortized cost and fair values of fixed income securities, by contractual maturity, as of December 31, 2020. Actual maturities may differ from contractual maturities because certain borrowers have the right to call or prepay certain obligations with or without call or prepayment penalties. Because most mortgage and asset-backed securities provide for periodic payments throughout their lives, they are listed separately in the table. Fixed income securities maturity schedule Table 5.2 December 31, 2020 (In thousands) Amortized Cost Fair Value Due in one year or less $ 390,510 $ 393,286 Due after one year through five years 1,945,158 2,033,183 Due after five years through ten years 1,280,760 1,402,640 Due after ten years 1,448,209 1,556,643 5,064,637 5,385,752 ABS 203,807 206,686 RMBS 425,532 431,166 CMBS 312,572 327,502 CLOs 310,616 310,490 Total as of December 31, 2020 $ 6,317,164 $ 6,661,596 Proceeds from the sale of fixed income securities classified as available-for-sale were $803.4 million, $228.1 million, and $365.6 million during the years ended December 31, 2020, 2019, and 2018, respectively. Gross gains of $21.3 million, $7.1 million, and $0.7 million and gross losses of $8.8 million, $3.5 million, and $3.8 million were realized on those sales during the years ended December 31, 2020, 2019, and 2018, respectively. We recorded $0.3 million of realized losses for the year ended December 31, 2020 related to our intent to sell certain securities. We also recorded a credit allowance of $49 thousand for the year ended December 31, 2020. For the years ended December 31, 2019, and 2018, we recorded $0.1 million and $1.8 million of OTTI losses in earnings, respectively. EQUITY SECURITIES The cost and fair value of investments in equity securities as of December 31, 2020 and December 31, 2019 are shown in tables 5.3a and 5.3b below. Details of equity investment securities as of December 31, 2020 Table 5.3a (In thousands) Cost Gross gains Gross losses Fair Value Equity securities 17,522 695 (2) 18,215 Details of equity investment securities as of December 31, 2019 Table 5.3b (In thousands) Cost Gross gains Gross losses Fair Value Equity securities 17,188 154 (14) 17,328 Proceeds from the sale of equity securities were $25.7 million and $1.7 million during the years ended December 31, 2020 and 2019, respectively. Gross gains of $1.8 million and $1.6 million were realized on those sales during the year ended December 31, 2020 and 2019, respectively. Gross losses of $0.4 million and zero were realized on those sales during the year ended December 31, 2020 and 2019, respectively. For the year ended December 31, 2020 and December 31, 2019, we recognized $0.6 million and $0.2 million of net gains on equity securities still held as of December 31, 2020 and December 31, 2019, respectively, which are reported in Net realized investment (losses) gains on our consolidated statements of operations. OTHER INVESTED ASSETS Other invested assets consists of an investment in Federal Home Loan Bank ("FHLB") stock that is carried at cost, which due to its nature approximates fair value. Ownership of FHLB stock provides access to a secured lending facility, and our current FHLB Advance amount is secured by eligible collateral whose fair value is maintained at a minimum of 102% of the outstanding principal balance of the FHLB Advance. As of December 31, 2020, that collateral consisted of fixed income securities included in our total investment portfolio, and cash and cash equivalents, with a total fair value of $163.9 million. UNREALIZED INVESTMENT LOSSES Tables 5.4a and 5.4b below summarize, for all available-for-sale investments in an unrealized loss position as of December 31, 2020 and 2019, the aggregate fair value and gross unrealized losses by the length of time those securities have been continuously in an unrealized loss position. Gross unrealized losses on our available-for-sale investments amounted to $5 million and $10 million as of December 31, 2020 and 2019, respectively. The fair value amounts reported in tables 5.4a and 5.4b below are estimated using the process described in Note 6 - "Fair Value Measurements" to these consolidated financial statements. Unrealized loss aging for securities by type and length of time as of December 31, 2020 Table 5.4a 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 $ 2,690 $ (2) $ — $ — $ 2,690 $ (2) Obligations of U.S. states and political subdivisions 31,416 (256) — — 31,416 (256) Corporate debt securities 44,968 (1,728) — — 44,968 (1,728) ABS 14,929 (18) — — 14,929 (18) RMBS 98,409 (773) 3,566 (65) 101,975 (838) CMBS 13,212 (789) 2,799 (336) 16,011 (1,125) CLOs 95,287 (261) 73,904 (431) 169,191 (692) Total $ 300,911 $ (3,827) $ 80,269 $ (832) $ 381,180 $ (4,659) Unrealized loss aging for securities by type and length of time as of December 31, 2019 Table 5.4b 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 $ 57,301 $ (200) $ 5,806 $ (10) $ 63,107 $ (210) Obligations of U.S. states and political subdivisions 74,859 (847) 6,957 (10) 81,816 (857) Corporate debt securities 221,357 (2,847) 43,505 (161) 264,862 (3,008) ABS 21,542 (118) 3,851 (60) 25,393 (178) RMBS 105,443 (461) 110,452 (2,766) 215,895 (3,227) CMBS 62,388 (728) 11,852 (51) 74,240 (779) CLOs 81,444 (225) 196,988 (1,418) 278,432 (1,643) Total $ 624,334 $ (5,426) $ 379,411 $ (4,476) $ 1,003,745 $ (9,902) Based on current facts and circumstances, we believe the unrealized losses as of December 31, 2020 presented in table 5.4a above are not indicative of the ultimate collectability of the current amortized cost of the securities. We believe the gross unrealized losses are primarily attributable to widening credit spreads over risk free rates, as a result of economic and market uncertainties arising from the COVID-19 pandemic, which includes demand shocks in multiple sectors that originated in 2020. We also rely upon estimates of several credit and non-credit factors in our review and evaluation of individual investments to determine whether a credit impairment exists. At December 31, 2020 we recorded an allowance for expected credit losses of $49 thousand. The unrealized losses in all categories of our investments as of December 31, 2019 were primarily caused by changes in interest rates between the time of purchase and the respective year end. There were 109 and 217 securities in an unrealized loss position as of December 31, 2020 and 2019, respectively. As of December 31, 2020, the fair value as a percent of amortized cost of the securities in an unrealized loss position was 99% and approximately 27% of the securities in an unrealized loss position were backed by the U.S. Government. We report accrued investment income separately from fixed income, available-for-sale securities, and we have determined an allowance for credit losses for accrued investment income is not required. Accrued investment income is written off through net realized investment gains (losses) if, and at the time, the issuer of the security defaults or is expected to default on payment s The source of net investment income is shown in table 5.5 below. Net investment income Table 5.5 (In thousands) 2020 2019 2018 Fixed income securities $ 157,065 $ 165,523 $ 140,539 Equity securities 620 406 228 Cash equivalents 1,648 4,444 3,423 Other 275 974 816 Investment income 159,608 171,347 145,006 Investment expenses (5,212) (4,302) (3,675) Net investment income $ 154,396 $ 167,045 $ 141,331 The change in unrealized gains (losses) of investments is shown in table 5.6 below. Change in unrealized gains (losses) Table 5.6 (In thousands) 2020 2019 2018 Fixed income securities $ 169,135 $ 220,139 $ (81,834) Equity securities — — — Change in unrealized gains/losses $ 169,135 $ 220,139 $ (81,834)

Fair Value Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2020
Fair Value Disclosures [Abstract]
Fair Value Measurements	NOTE 6 Fair Value Measurements The following describes the valuation methodologies generally used by the independent pricing sources, or by us, to measure financial instruments at fair value, including the general classification of such financial instruments pursuant to the valuation hierarchy. Level 1 measurements • Fixed income securities: Consist of primarily U.S. Treasury securities with valuations derived from quoted prices for identical instruments in active markets that we can access. • Equity securities: Consist of actively traded, exchange-listed equity securities with valuations derived from quoted prices for identical assets in active markets that we can access. • Cash Equivalents: Consists of money market funds and treasury bills with valuations derived from quoted prices for identical assets in active markets that we can access. The remaining instruments in this category are valued using market data for comparable instruments and are classified as Level 2. Level 2 measurements • Fixed income securities: Corporate Debt & U.S. Government and Agency Bonds are valued by surveying the dealer community, obtaining relevant trade data, benchmark quotes and spreads and incorporating this information into the valuation process. Obligations of U.S. States & Political Subdivisions are valued 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 valued 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 valued using 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. Evaluation uses regular reviews of the inputs for securities covered, including executed trades, broker quotes, credit information, collateral attributes and/or cash flow waterfall as applicable. Asset-Backed Securities ("ABS") are valued 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 offers are applied, resulting in tranche specific prices. Collateralized loan obligations ("CLO") are valued by evaluating 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. Other Investments. These securities primarily consist of commercial paper which are valued using market data for comparable instruments of similar maturity and average yield. Level 3 measurements • Real estate acquired is valued at 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. RECURRING FAIR VALUE MEASUREMENTS Assets carried at fair value included those listed, by hierarchy level, in the following tables as of December 31, 2020 and 2019: Assets carried at fair value by hierarchy level as of December 31, 2020 Table 6.1a (In thousands) 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 $ 265,693 $ 149,339 $ 116,354 $ — Obligations of U.S. states and political subdivisions 2,249,869 — 2,249,869 — Corporate debt securities 2,844,288 — 2,844,288 — ABS 206,686 — 206,686 — RMBS 431,166 — 431,166 — CMBS 327,502 — 327,502 — CLOs 310,490 — 310,490 — Debt foreign government 4,709 — 4,709 — Other Investments (1) 21,193 — 21,193 — Total fixed income securities 6,661,596 149,339 6,512,257 — Equity securities 18,215 18,215 — — Cash Equivalents 288,941 275,668 13,273 — Real estate acquired (2) 1,092 — — 1,092 Total $ 6,969,844 $ 443,222 $ 6,525,530 $ 1,092 Assets carried at fair value by hierarchy level as of December 31, 2019 Table 6.1b (In thousands) 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 $ 196,203 $ 34,240 $ 161,963 $ — Obligations of U.S. states and political subdivisions 1,653,865 — 1,653,865 — Corporate debt securities 2,785,122 — 2,785,122 — ABS 229,664 — 229,664 — RMBS 268,586 — 268,586 — CMBS 278,986 — 278,986 — CLOs 325,466 — 325,466 — Total fixed income securities 5,737,892 34,240 5,703,652 — Equity securities 17,328 17,328 — — Cash Equivalents 164,693 164,693 — — Real estate acquired (2) 7,252 — — 7,252 Total $ 5,927,165 $ 216,261 $ 5,703,652 $ 7,252 (1) Consists of commercial paper included in "Investment Portfolio: Fixed income" with original maturities greater than ninety days. (2) Real estate acquired through claim settlement, which is held for sale, is reported in "Other assets" on the consolidated balance sheets. Certain financial instruments, including insurance contracts, are excluded from fair value disclosure requirements. The carrying values of cash and cash equivalents (Level 1) and accrued investment income (Level 2) approximated their fair values. RECONCILIATIONS OF LEVEL 3 ASSETS For assets measured at fair value using significant unobservable inputs (Level 3), a reconciliation of the beginning and ending balances for the years ended December 31, 2020 and 2019 is shown in tables 6.2a and 6.2b below. There were no losses included in earnings for the years ended December 31, 2020 and 2019 attributable to the change in unrealized losses on assets still held at the end of each applicable year. Fair value roll-forward for financial instruments classified as Level 3 for the year ended December 31, 2020 Table 6.2a (In thousands) Debt Securities Real Estate Acquired Balance at December 31, 2019 $ — $ 7,252 Total realized/unrealized gains (losses): Included in earnings and reported as losses incurred, net — 660 Acquisitions — 8,609 Sales — (15,429) Balance at December 31, 2020 $ — $ 1,092 Fair value roll-forward for financial instruments classified as Level 3 for the year ended December 31, 2019 Table 6.2b (In thousands) Debt Securities Real Estate Acquired Balance at December 31, 2018 $ 13 $ 14,535 Total realized/unrealized gains (losses): Included in earnings and reported as losses incurred, net — (476) Acquisitions — 24,204 Sales (13) (31,011) Balance at December 31, 2019 $ — $ 7,252 Additional fair value disclosures related to our investment portfolio are included in Note 5 – “Investments. ” FINANCIAL LIABILITIES NOT CARRIED AT FAIR VALUE Other invested assets include an investment in FHLB stock that is carried at cost, which due to restrictions that require it to be redeemed or sold only to the security issuer at par value, approximates fair value. The fair value of other invested assets is categorized as Level 2. Financial liabilities include our outstanding debt obligations. The fair values of our 5.75% Notes 5.25% Notes, and 9% Debentures were based on observable market prices. The fair value of the FHLB Advance was estimated using cash flows discounted at current incremental borrowing rates for similar borrowing arrangements, and in all cases they are categorized as Level 2. See Note 7 - " D ebt" for a description of the financial liabilities in table 6.3. Table 6.3 compares the carrying value and fair value of our financial liabilities disclosed, but not carried, at fair value as of December 31, 2020 and 2019. Financial liabilities not carried at fair value Table 6.3 December 31, 2020 December 31, 2019 (In thousands) Carrying Value Fair Value Carrying Value Fair Value Financial assets Other invested assets $ 3,100 $ 3,100 $ 3,100 $ 3,100 Financial liabilities FHLB Advance $ 155,000 $ 160,865 $ 155,000 $ 156,422 5.75% Notes 240,597 261,752 420,867 471,827 5.25% Notes 638,782 696,449 — — 9% Debentures 208,814 273,569 256,872 346,289 Total financial liabilities $ 1,243,193 $ 1,392,635 $ 832,739 $ 974,538 The 5.75% Notes, 5.25% Notes, and 9% Debentures are obligations of our holding company, MGIC Investment Corporation.

Debt

Debt	12 Months Ended
	Dec. 31, 2020
Debt Disclosure [Abstract]
Debt	NOTE 7 Debt DEBT OBLIGATIONS Table 7.1 shows the carrying value of our long-term debt obligations as of December 31, 2020 and 2019. Long-term debt obligations Table 7.1 December 31, (In millions) 2020 2019 FHLB Advance - 1.91%, due February 2023 $ 155.0 $ 155.0 5.75% Notes, due August 2023 (par value: $242.3 million) 240.6 420.9 5.25% Notes, due August 2028 (par value: $650 million) 638.8 — 9% Debentures, due April 2063 208.8 256.9 Long-term debt, carrying value $ 1,243.2 $ 832.8 The 5.75% Senior Notes (“5.75% Notes”), 5.25% Senior Notes ("5.25% Notes") and 9% Convertible Junior Subordinated Debentures (“9% Debentures”) are obligations of our holding company, MGIC Investment Corporation. The Federal Home Loan Bank Advance (“FHLB Advance”) is an obligation of MGIC. 2020 Transactions In August 2020, we issued $650 million aggregate principal amount of 5.25% Notes, which are due in 2028 and received net proceeds, after the deduction of underwriting fees, of $640.3 million. In addition to underwriting fees, we incurred approximately $2.0 million of other expenses associated with the issuance of these notes. We repurchased $182.7 million in aggregate principal amount of our 5.75% notes at a purchase price of $197.8 million, plus accrued interest, using proceeds from the 5.25% Notes issuance. The excess of the purchase price over the carrying value, plus the write-off of unamortized issuance costs on the par value, is reflected as a loss on debt extinguishment of $16.5 million on our consolidated statement of operations. We repurchased $48.1 million in aggregate principal amount of our 9% Debentures at a purchase price of $61.6 million, plus accrued interest, using proceeds from the 5.25% Notes issuance. The repurchase of 9% Debentures resulted in a $10.2 million loss on debt extinguishment on our consolidated statement of operations; a reduction in our shareholders' equity of $2.7 million related to the reacquisition of the equity component of the 9% Debentures; and a reduction in our potentially dilutive shares by approximately 3.6 million shares. The net proceeds from the 5.25% Notes issuance were used, in part, as (i) cash consideration to purchase $182.7 million of our 5.75% Notes, and (ii) cash consideration to purchase $48.1 million of our 9% Debentures. The balance of the proceeds remains at the holding company. FHLB Advance MGIC borrowed $155.0 million in the form of a fixed rate advance from the Federal Home Loan Bank of Chicago ("Advance"). Interest on the Advance is payable monthly at an annual rate, fixed for the term of the Advance, of 1.91%. The principal of the Advance matures on February 10, 2023. MGIC may prepay the Advance at any time. Such prepayment would be below par if interest rates have risen after the Advance was originated, or above par if interest rates have declined. The Advance is secured by eligible collateral whose market value must be maintained at 102% of the principal balance of the Advance. MGIC provided eligible collateral from its investment portfolio. 5.25% Notes Interest on the 5.25% Notes is payable semi-annually on February 15 and August 15. Prior to August 15, 2023, we may redeem the 5.25% Notes at an amount equal to the sum of (a) the greater of: (i) the sum of the principal amount and the make-whole amount; and (ii) 102.625% of principal; and (b) accrued and unpaid interest. The make-whole amount is the excess of: (1) the present value of the remaining principal, premium and interest payments that would be payable with respect to the note if such note were redeemed on August 15, 2023 (at 102.625% of principal), computed using a discount rate equal to the treasury rate specified in the notes, plus 50 basis points, over (2) the outstanding principal amount of such note. On and after August 15, 2023, we may redeem the notes at 102.625% of principal; on or after August 15, 2024, we may redeem the notes at 101.313% of principal; and on or after August 15, 2025, we may redeem the notes at 100% of principal; in each case, plus accrued and unpaid interest. The 5.25% Notes have covenants customary for securities of this nature, including customary events of default and further provide that the trustee or holders of at least 25% in aggregate principal amount of the outstanding 5.25% Notes may declare them immediately due and payable upon the occurrence of certain events of default after the expiration of the applicable grace period. In addition, in the case of an event of default arising from certain events of bankruptcy, insolvency or reorganization relating to the Company or any of its significant subsidiaries, the 5.25% Notes will become due and payable immediately. This description is not intended to be complete in all respects and is qualified in its entirety by the terms of the 5.25% Notes, including their covenants and events of default. We were in compliance with all covenants as of December 31, 2020. 5.75% Notes Interest on the 5.75% Notes is payable semi-annually on February 15 and August 15 of each year. We have the option to redeem these notes, in whole or in part, at any time or from time to time prior to maturity at a redemption price equal to the greater of (i) 100% of the aggregate principal amount of the notes to be redeemed and (ii) the make-whole amount, which is the sum of the present values of the remaining scheduled payments of principal and interest discounted at the treasury rate defined in the notes plus 50 basis points and accrued interest. The 5.75% Notes have covenants customary for securities of this nature, including customary events of default, and further provide that the trustee or holders of at least 25% in aggregate principal amount of the outstanding 5.75% Notes may declare them immediately due and payable upon the occurrence of certain events of default after the expiration of the applicable grace period. In addition, in the case of an event of default arising from certain events of bankruptcy, insolvency or reorganization relating to the Company or any of its significant subsidiaries, the 5.75% Notes will become due and payable immediately. This description is not intended to be complete in all respects and is qualified in its entirety by the terms of the 5.75% Notes, including their covenants and events of default. We were in compliance with all covenants as of December 31, 2020. 9% Debentures The 9% Debentures are currently convertible, at the holder's option, at a conversion rate, which is subject to adjustment, of 75.5932 common shares per $1,000 principal amount of the 9% Debentures at any time prior to the maturity date. This represents a conversion price of approximately $13.23 per share. If a holder elects to convert their 9% Debentures, deferred interest, if any, owed on the 9% 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. The 9% Debentures include a conversion feature that allows us, at our option, to make a cash payment to converting holders in lieu of issuing shares of common stock upon conversion of the 9% Debentures. We may redeem the 9% Debentures in whole or in part from time to time, at our option, at a redemption price equal to 100% of the principal amount of the 9% Debentures being redeemed, plus any accrued and unpaid interest, if the closing sale price of our common stock exceeds $17.20 for at least 20 of the 30 trading days preceding notice of the redemption. Interest on the 9% Debentures is payable semi-annually in arrears on April 1 and October 1 of each year. As long as no event of default with respect to the debentures has occurred and is continuing, we may defer interest, under an optional deferral provision, for one or more consecutive interest periods up to 10 years without giving rise to an event of default. Deferred interest will accrue additional interest at the rate then applicable to the debentures. During an optional deferral period we may not pay or declare dividends on our common stock. When interest on the 9% Debentures is deferred, we are required, not later than a specified time, to use reasonable commercial efforts to begin selling qualifying securities to persons who are not our affiliates. The specified time is one business day after we pay interest on the 9% Debentures that was not deferred, or if earlier, the fifth anniversary of the scheduled interest payment date on which the deferral started. Qualifying securities are common stock, certain warrants and certain non-cumulative perpetual preferred stock. The requirement to use such efforts to sell such securities is called the Alternative Payment Mechanism. The net proceeds of Alternative Payment Mechanism sales are to be applied to the payment of deferred interest, including the compound portion. We cannot pay deferred interest other than from the net proceeds of Alternative Payment Mechanism sales, except at the final maturity of the debentures or at the tenth anniversary of the start of the interest deferral. The Alternative Payment Mechanism does not require us to sell common stock or warrants before the fifth anniversary of the interest payment date on which that deferral started if the net proceeds (counting any net proceeds of those securities previously sold under the Alternative Payment Mechanism) would exceed the 2% cap. The 2% cap is 2% of the average closing price of our common stock times the number of our outstanding shares of common stock. The average price is determined over a specified period ending before the issuance of the common stock or warrants being sold, and the number of outstanding shares is determined as of the date of our most recent publicly released financial statements. We are not required to issue under the Alternative Payment Mechanism a total of more than 10 million shares of common stock, including shares underlying qualifying warrants. In addition, we may not issue under the Alternative Payment Mechanism qualifying preferred stock if the total net proceeds of all issuances would exceed 25% of the aggregate principal amount of the debentures. The Alternative Payment Mechanism does not apply during any period between scheduled interest payment dates if there is a “market disruption event” that occurs over a specified portion of such period. Market disruption events include any material adverse change in domestic or international economic or financial conditions. This description is not intended to be complete in all respects and is qualified in its entirety by the terms of the 9% Debentures, including their covenants and events of default. We were in compliance with all covenants at December 31, 2020. The 9% Debentures rank junior to all of our existing and future senior indebtedness. INTEREST PAYMENTS Interest payments were $54.3 million during 2020, $50.8 million during 2019, and $51.3 million during 2018.

Loss Reserves

Loss Reserves	12 Months Ended
	Dec. 31, 2020
Insurance Loss Reserves [Abstract]
Loss Reserves	NOTE 8 Loss Reserves As described in Note 3 – “Summary of Significant Accounting Policies – Loss Reserves,” We establish case reserves and loss adjustment expenses ("LAE") reserves on delinquent loans that were reported to us as two or more payments past due and have not become current or resulted in a claim payment. Case 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. IBNR reserves are established for estimated losses from delinquencies we estimate have occurred prior to the close of an accounting period, but have not yet been reported to us. IBNR reserves are also established using estimated claim rates and claim severities 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 delinquency 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 and the continued impact of the COVID-19 pandemic, leading to a reduction in borrowers’ income and thus their ability to make mortgage payments, the impact of past and future government initiatives and actions taken by the GSEs (including mortgage forbearance programs and foreclosure moratoriums), 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. Loss reserves in future periods will also be dependent on the number of loans reported to us as delinquent. Changes to our estimates could result in a material impact to our consolidated results of operations and financial position, even in a stable economic environment. It is reasonably possible that given the uncertainty of the impacts of the COVID 19 pandemic, our reserve estimate may continue to be impacted. In considering the potential sensitivity of the factors underlying our estimate of loss reserves, it is possible that even a relatively small change in our estimated claim rate or severity could have a material impact on loss reserves and, correspondingly, on our consolidated results of operations even in a stable economic environment. For example, as of December 31, 2020, assuming all other factors remain constant, a $1,000 increase/decrease in the average severity reserve factor would change the loss reserve amount by approximately +/- $16 million. A one percentage point increase/decrease in the average claim rate reserve factor would change the loss reserve amount by approximately +/- $34 million. LOSSES INCURRED The “Losses incurred” section of table 8.1 below shows losses incurred on delinquencies that occurred in the current year and in prior years. The amount of losses incurred relating to delinquencies that occurred in the current year represents the estimated amount to be ultimately paid on such delinquencies. The amount of losses incurred relating to delinquencies that occurred in prior years represents the difference between the actual claim rate and severity associated with those delinquencies resolved in the current year compared to the estimated claim rate and severity at the prior year-end, as well as a re-estimation of amounts to be ultimately paid on delinquencies 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 delinquency inventory, such as percentages of delinquencies that have resulted in a claim, the amount of the claims relative to the average loan exposure, changes in the relative level of delinquencies by geography and changes in average loan exposure. Losses incurred on delinquencies that occurred in the current year increased in 2020 compared to 2019 due to an increase in the new delinquency notices reported and IBNR reserve estimates, due to the impact of the COVID-19 pandemic. Given the uncertainty surrounding the long-term economic impact of COVID-19, it is difficult to predict the ultimate effect of COVID-19 related delinquencies and forbearances on our loss incidence. Losses incurred on delinquencies that occurred in the current year decreased in 2019 compared to 2018 primarily due to a decrease in the number of new delinquencies, net of cures, as well as a decrease in the estimated claim rate on recently reported delinquencies. LOSSES PAID The “Losses paid” section of table 8.1 below shows the amount of losses paid on delinquencies that occurred in the current year and losses paid on delinquencies that occurred in prior years. For several years, the average time it took to receive a claim associated with a delinquency had increased significantly from our historical experience of approximately twelve months. This was, 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. In recent quarters, before the second quarter of 2020, we had begun to experience a decline in the average time it takes servicers to process foreclosures, which had reduced the average time to receive a claim associated with new delinquencies that do not cure. All else being equal, the longer the period between delinquency and claim filing, the greater the severity. In light of the uncertainty caused by the COVID-19 pandemic, specifically the foreclosure moratoriums and forbearance plans, the average time it takes to receive a claim may increase. Premium refunds Our estimate of premiums to be refunded on expected claim payments is accrued for separately in "Other liabilities" on our consolidated balance sheets and approximated $30 million each at December 31, 2020 and 2019. Table 8.1 provides a reconciliation of beginning and ending loss reserves for each of the past three years: Development of loss reserves Table 8.1 (In thousands) 2020 2019 2018 Reserve at beginning of year $ 555,334 $ 674,019 $ 985,635 Less reinsurance recoverable 21,641 33,328 48,474 Net reserve at beginning of year 533,693 640,691 937,161 Losses incurred: Losses and LAE incurred in respect of delinquent notices received in: Current year 345,170 189,581 203,928 Prior years (1) 19,604 (71,006) (167,366) Total losses incurred 364,774 118,575 36,562 Losses paid: Losses and LAE paid in respect of delinquent notices received in: Current year 3,069 4,018 7,298 Prior years 109,923 235,551 327,743 Reinsurance terminations (20) (13,996) (2,009) Total losses paid 112,972 225,573 333,032 Net reserve at end of year 785,495 533,693 640,691 Plus reinsurance recoverables 95,042 21,641 33,328 Reserve at end of year $ 880,537 $ 555,334 $ 674,019 (1) A positive number for prior year loss development indicates a deficiency of prior year reserves. A negative number for prior year losses incurred indicates a redundancy of prior year loss reserves. See table 8.2 below for more information about prior year loss development. Table 8.2 below shows the development of reserves in 2020, 2019 and 2018 for previously received delinquencies. Reserve development on previously received delinquencies Table 8.2 (In thousands) 2020 2019 2018 (Decrease) in estimated claim rate on primary delinquencies $ (2,536) $ (111,848) $ (212,738) Increase (decrease)in estimated severity on primary delinquencies 13,535 (434) 28,528 Change in estimates related to pool reserves, LAE reserves, reinsurance and other 8,605 41,276 16,844 Total prior year loss development (1) $ 19,604 $ (71,006) $ (167,366) (1) A positive number for prior year loss development indicates a deficiency of prior year loss reserves. A negative number for prior year loss development indicates a redundancy of prior year loss reserves. For the year ended December 31, 2020, we experienced adverse development on previously received delinquencies primarily related to severity and adjustments to LAE reserves. For the years ended December 31, 2019 and 2018, we experienced favorable development on previously received delinquencies. This development was, in part, due to the resolution of approximately 69% and 73% for the years ended December 31, 2019 and 2018, respectively, of the prior year delinquency inventory, with improved cure rates. During 2019 and 2018, cure activity on loans that were delinquent twelve months or more was significantly higher than our previous estimates. During 2019, the favorable development was offset by adjustments to LAE reserves and amounts paid in settlement of disputes for claim paying practices. See Note 17 – “Litigation and Contingencies.” The favorable development for the year ended 2018 was offset, in part, by an increase in the estimated severity on previously reported delinquencies remaining in the delinquency inventory. DELINQUENT INVENTORY A roll-forward of our primary delinquent inventory for the years ended December 31, 2020, 2019, and 2018 appears in table 8.3 below. 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 number of business days in a month and transfers of servicing between loan servicers. Primary delinquency inventory roll-forward Table 8.3 2020 2019 2018 Beginning delinquent inventory 30,028 32,898 46,556 New Notices 106,099 54,239 54,448 Cures (76,107) (52,035) (60,511) Paid claims (2,245) (4,267) (5,750) Rescissions and denials (65) (168) (267) Other items removed from inventory — (639) (1,578) Ending delinquent inventory 57,710 30,028 32,898 COVID-19 Activity New delinquency notices increased in 2020 because of the impacts of the COVID-19 pandemic, including the high level of unemployment and economic uncertainty resulting from measures to reduce the transmission of COVID-19. In the last half of 2020, we experienced an increase in cures associated with our COVID-19 new delinquency notices. Government initiatives and actions taken by the GSEs provide for payment forbearance on mortgages to borrowers experiencing hardship during the COVID-19 pandemic. These forbearance plans generally allow for mortgage payments to be suspended for up to 360 days: an initial forbearance period of up to 180 days and, if requested by the borrower, an extension of up to 180 days. For loans in a COVID-19 forbearance plan as of February 28, 2021, the plan may be extended for an additional three months, subject to certain limits. Other items removed from inventory During 2019 and 2018 our losses paid included amounts paid upon commutation of coverage on policies. The impacts of the commutations of coverage on policies and/or settlements were as follows: • 2019 - 639 notices removed from delinquent inventory with an amount paid of $30 million, • 2018 - 1,578 notices removed from delinquent inventory with an amount paid of $50 million. In 2019, our losses paid included $23.5 million paid in connection with settlements of disputes concerning our claims paying practices. Aging of delinquent inventory Historically as a delinquency ages it becomes more likely to result in a claim. The number of consecutive months that a borrower has been delinquent is shown in table 8.4 below. Primary delinquency inventory - consecutive months delinquent Table 8.4 December 31, 2020 2019 2018 3 months or less 11,542 9,447 9,829 4 - 11 months 34,620 9,664 9,655 12 months or more (1) 11,548 10,917 13,414 Total 57,710 30,028 32,898 3 months or less 20 % 32 % 30 % 4 - 11 months 60 % 32 % 29 % 12 months or more 20 % 36 % 41 % Total 100 % 100 % 100 % Primary claims received inventory included in ending delinquent inventory 159 538 809 (1) Approximately 31%, 36%, and 38% of the delinquent inventory that has been delinquent for 12 consecutive months or more has been delinquent for at least 36 consecutive months as of December 31, 2020, 2019 and 2018, respectively. The increase in delinquency inventory that is 4-11 consecutive months delinquent is primarily due to the number of new delinquency notices received in the second quarter of 2020 resulting from the impacts of the COVID-19 pandemic. This was partially offset by an increase in cures in the third and fourth quarter of 2020. POOL INSURANCE DEFAULT INVENTORY Pool insurance default inventory was 680 at December 31, 2020, 653 at December 31, 2019, and 859 at December 31, 2018. 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. For information about discussions and legal proceedings with customers with respect to our claims paying practices, see Note 17 – “Litigation and Contingencies.”

Reinsurance

Reinsurance	12 Months Ended
	Dec. 31, 2020
Reinsurance Disclosures [Abstract]
Reinsurance	NOTE 9 Reinsurance Our consolidated financial statements reflect the effects of assumed and ceded reinsurance transactions. Assumed reinsurance refers to the acceptance of certain insurance risks that other insurance companies have underwritten. Ceded reinsurance involves transferring certain insurance risks (along with the related earned premiums) we have underwritten to other insurance companies who agree to share these risks. The purpose of ceded reinsurance is to protect us, at a cost, against losses arising from our mortgage guaranty policies covered by the agreement and to manage our capital requirements under PMIERs. Reinsurance is currently placed on a quota share and excess of loss basis, but we also have immaterial captive reinsurance agreements that remain in effect through December 31, 2020. Table 9.1 below shows the effect of all reinsurance agreements on premiums earned and losses incurred as reflected in the consolidated statements of operations. Reinsurance Table 9.1 Years ended December 31, (In thousands) 2020 2019 2018 Premiums earned: Direct $ 1,199,824 $ 1,155,240 $ 1,084,748 Assumed 10,848 5,085 1,805 Ceded (188,729) (129,337) (111,391) Net premiums earned 1,021,943 1,030,988 975,162 Losses incurred: Direct 442,194 130,100 43,060 Assumed 555 (125) 331 Ceded (77,975) (11,400) (6,829) Net losses incurred $ 364,774 $ 118,575 $ 36,562 QUOTA SHARE REINSURANCE We have entered into quota share reinsurance ("QSR") agreements with panels of third-party reinsurers to cede a fixed quota share percentage on premiums earned and received and losses incurred on insurance covered by the transactions. We receive the benefit of a ceding commission equal to 20% of premiums ceded before profit commission. We also receive the benefit of a profit commission through a reduction of premiums we cede. The profit commission varies inversely with the level of losses on a “dollar for dollar” basis and can be eliminated at annual loss ratios higher than we have experienced on our QSR agreements. Each of our QSR agreements typically have annual loss ratio caps of 300% and lifetime loss ratios of 200% . Table 9.2 below provides additional detail regarding our QSR agreements. Reinsurance Table 9.2 Quota Share Contract Policy Year Quota Share % Annual Loss Ratio to Exhaust Profit Commission (1) Contractual Termination Date 2015 QSR Prior to 2017 15.0 % 68.0 % December 31, 2031 2017 QSR 2017 30.0 % 60.0 % December 31, 2028 2018 QSR 2018 30.0 % 62.0 % December 31, 2029 2019 QSR 2019 30.0 % 62.0 % December 31, 2030 2020 QSR - 1 Year 2020 12.5 % 62.0 % December 31, 2031 2020 QSR - 2 Year 2020 - 2021 17.5 % 62.0 % December 31, 2032 Credit Union QSR (2) 2020-2025 65.0 % 50.0 % December 31, 2039 (1) We will receive a profit commission provided the annual loss ratio on loans covered under the transaction remains below this ratio. (2) Eligible credit union business written before 2020 was covered by our 2019 and prior QSR Transactions. We have agreed to terms with a group of unaffiliated reinsurers for a reinsurance transaction with an effective date of January 1, 2021 with a similar structure to our existing QSR transactions that will cover most of our NIW in 2021 (with an additional 12.5% quota share) and 2022 (with a 15% quota share). Generally, we will receive an annual profit commission provided the annual loss ratio on the loans covered under the transaction remain below 57.5%. We can elect to terminate the quota share reinsurance agreements under specified scenarios without penalty upon prior written notice, including if we will receive less than 90% (80% for the Credit Union QSR Transaction ) of the full credit amount under the PMIERs, full financial statement credit or full credit under applicable regulatory capital requirements for the risk ceded in any required calculation period. Early termination of the QSR agreements can also be elected by us for a fee, or under specified scenarios for no fee upon prior written notice. Table 9.3 provides additional detail regarding optional termination dates and optional reductions to our quota share percentage. The optional reduction to the quota share percentage would give us an option to reduce our quota share percentage from the original percentage as shown in table 9.2. Reinsurance Table 9.3 Quota Share Contract Optional Termination Date (1) Optional Quota Share % Reduction Date (2) Quota Share % Reduction 2015 QSR June 30, 2021 NA NA 2017 QSR December 31, 2021 NA NA 2018 QSR December 31, 2021 NA NA 2019 QSR December 31, 2021 July 1, 2020 25% or 20% 2020 QSR - 1 Year December 31, 2022 July 1, 2021 10.5% or 8% 2020 QSR - 2 Year December 31, 2023 July 1, 2021 14.5% or 12% (1) We can elect early termination of the QSR agreement beginning on this date, and bi-annually thereafter for the 2015 QSR, 2019 QSR, and 2020 QSR. Early termination of the 2018 QSR can be elected annually after this date. (2) We can elect to reduce the quota share percentage beginning on this date, and bi-annually thereafter. Table 9.4 provides a summary of our quota share reinsurance agreements for 2020, 2019, and 2018. Quota share reinsurance Table 9.4 Years ended December 31, (In thousands) 2020 2019 2018 Ceded premiums written and earned, net of profit commission $ 167,930 $ 111,550 $ 108,337 Ceded losses incurred 78,012 11,395 6,543 Ceding commissions (1) 48,077 48,793 51,201 Profit commission 72,452 139,179 147,667 (1) Ceding commissions are reported within Other underwriting and operating expenses, net on the consolidated statements of operations. Ceded premiums written and earned, net of profit commission, increased in 2020 due to the decrease in profit commission. The decrease in profit commission was a result of higher ceded losses incurred, primarily due to an increase in the delinquency inventory due to the impacts of the COVID-19 pandemic. We terminated a portion of our 2015 QSR Transaction effective June 30, 2019 and entered into an amended quota share reinsurance agreement with certain participants from the existing reinsurance panel that effectively reduces the quota share cede rate from 30% to 15% on the remaining eligible insurance. During the second quarter of 2019, we incurred a termination fee of $6.8 million, which was paid to participants of the reinsurance panel that are not participating in the amended 2015 QSR Transaction. Under the terms of our QSR Transactions currently in effect, reinsurance premiums, ceding commission and profit commission are settled net on a quarterly basis. The reinsurance 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 was $95.0 million as of December 31, 2020 and $21.6 million as of December 31, 2019.The reinsurance recoverable balance is secured by funds on deposit from the reinsurers, the amount of which is based on the funding requirements of PMIERs. Each of the reinsurers under our quota share reinsurance agreements described above has an insurer financial strength rating of A- or better (or a comparable rating) by Standard and Poor's Rating Services, A.M. Best, Moody's, or a combination of the three. An allowance for credit losses was not required for 2020. EXCESS OF LOSS REINSURANCE We have aggregate excess of loss reinsurance agreements (“Home Re Transactions”) with unaffiliated special purpose insurers domiciled in Bermuda (“Home Re Entities”). For the reinsurance coverage periods, we retain the first layer of the respective aggregate losses, and a Home Re special purpose entity will then provide second layer coverage up to the outstanding reinsurance coverage amount. We retain losses in excess of the outstanding reinsurance coverage amount. The aggregate excess of loss reinsurance coverage decreases over a ten-year period, subject to certain conditions, as the underlying covered mortgages amortize or are repaid, or mortgage insurance losses are paid. A "Trigger Event" has occurred on each our outstanding ILN transactions. On the 2018 and 2019 ILN transactions a “Trigger Event” has occurred because the reinsured principal balance of loans that were reported 60 or more days delinquent exceeded 4% of the total reinsured principal balance of loans under each transaction. A “Trigger Event” has occurred on our 2020 ILN transaction because the credit enhancement of the most senior tranche is less than the target credit enhancement. While the “Trigger Event” is in effect, payment of principal on the related notes will be suspended and the reinsurance coverage available to MGIC under the transactions will not be reduced by such principal payments. MGIC has rights to terminate the Home Re Transactions under certain circumstances. The Home Re entities financed the coverages by issuing mortgage insurance-linked notes (“ILNs”) to unaffiliated investors in an aggregate amount equal to the initial reinsurance coverage amounts. The ILNs each have ten-year legal maturities and are non-recourse to any assets of MGIC or affiliates. The proceeds of the ILNs, which were deposited into reinsurance trusts for the benefit of MGIC, will be the source of reinsurance claim payments to MGIC and principal repayments on the ILNs. Table 9.5 provides a summary of our excess of loss reinsurance agreements as of December 31, 2020, December 31, 2019 and December 31, 2018. Excess of Loss Reinsurance Table 9.5 (In thousands) Home Re 2020-1, Ltd. Home Re 2019-1, Ltd. Home Re 2018-1, Ltd. Issue Date October, 2020 May 1, 2019 October 1, 2018 Policy Inforce Dates January 1, 2020 - July 31, 2020 January 1, 2018 - March 31, 2019 July 1, 2016 - December 31, 2017 Termination Option Date (1) October 25, 2030 May 25, 2026 October 25, 2025 Initial First Layer Retention 275,283 185,730 168,691 Initial Excess of Loss Reinsurance Coverage 412,917 315,739 318,636 2020 Remaining First Layer Retention 275,283 184,514 166,005 Remaining Excess of Loss Reinsurance Coverage 412,917 208,146 218,343 2019 Remaining First Layer Retention — 185,636 167,779 Remaining Excess of Loss Reinsurance Coverage — 271,021 260,957 2018 Remaining First Layer Retention — — 168,691 Remaining Excess of Loss Reinsurance Coverage — — 318,636 (1) We have the right to terminate the excess-of-loss reinsurance agreements under certain circumstances and on any payment date on or after the respective termination option date. In February 2021, MGIC entered into a $398.8 million excess-of-loss reinsurance agreement (executed through an insurance linked note transaction) that covers policies with inforce dates from August 1, 2020 through December 31, 2020. The reinsurance premiums ceded to each Home Re Entity are composed of coverage, initial expense and supplemental premiums. The coverage premiums are generally calculated as the difference between the amount of interest payable by the Home Re Entity on the unpaid portion of the ILNs it issued to raise funds to collateralize its reinsurance obligations to us, and the investment income collected on the collateral assets. The amount of monthly reinsurance coverage premium ceded will fluctuate due to changes in one-month LIBOR, (or the fallback reference rate, as applicable) and changes in money market rates that affect investment income collected on the assets in the reinsurance trust. As a result, we concluded that each reinsurance agreement contains an embedded derivative that is accounted for separately as a freestanding derivative. The fair values of the derivatives at December 31, 2020 and December 31, 2019, were not material to our consolidated balance sheet, and the change in fair values during the year ended December 31, 2020 and December 31, 2019 were not material to our consolidated statements of operations. Total ceded premiums were $20.8 million, $17.6 million, and $2.8 million for the years ended December 31, 2020, December 31, 2019 and December 31, 2018, respectively. At the time the Home Re Transactions were entered into, we concluded that each Home Re Entity is a variable interest entity (“VIE”). A VIE is a legal entity that does not have sufficient equity at risk to finance its activities without additional subordinated financial support or is structured such that equity investors lack the ability to make sufficient decisions relating to the entity’s operations through voting rights or do not substantively participate in gains and losses of the entity. Given that MGIC (1) does not have the unilateral power to direct the activities that most significantly affect each Home Re Entity’s economic performance and (2) does not have the obligation to absorb losses or the right to receive benefits of each Home Re Entity, consolidation of neither Home Re Entity is required. We are required to disclose our maximum exposure to loss, which we consider to be an amount that we could be required to record in our statements of operations, as a result of our involvement with the VIEs under our Home Re Transactions. As of December 31, 2020, December 31, 2019 and December 31, 2018, we did not have material exposure to the VIEs as we have no investment in the VIEs and had no reinsurance claim payments due from either VIE under our reinsurance agreements. We are unable to determine the timing or extent of claims from losses that are ceded under the reinsurance agreements. The VIE assets are deposited in reinsurance trusts for the benefit of MGIC that will be the source of reinsurance claim payments to MGIC. The purpose of the reinsurance trusts is to provide security to MGIC for the obligations of the VIEs under the reinsurance agreements. The trustee of the reinsurance trusts, a recognized provider of corporate trust services, has established segregated accounts within the reinsurance trusts for the benefit of MGIC, pursuant to the trust agreements. The trust agreements are governed by, and construed in accordance with, the laws of the State of New York. If the trustee of the reinsurance trusts failed to distribute claim payments to us as provided in the reinsurance trusts, we would incur a loss related to our losses ceded under the reinsurance agreements and deemed unrecoverable. We are also unable to determine the impact such possible failure by the trustee to perform pursuant to the reinsurance trust agreements may have on our consolidated financial statements. As a result, we are unable to quantify our maximum exposure to loss related to our involvement with the VIEs. MGIC has certain termination rights under the reinsurance agreements should its claims not be paid. We consider our exposure to loss from our reinsurance agreements with the VIEs to be remote. Table 9.6 presents the total assets of Home Re Entities as of December 31, 2020 , December 31, 2019 and December 31, 2018. Home Re Entities total assets Table 9.6 (In thousands) Home Re Entity Total VIE Assets December 31, 2020 Home Re 2018-01 Ltd. $ 218,343 Home Re 2019-01 Ltd. $ 208,146 Home Re 2020-01 Ltd. $ 412,917 December 31, 2019 Home Re 2018-01 Ltd. $ 269,451 Home Re 2019-01 Ltd. $ 283,150 December 31, 2018 Home Re 2018-01 Ltd. $ 318,636 The reinsurance trust agreements provide that the trust assets may generally only be invested in certain money market funds that (i) invest at least 99.5% of their total assets in cash or direct U.S. federal government obligations, such as U.S. Treasury bills, as well as other short-term securities backed by the full faith and credit of the U.S. federal government or issued by an agency of the U.S. federal government, (ii) have a principal stability fund rating of “AAAm” by S&P or a money market fund rating of “Aaa-mf” by Moody’s as of the Closing Date and thereafter maintain any rating with either S&P or Moody’s, and (iii) are permitted investments under the applicable credit for reinsurance laws and applicable PMIERs credit for reinsurance requirements. The assets of the Home Re Entities provide capital credit under the PMIERs financial requirements (see Note 1 - "Nature of Business" ). A decline in the assets available to pay claims would reduce the capital credit available to MGIC.

Other Comprehensive Income (Los

Other Comprehensive Income (Loss)	12 Months Ended
	Dec. 31, 2020
Comprehensive Income (Loss), Net of Tax, Attributable to Parent [Abstract]
Other Comprehensive Income (Loss)	NOTE 10 Other Comprehensive Income (Loss) The pretax components of our other comprehensive income (loss) and related income tax (expense) benefit for the years ended December 31, 2020, 2019 and 2018 are included in table 10.1 below. Components of other comprehensive income (loss) Table 10.1 (In thousands) 2020 2019 2018 Net unrealized investment gains (losses) on securities without an allowance for credit losses $ 169,135 $ 220,139 $ (81,834) Income tax (expense) benefit (35,519) (46,229) 17,188 Net of taxes 133,616 173,910 (64,646) Net changes in benefit plan assets and obligations 13,288 29,129 (19,958) Income tax (expense) benefit (2,791) (6,117) 4,191 Net of taxes 10,497 23,012 (15,767) Total other comprehensive income (loss) 182,423 249,268 (101,792) Total income tax expense, net (38,310) (52,346) 21,379 Total other comprehensive income, net of tax $ 144,113 $ 196,922 $ (80,413) The pretax and related income tax benefit (expense) components of the amounts reclassified from our accumulated other comprehensive income (loss) ( "AOCI", "AOCL") to our consolidated statements of operations for the years ended December 31, 2020, 2019 and 2018 are included in table 10.2 below. Reclassifications from Accumulated Other Comprehensive Income (Loss) Table 10.2 (In thousands) 2020 2019 2018 Reclassification adjustment for net realized gains (losses) included in net income (1) $ 13,862 $ 3,637 $ (7,037) Income tax (expense) benefit (2,912) (763) 1,477 Net of taxes 10,950 2,874 (5,560) Reclassification adjustment related to benefit plan assets and obligations (2) (15,968) (8,097) (2,232) Income tax benefit 3,353 1,701 469 Net of taxes (12,615) (6,396) (1,763) Total reclassifications (2,106) (4,460) (9,269) Total income tax benefit, net 441 938 1,946 Total reclassifications, net of tax $ (1,665) $ (3,522) $ (7,323) (1) (Decreases) increases Net realized investment gains on the consolidated statements of operations. (2) Decreases (increases) Other underwriting and operating expenses, net on the consolidated statements of operations. A roll-forward of AOCI (AOCL) for the years ended December 31, 2020, 2019, and 2018, including amounts reclassified from AOCI (AOCL), is included in table 10.3 below. Roll-forward of Accumulated Other Comprehensive Income (Loss) Table 10.3 (In thousands) Net unrealized gains and losses on available-for-sale securities Net benefit plan assets and obligations recognized in shareholders' equity Total AOCL Balance, December 31, 2017, net of tax $ 29,275 $ (73,058) $ (43,783) Cumulative effect of adopting the accounting standard update for financial instruments (18) — (18) Other comprehensive income (loss) before reclassifications (70,206) (17,530) (87,736) Less: Amounts reclassified from AOCL (5,560) (1,763) (7,323) Balance, December 31, 2018, net of tax (35,389) (88,825) (124,214) Other comprehensive income (loss) before reclassifications 176,784 16,616 193,400 Less: Amounts reclassified from AOCL 2,874 (6,396) (3,522) Balance, December 31, 2019, net of tax 138,521 (65,813) 72,708 Other comprehensive income (loss) before reclassifications 144,566 (2,118) 142,448 Less: Amounts reclassified from AOCL 10,950 (12,615) (1,665) Balance, December 31, 2020, net of tax $ 272,137 $ (55,316) 216,821

Benefit Plans

Benefit Plans	12 Months Ended
	Dec. 31, 2020
Retirement Benefits [Abstract]
Benefit Plans	NOTE 11 Benefit Plans We have a non-contributory defined benefit pension plan covering substantially all domestic employees, as well as a supplemental executive retirement plan. We also offer both medical and dental benefits for retired domestic employees, their eligible spouses and dependents under a postretirement benefit plan. The following tables 11.1, 11.2, and 11.3 provide the components of aggregate annual net periodic benefit cost for each of the years ended December 31, 2020, 2019, and 2018 and changes in the benefit obligation and the funded status of the pension, supplemental executive retirement and other postretirement benefit plans as recognized in the consolidated balance sheets as of December 31, 2020 and 2019. Components of net periodic benefit cost Table 11.1 Pension and Supplemental Executive Retirement Plans Other Postretirement Benefits (In thousands) 12/31/2020 12/31/2019 12/31/2018 12/31/2020 12/31/2019 12/31/2018 1. Company Service Cost $ 7,342 $ 8,345 $ 10,530 $ 1,263 $ 1,345 $ 1,160 2. Interest Cost 13,036 15,705 15,095 832 1,130 834 3. Expected Return on Assets (22,139) (19,466) (22,250) (7,407) (5,785) (6,359) 4. Other Adjustments — — — — — — Subtotal (1,761) 4,584 3,375 (5,312) (3,310) (4,365) 5. Amortization of: a. Net Transition Obligation/(Asset) — — — — — — b. Net Prior Service Cost/(Credit) (247) (281) (351) 51 (34) (4,104) c. Net Losses/(Gains) 6,578 8,412 6,937 (783) — (250) Total Amortization 6,331 8,131 6,586 (732) (34) (4,354) 6. Net Periodic Benefit Cost 4,570 12,715 9,961 (6,044) (3,344) (8,719) 7. Cost of settlements 10,369 1,933 — — — — 8. Total Expense for Year $ 14,939 $ 14,648 $ 9,961 $ (6,044) $ (3,344) $ (8,719) Development of funded status Table 11.2 Pension and Supplemental Executive Retirement Plans Other Postretirement Benefits (In thousands) 12/31/2020 12/31/2019 12/31/2020 12/31/2019 Actuarial Value of Benefit Obligations 1. Measurement Date 12/31/2020 12/31/2019 12/31/2020 12/31/2019 2. Accumulated Benefit Obligation $ 423,305 $ 412,939 $ 28,714 $ 27,496 Funded Status/Asset (Liability) on the Consolidated Balance Sheet 1. Projected Benefit Obligation $ (423,713) $ (413,350) $ (28,714) $ (27,496) 2. Plan Assets at Fair Value 411,245 402,691 119,024 99,590 3. Funded Status - Overfunded/Asset N/A N/A $ 90,310 $ 72,094 4. Funded Status - Underfunded/Liability (12,468) (10,659) N/A N/A Accumulated other comprehensive (income) loss Table 11.3 Pension and Supplemental Executive Retirement Plans Other Postretirement Benefits (In thousands) 12/31/2020 12/31/2019 12/31/2020 12/31/2019 1. Net Actuarial (Gain)/Loss $ 98,899 $ 99,826 $ (30,565) $ (18,005) 2. Net Prior Service Cost/(Credit) (988) (1,237) 2,673 2,724 3. Net Transition Obligation/(Asset) — — — — 4. Total at Year End $ 97,911 $ 98,589 $ (27,892) $ (15,281) The amortization of gains and losses resulting from actual experience different from assumed experience or changes in assumptions including discount rates is included as a component of Net Periodic Benefit Cost/(Income) for the year. The gain or loss in excess of a 10% corridor is amortized by the average remaining service period of participating employees expected to receive benefits under the plan. Table 11.4 shows the changes in the projected benefit obligation for 2020 and 2019. Change in projected benefit / accumulated benefit Table 11.4 Pension and Supplemental Executive Retirement Plans Other Postretirement Benefits (In thousands) 12/31/2020 12/31/2019 12/31/2020 12/31/2019 1. Benefit Obligation at Beginning of Year $ 413,350 $ 376,153 $ 27,496 $ 28,085 2. Company Service Cost 7,342 8,345 1,263 1,345 3. Interest Cost 13,036 15,705 832 1,130 4. Plan Participants' Contributions — — 425 382 5. Net Actuarial (Gain)/Loss 36,196 47,113 660 (2,075) 6. Benefit Payments from Fund (1) (40,260) (30,829) (1,975) (826) 7. Benefit Payments Directly by Company (5,953) (3,105) — — 8. Plan Amendments 2 (5) — — 9. Other Adjustment — — 13 (545) 10. Settlement (Gain)/Loss — (27) — — 11. Benefit Obligation at End of Year $ 423,713 $ 413,350 $ 28,714 $ 27,496 (1) Includes lump sum payments of $27.5 million and $18.5 million in 2020 and 2019, respectively, from our pension plan to eligible participants, which were former employees with vested benefits. The increase in our pension and supplemental executive retirement plans obligation in 2020 compared to 2019 was primarily due to a decrease in the discount rate used to calculate the obligation partially offset by benefits paid from the fund. Table 11.7 below includes the actuarial assumptions used to calculate the benefit obligations of our plans for 2020 and 2019. Tables 11.5 and 11.6 shows the changes in the fair value of the net assets available for plan benefits, and changes in other comprehensive income (loss) during 2020 and 2019. Change in plan assets Table 11.5 Pension and Supplemental Executive Retirement Plans Other Postretirement Benefits (In thousands) 12/31/2020 12/31/2019 12/31/2020 12/31/2019 1. Fair Value of Plan Assets at Beginning of Year $ 402,691 $ 359,719 $ 99,590 $ 77,762 2. Company Contributions 12,453 10,205 — — 3. Plan Participants' Contributions — — 425 382 4. Benefit Payments from Fund (40,260) (30,829) (1,975) (826) 5. Benefit Payments paid directly by Company (5,953) (3,105) — — 6. Actual Return on Assets 42,314 70,262 21,409 22,654 7. Other Adjustment — (3,561) (425) (382) 8. Fair Value of Plan Assets at End of Year $ 411,245 $ 402,691 $ 119,024 $ 99,590 Change in accumulated other comprehensive income (loss) ("AOCI") Table 11.6 Pension and Supplemental Executive Retirement Plans Other Postretirement Benefits (In thousands) 12/31/2020 12/31/2019 12/31/2020 12/31/2019 1. AOCI in Prior Year $ 98,589 $ 108,808 $ (15,281) $ 3,629 2. Increase/(Decrease) in AOCI a. Recognized during year - Prior Service (Cost)/Credit 247 281 (51) 34 b. Recognized during year - Net Actuarial (Losses)/Gains (16,948) (8,412) 782 — c. Occurring during year - Prior Service Cost 2 (5) — — d. Occurring during year - Net Actuarial Losses/(Gains) 16,021 (150) (13,342) (18,944) e. Occurring during year - Net Settlement Losses/(Gains) — (1,933) — — 3. AOCI in Current Year $ 97,911 $ 98,589 $ (27,892) $ (15,281) The projected benefit obligations, net periodic benefit costs and accumulated postretirement benefit obligation for the plans were determined using the following weighted average assumptions. Actuarial assumptions Table 11.7 Pension and Supplemental Executive Retirement Plans Other Postretirement Benefits 12/31/2020 12/31/2019 12/31/2020 12/31/2019 Weighted-Average Assumptions Used to Determine Benefit Obligations at year end 1. Discount Rate 2.75 % 3.45 % 2.35 % 3.20 % 2. Rate of Compensation Increase 3.00 % 3.00 % N/A N/A 3. Cash balance interest crediting rate 2.50 % 3.20 % N/A N/A Weighted-Average Assumptions Used to Determine Net Periodic Benefit Cost for Year 1. Discount Rate 3.30 % 4.40 % 3.20 % 4.25 % 2. Expected Long-term Return on Plan Assets 5.75 % 5.75 % 7.50 % 7.50 % 3. Rate of Compensation Increase 3.00 % 3.00 % N/A N/A Assumed Health Care Cost Trend Rates at year end 1. Health Care Cost Trend Rate Assumed for Next Year N/A N/A 6.00 % 6.00 % 2. Rate to Which the Cost Trend Rate is Assumed to Decline (Ultimate Trend Rate) N/A N/A 5.00 % 5.00 % 3. Year That the Rate Reaches the Ultimate Trend Rate N/A N/A 2024 2024 In selecting a discount rate, we performed a hypothetical cash flow bond matching exercise, matching our expected pension plan and postretirement medical plan cash flows, respectively, against a selected portfolio of high quality corporate bonds. The modeling was performed using a bond portfolio of noncallable bonds with at least $50 million outstanding. The average yield of these hypothetical bond portfolios was used as the benchmark for determining the discount rate. In selecting the expected long-term rate of return on assets, we considered the average rate of earnings expected on the classes of funds invested or to be invested to provide for the benefits of these plans. This included considering the trusts' targeted asset allocation for the year and the expected returns likely to be earned over the next 20 years. The year-end asset allocations of the plans are shown in table 11.8 below. Plan assets Table 11.8 Pension Plan Other Postretirement Benefits 12/31/2020 12/31/2019 12/31/2020 12/31/2019 1. Equity Securities 21 % 23 % 100 % 100 % 2. Debt Securities 79 % 77 % — % — % 3. Total 100 % 100 % 100 % 100 % In accordance with fair value guidance, we applied the following fair value hierarchy in order to measure fair value of our benefit plan assets: è Level 1 Quoted prices for identical instruments in active markets that we can access. Financial assets using Level 1 inputs include equity securities, mutual funds, money market funds, certain U.S. Treasury securities and exchange traded funds ("ETFs"). è Level 2 Quoted prices for similar instruments in active markets; 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 using Level 2 inputs include certain municipal, corporate and foreign bonds, obligations of U.S. government corporations and agencies, and pooled equity accounts. To determine the fair value of securities in Level 1 and Level 2 of the fair value hierarchy, independent pricing sources have been used. 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 used 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 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. In addition, on a quarterly basis, we perform quality controls over values received from the pricing source (the “Trustee”) which include comparing values to other independent pricing sources. In addition, we review annually the Trustee’s auditor’s report on internal controls in order to determine that their controls around valuing securities are operating effectively. We have not made any adjustments to the prices obtained from the independent sources. Tables 11.9a and 11.9b set forth by level, within the fair value hierarchy, the pension plan assets and related accrued investment income at fair value as of December 31, 2020 and 2019. There were no securities that used Level 3 inputs. Pension plan assets at fair value as of December 31, 2020 Table 11.9a (In thousands) Level 1 Level 2 Total Domestic Mutual Funds $ 4,842 $ — $ 4,842 Corporate Bonds — 231,190 231,190 U.S. Government Securities 26,407 — 26,407 Municipal Bonds — 32,891 32,891 Foreign Bonds — 33,368 33,368 Pooled Equity Accounts — 82,547 82,547 Total Assets at fair value $ 31,249 $ 379,996 $ 411,245 Pension plan assets at fair value as of December 31, 2019 Table 11.9b (In thousands) Level 1 Level 2 Total Domestic Mutual Funds $ 7,325 $ — $ 7,325 Corporate Bonds — 203,684 203,684 U.S. Government Securities 32,166 2,511 34,677 Municipal Bonds — 38,998 38,998 Foreign Bonds — 34,024 34,024 Pooled Equity Accounts — 83,983 83,983 Total Assets at fair value $ 39,491 $ 363,200 $ 402,691 The pension plan has implemented a strategy to reduce risk through the use of a targeted funded ratio. The liability driven component is key to the asset allocation. The liability driven component seeks to align the duration of the fixed income asset allocation with the expected duration of the plan liabilities or benefit payments. Overall asset allocation is dynamic and specifies target allocation weights and ranges based on the funded status. An improvement in funded status results in the de-risking of the portfolio, allocating more funds to fixed income and less to equity. A decline in funded status would result in a higher allocation to equity. The maximum equity allocation is 40%. The equity investments use combinations of mutual funds, ETFs, and pooled equity account structures focused on the following strategies: Strategy Objective Investment types Return seeking growth Funded ratio improvement over the long term ● Global quality growth ● Global low volatility Return seeking bridge Downside protection in the event of a declining equity market ● Enduring asset ● Durable company The fixed income objective is to preserve capital and to provide monthly cash flows for the payment of plan liabilities. Fixed income investments can include government, government agency, corporate, mortgage-backed, asset-backed, and municipal securities, and other classes of bonds. The duration of the fixed income portfolio has an objective of being within one year of the duration of the accumulated benefit obligation. The fixed income investments have an objective of a weighted average credit of A3/A-/A- by Moody’s, S&P, and Fitch, respectively. Tables 11.10a and 11.10b set forth the other postretirement benefits plan assets at fair value as of December 31, 2020 and 2019. All are Level 1 assets. Other postretirement benefits plan assets at fair value as of December 31, 2020 Table 11.10a (In thousands) Level 1 Domestic Mutual Funds $ 91,454 International Mutual Funds 27,570 Total Assets at fair value $ 119,024 Other postretirement benefits plan assets at fair value as of December 31, 2019 Table 11.10b (In thousands) Level 1 Domestic Mutual Funds $ 77,640 International Mutual Funds 21,950 Total Assets at fair value $ 99,590 Our postretirement plan portfolio is designed to achieve the following objectives over each market cycle and for at least 5 years: è Total return should exceed growth in the Consumer Price Index by 5.75% annually è Achieve competitive investment results The primary focus in developing asset allocation ranges for the portfolio is the assessment of the portfolio's investment objectives and the level of risk that is acceptable to obtain those objectives. To achieve these objectives the minimum and maximum allocation ranges for fixed income securities and equity securities are: Minimum Maximum Equities (long only) 70 % 100 % Real estate 0 % 15 % Commodities 0 % 10 % Fixed income/Cash 0 % 10 % Given the long term nature of this portfolio and the lack of any immediate need for significant cash flow, it is anticipated that the equity investments will consist of growth stocks and will typically be at the higher end of the allocation ranges above. Investment in international mutual funds is limited to a maximum of 30% of the equity range. The allocation as of December 31, 2020 included 3% that was primarily invested in equity securities of emerging market countries and another 20% was invested in securities of companies primarily based in Europe and the Pacific Basin. Tables 11.12 and 11.13 show the current and estimated future contributions and benefit payments. Company contributions Table 11.12 Pension and Supplemental Executive Retirement Plans Other Postretirement Benefits (In thousands) 12/31/2020 12/31/2020 Company Contributions for the Year Ending: 1. Current $ 12,453 $ — 2. Current + 1 6,200 — Benefits payments - total Table 11.13 Pension and Supplemental Executive Retirement Plans Other Postretirement Benefits (In thousands) 12/31/2020 12/31/2020 Actual Benefit Payments for the Year Ending: 1. Current $ 46,213 $ 1,975 Expected Benefit Payments for the Year Ending: 2. Current + 1 30,082 1,765 3. Current + 2 29,929 1,995 4. Current + 3 30,076 2,157 5. Current + 4 29,567 2,241 6. Current + 5 28,852 2,357 7. Current + 6 - 10 135,830 10,916 PROFIT SHARING AND 401(K)

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2020
Income Tax Disclosure [Abstract]
Income Taxes	NOTE 12 Income Taxes Net deferred tax (liabilities) assets, included on the Consolidated Balance Sheet at December 31, 2020 and 2019 as a component of Other liabilities and Other assets, respectively, are as follows: Deferred tax assets and liabilities Table 12.1 (In thousands) 2020 2019 Total deferred tax assets $ 38,443 $ 63,533 Total deferred tax liabilities (98,485) (57,791) Net deferred tax (liability) asset $ (60,042) $ 5,742 Table 12.2 includes the components of the net deferred tax (liability) asset as of December 31, 2020 and 2019. Deferred tax components Table 12.2 (In thousands) 2020 2019 Unearned premium reserves $ 23,163 $ 30,487 Benefit plans (13,977) (10,790) Loss reserves 3,542 2,175 Unrealized appreciation in investments (72,341) (36,822) Mortgage investments — 8,359 Deferred compensation 6,776 9,270 AMT credit carryforward — 8,303 Other, net (7,205) (5,240) Net deferred tax (liability) asset $ (60,042) $ 5,742 We believe that all gross deferred tax assets at December 31, 2019 and 2020 are fully realizable and no valuation allowance has been established. If the federal income tax rate increases, our net deferred tax liability or asset would increase. In addition, we would set up a deferred tax liability related to tax and loss bonds for the difference in the new federal income tax rate and the 21% federal income tax rate at which the tax and loss bonds were purchased. Table 12.3 summarizes the components of the provision for (benefit from) income taxes: Provision for (benefit from) income taxes Table 12.3 (In thousands) 2020 2019 2018 Current Federal $ 85,574 $ 162,911 $ (16,272) Deferred Federal 28,244 11,860 185,598 Other (648) (557) 4,727 Provision for income taxes $ 113,170 $ 174,214 $ 174,053 The CARES Act provides financial relief to individuals and businesses in the form of loans, grants, and tax changes, among other types of assistance. The tax changes in the CARES Act did not materially impact our financial results. Current federal income tax payments were$79.6 million, $158.3 million, and $12.2 million in 2020, 2019 and 2018, respectively. At December 31, 2020 we owned $271.0 million of tax and loss bonds. Table 12.4 reconciles the federal statutory income tax rate to our effective tax provision rate. Effective tax rate reconciliation Table 12.4 2020 2019 2018 Federal statutory income tax rate 21.0 % 21.0 % 21.0 % Additional income tax benefit related to IRS litigation — % — % (0.3) % Tax exempt municipal bond interest (0.9) % (0.6) % (0.7) % Other, net 0.1 % 0.1 % 0.6 % Effective tax rate 20.2 % 20.5 % 20.6 % 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"). In 2018, we finalized an agreement with the IRS to settle all issues in the examinations and related U.S. Tax Court case. As a result of our settlement, we made federal tax and interest payments of $14.8 million during 2018. We also made state tax and interest payments of $36.8 million during 2018. The impact of the agreed upon settlement was previously reflected in our consolidated statements of operations. We have not recorded any uncertain tax positions during 2019 and 2020 and have no unrecognized tax benefits at December 31, 2019 and December 31, 2020. We recognize interest accrued and penalties related to unrecognized tax benefits in income taxes. The statute of limitations related to the consolidated federal income tax return is closed for all years prior to 2016.

Shareholders' Equity

Shareholders' Equity	12 Months Ended
	Dec. 31, 2020
Stockholders' Equity Note [Abstract]
Shareholders' Equity	NOTE 13 Shareholders' Equity CHANGE IN ACCOUNTING PRINCIPLE As of January 1, 2018, the updated guidance of "Recognition and Measurement of Financial Assets and Financial Liabilities" became effective. The application of this guidance resulted in an immaterial cumulative effect adjustment to our 2018 beginning accumulated other comprehensive (loss) income and retained earnings to recognize unrealized gains on equity securities. SHARE REPURCHASE PROGRAM During the first quarter of 2020 we repurchased approximately 9.6 million shares of our common stock at a weighted average cost per share of $12.47, which included commissions. We may repurchase up to an additional $291 million of our common stock through the end of 2021 under a share repurchase program approved by our Board of Directors in January 2020. During 2019, we repurchased approximately 8.7 million shares of our common stock at a weighted average cost per share of $13.13, which included commissions. As of December 31, 2019, the authorized share repurchase program had approximately $111 million remaining. During 2018, we repurchased approximately 16.0 million shares of our common stock at a weighted average cost per share of $10.95, which included commissions. As of December 31, 2018, the authorized share repurchase program had approximately $25 million remaining. Repurchases may be made from time to time on the open market (including through 10b5-1 plans) or through privately negotiated transactions. The repurchase program may be suspended for periods or discontinued at any time, and in light of the uncertainty caused by the COVID-19 pandemic, we have temporarily suspended stock repurchases, but may resume them in the future. Cash dividends In 2020, we paid quarterly cash dividends of $0.06 per share to shareholders which totaled $82.6 million. On January 26, 2021, the Board of Directors declared a quarterly cash dividend to holders of the company's common stock of $0.06 per share payable on March 3, 2021, to shareholders of record at the close of business on February 17, 2021.

Statutory Information

Statutory Information	12 Months Ended
	Dec. 31, 2020
Statutory Capital [Abstract]
Statutory Information	NOTE 14 Statutory Information STATUTORY ACCOUNTING PRINCIPLES The statutory financial statements of our insurance companies are presented on the basis of accounting principles prescribed, or practices permitted, by the Office of the Commissioner of Insurance of the State of Wisconsin (the "OCI"), which has adopted the National Association of Insurance Commissioners ("NAIC") Statements of Statutory Accounting Principles ("SSAP") as the basis of its statutory accounting principles. In converting from statutory to GAAP, typical adjustments include deferral of policy acquisition costs, the inclusion of net unrealized holding gains or losses in shareholders' equity relating to fixed income securities, and the inclusion of statutory non-admitted assets. In addition to the typical adjustments from statutory to GAAP, mortgage insurance companies are required to maintain contingency loss reserves equal to 50% of premiums earned under SSAP and principles prescribed by the OCI. Such amounts cannot be withdrawn for a period of ten years except as permitted by insurance regulations. With regulatory approval, a mortgage guaranty insurance company may make early withdrawals from the contingency reserve when incurred losses exceed 35% of net premiums earned in a calendar year. For the year ended 2020, MGIC's withdrew $30.4 million from its contingency reserve. Changes in contingency loss reserves impact the statutory statement of operations. Contingency loss reserves are not reflected as liabilities under GAAP and changes in contingency loss reserves do not impact the GAAP statements of operations. As a mortgage guaranty insurer, we are eligible for a tax deduction, subject to certain limitations, under Section 832(e) of the IRC for amounts required by state law or regulation to be set aside in statutory contingency reserves. The deduction is allowed only to the extent that we purchase tax and loss bonds (“T&L Bonds”) in an amount equal to the tax benefit derived from deducting any portion of our statutory contingency reserves. Under statutory accounting practices, purchases of T&L Bonds are accounted for as investments. Under GAAP, purchases of T&L Bonds are accounted for as a payment of current taxes. The statutory net income loss, policyholders' surplus and contingency reserve liability of the insurance subsidiaries of our holding company are shown in table 14.1 below. The surplus amounts included in the following table are the combined policyholders' surplus of our insurance operations as utilized in our risk-to-capital calculations. Statutory financial information of insurance subsidiaries Table 14.1 As of and for the Years Ended December 31, (In thousands) 2020 2019 2018 Statutory net income $ 65,201 $ 305,857 $ 375,484 Statutory policyholders' surplus 1,339,509 1,619,069 1,683,058 Contingency reserve 3,585,864 3,021,055 2,442,996 For the years ended December 31, 2020, 2019, and 2018 there were no surplus contributions made to MGIC or distributions from other insurance subsidiaries to us. Dividends paid by MGIC are shown in table 14.2 below. Surplus contributions and dividends of insurance subsidiaries Table 14.2 Years Ended December 31, (In thousands) 2020 2019 2018 Dividends paid by MGIC to the parent company (1) $ 390,000 280,000 220,000 (1) Dividends paid in cash and/or investment securities. Also in 2020, MGIC distributed to the holding company, as a dividend, its ownership in the 9% Debentures held at an amortized cost of $139.5 million. 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 RIF (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” and, together with the GSE Financial Requirements, the “Financial 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 December 31, 2020, MGIC’s risk-to-capital ratio was 9.2 to 1, below the maximum allowed by the jurisdictions with State Capital Requirements and its policyholder position was $3.2 billion above the required MPP of $1.7 billion. The calculation of our risk-to-capital ratio and MPP reflect credit for the risk ceded under our reinsurance transactions. 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 agreements, 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 December 31, 2020, the risk-to-capital ratio of our combined insurance operations (which includes a reinsurance affiliate) was 9.1 to 1. The NAIC has previously announced plans to revise the State Capital Requirements that are provided for in its Mortgage Guaranty Insurance Model Act. In December 2019, a working group of state regulators released an exposure draft of a revised Mortgage Guaranty Insurance Model Act and 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 and certain items have not yet been completely addressed by the framework, including the treatment of ceded risk and minimum capital floors. Currently we believe that the PMIERs contain more restrictive capital requirements than the draft Mortgage Guaranty Insurance Model Act in most circumstances. While MGIC currently meets, and expects to continue to meet, 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 a particular 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 IIF 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, including the effects of the COVID-19 pandemic. DIVIDEND RESTRICTIONS During 2020, MGIC paid $390 million in cash and/or investment security dividends to our holding company. In the third quarter of 2020, MGIC distributed to the holding company, as a dividend, its ownership in the 9% Debentures held at an amortized cost of $139.5 million, which was non-admitted for statutory reporting. 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. Before making any dividend payments in 2021, we will notify the OCI to ensure it does not object. Under the PMIERS guidance, any dividend paid by MGIC to our holding company, through June 30, 2021, requires GSE approval. The OCI recognizes only statutory accounting principles prescribed, or practices 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 a change in underwriting deduction. As a result, in periods in which MGIC is increasing contingency

Share-based Compensation Plans

Share-based Compensation Plans	12 Months Ended
	Dec. 31, 2020
Share-based Payment Arrangement [Abstract]
Share-based Compensation Plans	NOTE 15 Share-based Compensation Plans 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. We have an omnibus incentive plan that was adopted on April 23, 2020. When the 2020 plan was adopted, no further awards could be made under our previous 2015 plan. The purpose of the 2020 plan is to motivate and incentivize performance by, and to retain the services of, key employees and non-employee directors through receipt of equity-based and other incentive awards under the plan. The maximum number of shares of stock that can be awarded under the 2020 plan is 11.0 million. Awards issued under the plan that are subsequently forfeited will not count against the limit on the maximum number of shares that may be issued under the plan. The 2020 plan provides for the award of stock options, stock appreciation rights, restricted stock and restricted stock units, as well as cash incentive awards. No awards may be granted after April 23, 2030 under the 2020 plan. The vesting provisions of options, restricted stock and restricted stock units are determined at the time of grant. Awards forfeited under the 2015 plan after April 23, 2020 will increase the 2020 plan's limit of shares available for future grant. At December 31, 2020, 11.1 million shares were available for future grant under the 2020 plan. The excess of available shares for future grant above the maximum number of shares that may be issued under the 2020 plan is the result of awards under the 2015 plan being forfeited subsequent to April 23, 2020. The compensation cost that has been charged against income for share-based plans was $13.8 million, $18.9 million, and $20.9 million for the years ended December 31, 2020, 2019 and 2018, respectively. The related income tax benefit recognized for share-based plans was $1.7 million, $2.7 million, and $3.0 million for the years ended December 31, 2020, 2019, and 2018, respectively. Table 15.1 summarizes restricted stock or restricted stock unit (collectively called “restricted stock”) activity during 2020. Restricted stock Table 15.1 Weighted Average Grant Date Fair Market Value Shares Restricted stock outstanding at December 31, 2019 $ 12.81 4,150,394 Granted 13.62 1,672,060 Vested 11.67 (1,564,843) Forfeited 13.24 (118,368) Restricted stock outstanding at December 31, 2020 $ 13.57 4,139,243 At December 31, 2020, the 4.1 million shares of restricted stock outstanding consisted of 3.1 million shares that are subject to performance conditions (“performance shares”) and 1.0 million shares that are subject only to service conditions (“time vested shares”). The weighted-average grant date fair value of restricted stock granted during 2019 and 2018 was $11.92 and $15.69, respectively. The fair value of restricted stock granted is the closing price of the common stock on the New York Stock Exchange on the date of grant or previous trading day if the Exchange is closed on the date of grant. The total fair value of restricted stock vested during 2020, 2019 and 2018 was $20.4 million, $13.7 million, and $19.1 million, respectively. As of December 31, 2020, there was $25.8 million of total unrecognized compensation cost related to non-vested share-based compensation agreements granted under the plans. Of this total, $19.8 million of unrecognized compensation costs relate to performance shares and $5.9 million relates to time vested shares. A portion of the unrecognized costs associated with the performance shares may or may not be recognized in future periods, depending upon whether or not the performance and service conditions are met. The cost associated with the time vested shares is expected to be recognized over a weighted-average period of 1.7 years.

Leases

Leases	12 Months Ended
	Dec. 31, 2020
Leases [Abstract]
Leases	NOTE 16 Leases We lease data processing equipment and autos under operating leases that expire during the next four years. Generally, rental payments are fixed. Table 16.1 shows minimum the future operating lease payments as of December 31, 2020. Minimum future operating lease payments Table 16.1 (In thousands) Amount 2021 $ 836 2022 687 2023 311 2024 81 2025 and thereafter — Total $ 1,915 Total lease expense under operating leases was $1.9 million in 2020, $2.1 million in 2019, and $1.9 million in 2018.

Litigation and Contingencies

Litigation and Contingencies	12 Months Ended
	Dec. 31, 2020
Commitments and Contingencies Disclosure [Abstract]
Litigation and Contingencies	NOTE 17 Litigation and Contingencies Before paying an insurance claim, generally 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 or deny a claim on the loan (both referred to as “rescissions”). In addition, our insurance policies generally provide that we can reduce a claim if the servicer did not comply with its obligations under our insurance policy (such reduction referred to as a "curtailment"). In recent quarters, an immaterial percentage of claims received in a quarter have been resolved by rescissions. In 2020 and 2019 , curtailments reduced our average claim paid by approximately 3.6% and 5.0%, respectively. 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 may be determined by legal proceedings. Under ASC 450-20, until a loss 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. When we determine that a loss is probable and can be reasonably estimated, we record our best estimate of our probable loss. In those cases, until settlement negotiations or legal proceedings are concluded (including the receipt of any necessary GSE approvals), it is reasonably possible that we will record an additional loss. We are currently involved in discussions and/or proceedings with respect to our claims paying practices. Although it is reasonably possible that, when all of these matters are resolved, we will not prevail on all matters, we are unable to make a reasonable estimate or range of estimates of the potential liability. We estimate the maximum exposure where a loss is reasonably possible to be approximately $40 million. This estimate of maximum exposure is based upon currently available information; is subject to significant judgment, numerous assumptions and known and unknown uncertainties; will include an amount for matters for which we have recorded a probable loss until such matters are concluded; will include different matters from time to time; and does not include interest or consequential or exemplary damages. Mortgage insurers, including MGIC, have in the past been involved in litigation and regulatory actions related to alleged violations of the anti-referral fee provisions of the Real Estate Settlement Procedures Act ("RESPA") and the notice provisions of the Fair Credit Reporting Act ("FCRA"). While these proceedings in the aggregate did not result 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 effect on us. To the extent that we are construed to make independent credit decisions in connection with our contract underwriting activities, we also could be subject to increased regulatory requirements under the Equal Credit Opportunity Act (“EOCA”), FCRA, and other laws. Under ECOA, examination may also be made of whether a mortgage insurer’s underwriting decisions have a disparate impact on persons belonging to a protected class in violation of the law. 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 related contract underwriting remedy expense for each of the years ended December 31, 2020, 2019, and 2018, 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.

Unaudited Quarterly Financial D

Unaudited Quarterly Financial Data	12 Months Ended
	Dec. 31, 2020
Quarterly Financial Information Disclosure [Abstract]
Unaudited Quarterly Financial Data	NOTE 18 Unaudited Quarterly Financial Data Unaudited quarterly financial data - current year: Table: 18.1a 2020: Quarter Full (In thousands, except per share data) First Second Third Fourth Year Net premiums earned $ 260,901 $ 243,562 $ 256,113 $ 261,367 $ 1,021,943 Investment income, net of expenses 41,347 39,679 37,252 36,118 154,396 Realized gains (losses) 1,891 6,701 2,259 2,901 13,752 Other revenue 2,754 4,026 380 1,895 9,055 Loss incurred, net 60,956 217,374 40,686 45,758 364,774 Underwriting and other expenses, net 57,698 60,111 64,253 66,311 248,373 Loss on debt extinguishment — — 26,736 — 26,736 Provision for income tax 38,434 2,436 33,518 38,782 113,170 Net income 149,805 14,047 130,811 151,430 446,093 Income per share (a) (b) : Basic 0.44 0.04 0.39 0.45 1.31 Diluted 0.42 0.04 0.38 0.44 1.29 Unaudited quarterly financial statements - prior year: Table: 18.1b 2019: Quarter Full (In thousands, except per share data) First Second Third Fourth Year Net premiums earned $ 249,762 $ 247,102 $ 267,857 $ 266,267 $ 1,030,988 Investment income, net of expenses 40,585 42,423 42,715 41,322 167,045 Realized gains (losses) (526) 307 4,205 1,320 5,306 Other revenue 1,830 2,485 3,606 2,717 10,638 Loss incurred, net 39,064 21,836 33,985 23,690 118,575 Underwriting and other expenses, net 61,650 59,270 61,278 65,227 247,425 Provision for income tax 38,996 43,433 46,186 45,599 174,214 Net income 151,941 167,778 176,934 177,110 673,763 Income per share (a) (b) : Basic 0.43 0.47 0.50 0.51 1.91 Diluted 0.42 0.46 0.49 0.49 1.85 (a) Due to the use of weighted average shares outstanding when calculating earnings per share, the sum of the quarterly per share data may not equal the per share data for the year. (b) In periods where convertible debt instruments are dilutive to earnings per share the “if-converted” method of computing diluted EPS requires an interest expense adjustment, net of tax, to net income available to shareholders. See Note 4 – “Earnings Per Share” for further discussion on our calculation of diluted EPS.

SCHEDULE I - SUMMARY OF INVESTM

SCHEDULE I - SUMMARY OF INVESTMENTS - OTHER THAN INVESTMENTS IN RELATED PARTIES	12 Months Ended
	Dec. 31, 2020
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Abstract]
SCHEDULE I - SUMMARY OF INVESTMENTS - OTHER THAN INVESTMENTS IN RELATED PARTIES	SCHEDULE I — Summary of investments - Other than investments in related parties - December 31, 2020 (In thousands) Type of Investment Amortized Cost Fair Value Amount at which shown in the balance sheet Fixed income: Bonds: United States Government and government agencies and authorities $ 264,531 $ 265,693 $ 265,693 States, municipalities and political subdivisions 2,083,568 2,249,869 2,249,869 Foreign Governments 4,485 4,709 4,709 Public utilities 303,285 303,011 303,011 Asset-backed securities 203,807 206,686 206,686 Collateralized loan obligations 310,616 310,490 310,490 Mortgage-backed 738,104 758,668 758,668 All other corporate bonds 2,387,575 2,541,277 2,541,277 Other short-term investments 21,193 21,193 21,193 Total fixed income 6,317,164 6,661,596 6,661,596 Equity securities: Common stocks: Industrial, miscellaneous and all other 17,522 18,215 18,215 Total equity securities 17,522 18,215 18,215 Total investments $ 6,334,686 $ 6,679,811 $ 6,679,811

SCHEDULE II - CONDENSED FINANCI

SCHEDULE II - CONDENSED FINANCIAL INFORMATION OF REGISTRANT	12 Months Ended
	Dec. 31, 2020
Condensed Financial Information Disclosure [Abstract]
SCHEDULE II - CONDENSED FINANCIAL INFORMATION OF REGISTRANT	SCHEDULE II - Condensed Financial Information of Registrant Condensed Balance Sheets Parent Company Only December 31, (In thousands) 2020 2019 ASSETS Fixed income, available-for-sale, at fair value (amortized cost, 2020 – $773,881; 2019 – $287,489) $ 773,995 $ 288,362 Cash and cash equivalents 73,000 36,621 Investment in subsidiaries, at equity in net assets 4,740,074 4,611,356 Accounts receivable - affiliates 1,450 2,129 Income taxes -current and deferred 219,059 196,978 Accrued investment income 3,760 2,498 Other assets — 81 Total assets $ 5,811,338 $ 5,138,025 LIABILITIES AND SHAREHOLDERS' EQUITY Liabilities: Senior notes $ 879,379 $ 420,867 Convertible junior subordinated debentures 208,814 389,522 Accrued interest 23,004 17,928 Other liabilities 1,155 474 Total liabilities 1,112,352 828,791 Shareholders’ equity: Common stock, (one dollar par value, shares authorized 1,000,000; shares issued 2020 – 371,353; 2019 – 371,353; outstanding 2020 – 338,573; 2019 – 347,308) 371,353 371,353 Paid-in capital 1,862,042 1,869,719 Treasury stock (shares at cost 2020 – 32,779; 2019 – 24,045) (393,326) (283,196) Accumulated other comprehensive income, net of tax 216,821 72,708 Retained earnings 2,642,096 2,278,650 Total shareholders’ equity 4,698,986 4,309,234 Total liabilities and shareholders’ equity $ 5,811,338 $ 5,138,025 See accompanying supplementary notes to Parent Company condensed financial statements. MGIC INVESTMENT CORPORATION SCHEDULE II - Condensed Financial Information of Registrant Condensed Statements of Operations Parent Company Only Years Ended December 31, (In thousands) 2020 2019 2018 Revenues: Investment income, net of expenses $ 7,090 $ 7,695 $ 4,685 Net realized investment gains (losses) 1,454 (311) (532) Total revenues 8,544 7,384 4,153 Expenses: Operating expenses 719 793 637 Interest expense 65,472 61,593 61,930 Loss on debt extinguishment 35,033 — — Total expenses 101,224 62,386 62,567 Loss before tax (92,680) (55,002) (58,414) (Benefit from) provision for income taxes (18,431) (12,263) (13,517) Equity in net income of subsidiaries 520,342 716,502 714,994 Net income 446,093 673,763 670,097 Other comprehensive income (loss), net of tax 144,113 196,922 (80,413) Comprehensive income $ 590,206 $ 870,685 $ 589,684 See accompanying supplementary notes to Parent Company condensed financial statements. MGIC INVESTMENT CORPORATION SCHEDULE II - Condensed Financial Information of Registrant Condensed Statements of Cash Flows Parent Company Only Years Ended December 31, (In thousands) 2020 2019 2018 Cash flows from operating activities: Net income 446,093 $ 673,763 $ 670,097 Adjustments to reconcile net income to net cash provided by operating activities: Equity in net income of subsidiaries (520,342) (716,502) (714,994) Dividends received from subsidiaries 221,024 154,413 199,692 Deferred tax (benefit) expense (18,252) (10,416) (11,756) Loss on debt extinguishment 35,033 — — Other 19,088 21,104 24,303 Change in certain assets and liabilities: Accounts receivable - affiliates 972 (735) 18 Income taxes receivable — 1 17,859 Accrued investment income (1,262) (478) 112 Accrued interest 5,076 (2) (4) Net cash provided by operating activities 187,430 121,148 185,327 Cash flows from investing activities: Purchases of investments (1,131,060) (117,663) (83,003) Proceeds from sales of investments 812,188 160,040 93,481 Net cash provided by investing activities (318,872) 42,377 10,478 Cash flows from financing activities: Proceeds from issuance of senior notes 640,250 — — Purchase of senior notes (179,735) — — Payment of original issue discount - senior notes (2,969) — — Purchase of convertible junior subordinated debentures (36,392) — — Payment of original issue discount - convertible junior subordinated debentures (15,049) — — Cash portion of loss on debt extinguishment (25,266) — — Repurchase of common stock (119,997) (125,766) (163,419) Dividends paid (82,061) (41,914) — Payment of debt issuance costs (2,020) — — Payment of withholding taxes related to share-based compensation net share settlement (8,940) (5,726) (8,131) Net cash provided by (used in) financing activities 167,821 (173,406) (171,550) Net increase (decrease) in cash and cash equivalents 36,379 (9,881) 24,255 Cash and cash equivalents at beginning of year 36,621 46,502 22,247 Cash and cash equivalents at end of year $ 73,000 $ 36,621 $ 46,502 See accompanying supplementary notes to Parent Company condensed financial statements. SCHEDULE II — CONDENSED FINANCIAL INFORMATION OF REGISTRANT PARENT COMPANY ONLY SUPPLEMENTARY NOTES Note A The accompanying Parent Company financial statements should be read in conjunction with the consolidated financial statements and notes to consolidated financial statements appearing this annual report. Note B Our insurance subsidiaries are subject to statutory regulations as to maintenance of policyholders’ surplus and payment of dividends. The maximum amount of dividends that the insurance subsidiaries may pay in any twelve-month period without regulatory approval by the 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 payment of dividends from our insurance subsidiaries is the principal source of cash inflow for MGIC Investment Corporation, our holding company, other than investment income and raising capital in the public markets. The payment of dividends by our insurance subsidiaries is restricted by insurance regulation as discussed above. MGIC is the principal source of dividend-paying capacity and paid a total of $390 million, $280 million and $220 million in dividends in cash and fixed income securities to our holding company during 2020, 2019 and 2018, respectively. No contributions were made to our insurance subsidiaries in 2020, 2019 or 2018. Note C The senior notes and convertible junior subordinated debentures ("9% Debentures"), discussed in Note 7 – “Debt” to our consolidated financial statements, are obligations of MGIC Investment Corporation, our holding company, and not of its subsidiaries. MGIC's ownership of our holding company's 9% Debentures of $132.7 million were previously eliminated in consolidation, but remained an obligation of our holding company. In the third quarter of 2020, MGIC distributed to the holding company, as a dividend, its ownership in the 9% Debentures, retiring those 9% Debentures.

SCHEDULE IV - REINSURANCE

SCHEDULE IV - REINSURANCE	12 Months Ended
	Dec. 31, 2020
SEC Schedule, 12-17, Insurance Companies, Reinsurance [Abstract]
SCHEDULE IV - REINSURANCE	SCHEDULE IV — Reinsurance Mortgage Insurance Premiums Earned Years Ended December 31, 2020, 2019 and 2018 (Dollars in thousands) Gross Amount Ceded to Other Companies Assumed From Other Companies Net Amount Percentage of Amount Assumed to Net Years ended December 31, 2020 $ 1,199,824 $ 188,729 $ 10,848 $ 1,021,943 1.1 % 2019 1,155,240 129,337 5,085 1,030,988 0.5 % 2018 1,084,748 111,391 1,805 975,162 0.2 %

Significant Accounting Polici_2

Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2020
Accounting Policies [Abstract]
Basis of presentation	The accompanying consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America ("GAAP"), as codified in the Accounting Standards Codification ("ASC"). Our consolidated financial statements include the accounts of MGIC Investment Corporation and its majority-owned subsidiaries. Intercompany transactions and balances have been eliminated. In accordance with GAAP, we are required to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the consolidated financial statements and the reported amounts of revenues and expenses during the reporting periods. Actual results could differ from those estimates.
Reclassifications	Certain reclassifications to 2019 and 2018 amounts have been made in the accompanying consolidated financial statements to conform to the 2020 presentation.
Cash and Cash Equivalents	We consider money market funds and investments with original maturities of three months or less to be cash equivalents.
Restricted Cash and Cash Equivalents	Restricted cash and cash equivalents consists of cash and money market funds held in trusts for the benefit of contractual counterparties under reinsurance agreements.
Fair value measurements	We carry certain financial instruments at fair value and disclose the fair value of all financial instruments. Our financial instruments carried at fair value are predominantly measured on a recurring basis. Financial instruments measured on a nonrecurring basis are subject to fair value adjustments only in certain circumstances (for example, when there is evidence of impairment). The fair value of an asset or liability is defined as the price that would be received upon a sale of an asset, or paid to transfer a liability, in an orderly transaction between market participants at the measurement date. Fair value is based on quoted market prices or inputs, where available. If prices or quotes are not available, fair value is based on valuation models or other valuation techniques that consider relevant transaction characteristics (such as maturity) and use as inputs observable or unobservable market parameters including yield curves, interest rates, volatilities, equity or debt prices, and credit curves. Valuation adjustments may be made to ensure that financial instruments are recorded at fair value, as described below. Valuation process We use independent pricing sources to determine the fair value of a substantial majority of our financial instruments, which primarily consist of assets in our investment portfolio, but also includes cash and cash equivalents and restricted cash and cash equivalents. A variety of inputs are used; in approximate order of priority, they are: benchmark yields, reported trades, broker/dealer quotes, issuer spreads, two-sided markets, benchmark securities, bids, offers, and reference data including market research publications. 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. On a quarterly basis, we perform quality controls over values received from the pricing sources which also include reviewing tolerance reports, data changes, and directional moves compared to market moves. We have not made any adjustments to the prices obtained from the independent pricing sources. Valuation hierarchy A three-level valuation hierarchy has been established under GAAP for disclosure of fair value measurements. The valuation hierarchy is based on the transparency of inputs to the valuation of a financial instrument as of the measurement date. To determine the fair value of securities available-for-sale in Level 1 and Level 2 of the fair value hierarchy, independent pricing sources, as described in " Valuation process, " 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. The three levels are defined as follows: è Level 1 Quoted prices for identical instruments in active markets that we can access. Financial assets using Level 1 inputs primarily include U.S. Treasury securities, money market funds, treasury bills, and certain equity securities. è 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 using Level 2 inputs primarily include obligations of U.S. government corporations and agencies, corporate bonds, mortgage-backed securities, asset-backed securities, most municipal bonds, and commercial paper. è Level 3 Valuations derived from valuation techniques in which one or more significant inputs or value drivers are unobservable or, from par values due to restrictions on certain securities that require them to be redeemed or sold only to the security issuer at par value. 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. 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.
Investments	Fixed income securities. Our fixed income securities are classified as available-for-sale and are reported at fair value. The related unrealized investment gains or losses are, after considering the related tax expense or benefit, recognized as a component of accumulated other comprehensive income (loss) in shareholders' equity. Realized investment gains and losses on fixed income securities are reported in income based upon specific identification of securities sold as well as any credit allowance (2020), and any "other than temporary" impairments ("OTTI") (2019). Equity securities. Equity securities are reported at fair value, except for certain securities that are carried at cost. Equity securities carried at cost are reported as Other invested assets. Realized investment gains and losses on equity securities are reported in income based upon specific identification of securities sold, as well as any change in fair value of equity securities. Other invested assets. Other invested assets are carried at cost. These assets represent our investment in Federal Home Loan Bank of Chicago ("FHLB") stock, which due to restrictions, is required to be redeemed or sold only to the security issuer at par value. Unrealized losses and allowance for credit losses Effective January 1, 2020, each quarter we perform reviews of our investments to assess if declines in fair value of available-for-sale securities are impaired. In evaluating the decline in fair value, we consider several factors including, but not limited to: è our intent to sell the security or whether it is more likely than not that we will be required to sell the security before recovery of its amortized cost basis; è the present value of the discounted cash flows we expect to collect compared to the amortized cost basis of the security; è failure of the issuer to make scheduled interest or principal payments; è change in rating below investment grade; and è adverse conditions specifically related to the security, an industry, or a geographic area. Based on our evaluation, we will record a realized loss on a security if we intend to sell the impaired security, if it is more likely than not that we will be required to sell the impaired security prior to recovery of its amortized cost basis, or if the present value of the discounted cash flows we expect to collect is less than the amortized cost basis of the security. When a security is considered to be impaired, the losses are separated into the portion of the loss that represents the credit loss and the portion that is due to other factors. An allowance for credit losses is recorded, subject to reversal, for the credit loss portion in the statement of operations, while the loss due to other factors is recognized in accumulated other comprehensive loss, net of taxes. A credit loss is determined to exist if the present value of the discounted cash flows, using the security’s original yield, expected to be collected from the security is less than the cost basis of the security. For 2019, our evaluation of whether a decline in fair values is other-than-temporary also includes reviewing the extent and duration of the decline. Based on our evaluation, if the fair value of a security is below its amortized cost at the time of our intent to sell, the security is classified as other-than-temporarily impaired and the full amount of the impairment is recognized as a loss in the statement of operations.
Home office and equipment	Home office and equipment is carried at cost net of depreciation. For financial reporting purposes, depreciation is determined on a straight-line basis for the home office and equipment over estimated lives ranging from 3 to 45 years. For income tax purposes, we use accelerated depreciation methods.
Deferred Insurance Policy Acquisition Costs	Costs directly associated with the successful acquisition of mortgage insurance business, consisting of employee compensation and other policy issuance and underwriting expenses, are initially deferred and reported as deferred insurance policy acquisition costs ("DAC"). The deferred costs are net of any ceding commissions received associated with our reinsurance agreements.  For each underwriting year of business, these costs are amortized to income in proportion to estimated gross profits over the estimated life of the policies.  We utilize anticipated investment income in our calculation. This includes accruing interest on the unamortized balance of DAC. The estimates for each underwriting year are reviewed quarterly and updated when necessary to reflect actual experience and any changes to key variables such as persistency or loss development.
Loss Reserves	Case reserves and loss adjustment expenses ("LAE") reserves are established when notices of delinquency on insured mortgage loans are received. Such loans are referred to as being in our delinquency inventory. For reporting purposes, we consider a loan delinquent when it is two or more payments past due and has not become current or resulted in a claim payment. Even though the accounting standard, ASC 944, regarding accounting and reporting by insurance entities specifically excludes mortgage insurance from its guidance relating to loss reserves, we establish loss reserves using the general principles contained in the insurance standard. However, consistent with industry standards for mortgage insurers, we do not establish case reserves for future claims on insured loans which are not currently delinquent. Case 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. Our case reserve estimates are established based upon historical experience, including rescissions of policies, curtailments of claims, and loan modification activity. Adjustments to reserve estimates are reflected in the financial statements in the years in which the adjustments are made. The liability for reinsurance assumed is based on information provided by the ceding companies. Incurred but not reported ("IBNR") reserves are established for delinquencies estimated to have occurred prior to the close of an accounting period, but not yet reported to us. Consistent with reserves for reported delinquencies, IBNR reserves are also established using estimated claim rates and claim severities. LAE reserves are established for the estimated costs of settling claims, including legal and other expenses, and general expenses of administering the claims settlement process.
Premium Deficiency Reserve	After our loss reserves are initially established, we perform premium deficiency tests using our best estimate assumptions as of the testing date. Premium deficiency reserves are established, if necessary, when the present value of expected future losses and expenses exceeds the present value of expected future premium and already established reserves.  Products are grouped for premium deficiency testing purposes based on similarities in the way the products are acquired, serviced and measured for profitability.
Revenue Recognition	We write policies which are guaranteed renewable contracts at the insured's option on a monthly, single, or annual premium basis. We have no ability to re-underwrite or reprice these contracts. Premiums written on monthly premium policies are earned as coverage is provided. Premiums written on single premium policies and annual premium policies are initially deferred as unearned premium reserve and earned over the estimated policy life. Premiums written on policies covering more than one year are amortized over the estimated policy life based on historical experience, which includes the anticipated incurred loss pattern. Premiums written on annual premium policies are earned on a monthly pro rata basis. When a policy is cancelled for a reason other than rescission or claim payment, all premium that is non-refundable is immediately earned. Any refundable premium is returned to the servicer or borrower. When a policy is cancelled due to rescission, all previously collected premium is returned to the servicer and when a policy is cancelled because a claim is paid, premium collected since the date of delinquency is returned. The liability associated with our estimate of premium to be returned is accrued for separately and included in "Other liabilities" on our consolidated balance sheets. Changes in this liability, and the actual return of premiums for all periods, affects premiums written and earned. Effective, January 1, 2020, we assess whether a credit loss exists for our premium receivable. In determining if a credit loss allowance is required for premium receivable, consideration is given to the life of the premium receivable asset, areas of potential credit loss, and forward-looking predictive indicators. Any estimated credit loss would be immediately recognized. Fee income of our non-insurance subsidiaries is earned and recognized as the services are provided and the customer is obligated to pay. Fee income consists primarily of contract underwriting and related fee-based services provided to lenders and is included in “Other revenue” on the consolidated statements of operations.
Income Taxes	Deferred income taxes are provided under the liability method, which recognizes the future tax effects of temporary differences between amounts reported in the consolidated financial statements and the tax bases of these items. The estimated tax effects are computed at the enacted federal statutory income tax rate. Changes in tax laws, rates, regulations, and policies or the final determination of tax audits or examinations, could materially affect our estimates and can be significant to our operating results. We evaluate the realizability of the deferred tax assets based on the weight of all available positive and negative evidence. Deferred tax assets are reduced by a valuation allowance if it is more likely than not that all or some portion of the deferred tax assets will not be realized. The recognition of a tax position is determined using a two-step approach. The first step applies a more-likely-than-not threshold for recognition and derecognition. The second step measures the tax position as the greatest amount of benefit that is cumulatively greater than 50% likely to be realized. When evaluating a tax position for recognition and measurement, we presume that the tax position will be examined by the relevant taxing authority that has full knowledge of all relevant information. We recognize interest accrued and penalties related to unrecognized tax benefits in our provision for income taxes.
Benefit Plans	We have a non-contributory defined benefit pension plan covering substantially all domestic employees, as well as a supplemental executive retirement plan. Retirement benefits are based on compensation and years of service.  Effective January 1, 2019, all participants, regardless of hire or rehire date, earn benefits using a cash balance formula. Participants hired or rehired prior to January 1, 2014, earned benefits under a traditional formula through December 31, 2018. which calculated a pension credit for each year of eligible service. Under the cash balance formula, participants’ accounts are credited each year with an employer contribution and interest. The employer contribution is a percentage of eligible earnings based on the participant’s age on January 1, 2019. We recognize these retirement benefit costs over the period during which employees render the service that qualifies them for benefits. Our policy is to fund pension cost as required under the Employee Retirement Income Security Act of 1974.We offer both medical and dental benefits for retired domestic employees, their eligible spouses and dependents until the retiree reaches the age of 65. Under the plan retirees pay a premium for these benefits. We accrue the estimated costs of retiree medical and dental benefits over the period during which employees render the service that qualifies them for benefits.
Reinsurance	Loss reserves are reported before taking credit for amounts ceded under reinsurance agreements. Ceded loss reserves are reflected as "Reinsurance recoverable on loss reserves." Amounts due from reinsurers on paid claims are reflected as “Reinsurance recoverable on paid losses.” Ceded premiums payable are included in “Other liabilities.” Profit commissions are included with “Premiums written – Ceded” and ceding commissions are included with “Other underwriting and operating expenses, net.” We remain liable for all insurance ceded.
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.
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. The computation of basic EPS includes as "participating securities" an immaterial number of unvested share-based compensation awards that contain non-forfeitable rights to dividends or dividend equivalents, whether paid or unpaid, under the "two-class" method. Our participating securities are composed of vested restricted stock and restricted stock units ("RSUs") with non-forfeitable rights to dividends. 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 treasury stock method, diluted EPS reflects the potential dilution that could occur if our unvested restricted stock units result in the issuance of common stock. Under the if-converted method, diluted EPS reflects the potential dilution that could occur if our 9% Debentures 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. For purposes of calculating basic and diluted EPS, vested restricted stock and RSUs are considered outstanding.

Significant Accounting Polici_3

Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2020
Accounting Policies [Abstract]
Schedule of Recent Accounting and Reporting Developments	Table 2.1 shows the relevant new amendments to accounting standards, which are not yet effective or adopted. Standard / Interpretation Table 2.1 Amended Standards Effective date ASC 321, 323, 815 Investments • ASU 2020-01 - Investments-Equity Securities (Topic 321), Investments-Equity Method and Joint Ventures (Topic 323), and Derivatives and Hedging (Topic 815) January 1, 2021 ASC 740 Income Taxes • ASU 2019-12 - Simplifying the Accounting for Income Taxes January 1, 2021 ASC 310-20 Receivables • ASU 2020-08 - Codification Improvements to Subtopic 310-20, Receivables - Nonrefundable Fees and Other Costs January 1, 2021 ASC 470, 815 Debt • ASU 2020-06 - Debt with conversion and other options (Topic 470), derivatives and hedging - contracts in entity’s own equity (Topic 815) January 1, 2022

Earnings per Share (Tables)

Earnings per Share (Tables)	12 Months Ended
	Dec. 31, 2020
Earnings Per Share [Abstract]
Calculation of earnings (loss) per share	Table 4.1 reconciles basic and diluted EPS amounts: Earnings per share Table 4.1 Years Ended December 31, (In thousands, except per share data) 2020 2019 2018 Basic earnings per share: Net income $ 446,093 $ 673,763 $ 670,097 Weighted average common shares outstanding - basic 339,953 352,827 365,406 Basic earnings per share $ 1.31 $ 1.91 $ 1.83 Diluted earnings per share: Net income $ 446,093 $ 673,763 $ 670,097 Interest expense, net of tax (1) : 9% Debentures 17,004 18,264 18,264 Diluted income available to common shareholders $ 463,097 $ 692,027 $ 688,361 Weighted-average shares - basic 339,953 352,827 365,406 Effect of dilutive securities: Unvested restricted stock units 1,589 2,069 1,644 9% Debentures 17,751 19,028 19,028 Weighted average common shares outstanding - diluted 359,293 373,924 386,078 Diluted income per share $ 1.29 $ 1.85 $ 1.78 (1) Interest expense for the years ended December 31, 2020, 2019 and 2018 has been tax effected at a rate of 21%.

Investments (Tables)

Investments (Tables)	12 Months Ended
	Dec. 31, 2020
Investments [Abstract]
Amortized cost, gross unrealized gains and losses and fair value of investment portfolio	Our fixed income securities consisted of the following as of December 31, 2020 and 2019: Details of fixed income investment securities by category as of December 31, 2020 Table 5.1a (In thousands) Amortized Cost Allowance for Expected Credit Loss Gross Unrealized Gains Gross Unrealized Losses Fair Value U.S. Treasury securities and obligations of U.S. government corporations and agencies $ 264,531 $ — $ 1,164 $ (2) $ 265,693 Obligations of U.S. states and political subdivisions 2,083,568 — 166,557 (256) 2,249,869 Corporate debt securities 2,690,860 — 155,156 (1,728) 2,844,288 ABS 203,807 (49) 2,946 (18) 206,686 RMBS 425,532 — 6,472 (838) 431,166 CMBS 312,572 — 16,055 (1,125) 327,502 CLOs 310,616 — 566 (692) 310,490 Debt securities issued by foreign sovereign governments 4,485 — 224 — 4,709 Other Investments (1) 21,193 — — — 21,193 Total fixed income securities $ 6,317,164 $ (49) $ 349,140 $ (4,659) $ 6,661,596 Details of fixed income investment securities by category as of December 31, 2019 Table 5.1b (In thousands) Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value U.S. Treasury securities and obligations of U.S. government corporations and agencies $ 195,176 $ 1,237 $ (210) $ 196,203 Obligations of U.S. states and political subdivisions 1,555,394 99,328 (857) 1,653,865 Corporate debt securities 2,711,910 76,220 (3,008) 2,785,122 ABS 227,376 2,466 (178) 229,664 RMBS 271,384 429 (3,227) 268,586 CMBS 274,234 5,531 (779) 278,986 CLOs 327,076 33 (1,643) 325,466 Total fixed income securities $ 5,562,550 $ 185,244 $ (9,902) $ 5,737,892 (1) Consists of short-term commercial paper with original maturities greater than ninety days.
Amortized cost and fair values of debt securities by contractual maturity	Table 5.2 compares the amortized cost and fair values of fixed income securities, by contractual maturity, as of December 31, 2020. Actual maturities may differ from contractual maturities because certain borrowers have the right to call or prepay certain obligations with or without call or prepayment penalties. Because most mortgage and asset-backed securities provide for periodic payments throughout their lives, they are listed separately in the table. Fixed income securities maturity schedule Table 5.2 December 31, 2020 (In thousands) Amortized Cost Fair Value Due in one year or less $ 390,510 $ 393,286 Due after one year through five years 1,945,158 2,033,183 Due after five years through ten years 1,280,760 1,402,640 Due after ten years 1,448,209 1,556,643 5,064,637 5,385,752 ABS 203,807 206,686 RMBS 425,532 431,166 CMBS 312,572 327,502 CLOs 310,616 310,490 Total as of December 31, 2020 $ 6,317,164 $ 6,661,596
Cost and fair value of investments in equity securities	The cost and fair value of investments in equity securities as of December 31, 2020 and December 31, 2019 are shown in tables 5.3a and 5.3b below. Details of equity investment securities as of December 31, 2020 Table 5.3a (In thousands) Cost Gross gains Gross losses Fair Value Equity securities 17,522 695 (2) 18,215 Details of equity investment securities as of December 31, 2019 Table 5.3b (In thousands) Cost Gross gains Gross losses Fair Value Equity securities 17,188 154 (14) 17,328
Aging of the fair values of securities in an unrealized loss position	Tables 5.4a and 5.4b below summarize, for all available-for-sale investments in an unrealized loss position as of December 31, 2020 and 2019, the aggregate fair value and gross unrealized losses by the length of time those securities have been continuously in an unrealized loss position. Gross unrealized losses on our available-for-sale investments amounted to $5 million and $10 million as of December 31, 2020 and 2019, respectively. The fair value amounts reported in tables 5.4a and 5.4b below are estimated using the process described in Note 6 - "Fair Value Measurements" to these consolidated financial statements. Unrealized loss aging for securities by type and length of time as of December 31, 2020 Table 5.4a 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 $ 2,690 $ (2) $ — $ — $ 2,690 $ (2) Obligations of U.S. states and political subdivisions 31,416 (256) — — 31,416 (256) Corporate debt securities 44,968 (1,728) — — 44,968 (1,728) ABS 14,929 (18) — — 14,929 (18) RMBS 98,409 (773) 3,566 (65) 101,975 (838) CMBS 13,212 (789) 2,799 (336) 16,011 (1,125) CLOs 95,287 (261) 73,904 (431) 169,191 (692) Total $ 300,911 $ (3,827) $ 80,269 $ (832) $ 381,180 $ (4,659) Unrealized loss aging for securities by type and length of time as of December 31, 2019 Table 5.4b 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 $ 57,301 $ (200) $ 5,806 $ (10) $ 63,107 $ (210) Obligations of U.S. states and political subdivisions 74,859 (847) 6,957 (10) 81,816 (857) Corporate debt securities 221,357 (2,847) 43,505 (161) 264,862 (3,008) ABS 21,542 (118) 3,851 (60) 25,393 (178) RMBS 105,443 (461) 110,452 (2,766) 215,895 (3,227) CMBS 62,388 (728) 11,852 (51) 74,240 (779) CLOs 81,444 (225) 196,988 (1,418) 278,432 (1,643) Total $ 624,334 $ (5,426) $ 379,411 $ (4,476) $ 1,003,745 $ (9,902)
Net investment income	The source of net investment income is shown in table 5.5 below. Net investment income Table 5.5 (In thousands) 2020 2019 2018 Fixed income securities $ 157,065 $ 165,523 $ 140,539 Equity securities 620 406 228 Cash equivalents 1,648 4,444 3,423 Other 275 974 816 Investment income 159,608 171,347 145,006 Investment expenses (5,212) (4,302) (3,675) Net investment income $ 154,396 $ 167,045 $ 141,331
Change in unrealized gains (losses) of investments	The change in unrealized gains (losses) of investments is shown in table 5.6 below. Change in unrealized gains (losses) Table 5.6 (In thousands) 2020 2019 2018 Fixed income securities $ 169,135 $ 220,139 $ (81,834) Equity securities — — — Change in unrealized gains/losses $ 169,135 $ 220,139 $ (81,834)

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2020
Fair Value Disclosures [Abstract]
Fair value measurements for items measured at fair value	Assets carried at fair value included those listed, by hierarchy level, in the following tables as of December 31, 2020 and 2019: Assets carried at fair value by hierarchy level as of December 31, 2020 Table 6.1a (In thousands) 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 $ 265,693 $ 149,339 $ 116,354 $ — Obligations of U.S. states and political subdivisions 2,249,869 — 2,249,869 — Corporate debt securities 2,844,288 — 2,844,288 — ABS 206,686 — 206,686 — RMBS 431,166 — 431,166 — CMBS 327,502 — 327,502 — CLOs 310,490 — 310,490 — Debt foreign government 4,709 — 4,709 — Other Investments (1) 21,193 — 21,193 — Total fixed income securities 6,661,596 149,339 6,512,257 — Equity securities 18,215 18,215 — — Cash Equivalents 288,941 275,668 13,273 — Real estate acquired (2) 1,092 — — 1,092 Total $ 6,969,844 $ 443,222 $ 6,525,530 $ 1,092 Assets carried at fair value by hierarchy level as of December 31, 2019 Table 6.1b (In thousands) 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 $ 196,203 $ 34,240 $ 161,963 $ — Obligations of U.S. states and political subdivisions 1,653,865 — 1,653,865 — Corporate debt securities 2,785,122 — 2,785,122 — ABS 229,664 — 229,664 — RMBS 268,586 — 268,586 — CMBS 278,986 — 278,986 — CLOs 325,466 — 325,466 — Total fixed income securities 5,737,892 34,240 5,703,652 — Equity securities 17,328 17,328 — — Cash Equivalents 164,693 164,693 — — Real estate acquired (2) 7,252 — — 7,252 Total $ 5,927,165 $ 216,261 $ 5,703,652 $ 7,252 (1) Consists of commercial paper included in "Investment Portfolio: Fixed income" with original maturities greater than ninety days. (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)	For assets measured at fair value using significant unobservable inputs (Level 3), a reconciliation of the beginning and ending balances for the years ended December 31, 2020 and 2019 is shown in tables 6.2a and 6.2b below. There were no losses included in earnings for the years ended December 31, 2020 and 2019 attributable to the change in unrealized losses on assets still held at the end of each applicable year. Fair value roll-forward for financial instruments classified as Level 3 for the year ended December 31, 2020 Table 6.2a (In thousands) Debt Securities Real Estate Acquired Balance at December 31, 2019 $ — $ 7,252 Total realized/unrealized gains (losses): Included in earnings and reported as losses incurred, net — 660 Acquisitions — 8,609 Sales — (15,429) Balance at December 31, 2020 $ — $ 1,092 Fair value roll-forward for financial instruments classified as Level 3 for the year ended December 31, 2019 Table 6.2b (In thousands) Debt Securities Real Estate Acquired Balance at December 31, 2018 $ 13 $ 14,535 Total realized/unrealized gains (losses): Included in earnings and reported as losses incurred, net — (476) Acquisitions — 24,204 Sales (13) (31,011) Balance at December 31, 2019 $ — $ 7,252
Schedule of carrying value and fair value of financial liabilities measured on a recurring basis	Table 6.3 compares the carrying value and fair value of our financial liabilities disclosed, but not carried, at fair value as of December 31, 2020 and 2019. Financial liabilities not carried at fair value Table 6.3 December 31, 2020 December 31, 2019 (In thousands) Carrying Value Fair Value Carrying Value Fair Value Financial assets Other invested assets $ 3,100 $ 3,100 $ 3,100 $ 3,100 Financial liabilities FHLB Advance $ 155,000 $ 160,865 $ 155,000 $ 156,422 5.75% Notes 240,597 261,752 420,867 471,827 5.25% Notes 638,782 696,449 — — 9% Debentures 208,814 273,569 256,872 346,289 Total financial liabilities $ 1,243,193 $ 1,392,635 $ 832,739 $ 974,538

Debt (Tables)

Debt (Tables)	12 Months Ended
	Dec. 31, 2020
Debt Disclosure [Abstract]
Schedule of debt	Table 7.1 shows the carrying value of our long-term debt obligations as of December 31, 2020 and 2019. Long-term debt obligations Table 7.1 December 31, (In millions) 2020 2019 FHLB Advance - 1.91%, due February 2023 $ 155.0 $ 155.0 5.75% Notes, due August 2023 (par value: $242.3 million) 240.6 420.9 5.25% Notes, due August 2028 (par value: $650 million) 638.8 — 9% Debentures, due April 2063 208.8 256.9 Long-term debt, carrying value $ 1,243.2 $ 832.8

Loss Reserves (Tables)

Loss Reserves (Tables)	12 Months Ended
	Dec. 31, 2020
Insurance Loss Reserves [Abstract]
Reconciliation of beginning and ending loss reserves	Table 8.1 provides a reconciliation of beginning and ending loss reserves for each of the past three years: Development of loss reserves Table 8.1 (In thousands) 2020 2019 2018 Reserve at beginning of year $ 555,334 $ 674,019 $ 985,635 Less reinsurance recoverable 21,641 33,328 48,474 Net reserve at beginning of year 533,693 640,691 937,161 Losses incurred: Losses and LAE incurred in respect of delinquent notices received in: Current year 345,170 189,581 203,928 Prior years (1) 19,604 (71,006) (167,366) Total losses incurred 364,774 118,575 36,562 Losses paid: Losses and LAE paid in respect of delinquent notices received in: Current year 3,069 4,018 7,298 Prior years 109,923 235,551 327,743 Reinsurance terminations (20) (13,996) (2,009) Total losses paid 112,972 225,573 333,032 Net reserve at end of year 785,495 533,693 640,691 Plus reinsurance recoverables 95,042 21,641 33,328 Reserve at end of year $ 880,537 $ 555,334 $ 674,019 (1) A positive number for prior year loss development indicates a deficiency of prior year reserves. A negative number for prior year losses incurred indicates a redundancy of prior year loss reserves. See table 8.2 below for more information about prior year loss development.
Prior year development of the reserves	Table 8.2 below shows the development of reserves in 2020, 2019 and 2018 for previously received delinquencies. Reserve development on previously received delinquencies Table 8.2 (In thousands) 2020 2019 2018 (Decrease) in estimated claim rate on primary delinquencies $ (2,536) $ (111,848) $ (212,738) Increase (decrease)in estimated severity on primary delinquencies 13,535 (434) 28,528 Change in estimates related to pool reserves, LAE reserves, reinsurance and other 8,605 41,276 16,844 Total prior year loss development (1) $ 19,604 $ (71,006) $ (167,366)
Rollforward of delinquent inventory roll-forward	A roll-forward of our primary delinquent inventory for the years ended December 31, 2020, 2019, and 2018 appears in table 8.3 below. 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 number of business days in a month and transfers of servicing between loan servicers. Primary delinquency inventory roll-forward Table 8.3 2020 2019 2018 Beginning delinquent inventory 30,028 32,898 46,556 New Notices 106,099 54,239 54,448 Cures (76,107) (52,035) (60,511) Paid claims (2,245) (4,267) (5,750) Rescissions and denials (65) (168) (267) Other items removed from inventory — (639) (1,578) Ending delinquent inventory 57,710 30,028 32,898
Aging of the primary default inventory	The number of consecutive months that a borrower has been delinquent is shown in table 8.4 below. Primary delinquency inventory - consecutive months delinquent Table 8.4 December 31, 2020 2019 2018 3 months or less 11,542 9,447 9,829 4 - 11 months 34,620 9,664 9,655 12 months or more (1) 11,548 10,917 13,414 Total 57,710 30,028 32,898 3 months or less 20 % 32 % 30 % 4 - 11 months 60 % 32 % 29 % 12 months or more 20 % 36 % 41 % Total 100 % 100 % 100 % Primary claims received inventory included in ending delinquent inventory 159 538 809 (1) Approximately 31%, 36%, and 38% of the delinquent inventory that has been delinquent for 12 consecutive months or more has been delinquent for at least 36 consecutive months as of December 31, 2020, 2019 and 2018, respectively.

Reinsurance (Tables)

Reinsurance (Tables)	12 Months Ended
	Dec. 31, 2020
Reinsurance Disclosures [Abstract]
Effect of reinsurance agreements on premiums earned and losses incurred	Table 9.1 below shows the effect of all reinsurance agreements on premiums earned and losses incurred as reflected in the consolidated statements of operations. Reinsurance Table 9.1 Years ended December 31, (In thousands) 2020 2019 2018 Premiums earned: Direct $ 1,199,824 $ 1,155,240 $ 1,084,748 Assumed 10,848 5,085 1,805 Ceded (188,729) (129,337) (111,391) Net premiums earned 1,021,943 1,030,988 975,162 Losses incurred: Direct 442,194 130,100 43,060 Assumed 555 (125) 331 Ceded (77,975) (11,400) (6,829) Net losses incurred $ 364,774 $ 118,575 $ 36,562
Schedule of Quota Share Reinsurance Agreements	Table 9.2 below provides additional detail regarding our QSR agreements. Reinsurance Table 9.2 Quota Share Contract Policy Year Quota Share % Annual Loss Ratio to Exhaust Profit Commission (1) Contractual Termination Date 2015 QSR Prior to 2017 15.0 % 68.0 % December 31, 2031 2017 QSR 2017 30.0 % 60.0 % December 31, 2028 2018 QSR 2018 30.0 % 62.0 % December 31, 2029 2019 QSR 2019 30.0 % 62.0 % December 31, 2030 2020 QSR - 1 Year 2020 12.5 % 62.0 % December 31, 2031 2020 QSR - 2 Year 2020 - 2021 17.5 % 62.0 % December 31, 2032 Credit Union QSR (2) 2020-2025 65.0 % 50.0 % December 31, 2039 (1) We will receive a profit commission provided the annual loss ratio on loans covered under the transaction remains below this ratio. (2) Eligible credit union business written before 2020 was covered by our 2019 and prior QSR Transactions. Table 9.3 provides additional detail regarding optional termination dates and optional reductions to our quota share percentage. The optional reduction to the quota share percentage would give us an option to reduce our quota share percentage from the original percentage as shown in table 9.2. Reinsurance Table 9.3 Quota Share Contract Optional Termination Date (1) Optional Quota Share % Reduction Date (2) Quota Share % Reduction 2015 QSR June 30, 2021 NA NA 2017 QSR December 31, 2021 NA NA 2018 QSR December 31, 2021 NA NA 2019 QSR December 31, 2021 July 1, 2020 25% or 20% 2020 QSR - 1 Year December 31, 2022 July 1, 2021 10.5% or 8% 2020 QSR - 2 Year December 31, 2023 July 1, 2021 14.5% or 12% (1) We can elect early termination of the QSR agreement beginning on this date, and bi-annually thereafter for the 2015 QSR, 2019 QSR, and 2020 QSR. Early termination of the 2018 QSR can be elected annually after this date. (2)
Quota share reinsurance agreements on premiums earned and losses incurred	Table 9.4 provides a summary of our quota share reinsurance agreements for 2020, 2019, and 2018. Quota share reinsurance Table 9.4 Years ended December 31, (In thousands) 2020 2019 2018 Ceded premiums written and earned, net of profit commission $ 167,930 $ 111,550 $ 108,337 Ceded losses incurred 78,012 11,395 6,543 Ceding commissions (1) 48,077 48,793 51,201 Profit commission 72,452 139,179 147,667 (1) Ceding commissions are reported within Other underwriting and operating expenses, net on the consolidated statements of operations.
Reinsurance retention policy	Table 9.5 provides a summary of our excess of loss reinsurance agreements as of December 31, 2020, December 31, 2019 and December 31, 2018. Excess of Loss Reinsurance Table 9.5 (In thousands) Home Re 2020-1, Ltd. Home Re 2019-1, Ltd. Home Re 2018-1, Ltd. Issue Date October, 2020 May 1, 2019 October 1, 2018 Policy Inforce Dates January 1, 2020 - July 31, 2020 January 1, 2018 - March 31, 2019 July 1, 2016 - December 31, 2017 Termination Option Date (1) October 25, 2030 May 25, 2026 October 25, 2025 Initial First Layer Retention 275,283 185,730 168,691 Initial Excess of Loss Reinsurance Coverage 412,917 315,739 318,636 2020 Remaining First Layer Retention 275,283 184,514 166,005 Remaining Excess of Loss Reinsurance Coverage 412,917 208,146 218,343 2019 Remaining First Layer Retention — 185,636 167,779 Remaining Excess of Loss Reinsurance Coverage — 271,021 260,957 2018 Remaining First Layer Retention — — 168,691 Remaining Excess of Loss Reinsurance Coverage — — 318,636
Schedule of total assets of Home Re Entities	Table 9.6 presents the total assets of Home Re Entities as of December 31, 2020 , December 31, 2019 and December 31, 2018. Home Re Entities total assets Table 9.6 (In thousands) Home Re Entity Total VIE Assets December 31, 2020 Home Re 2018-01 Ltd. $ 218,343 Home Re 2019-01 Ltd. $ 208,146 Home Re 2020-01 Ltd. $ 412,917 December 31, 2019 Home Re 2018-01 Ltd. $ 269,451 Home Re 2019-01 Ltd. $ 283,150 December 31, 2018 Home Re 2018-01 Ltd. $ 318,636

Other Comprehensive Income (L_2

Other Comprehensive Income (Loss) (Tables)	12 Months Ended
	Dec. 31, 2020
Comprehensive Income (Loss), Net of Tax, Attributable to Parent [Abstract]
Other comprehensive income	The pretax components of our other comprehensive income (loss) and related income tax (expense) benefit for the years ended December 31, 2020, 2019 and 2018 are included in table 10.1 below. Components of other comprehensive income (loss) Table 10.1 (In thousands) 2020 2019 2018 Net unrealized investment gains (losses) on securities without an allowance for credit losses $ 169,135 $ 220,139 $ (81,834) Income tax (expense) benefit (35,519) (46,229) 17,188 Net of taxes 133,616 173,910 (64,646) Net changes in benefit plan assets and obligations 13,288 29,129 (19,958) Income tax (expense) benefit (2,791) (6,117) 4,191 Net of taxes 10,497 23,012 (15,767) Total other comprehensive income (loss) 182,423 249,268 (101,792) Total income tax expense, net (38,310) (52,346) 21,379 Total other comprehensive income, net of tax $ 144,113 $ 196,922 $ (80,413)
Reclassification out of accumulated other comprehensive income	The pretax and related income tax benefit (expense) components of the amounts reclassified from our accumulated other comprehensive income (loss) ( "AOCI", "AOCL") to our consolidated statements of operations for the years ended December 31, 2020, 2019 and 2018 are included in table 10.2 below. Reclassifications from Accumulated Other Comprehensive Income (Loss) Table 10.2 (In thousands) 2020 2019 2018 Reclassification adjustment for net realized gains (losses) included in net income (1) $ 13,862 $ 3,637 $ (7,037) Income tax (expense) benefit (2,912) (763) 1,477 Net of taxes 10,950 2,874 (5,560) Reclassification adjustment related to benefit plan assets and obligations (2) (15,968) (8,097) (2,232) Income tax benefit 3,353 1,701 469 Net of taxes (12,615) (6,396) (1,763) Total reclassifications (2,106) (4,460) (9,269) Total income tax benefit, net 441 938 1,946 Total reclassifications, net of tax $ (1,665) $ (3,522) $ (7,323) (1) (Decreases) increases Net realized investment gains on the consolidated statements of operations.
Accumulated other comprehensive income (loss)	A roll-forward of AOCI (AOCL) for the years ended December 31, 2020, 2019, and 2018, including amounts reclassified from AOCI (AOCL), is included in table 10.3 below. Roll-forward of Accumulated Other Comprehensive Income (Loss) Table 10.3 (In thousands) Net unrealized gains and losses on available-for-sale securities Net benefit plan assets and obligations recognized in shareholders' equity Total AOCL Balance, December 31, 2017, net of tax $ 29,275 $ (73,058) $ (43,783) Cumulative effect of adopting the accounting standard update for financial instruments (18) — (18) Other comprehensive income (loss) before reclassifications (70,206) (17,530) (87,736) Less: Amounts reclassified from AOCL (5,560) (1,763) (7,323) Balance, December 31, 2018, net of tax (35,389) (88,825) (124,214) Other comprehensive income (loss) before reclassifications 176,784 16,616 193,400 Less: Amounts reclassified from AOCL 2,874 (6,396) (3,522) Balance, December 31, 2019, net of tax 138,521 (65,813) 72,708 Other comprehensive income (loss) before reclassifications 144,566 (2,118) 142,448 Less: Amounts reclassified from AOCL 10,950 (12,615) (1,665) Balance, December 31, 2020, net of tax $ 272,137 $ (55,316) 216,821

Benefit Plans (Tables)

Benefit Plans (Tables)	12 Months Ended
	Dec. 31, 2020
Retirement Benefits [Abstract]
Components of net periodic benefit cost	The following tables 11.1, 11.2, and 11.3 provide the components of aggregate annual net periodic benefit cost for each of the years ended December 31, 2020, 2019, and 2018 and changes in the benefit obligation and the funded status of the pension, supplemental executive retirement and other postretirement benefit plans as recognized in the consolidated balance sheets as of December 31, 2020 and 2019. Components of net periodic benefit cost Table 11.1 Pension and Supplemental Executive Retirement Plans Other Postretirement Benefits (In thousands) 12/31/2020 12/31/2019 12/31/2018 12/31/2020 12/31/2019 12/31/2018 1. Company Service Cost $ 7,342 $ 8,345 $ 10,530 $ 1,263 $ 1,345 $ 1,160 2. Interest Cost 13,036 15,705 15,095 832 1,130 834 3. Expected Return on Assets (22,139) (19,466) (22,250) (7,407) (5,785) (6,359) 4. Other Adjustments — — — — — — Subtotal (1,761) 4,584 3,375 (5,312) (3,310) (4,365) 5. Amortization of: a. Net Transition Obligation/(Asset) — — — — — — b. Net Prior Service Cost/(Credit) (247) (281) (351) 51 (34) (4,104) c. Net Losses/(Gains) 6,578 8,412 6,937 (783) — (250) Total Amortization 6,331 8,131 6,586 (732) (34) (4,354) 6. Net Periodic Benefit Cost 4,570 12,715 9,961 (6,044) (3,344) (8,719) 7. Cost of settlements 10,369 1,933 — — — — 8. Total Expense for Year $ 14,939 $ 14,648 $ 9,961 $ (6,044) $ (3,344) $ (8,719)
Development of funded status	Development of funded status Table 11.2 Pension and Supplemental Executive Retirement Plans Other Postretirement Benefits (In thousands) 12/31/2020 12/31/2019 12/31/2020 12/31/2019 Actuarial Value of Benefit Obligations 1. Measurement Date 12/31/2020 12/31/2019 12/31/2020 12/31/2019 2. Accumulated Benefit Obligation $ 423,305 $ 412,939 $ 28,714 $ 27,496 Funded Status/Asset (Liability) on the Consolidated Balance Sheet 1. Projected Benefit Obligation $ (423,713) $ (413,350) $ (28,714) $ (27,496) 2. Plan Assets at Fair Value 411,245 402,691 119,024 99,590 3. Funded Status - Overfunded/Asset N/A N/A $ 90,310 $ 72,094 4. Funded Status - Underfunded/Liability (12,468) (10,659) N/A N/A Accumulated other comprehensive (income) loss Table 11.3 Pension and Supplemental Executive Retirement Plans Other Postretirement Benefits (In thousands) 12/31/2020 12/31/2019 12/31/2020 12/31/2019 1. Net Actuarial (Gain)/Loss $ 98,899 $ 99,826 $ (30,565) $ (18,005) 2. Net Prior Service Cost/(Credit) (988) (1,237) 2,673 2,724 3. Net Transition Obligation/(Asset) — — — — 4. Total at Year End $ 97,911 $ 98,589 $ (27,892) $ (15,281)
Change in projected benefit obligation	Table 11.4 shows the changes in the projected benefit obligation for 2020 and 2019. Change in projected benefit / accumulated benefit Table 11.4 Pension and Supplemental Executive Retirement Plans Other Postretirement Benefits (In thousands) 12/31/2020 12/31/2019 12/31/2020 12/31/2019 1. Benefit Obligation at Beginning of Year $ 413,350 $ 376,153 $ 27,496 $ 28,085 2. Company Service Cost 7,342 8,345 1,263 1,345 3. Interest Cost 13,036 15,705 832 1,130 4. Plan Participants' Contributions — — 425 382 5. Net Actuarial (Gain)/Loss 36,196 47,113 660 (2,075) 6. Benefit Payments from Fund (1) (40,260) (30,829) (1,975) (826) 7. Benefit Payments Directly by Company (5,953) (3,105) — — 8. Plan Amendments 2 (5) — — 9. Other Adjustment — — 13 (545) 10. Settlement (Gain)/Loss — (27) — — 11. Benefit Obligation at End of Year $ 423,713 $ 413,350 $ 28,714 $ 27,496 (1) Includes lump sum payments of $27.5 million and $18.5 million in 2020 and 2019, respectively, from our pension plan to eligible participants, which were former employees with vested benefits.
Change in plan assets	Tables 11.5 and 11.6 shows the changes in the fair value of the net assets available for plan benefits, and changes in other comprehensive income (loss) during 2020 and 2019. Change in plan assets Table 11.5 Pension and Supplemental Executive Retirement Plans Other Postretirement Benefits (In thousands) 12/31/2020 12/31/2019 12/31/2020 12/31/2019 1. Fair Value of Plan Assets at Beginning of Year $ 402,691 $ 359,719 $ 99,590 $ 77,762 2. Company Contributions 12,453 10,205 — — 3. Plan Participants' Contributions — — 425 382 4. Benefit Payments from Fund (40,260) (30,829) (1,975) (826) 5. Benefit Payments paid directly by Company (5,953) (3,105) — — 6. Actual Return on Assets 42,314 70,262 21,409 22,654 7. Other Adjustment — (3,561) (425) (382) 8. Fair Value of Plan Assets at End of Year $ 411,245 $ 402,691 $ 119,024 $ 99,590
Change in accumulated other comprehensive income (AOCI)	Change in accumulated other comprehensive income (loss) ("AOCI") Table 11.6 Pension and Supplemental Executive Retirement Plans Other Postretirement Benefits (In thousands) 12/31/2020 12/31/2019 12/31/2020 12/31/2019 1. AOCI in Prior Year $ 98,589 $ 108,808 $ (15,281) $ 3,629 2. Increase/(Decrease) in AOCI a. Recognized during year - Prior Service (Cost)/Credit 247 281 (51) 34 b. Recognized during year - Net Actuarial (Losses)/Gains (16,948) (8,412) 782 — c. Occurring during year - Prior Service Cost 2 (5) — — d. Occurring during year - Net Actuarial Losses/(Gains) 16,021 (150) (13,342) (18,944) e. Occurring during year - Net Settlement Losses/(Gains) — (1,933) — — 3. AOCI in Current Year $ 97,911 $ 98,589 $ (27,892) $ (15,281)
Actuarial assumptions	The projected benefit obligations, net periodic benefit costs and accumulated postretirement benefit obligation for the plans were determined using the following weighted average assumptions. Actuarial assumptions Table 11.7 Pension and Supplemental Executive Retirement Plans Other Postretirement Benefits 12/31/2020 12/31/2019 12/31/2020 12/31/2019 Weighted-Average Assumptions Used to Determine Benefit Obligations at year end 1. Discount Rate 2.75 % 3.45 % 2.35 % 3.20 % 2. Rate of Compensation Increase 3.00 % 3.00 % N/A N/A 3. Cash balance interest crediting rate 2.50 % 3.20 % N/A N/A Weighted-Average Assumptions Used to Determine Net Periodic Benefit Cost for Year 1. Discount Rate 3.30 % 4.40 % 3.20 % 4.25 % 2. Expected Long-term Return on Plan Assets 5.75 % 5.75 % 7.50 % 7.50 % 3. Rate of Compensation Increase 3.00 % 3.00 % N/A N/A Assumed Health Care Cost Trend Rates at year end 1. Health Care Cost Trend Rate Assumed for Next Year N/A N/A 6.00 % 6.00 % 2. Rate to Which the Cost Trend Rate is Assumed to Decline (Ultimate Trend Rate) N/A N/A 5.00 % 5.00 % 3. Year That the Rate Reaches the Ultimate Trend Rate N/A N/A 2024 2024
Year-end asset allocations of the plans	The year-end asset allocations of the plans are shown in table 11.8 below. Plan assets Table 11.8 Pension Plan Other Postretirement Benefits 12/31/2020 12/31/2019 12/31/2020 12/31/2019 1. Equity Securities 21 % 23 % 100 % 100 % 2. Debt Securities 79 % 77 % — % — % 3. Total 100 % 100 % 100 % 100 %
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Schedule of investment allocation strategies	The equity investments use combinations of mutual funds, ETFs, and pooled equity account structures focused on the following strategies: Strategy Objective Investment types Return seeking growth Funded ratio improvement over the long term ● Global quality growth ● Global low volatility Return seeking bridge Downside protection in the event of a declining equity market ● Enduring asset ● Durable company
Minimum and maximum allocation ranges for fixed income securities and equity securities	The primary focus in developing asset allocation ranges for the portfolio is the assessment of the portfolio's investment objectives and the level of risk that is acceptable to obtain those objectives. To achieve these objectives the minimum and maximum allocation ranges for fixed income securities and equity securities are: Minimum Maximum Equities (long only) 70 % 100 % Real estate 0 % 15 % Commodities 0 % 10 % Fixed income/Cash 0 % 10 %
Actual and estimated future contributions and actual and estimated future benefit payments	Tables 11.12 and 11.13 show the current and estimated future contributions and benefit payments. Company contributions Table 11.12 Pension and Supplemental Executive Retirement Plans Other Postretirement Benefits (In thousands) 12/31/2020 12/31/2020 Company Contributions for the Year Ending: 1. Current $ 12,453 $ — 2. Current + 1 6,200 — Benefits payments - total Table 11.13 Pension and Supplemental Executive Retirement Plans Other Postretirement Benefits (In thousands) 12/31/2020 12/31/2020 Actual Benefit Payments for the Year Ending: 1. Current $ 46,213 $ 1,975 Expected Benefit Payments for the Year Ending: 2. Current + 1 30,082 1,765 3. Current + 2 29,929 1,995 4. Current + 3 30,076 2,157 5. Current + 4 29,567 2,241 6. Current + 5 28,852 2,357 7. Current + 6 - 10 135,830 10,916
Pension Plan
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	Tables 11.9a and 11.9b set forth by level, within the fair value hierarchy, the pension plan assets and related accrued investment income at fair value as of December 31, 2020 and 2019. There were no securities that used Level 3 inputs. Pension plan assets at fair value as of December 31, 2020 Table 11.9a (In thousands) Level 1 Level 2 Total Domestic Mutual Funds $ 4,842 $ — $ 4,842 Corporate Bonds — 231,190 231,190 U.S. Government Securities 26,407 — 26,407 Municipal Bonds — 32,891 32,891 Foreign Bonds — 33,368 33,368 Pooled Equity Accounts — 82,547 82,547 Total Assets at fair value $ 31,249 $ 379,996 $ 411,245 Pension plan assets at fair value as of December 31, 2019 Table 11.9b (In thousands) Level 1 Level 2 Total Domestic Mutual Funds $ 7,325 $ — $ 7,325 Corporate Bonds — 203,684 203,684 U.S. Government Securities 32,166 2,511 34,677 Municipal Bonds — 38,998 38,998 Foreign Bonds — 34,024 34,024 Pooled Equity Accounts — 83,983 83,983 Total Assets at fair value $ 39,491 $ 363,200 $ 402,691
Other Postretirement Benefit Plan
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	Tables 11.10a and 11.10b set forth the other postretirement benefits plan assets at fair value as of December 31, 2020 and 2019. All are Level 1 assets. Other postretirement benefits plan assets at fair value as of December 31, 2020 Table 11.10a (In thousands) Level 1 Domestic Mutual Funds $ 91,454 International Mutual Funds 27,570 Total Assets at fair value $ 119,024 Other postretirement benefits plan assets at fair value as of December 31, 2019 Table 11.10b (In thousands) Level 1 Domestic Mutual Funds $ 77,640 International Mutual Funds 21,950 Total Assets at fair value $ 99,590

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2020
Income Tax Disclosure [Abstract]
Net deferred tax assets and liabilities	Net deferred tax (liabilities) assets, included on the Consolidated Balance Sheet at December 31, 2020 and 2019 as a component of Other liabilities and Other assets, respectively, are as follows: Deferred tax assets and liabilities Table 12.1 (In thousands) 2020 2019 Total deferred tax assets $ 38,443 $ 63,533 Total deferred tax liabilities (98,485) (57,791) Net deferred tax (liability) asset $ (60,042) $ 5,742
Components of the net deferred tax asset (liability)	Table 12.2 includes the components of the net deferred tax (liability) asset as of December 31, 2020 and 2019. Deferred tax components Table 12.2 (In thousands) 2020 2019 Unearned premium reserves $ 23,163 $ 30,487 Benefit plans (13,977) (10,790) Loss reserves 3,542 2,175 Unrealized appreciation in investments (72,341) (36,822) Mortgage investments — 8,359 Deferred compensation 6,776 9,270 AMT credit carryforward — 8,303 Other, net (7,205) (5,240) Net deferred tax (liability) asset $ (60,042) $ 5,742
Components of the provision for (benefit from) income taxes	Table 12.3 summarizes the components of the provision for (benefit from) income taxes: Provision for (benefit from) income taxes Table 12.3 (In thousands) 2020 2019 2018 Current Federal $ 85,574 $ 162,911 $ (16,272) Deferred Federal 28,244 11,860 185,598 Other (648) (557) 4,727 Provision for income taxes $ 113,170 $ 174,214 $ 174,053
Reconciliation of federal statutory income tax rate	Table 12.4 reconciles the federal statutory income tax rate to our effective tax provision rate. Effective tax rate reconciliation Table 12.4 2020 2019 2018 Federal statutory income tax rate 21.0 % 21.0 % 21.0 % Additional income tax benefit related to IRS litigation — % — % (0.3) % Tax exempt municipal bond interest (0.9) % (0.6) % (0.7) % Other, net 0.1 % 0.1 % 0.6 % Effective tax rate 20.2 % 20.5 % 20.6 %

Statutory Information (Tables)

Statutory Information (Tables)	12 Months Ended
	Dec. 31, 2020
Statutory Capital [Abstract]
Summary of amounts disclosed under statutory accounting practices	The statutory net income loss, policyholders' surplus and contingency reserve liability of the insurance subsidiaries of our holding company are shown in table 14.1 below. The surplus amounts included in the following table are the combined policyholders' surplus of our insurance operations as utilized in our risk-to-capital calculations. Statutory financial information of insurance subsidiaries Table 14.1 As of and for the Years Ended December 31, (In thousands) 2020 2019 2018 Statutory net income $ 65,201 $ 305,857 $ 375,484 Statutory policyholders' surplus 1,339,509 1,619,069 1,683,058 Contingency reserve 3,585,864 3,021,055 2,442,996 For the years ended December 31, 2020, 2019, and 2018 there were no surplus contributions made to MGIC or distributions from other insurance subsidiaries to us. Dividends paid by MGIC are shown in table 14.2 below. Surplus contributions and dividends of insurance subsidiaries Table 14.2 Years Ended December 31, (In thousands) 2020 2019 2018 Dividends paid by MGIC to the parent company (1) $ 390,000 280,000 220,000 (1) Dividends paid in cash and/or investment securities. Also in 2020, MGIC distributed to the holding company, as a dividend, its ownership in the 9% Debentures held at an amortized cost of $139.5 million.

Share-based Compensation Plans

Share-based Compensation Plans (Tables)	12 Months Ended
	Dec. 31, 2020
Share-based Payment Arrangement [Abstract]
Summary of restricted stock or restricted stock unit activity	Table 15.1 summarizes restricted stock or restricted stock unit (collectively called “restricted stock”) activity during 2020. Restricted stock Table 15.1 Weighted Average Grant Date Fair Market Value Shares Restricted stock outstanding at December 31, 2019 $ 12.81 4,150,394 Granted 13.62 1,672,060 Vested 11.67 (1,564,843) Forfeited 13.24 (118,368) Restricted stock outstanding at December 31, 2020 $ 13.57 4,139,243

Leases (Tables)

Leases (Tables)	12 Months Ended
	Dec. 31, 2020
Leases [Abstract]
Lessee, operating lease, liability, maturity	Table 16.1 shows minimum the future operating lease payments as of December 31, 2020. Minimum future operating lease payments Table 16.1 (In thousands) Amount 2021 $ 836 2022 687 2023 311 2024 81 2025 and thereafter — Total $ 1,915

Unaudited Quarterly Financial_2

Unaudited Quarterly Financial Data (Tables)	12 Months Ended
	Dec. 31, 2020
Quarterly Financial Information Disclosure [Abstract]
Unaudited quarterly financial data	Unaudited quarterly financial data - current year: Table: 18.1a 2020: Quarter Full (In thousands, except per share data) First Second Third Fourth Year Net premiums earned $ 260,901 $ 243,562 $ 256,113 $ 261,367 $ 1,021,943 Investment income, net of expenses 41,347 39,679 37,252 36,118 154,396 Realized gains (losses) 1,891 6,701 2,259 2,901 13,752 Other revenue 2,754 4,026 380 1,895 9,055 Loss incurred, net 60,956 217,374 40,686 45,758 364,774 Underwriting and other expenses, net 57,698 60,111 64,253 66,311 248,373 Loss on debt extinguishment — — 26,736 — 26,736 Provision for income tax 38,434 2,436 33,518 38,782 113,170 Net income 149,805 14,047 130,811 151,430 446,093 Income per share (a) (b) : Basic 0.44 0.04 0.39 0.45 1.31 Diluted 0.42 0.04 0.38 0.44 1.29 Unaudited quarterly financial statements - prior year: Table: 18.1b 2019: Quarter Full (In thousands, except per share data) First Second Third Fourth Year Net premiums earned $ 249,762 $ 247,102 $ 267,857 $ 266,267 $ 1,030,988 Investment income, net of expenses 40,585 42,423 42,715 41,322 167,045 Realized gains (losses) (526) 307 4,205 1,320 5,306 Other revenue 1,830 2,485 3,606 2,717 10,638 Loss incurred, net 39,064 21,836 33,985 23,690 118,575 Underwriting and other expenses, net 61,650 59,270 61,278 65,227 247,425 Provision for income tax 38,996 43,433 46,186 45,599 174,214 Net income 151,941 167,778 176,934 177,110 673,763 Income per share (a) (b) : Basic 0.43 0.47 0.50 0.51 1.91 Diluted 0.42 0.46 0.49 0.49 1.85 (a) Due to the use of weighted average shares outstanding when calculating earnings per share, the sum of the quarterly per share data may not equal the per share data for the year. (b) In periods where convertible debt instruments are dilutive to earnings per share the “if-converted” method of computing diluted EPS requires an interest expense adjustment, net of tax, to net income available to shareholders. See Note 4 – “Earnings Per Share” for further discussion on our calculation of diluted EPS.

Nature of Business (Details)

Nature of Business (Details) $ in Billions	Dec. 31, 2020USD ($)
Nature of Business [Abstract]
Direct domestic primary insurance in force	$ 246.6
Direct domestic primary risk in force	$ 61.8

Significant Accounting Polici_4

Significant Accounting Policies (Details)	12 Months Ended
	Dec. 31, 2020USD ($)Payment	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)
Home office and equipment [Abstract]
Accumulated depreciation of home office and equipment	$ 51,200,000	$ 43,000,000	$ 38,100,000
Depreciation expense of home office and equipment	$ 6,300,000	6,500,000	6,000,000
Minimum number of payments past due to be in default | Payment	2
Maximum age for qualified employees for both medical and dental benefits	65 years
Related party transaction amount		$ 0	$ 0
Minimum
Home office and equipment [Abstract]
Estimated useful life	3 years
Award vesting period	1 year
Maximum
Home office and equipment [Abstract]
Estimated useful life	45 years
Award vesting period	3 years

Earnings per Share (Details)

Earnings per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Basic earnings per share [Abstract]
Net income	$ 151,430	$ 130,811	$ 14,047	$ 149,805	$ 177,110	$ 176,934	$ 167,778	$ 151,941	$ 446,093	$ 673,763	$ 670,097
Weighted average common shares outstanding - basic (in shares)									339,953	352,827	365,406
Basic earnings per share (in dollars per share)	$ 0.45	$ 0.39	$ 0.04	$ 0.44	$ 0.51	$ 0.50	$ 0.47	$ 0.43	$ 1.31	$ 1.91	$ 1.83
Diluted earnings per share [Abstract]
Net income	$ 151,430	$ 130,811	$ 14,047	$ 149,805	$ 177,110	$ 176,934	$ 167,778	$ 151,941	$ 446,093	$ 673,763	$ 670,097
Diluted income available to common shareholders									$ 463,097	$ 692,027	$ 688,361
Weighted-average shares - basic (in shares)									339,953	352,827	365,406
Effect of dilutive securities [Abstract]
Weighted-average shares - diluted (in shares)									359,293	373,924	386,078
Diluted income per share (in dollars per share)	$ 0.44	$ 0.38	$ 0.04	$ 0.42	$ 0.49	$ 0.49	$ 0.46	$ 0.42	$ 1.29	$ 1.85	$ 1.78
Federal statutory income tax rate (in hundredths)									21.00%	21.00%	21.00%
9% Convertible Junior Subordinated Debentures due 2063
Diluted earnings per share [Abstract]
Dilutive securities									$ 17,004	$ 18,264	$ 18,264
Effect of dilutive securities [Abstract]
Dilutive securities (in shares)									17,751	19,028	19,028
Stated interest rate (in hundredths)	9.00%				9.00%				9.00%	9.00%	9.00%
Unvested Restricted Stock Units
Effect of dilutive securities [Abstract]
Dilutive securities - Share based compensation (in shares)									1,589	2,069	1,644

Investments (Details)

Investments (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2020USD ($)security	Dec. 31, 2019USD ($)security	Dec. 31, 2018USD ($)
Debt Securities, Available-for-sale [Line Items]
Total at end of period	$ 6,317,164	$ 5,562,550
Total at end of period	6,661,596	5,737,892
Assets held by insurance regulatory requirements	14,100	13,900
Assets held in trust for the benefit of contractual counterparties	$ 165,900	88,900
Collateral pledged to principal balance of FHLB advance (as a percent)	102.00%
Collateral pledged for FHLB advance	$ 163,900
Maturities, Amortized Cost [Abstract]
Due in one year or less	390,510
Due after one year through five years	1,945,158
Due after five years through ten years	1,280,760
Due after ten years	1,448,209
Total debt securities with single maturity date	5,064,637
Total at end of period	6,317,164	5,562,550
Maturities, Fair Value [Abstract]
Due in one year or less	393,286
Due after one year through five years	2,033,183
Due after five years through ten years	1,402,640
Due after ten years	1,556,643
Total debt securities with single maturity date	5,385,752
Total at end of period	6,661,596	5,737,892
Equity Securities, FV-NI, Gain (Loss) [Abstract]
Equity securities, cost	17,522	17,188
Equity securities, at fair value (cost, 2020 - $17,522; 2019 - $17,188)	18,215	17,328
Continuous Unrealized Loss Portion, Unrealized Loses [Abstract]
Less than 12 months	300,911	624,334
12 months or greater	80,269	379,411
Total	381,180	1,003,745
Less than 12 months	(3,827)	(5,426)
12 months or greater	(832)	(4,476)
Total	$ (4,659)	$ (9,902)
Number of securities in unrealized loss position | security	109	217
For securities in an unrealized loss position, percentage of fair value to amortized cost (in hundredths)	99.00%
For securities in an unrealized loss position, percentage backed by the U.S. Government (in hundredths)	27.00%
Total fixed income securities
Debt Securities, Available-for-sale [Line Items]
Total at end of period	$ 6,317,164	$ 5,562,550
Allowance for Expected Credit Loss	(49)
Gross Unrealized Gains	349,140	185,244
Gross Unrealized Losses	(4,659)	(9,902)
Total at end of period	6,661,596	5,737,892
Maturities, Amortized Cost [Abstract]
Total at end of period	6,317,164	5,562,550
Maturities, Fair Value [Abstract]
Total at end of period	6,661,596	5,737,892
Proceeds from sale of fixed income securities available for sale	803,400	228,100	$ 365,600
Gross realized gains	21,300	7,100	700
Gross realized losses	8,800	3,500	3,800
Debt Securities, Available for Sale, Impairment Charges Intent To Sell No Allowance Previously Recorded Recognized in Net Realized Investment Gains Losses	300
Increase in credit allowance for the period	49
Recognized other than temporary impairments		100	$ 1,800
U.S. Treasury securities and obligations of U.S. government corporations and agencies
Debt Securities, Available-for-sale [Line Items]
Total at end of period	264,531	195,176
Allowance for Expected Credit Loss	0
Gross Unrealized Gains	1,164	1,237
Gross Unrealized Losses	(2)	(210)
Total at end of period	265,693	196,203
Maturities, Amortized Cost [Abstract]
Total at end of period	264,531	195,176
Maturities, Fair Value [Abstract]
Total at end of period	265,693	196,203
Continuous Unrealized Loss Portion, Unrealized Loses [Abstract]
Less than 12 months	2,690	57,301
12 months or greater	0	5,806
Total	2,690	63,107
Less than 12 months	(2)	(200)
12 months or greater	0	(10)
Total	(2)	(210)
Obligations of U.S. states and political subdivisions
Debt Securities, Available-for-sale [Line Items]
Total at end of period	2,083,568	1,555,394
Allowance for Expected Credit Loss	0
Gross Unrealized Gains	166,557	99,328
Gross Unrealized Losses	(256)	(857)
Total at end of period	2,249,869	1,653,865
Maturities, Amortized Cost [Abstract]
Total at end of period	2,083,568	1,555,394
Maturities, Fair Value [Abstract]
Total at end of period	2,249,869	1,653,865
Continuous Unrealized Loss Portion, Unrealized Loses [Abstract]
Less than 12 months	31,416	74,859
12 months or greater	0	6,957
Total	31,416	81,816
Less than 12 months	(256)	(847)
12 months or greater	0	(10)
Total	(256)	(857)
Corporate debt securities
Debt Securities, Available-for-sale [Line Items]
Total at end of period	2,690,860	2,711,910
Allowance for Expected Credit Loss	0
Gross Unrealized Gains	155,156	76,220
Gross Unrealized Losses	(1,728)	(3,008)
Total at end of period	2,844,288	2,785,122
Maturities, Amortized Cost [Abstract]
Total at end of period	2,690,860	2,711,910
Maturities, Fair Value [Abstract]
Total at end of period	2,844,288	2,785,122
Continuous Unrealized Loss Portion, Unrealized Loses [Abstract]
Less than 12 months	44,968	221,357
12 months or greater	0	43,505
Total	44,968	264,862
Less than 12 months	(1,728)	(2,847)
12 months or greater	0	(161)
Total	(1,728)	(3,008)
ABS
Debt Securities, Available-for-sale [Line Items]
Total at end of period	203,807	227,376
Allowance for Expected Credit Loss	(49)
Gross Unrealized Gains	2,946	2,466
Gross Unrealized Losses	(18)	(178)
Total at end of period	206,686	229,664
Maturities, Amortized Cost [Abstract]
Debt securities without single maturity date	203,807
Total at end of period	203,807	227,376
Maturities, Fair Value [Abstract]
Debt securities without single maturity date	206,686
Total at end of period	206,686	229,664
Continuous Unrealized Loss Portion, Unrealized Loses [Abstract]
Less than 12 months	14,929	21,542
12 months or greater	0	3,851
Total	14,929	25,393
Less than 12 months	(18)	(118)
12 months or greater	0	(60)
Total	(18)	(178)
RMBS
Debt Securities, Available-for-sale [Line Items]
Total at end of period	425,532	271,384
Allowance for Expected Credit Loss	0
Gross Unrealized Gains	6,472	429
Gross Unrealized Losses	(838)	(3,227)
Total at end of period	431,166	268,586
Maturities, Amortized Cost [Abstract]
Debt securities without single maturity date	425,532
Total at end of period	425,532	271,384
Maturities, Fair Value [Abstract]
Debt securities without single maturity date	431,166
Total at end of period	431,166	268,586
Continuous Unrealized Loss Portion, Unrealized Loses [Abstract]
Less than 12 months	98,409	105,443
12 months or greater	3,566	110,452
Total	101,975	215,895
Less than 12 months	(773)	(461)
12 months or greater	(65)	(2,766)
Total	(838)	(3,227)
CMBS
Debt Securities, Available-for-sale [Line Items]
Total at end of period	312,572	274,234
Allowance for Expected Credit Loss	0
Gross Unrealized Gains	16,055	5,531
Gross Unrealized Losses	(1,125)	(779)
Total at end of period	327,502	278,986
Maturities, Amortized Cost [Abstract]
Debt securities without single maturity date	312,572
Total at end of period	312,572	274,234
Maturities, Fair Value [Abstract]
Debt securities without single maturity date	327,502
Total at end of period	327,502	278,986
Continuous Unrealized Loss Portion, Unrealized Loses [Abstract]
Less than 12 months	13,212	62,388
12 months or greater	2,799	11,852
Total	16,011	74,240
Less than 12 months	(789)	(728)
12 months or greater	(336)	(51)
Total	(1,125)	(779)
CLOs
Debt Securities, Available-for-sale [Line Items]
Total at end of period	310,616	327,076
Allowance for Expected Credit Loss	0
Gross Unrealized Gains	566	33
Gross Unrealized Losses	(692)	(1,643)
Total at end of period	310,490	325,466
Maturities, Amortized Cost [Abstract]
Debt securities without single maturity date	310,616
Total at end of period	310,616	327,076
Maturities, Fair Value [Abstract]
Debt securities without single maturity date	310,490
Total at end of period	310,490	325,466
Continuous Unrealized Loss Portion, Unrealized Loses [Abstract]
Less than 12 months	95,287	81,444
12 months or greater	73,904	196,988
Total	169,191	278,432
Less than 12 months	(261)	(225)
12 months or greater	(431)	(1,418)
Total	(692)	(1,643)
Debt securities issued by foreign sovereign governments
Debt Securities, Available-for-sale [Line Items]
Total at end of period	4,485
Allowance for Expected Credit Loss	0
Gross Unrealized Gains	224
Gross Unrealized Losses	0
Total at end of period	4,709
Maturities, Amortized Cost [Abstract]
Total at end of period	4,485
Maturities, Fair Value [Abstract]
Total at end of period	4,709
Other investments
Debt Securities, Available-for-sale [Line Items]
Total at end of period	21,193
Allowance for Expected Credit Loss	0
Gross Unrealized Gains	0
Gross Unrealized Losses	0
Total at end of period	21,193
Maturities, Amortized Cost [Abstract]
Total at end of period	21,193
Maturities, Fair Value [Abstract]
Total at end of period	21,193
Equity securities
Equity Securities, FV-NI, Gain (Loss) [Abstract]
Equity securities, cost	17,522	17,188
Gross gains	695	154
Gross losses	(2)	(14)
Equity securities, at fair value (cost, 2020 - $17,522; 2019 - $17,188)	18,215	17,328
Proceeds from sale of equity securities	25,700	1,700
Gross realized gains on equity securities	1,800	1,600
Gross realized losses on equity securities	400	0
Recognized net gains (losses) on equity securities still held	$ 600	$ 200

Investments, Investment Income

Investments, Investment Income By Category (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Investment income									$ 159,608	$ 171,347	$ 145,006
Investment expenses									(5,212)	(4,302)	(3,675)
Net investment income	$ 36,118	$ 37,252	$ 39,679	$ 41,347	$ 41,322	$ 42,715	$ 42,423	$ 40,585	154,396	167,045	141,331
Fixed income securities
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Investment income									157,065	165,523	140,539
Equity securities
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Investment income									620	406	228
Cash equivalents
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Investment income									1,648	4,444	3,423
Other investments
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Investment income									$ 275	$ 974	$ 816

Investments, Gain (Loss) on Inv

Investments, Gain (Loss) on Investments (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Gain (Loss) on Securities [Line Items]
Change in unrealized gains (losses)	$ 169,135	$ 220,139	$ (81,834)
Available-for-Sale Securities | Fixed income
Gain (Loss) on Securities [Line Items]
Change in unrealized gains (losses)	$ 169,135	$ 220,139	$ (81,834)

Fair Value Measurements (Detail

Fair Value Measurements (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed income, available-for-sale	$ 6,661,596	$ 5,737,892
Equity securities, at fair value (cost, 2020 - $17,522; 2019 - $17,188)	18,215	17,328
Cash Equivalents	288,941	164,693
Real estate acquired	1,092	7,252
Total assets	6,969,844	5,927,165
Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash Equivalents	275,668	164,693
Real estate acquired	0	0
Total assets	443,222	216,261
Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash Equivalents	13,273	0
Real estate acquired	0	0
Total assets	6,525,530	5,703,652
Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash Equivalents	0	0
Real estate acquired	1,092	7,252
Total assets	1,092	7,252
Total fixed income securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed income, available-for-sale	6,661,596	5,737,892
Total fixed income securities | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed income, available-for-sale	149,339	34,240
Total fixed income securities | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed income, available-for-sale	6,512,257	5,703,652
Total fixed income securities | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed income, available-for-sale	0	0
U.S. Treasury securities and obligations of U.S. government corporations and agencies
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed income, available-for-sale	265,693	196,203
U.S. Treasury securities and obligations of U.S. government corporations and agencies | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed income, available-for-sale	149,339	34,240
U.S. Treasury securities and obligations of U.S. government corporations and agencies | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed income, available-for-sale	116,354	161,963
U.S. Treasury securities and obligations of U.S. government corporations and agencies | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed income, available-for-sale	0	0
Obligations of U.S. states and political subdivisions
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed income, available-for-sale	2,249,869	1,653,865
Obligations of U.S. states and political subdivisions | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed income, available-for-sale	0	0
Obligations of U.S. states and political subdivisions | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed income, available-for-sale	2,249,869	1,653,865
Obligations of U.S. states and political subdivisions | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed income, available-for-sale	0	0
Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed income, available-for-sale	2,844,288	2,785,122
Corporate debt securities | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed income, available-for-sale	0	0
Corporate debt securities | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed income, available-for-sale	2,844,288	2,785,122
Corporate debt securities | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed income, available-for-sale	0	0
ABS
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed income, available-for-sale	206,686	229,664
ABS | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed income, available-for-sale	0	0
ABS | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed income, available-for-sale	206,686	229,664
ABS | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed income, available-for-sale	0	0
RMBS
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed income, available-for-sale	431,166	268,586
RMBS | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed income, available-for-sale	0	0
RMBS | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed income, available-for-sale	431,166	268,586
RMBS | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed income, available-for-sale	0	0
CMBS
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed income, available-for-sale	327,502	278,986
CMBS | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed income, available-for-sale	0	0
CMBS | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed income, available-for-sale	327,502	278,986
CMBS | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed income, available-for-sale	0	0
CLOs
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed income, available-for-sale	310,490	325,466
CLOs | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed income, available-for-sale	0	0
CLOs | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed income, available-for-sale	310,490	325,466
CLOs | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed income, available-for-sale	0	0
Debt securities issued by foreign sovereign governments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed income, available-for-sale	4,709
Debt securities issued by foreign sovereign governments | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed income, available-for-sale	0
Debt securities issued by foreign sovereign governments | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed income, available-for-sale	4,709
Debt securities issued by foreign sovereign governments | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed income, available-for-sale	0
Other investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed income, available-for-sale	21,193
Other investments | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed income, available-for-sale	0
Other investments | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed income, available-for-sale	21,193
Other investments | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed income, available-for-sale	0
Equity securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities, at fair value (cost, 2020 - $17,522; 2019 - $17,188)	18,215	17,328
Equity securities | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities, at fair value (cost, 2020 - $17,522; 2019 - $17,188)	18,215	17,328
Equity securities | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities, at fair value (cost, 2020 - $17,522; 2019 - $17,188)	0	0
Equity securities | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities, at fair value (cost, 2020 - $17,522; 2019 - $17,188)	$ 0	$ 0

Fair Value Measurements - Unobs

Fair Value Measurements - Unobservable Input Reconciliation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Total fixed income securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at beginning of period	$ 0	$ 13
Total realized/unrealized gains (losses) [Abstract]
Included in earnings and reported as losses incurred, net	0	0
Acquisitions	0	0
Sales	0	(13)
Balance at end of period	0	0
Real Estate Acquired
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at beginning of period	7,252	14,535
Total realized/unrealized gains (losses) [Abstract]
Included in earnings and reported as losses incurred, net	660	(476)
Acquisitions	8,609	24,204
Sales	(15,429)	(31,011)
Balance at end of period	$ 1,092	$ 7,252

Fair Value Measurements - Asset

Fair Value Measurements - Assets and Liabilities Not Measured at Fair Value (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Aug. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Senior Notes | 5.75% Senior Notes due 2023
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Stated interest rate (in hundredths)	5.75%
Senior Notes | 5.25% Senior Notes due 2028
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Stated interest rate (in hundredths)	5.25%	5.25%
9% Convertible Junior Subordinated Debentures due 2063
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Stated interest rate (in hundredths)	9.00%		9.00%	9.00%
Carrying Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other invested assets	$ 3,100		$ 3,100
FHLB Advance	155,000		155,000
9% Debentures	208,814		256,872
Total financial liabilities	1,243,193		832,739
Carrying Value | Senior Notes | 5.75% Senior Notes due 2023
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Senior Notes	240,597		420,867
Carrying Value | Senior Notes | 5.25% Senior Notes due 2028
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Senior Notes	638,782		0
Fair Value | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other invested assets	3,100		3,100
FHLB Advance	160,865		156,422
9% Debentures	273,569		346,289
Total financial liabilities	1,392,635		974,538
Fair Value | Significant Other Observable Inputs (Level 2) | Senior Notes | 5.75% Senior Notes due 2023
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Senior Notes	261,752		471,827
Fair Value | Significant Other Observable Inputs (Level 2) | Senior Notes | 5.25% Senior Notes due 2028
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Senior Notes	$ 696,449		$ 0

Debt Summary of Obligations (De

Debt Summary of Obligations (Details) - USD ($) $ in Millions	Dec. 31, 2020	Aug. 31, 2020	Dec. 31, 2019
Debt Instrument [Line Items]
Long-term debt, carrying value	$ 1,243.2		$ 832.8
Federal Home Loan Bank Advances (FHLB)
Debt Instrument [Line Items]
Long-term debt, carrying value	$ 155		155
Stated interest rate (in hundredths)	1.91%
Senior Notes | 5.75% Senior Notes due 2023
Debt Instrument [Line Items]
Long-term debt, carrying value	$ 240.6		420.9
Stated interest rate (in hundredths)	5.75%
Debt instrument, face amount	$ 242.3
Senior Notes | 5.25% Senior Notes due 2028
Debt Instrument [Line Items]
Long-term debt, carrying value	$ 638.8		0
Stated interest rate (in hundredths)	5.25%	5.25%
Debt instrument, face amount	$ 650	$ 650
Convertible Junior Subordinated Debentures, at 9% per annum, Due 2063
Debt Instrument [Line Items]
Long-term debt, carrying value	$ 208.8		$ 256.9
Stated interest rate (in hundredths)	9.00%

Debt (Details)

Debt (Details)	1 Months Ended	3 Months Ended				12 Months Ended
	Aug. 31, 2020USD ($)	Dec. 31, 2020USD ($)Period$ / sharesshares	Sep. 30, 2020USD ($)	Jun. 30, 2020USD ($)	Mar. 31, 2020USD ($)	Dec. 31, 2020USD ($)Period$ / sharesshares	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)
Debt Instrument [Line Items]
Early repayment of debt						$ 179,735,000	$ 0	$ 0
Loss on debt extinguishment		$ 0	$ 26,736,000	$ 0	$ 0	26,736,000	0	0
FHLBC advances		$ 155,000,000				$ 155,000,000
FHLBC fixed interest rate		1.91%				1.91%
Collateral pledged to principal balance of FHLB advance (as a percent)						102.00%
Interest paid						$ 54,300,000	$ 50,800,000	$ 51,300,000
Senior Notes | 5.75% Senior Notes due 2023
Debt Instrument [Line Items]
Stated interest rate (in hundredths)		5.75%				5.75%
Debt instrument, face amount		$ 242,300,000				$ 242,300,000
Extinguishment of debt						182,700,000
Early repayment of debt						197,800,000
Loss on debt extinguishment						$ 16,500,000
Redemption price, percentage (in hundredths)						100.00%
Ownership percentage threshold for declaration of due and payable						25.00%
Senior Notes | 5.25% Senior Notes due 2028
Debt Instrument [Line Items]
Stated interest rate (in hundredths)	5.25%	5.25%				5.25%
Debt instrument, face amount	$ 650,000,000	$ 650,000,000				$ 650,000,000
Proceeds from issuance of debt	640,300,000
Debt issuance costs	$ 2,000,000
Ownership percentage threshold for declaration of due and payable						25.00%
Senior Notes | 5.25% Senior Notes due 2028 | Debt Instrument, Redemption, Period One
Debt Instrument [Line Items]
Redemption price, percentage (in hundredths)						102.625%
Senior Notes | 5.25% Senior Notes due 2028 | Debt Instrument, Redemption, Period Two
Debt Instrument [Line Items]
Redemption price, percentage (in hundredths)						102.625%
Senior Notes | 5.25% Senior Notes due 2028 | Debt Instrument, Redemption, Period Two | US Treasury (UST) Interest Rate
Debt Instrument [Line Items]
Basis spread on variable rate						0.50%
Senior Notes | 5.25% Senior Notes due 2028 | Debt Instrument, Redemption, Period Three
Debt Instrument [Line Items]
Redemption price, percentage (in hundredths)						102.625%
Senior Notes | 5.25% Senior Notes due 2028 | Debt Instrument, Redemption, Period Four
Debt Instrument [Line Items]
Redemption price, percentage (in hundredths)						101.313%
Senior Notes | 5.25% Senior Notes due 2028 | Debt Instrument, Redemption, Period Five
Debt Instrument [Line Items]
Redemption price, percentage (in hundredths)						100.00%
Convertible Junior Subordinated Debentures, at 9% per annum, Due 2063
Debt Instrument [Line Items]
Stated interest rate (in hundredths)		9.00%				9.00%
Extinguishment of debt						$ 48,100,000
Loss on debt extinguishment						10,200,000
Repayments of long-term debt						61,600,000
Reacquisition of convertible junior subordinated debentures-equity component						$ 2,700,000
Reduction in potentially dilutive shares due to debt extinguishment | shares						3,600,000
Redemption price, percentage (in hundredths)						100.00%
Conversion price (in dollars per share) | $ / shares		$ 13.23				$ 13.23
Conversion rate (in shares per $1,000 note) | shares						75.5932
Principal amount of notes used in determining conversion rate		$ 1,000				$ 1,000
Period preceding election to convert						5 days
Closing sale price of our common stock for consideration of redemption (in dollars per share) | $ / shares		$ 17.20				$ 17.20
Minimum number of trading days						20 days
Maximum number of trading days						30 days
Minimum number of consecutive interest periods for which interest payments may be deferred | Period		1				1
Maximum period for which interest payments may be deferred without giving rise to an event of default						10 years
Period in which reasonable commercial efforts must begin, maximum						1 day
Anniversary payment release of the start of the interest deferral to the Alternative Payment Mechanism in lieu of the final maturity of the debentures						10 years
Net proceeds cap (in hundredths)		2.00%				2.00%
Maximum number of shares of common stock issuable under the Alternative Payment Mechanism (in shares) | shares		10,000,000				10,000,000
Maximum percentage of aggregate principal amount of the debentures (in hundredths)		25.00%				25.00%

Loss Reserves - Narrative (Deta

Loss Reserves - Narrative (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2020USD ($)loanPayment	Dec. 31, 2019USD ($)loan	Dec. 31, 2018USD ($)loan
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Loss reserves	$ 325,203	$ (118,685)	$ (311,616)
Minimum number of payments past due to be in default | Payment	2
Premium refund liability, expected claim payments	$ 30,000	$ 30,000
Percentage of prior year default inventory resolved (in hundredths)		69.00%	73.00%
Other items removed from inventory | loan	0	639	1,578
Losses for unpaid claims and adjustment expense	$ 109,923	$ 235,551	$ 327,743
Pool insurance notice inventory (in number of loans) | loan	680	653	859
Settlements for commutations of coverage, pools of nonperforming loans
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Losses for unpaid claims and adjustment expense		$ 30,000	$ 50,000
Settlements for claims paying practices
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Losses for unpaid claims and adjustment expense		$ 23,500
$1,000 Increase/Decrease In Average Severity Reserve Factor
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Loss reserves	$ 16,000
One Percentage Point Increase/Decrease In Average Claim Rate Reserve Factor
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Loss reserves	$ 34,000

Loss Reserves - Reconciliation

Loss Reserves - Reconciliation of Changes in Loss Reserves (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Loss Reserve [Roll Forward]
Reserve at beginning of year	$ 555,334	$ 674,019	$ 985,635
Less reinsurance recoverable	95,042	21,641	33,328	$ 48,474
Net reserve at beginning of year	785,495	533,693	640,691	$ 937,161
Losses incurred: [Abstract]
Current year	345,170	189,581	203,928
Prior years	19,604	(71,006)	(167,366)
Total losses incurred	364,774	118,575	36,562
Losses paid [Abstract]
Current year	3,069	4,018	7,298
Prior years	109,923	235,551	327,743
Reinsurance terminations	(20)	(13,996)	(2,009)
Total losses paid	112,972	225,573	333,032
Reserve at end of year	$ 880,537	$ 555,334	$ 674,019

Loss Reserves - Prior Year Loss

Loss Reserves - Prior Year Loss Reserves (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Liability for Claims and Claims Adjustment Expense [Line Items]
Prior years	$ 19,604	$ (71,006)	$ (167,366)
(Decrease) in estimated claim rate on primary delinquencies
Liability for Claims and Claims Adjustment Expense [Line Items]
Prior years	(2,536)	(111,848)	(212,738)
Increase (decrease)in estimated severity on primary delinquencies
Liability for Claims and Claims Adjustment Expense [Line Items]
Prior years	13,535	(434)	28,528
Change in estimates related to pool reserves, LAE reserves, reinsurance and other
Liability for Claims and Claims Adjustment Expense [Line Items]
Prior years	$ 8,605	$ 41,276	$ 16,844

Loss Reserves - Default Invento

Loss Reserves - Default Inventory Reconciliation (Details) - loan	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Primary Default Inventory [Roll Forward]
Beginning delinquent inventory	30,028	32,898	46,556
New Notices	106,099	54,239	54,448
Cures	(76,107)	(52,035)	(60,511)
Paid claims	(2,245)	(4,267)	(5,750)
Rescissions and denials	(65)	(168)	(267)
Other items removed from inventory	0	(639)	(1,578)
Ending delinquent inventory	57,710	30,028	32,898

Loss Reserves - Aging of Primar

Loss Reserves - Aging of Primary Default Inventory (Details) - loan	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Aging of the Primary Default Inventory [Abstract]
3 months or less	11,542	9,447	9,829
4 - 11 months	34,620	9,664	9,655
12 months or more	11,548	10,917	13,414
Total primary default inventory	57,710	30,028	32,898	46,556
3 months or less (in hundredths)	20.00%	32.00%	30.00%
4 - 11 months (in hundredths)	60.00%	32.00%	29.00%
12 months or more (in hundredths)	20.00%	36.00%	41.00%
Total primary default inventory (in hundredths)	100.00%	100.00%	100.00%
Primary claims received inventory included in ending default inventory	159	538	809
Percent of inventory in default for more than 36 consecutive months	31.00%	36.00%	38.00%

Reinsurance - Summary of Reinsu

Reinsurance - Summary of Reinsurance Agreements (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Premiums Earned, Net [Abstract]
Premiums earned, direct									$ 1,199,824	$ 1,155,240	$ 1,084,748
Premiums earned, assumed									10,848	5,085	1,805
Premiums earned, ceded									(188,729)	(129,337)	(111,391)
Net premiums earned	$ 261,367	$ 256,113	$ 243,562	$ 260,901	$ 266,267	$ 267,857	$ 247,102	$ 249,762	1,021,943	1,030,988	975,162
Policyholder Benefits and Claims Incurred, Net [Abstract]
Losses incurred, direct									442,194	130,100	43,060
Losses incurred, assumed									555	(125)	331
Losses incurred, ceded									(77,975)	(11,400)	(6,829)
Net losses incurred	$ 45,758	$ 40,686	$ 217,374	$ 60,956	$ 23,690	$ 33,985	$ 21,836	$ 39,064	$ 364,774	$ 118,575	$ 36,562

Reinsurance - Narrative (Detail

Reinsurance - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended		12 Months Ended
	Jun. 30, 2019	Dec. 31, 2019	Jun. 30, 2019	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Feb. 28, 2021	Dec. 31, 2017
Effects of Reinsurance [Line Items]
Reinsurance recoverable on loss reserves		$ 21,641				$ 95,042	$ 21,641	$ 33,328		$ 48,474
Ceded premiums earned						$ 188,729	129,337	111,391
Quota Share Reinsurance Agreements
Effects of Reinsurance [Line Items]
Ceding commission, percentage						20.00%
Annual loss ratio cap						300.00%
Lifetime loss ratio cap						200.00%
Threshold for private mortgage insurer eligibility requirements for termination election						90.00%
Reinsurance recoverable on loss reserves		$ 21,600				$ 95,000	21,600
Quota Share Reinsurance Agreement, 2021 | Forecast
Effects of Reinsurance [Line Items]
Quota Share %				15.00%	12.50%
Annual loss ratio					57.50%
Credit Union QSR
Effects of Reinsurance [Line Items]
Quota Share %						65.00%
Annual loss ratio						50.00%
Threshold for private mortgage insurer eligibility requirements for termination election						80.00%
2015 QSR
Effects of Reinsurance [Line Items]
Quota Share %		15.00%	30.00%			15.00%
Annual loss ratio						68.00%
Contingent termination fee	$ 6,800
Excess of Loss Reinsurance Agreements, Home Re Entities
Effects of Reinsurance [Line Items]
Amortization period excess of loss reinsurance coverage						10 years
Ceded premiums earned						$ 20,800	$ 17,600	$ 2,800
Excess of Loss Reinsurance Agreements, Home Re Entities | Financial Asset Equal To Or Greater Than 60 Days Past Due
Effects of Reinsurance [Line Items]
Percent of delinquent reinsured loans to total reinsured loans						4.00%
Home Re special purpose insurers
Effects of Reinsurance [Line Items]
Debt issued to cover insurance, term						10 years
Percent of total trust assets invested in cash or direct U.S. federal government obligations						99.50%
Home Re special purpose insurers | Subsequent Event
Effects of Reinsurance [Line Items]
Remaining Excess of Loss Reinsurance Coverage									$ 398,800

Reinsurance - Quota Share Agree

Reinsurance - Quota Share Agreement Terms (Details)	6 Months Ended		12 Months Ended
	Dec. 31, 2019	Jun. 30, 2019	Dec. 31, 2020
2015 QSR
Effects of Reinsurance [Line Items]
Quota Share %	15.00%	30.00%	15.00%
Annual Loss Ratio to Exhaust Profit Commission			68.00%
2017 QSR
Effects of Reinsurance [Line Items]
Quota Share %			30.00%
Annual Loss Ratio to Exhaust Profit Commission			60.00%
2018 QSR
Effects of Reinsurance [Line Items]
Quota Share %			30.00%
Annual Loss Ratio to Exhaust Profit Commission			62.00%
2019 QSR
Effects of Reinsurance [Line Items]
Quota Share %			30.00%
Annual Loss Ratio to Exhaust Profit Commission			62.00%
Cede rate, option 1			25.00%
Cede rate, option 2			20.00%
2020 QSR - 1 Year
Effects of Reinsurance [Line Items]
Quota Share %			12.50%
Annual Loss Ratio to Exhaust Profit Commission			62.00%
Cede rate, option 1			10.50%
Cede rate, option 2			8.00%
2020 QSR - 2 Year
Effects of Reinsurance [Line Items]
Quota Share %			17.50%
Annual Loss Ratio to Exhaust Profit Commission			62.00%
Cede rate, option 1			14.50%
Cede rate, option 2			12.00%
Credit Union QSR
Effects of Reinsurance [Line Items]
Quota Share %			65.00%
Annual Loss Ratio to Exhaust Profit Commission			50.00%

Reinsurance - Quota Share Reins

Reinsurance - Quota Share Reinsurance (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Effects of Reinsurance [Line Items]
Ceded losses incurred	$ 77,975	$ 11,400	$ 6,829
Quota Share Reinsurance Agreements
Effects of Reinsurance [Line Items]
Ceded premiums written and earned, net of profit commission	167,930	111,550	108,337
Ceded losses incurred	78,012	11,395	6,543
Ceding commisisons	48,077	48,793	51,201
Profit commission	$ 72,452	$ 139,179	$ 147,667

Reinsurance - Excess of Loss Re

Reinsurance - Excess of Loss Reinsurance (Details) - USD ($) $ in Thousands	May 01, 2019	Oct. 01, 2018	Oct. 31, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Home Re 2020-1
Effects of Reinsurance [Line Items]
Remaining First Layer Retention			$ 275,283	$ 275,283	$ 0	$ 0
Remaining Excess of Loss Reinsurance Coverage			$ 412,917	412,917	0	0
Home Re 2019-1
Effects of Reinsurance [Line Items]
Remaining First Layer Retention	$ 185,730			184,514	185,636	0
Remaining Excess of Loss Reinsurance Coverage	$ 315,739			208,146	271,021	0
Home Re 2018-1
Effects of Reinsurance [Line Items]
Remaining First Layer Retention		$ 168,691		166,005	167,779	168,691
Remaining Excess of Loss Reinsurance Coverage		$ 318,636		$ 218,343	$ 260,957	$ 318,636

Reinsurance - Home Re Entities

Reinsurance - Home Re Entities Total Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Home Re 2018-1
Effects of Reinsurance [Line Items]
Total VIE Assets	$ 218,343	$ 269,451	$ 318,636
Home Re 2019-1
Effects of Reinsurance [Line Items]
Total VIE Assets	208,146	$ 283,150
Home Re 2020-1
Effects of Reinsurance [Line Items]
Total VIE Assets	$ 412,917

Other Comprehensive Income (L_3

Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Components of Other Comprehensive Income (Loss) [Abstract]
Net unrealized investment gains (losses) on securities without an allowance for credit losses									$ 169,135	$ 220,139	$ (81,834)
Income tax (expense) benefit									(35,519)	(46,229)	17,188
Net of taxes									133,616	173,910	(64,646)
Net changes in benefit plan assets and obligations									13,288	29,129	(19,958)
Income tax (expense) benefit									(2,791)	(6,117)	4,191
Net of taxes									10,497	23,012	(15,767)
Total other comprehensive income (loss)									182,423	249,268	(101,792)
Total income tax expense, net									(38,310)	(52,346)	21,379
Other comprehensive income (loss), net of tax									144,113	196,922	(80,413)
Amounts Reclassified From Accumulated Other Comprehensive Income [Abstract]
Total reclassifications									559,263	847,977	844,150
Income tax (expense) benefit	$ (38,782)	$ (33,518)	$ (2,436)	$ (38,434)	$ (45,599)	$ (46,186)	$ (43,433)	$ (38,996)	(113,170)	(174,214)	(174,053)
Net income	151,430	$ 130,811	$ 14,047	149,805	177,110	$ 176,934	$ 167,778	151,941	446,093	673,763	670,097
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance, beginning of year				4,309,234				3,581,891	4,309,234	3,581,891
Balance, end of year	4,698,986				4,309,234				4,698,986	4,309,234	3,581,891
Accumulated other comprehensive income (loss)
Components of Other Comprehensive Income (Loss) [Abstract]
Other comprehensive income (loss), net of tax									144,113	196,922	(80,413)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance, beginning of year				72,708				(124,214)	72,708	(124,214)	(43,783)
Cumulative effect of adopting the accounting standard update for financial instruments											(18)
Other comprehensive income (loss) before reclassifications									142,448	193,400	(87,736)
Less: Amounts reclassified from AOCL									(1,665)	(3,522)	(7,323)
Balance, end of year	216,821				72,708				216,821	72,708	(124,214)
Net unrealized gains and losses on available-for-sale securities
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance, beginning of year				138,521				(35,389)	138,521	(35,389)	29,275
Cumulative effect of adopting the accounting standard update for financial instruments											(18)
Other comprehensive income (loss) before reclassifications									144,566	176,784	(70,206)
Less: Amounts reclassified from AOCL									10,950	2,874	(5,560)
Balance, end of year	272,137				138,521				272,137	138,521	(35,389)
Net benefit plan assets and obligations recognized in shareholders' equity
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance, beginning of year				$ (65,813)				$ (88,825)	(65,813)	(88,825)	(73,058)
Cumulative effect of adopting the accounting standard update for financial instruments											0
Other comprehensive income (loss) before reclassifications									(2,118)	16,616	(17,530)
Less: Amounts reclassified from AOCL									(12,615)	(6,396)	(1,763)
Balance, end of year	$ (55,316)				$ (65,813)				(55,316)	(65,813)	(88,825)
Reclassification from Accumulated Other Comprehensive Income
Amounts Reclassified From Accumulated Other Comprehensive Income [Abstract]
Total reclassifications									(2,106)	(4,460)	(9,269)
Income tax (expense) benefit									441	938	1,946
Net income									(1,665)	(3,522)	(7,323)
Reclassification from Accumulated Other Comprehensive Income | Net unrealized gains and losses on available-for-sale securities
Amounts Reclassified From Accumulated Other Comprehensive Income [Abstract]
Total reclassifications									13,862	3,637	(7,037)
Income tax (expense) benefit									(2,912)	(763)	1,477
Net income									10,950	2,874	(5,560)
Reclassification from Accumulated Other Comprehensive Income | Net benefit plan assets and obligations recognized in shareholders' equity
Amounts Reclassified From Accumulated Other Comprehensive Income [Abstract]
Total reclassifications									(15,968)	(8,097)	(2,232)
Income tax (expense) benefit									3,353	1,701	469
Net income									$ (12,615)	$ (6,396)	$ (1,763)

Benefit Plans - Components of N

Benefit Plans - Components of Net Periodic Benefit Costs (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Pension and Supplemental Executive Retirement Plans
Defined Benefit Plan Disclosure [Line Items]
Company Service Cost	$ 7,342	$ 8,345	$ 10,530
Interest Cost	13,036	15,705	15,095
Expected Return on Assets	(22,139)	(19,466)	(22,250)
Other Adjustments	0	0	0
Subtotal	(1,761)	4,584	3,375
Amortization of Net Transition Obligation/(Asset)	0	0	0
Amortization of Net Prior Service Cost/(Credit)	(247)	(281)	(351)
Amortization of Net Losses/(Gains)	6,578	8,412	6,937
Total Amortization	6,331	8,131	6,586
Net Periodic Benefit Cost	4,570	12,715	9,961
Cost of settlements	10,369	1,933	0
Total Expense for Year	14,939	14,648	9,961
Other Postretirement Benefit Plan
Defined Benefit Plan Disclosure [Line Items]
Company Service Cost	1,263	1,345	1,160
Interest Cost	832	1,130	834
Expected Return on Assets	(7,407)	(5,785)	(6,359)
Other Adjustments	0	0	0
Subtotal	(5,312)	(3,310)	(4,365)
Amortization of Net Transition Obligation/(Asset)	0	0	0
Amortization of Net Prior Service Cost/(Credit)	51	(34)	(4,104)
Amortization of Net Losses/(Gains)	(783)	0	(250)
Total Amortization	(732)	(34)	(4,354)
Net Periodic Benefit Cost	(6,044)	(3,344)	(8,719)
Cost of settlements	0	0	0
Total Expense for Year	$ (6,044)	$ (3,344)	$ (8,719)

Benefit Plans - Development of

Benefit Plans - Development of Funded Status (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Pension and Supplemental Executive Retirement Plans
Defined Benefit Plan Disclosure [Line Items]
Accumulated Benefit Obligation	$ 423,305	$ 412,939
Projected Benefit Obligation	(423,713)	(413,350)	$ (376,153)
Plan Assets at Fair Value	411,245	402,691	359,719
Funded Status - Overfunded/(Underfunded)	(12,468)	(10,659)
Other Postretirement Benefit Plan
Defined Benefit Plan Disclosure [Line Items]
Accumulated Benefit Obligation	28,714	27,496
Projected Benefit Obligation	(28,714)	(27,496)	(28,085)
Plan Assets at Fair Value	119,024	99,590	$ 77,762
Funded Status - Overfunded/(Underfunded)	$ 90,310	$ 72,094

Benefit Plans - Accumulated Oth

Benefit Plans - Accumulated Other Comprehensive Income (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Pension and Supplemental Executive Retirement Plans
Defined Benefit Plan Disclosure [Line Items]
Net Actuarial (Gain)/Loss	$ 98,899	$ 99,826
Net Prior Service Cost/(Credit)	(988)	(1,237)
Net Transition Obligation/(Asset)	0	0
Total at Year End	97,911	98,589	$ 108,808
Other Postretirement Benefit Plan
Defined Benefit Plan Disclosure [Line Items]
Net Actuarial (Gain)/Loss	(30,565)	(18,005)
Net Prior Service Cost/(Credit)	2,673	2,724
Net Transition Obligation/(Asset)	0	0
Total at Year End	$ (27,892)	$ (15,281)	$ 3,629

Benefit Plans - Change in Proje

Benefit Plans - Change in Project Benefit/Accumulated Benefit Obligations (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Pension and Supplemental Executive Retirement Plans
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit Obligation at Beginning of Year	$ 413,350	$ 376,153
Company Service Cost	7,342	8,345	$ 10,530
Interest Cost	13,036	15,705	15,095
Plan Participants' Contributions	0	0
Net Actuarial (Gain)/Loss	36,196	47,113
Benefit Payments from the Fund	(40,260)	(30,829)
Benefit Payments Directly by Company	(5,953)	(3,105)
Plan Amendments	2	(5)
Other Adjustment	0	0
Settlement (Gain)Loss	0	(27)
Benefit Obligation at End of Year	423,713	413,350	376,153
Other Postretirement Benefit Plan
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit Obligation at Beginning of Year	27,496	28,085
Company Service Cost	1,263	1,345	1,160
Interest Cost	832	1,130	834
Plan Participants' Contributions	425	382
Net Actuarial (Gain)/Loss	660	(2,075)
Benefit Payments from the Fund	(1,975)	(826)
Benefit Payments Directly by Company	0	0
Plan Amendments	0	0
Other Adjustment	13	(545)
Settlement (Gain)Loss	0	0
Benefit Obligation at End of Year	$ 28,714	$ 27,496	$ 28,085

Benefit Plans - Change in Plan

Benefit Plans - Change in Plan Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Pension and Supplemental Executive Retirement Plans
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair Value of Plan Assets at Beginning of Year	$ 402,691	$ 359,719
Company Contributions	12,453	10,205
Plan Participants' Contributions	0	0
Benefit Payments from the Fund	(40,260)	(30,829)
Benefit Payments paid directly by Company	(5,953)	(3,105)
Actual Return on Assets	42,314	70,262
Other Adjustments	0	(3,561)
Fair Value of Plan Assets at End of Year	411,245	402,691
Other Postretirement Benefit Plan
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair Value of Plan Assets at Beginning of Year	99,590	77,762
Company Contributions	0	0
Plan Participants' Contributions	425	382
Benefit Payments from the Fund	(1,975)	(826)
Benefit Payments paid directly by Company	0	0
Actual Return on Assets	21,409	22,654
Other Adjustments	(425)	(382)
Fair Value of Plan Assets at End of Year	$ 119,024	$ 99,590

Benefit Plans - Change in Accum

Benefit Plans - Change in Accumulated Other Comprehensive Income (AOCI) and Expected Amortization (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Pension and Supplemental Executive Retirement Plans
AOCI Attributable to Parent, Net of Tax [Roll Forward]
AOCI in Prior Year	$ 98,589	$ 108,808
Recognized during year - Prior Service (Cost)/Credit	247	281
Recognized during year - Net Actuarial (Losses)/Gains	(16,948)	(8,412)
Occurring during year - Prior Service Cost	2	(5)
Occurring during year - Net Actuarial Losses/(Gains)	16,021	(150)
Occuring during year - Net Settlement Losses/(Gains)	0	(1,933)
AOCI in Current Year	97,911	98,589
Other Postretirement Benefit Plan
AOCI Attributable to Parent, Net of Tax [Roll Forward]
AOCI in Prior Year	(15,281)	3,629
Recognized during year - Prior Service (Cost)/Credit	(51)	34
Recognized during year - Net Actuarial (Losses)/Gains	782	0
Occurring during year - Prior Service Cost	0	0
Occurring during year - Net Actuarial Losses/(Gains)	(13,342)	(18,944)
Occuring during year - Net Settlement Losses/(Gains)	0	0
AOCI in Current Year	$ (27,892)	$ (15,281)

Benefit Plans - Actuarial Assum

Benefit Plans - Actuarial Assumptions and Year-End Asset Allocations (Details)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Pension and Supplemental Executive Retirement Plans
Defined Benefit Plan Disclosure [Line Items]
Discount Rate Used to Determine Benefit Obligation(in hundredths)	2.75%	3.45%
Rate of Compensation Increase Used to Determine Benefit Obligation (in hundredths)	3.00%	3.00%
Cash Balance Interest Crediting Rate Used to Determine Benefit Obligation (in hundredths)	2.50%	3.20%
Discount Rate Used to Determine Net Periodic Benefit Cost (in hundredths)	3.30%	4.40%
Expected Long-term Return on Plan Assets Used to Determine Net Periodic Benefit Cost (in hundredths)	5.75%	5.75%
Rate of Compensation Increase Used to Determine Net Periodic Benefit Cost (in hundredths)	3.00%	3.00%
Other Postretirement Benefit Plan
Defined Benefit Plan Disclosure [Line Items]
Discount Rate Used to Determine Benefit Obligation(in hundredths)	2.35%	3.20%
Discount Rate Used to Determine Net Periodic Benefit Cost (in hundredths)	3.20%	4.25%
Expected Long-term Return on Plan Assets Used to Determine Net Periodic Benefit Cost (in hundredths)	7.50%	7.50%
Health Care Cost Trend Rate Assumed for Next Year (in hundredths)	6.00%	6.00%
Rate to Which the Cost Trend Rate is Assumed to Decline (Ultimate Trend Rate) (in hundredths)	5.00%	5.00%
Weighted-average asset allocations of plans (in hundredths)	100.00%	100.00%
Other Postretirement Benefit Plan | Equity securities
Defined Benefit Plan Disclosure [Line Items]
Weighted-average asset allocations of plans (in hundredths)	100.00%	100.00%
Other Postretirement Benefit Plan | Total fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Weighted-average asset allocations of plans (in hundredths)	0.00%	0.00%
Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Weighted-average asset allocations of plans (in hundredths)	100.00%	100.00%
Pension Plan | Equity securities
Defined Benefit Plan Disclosure [Line Items]
Weighted-average asset allocations of plans (in hundredths)	21.00%	23.00%
Pension Plan | Total fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Weighted-average asset allocations of plans (in hundredths)	79.00%	77.00%

Benefit Plans - Fair Value of P

Benefit Plans - Fair Value of Plan Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Plan Assets at Fair Value	$ 411,245	$ 402,691
Pension Plan | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Plan Assets at Fair Value	31,249	39,491
Pension Plan | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Plan Assets at Fair Value	379,996	363,200
Pension Plan | Domestic Mutual Funds
Defined Benefit Plan Disclosure [Line Items]
Plan Assets at Fair Value	4,842	7,325
Pension Plan | Domestic Mutual Funds | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Plan Assets at Fair Value	4,842	7,325
Pension Plan | Domestic Mutual Funds | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Plan Assets at Fair Value	0	0
Pension Plan | Corporate Bonds
Defined Benefit Plan Disclosure [Line Items]
Plan Assets at Fair Value	231,190	203,684
Pension Plan | Corporate Bonds | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Plan Assets at Fair Value	0	0
Pension Plan | Corporate Bonds | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Plan Assets at Fair Value	231,190	203,684
Pension Plan | U.S. Government Securities
Defined Benefit Plan Disclosure [Line Items]
Plan Assets at Fair Value	26,407	34,677
Pension Plan | U.S. Government Securities | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Plan Assets at Fair Value	26,407	32,166
Pension Plan | U.S. Government Securities | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Plan Assets at Fair Value	0	2,511
Pension Plan | Municipal Bonds
Defined Benefit Plan Disclosure [Line Items]
Plan Assets at Fair Value	32,891	38,998
Pension Plan | Municipal Bonds | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Plan Assets at Fair Value	0	0
Pension Plan | Municipal Bonds | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Plan Assets at Fair Value	32,891	38,998
Pension Plan | Foreign Bonds
Defined Benefit Plan Disclosure [Line Items]
Plan Assets at Fair Value	33,368	34,024
Pension Plan | Foreign Bonds | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Plan Assets at Fair Value	0	0
Pension Plan | Foreign Bonds | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Plan Assets at Fair Value	33,368	34,024
Pension Plan | Pooled Equity Accounts
Defined Benefit Plan Disclosure [Line Items]
Plan Assets at Fair Value	82,547	83,983
Pension Plan | Pooled Equity Accounts | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Plan Assets at Fair Value	0	0
Pension Plan | Pooled Equity Accounts | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Plan Assets at Fair Value	82,547	83,983
Other Postretirement Benefit Plan
Defined Benefit Plan Disclosure [Line Items]
Plan Assets at Fair Value	119,024	99,590	$ 77,762
Other Postretirement Benefit Plan | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Plan Assets at Fair Value	119,024	99,590
Other Postretirement Benefit Plan | Domestic Mutual Funds | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Plan Assets at Fair Value	91,454	77,640
Other Postretirement Benefit Plan | International Mutual Funds | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Plan Assets at Fair Value	$ 27,570	$ 21,950

Benefit Plans - Additional Disc

Benefit Plans - Additional Disclosures (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Other Postretirement Benefit Plan
Defined Benefit Plan Disclosure [Line Items]
Company Contributions	$ 0	$ 0
Current plus 1	0
Actual Benefit Payments for the Year Ending: Current	1,975
Expected Benefit Payments for the Year Ending: Current plus 1	1,765
Expected Benefit Payments for the Year Ending: Current plus 2	1,995
Expected Benefit Payments for the Year Ending: Current plus 3	2,157
Expected Benefit Payments for the Year Ending: Current plus 4	2,241
Expected Benefit Payments for the Year Ending: Current plus 5	2,357
Expected Benefit Payments for the Year Ending: Current plus 6 - 10	$ 10,916
Other Postretirement Benefit Plan | Equity securities | Minimum
Defined Benefit Plan Disclosure [Line Items]
Target asset allocations (in hundredths)	70.00%
Other Postretirement Benefit Plan | Equity securities | Maximum
Defined Benefit Plan Disclosure [Line Items]
Target asset allocations (in hundredths)	100.00%
Other Postretirement Benefit Plan | Real Estate | Minimum
Defined Benefit Plan Disclosure [Line Items]
Target asset allocations (in hundredths)	0.00%
Other Postretirement Benefit Plan | Real Estate | Maximum
Defined Benefit Plan Disclosure [Line Items]
Target asset allocations (in hundredths)	15.00%
Other Postretirement Benefit Plan | Commodities | Minimum
Defined Benefit Plan Disclosure [Line Items]
Target asset allocations (in hundredths)	0.00%
Other Postretirement Benefit Plan | Commodities | Maximum
Defined Benefit Plan Disclosure [Line Items]
Target asset allocations (in hundredths)	10.00%
Other Postretirement Benefit Plan | Fixed Income/Cash | Minimum
Defined Benefit Plan Disclosure [Line Items]
Target asset allocations (in hundredths)	0.00%
Other Postretirement Benefit Plan | Fixed Income/Cash | Maximum
Defined Benefit Plan Disclosure [Line Items]
Target asset allocations (in hundredths)	10.00%
Pension and Supplemental Executive Retirement Plans
Defined Benefit Plan Disclosure [Line Items]
Company Contributions	$ 12,453	$ 10,205
Current plus 1	6,200
Actual Benefit Payments for the Year Ending: Current	46,213
Expected Benefit Payments for the Year Ending: Current plus 1	30,082
Expected Benefit Payments for the Year Ending: Current plus 2	29,929
Expected Benefit Payments for the Year Ending: Current plus 3	30,076
Expected Benefit Payments for the Year Ending: Current plus 4	29,567
Expected Benefit Payments for the Year Ending: Current plus 5	28,852
Expected Benefit Payments for the Year Ending: Current plus 6 - 10	$ 135,830

Benefit Plans - Narrative (Deta

Benefit Plans - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Defined Benefit Plan Disclosure [Line Items]
Minimum percentages of gain loss consider for amortization (in hundredths)	10.00%
Minimum value of outstanding noncallable bonds used in hypothetical cash flow bond matching exercise	$ 50
Future earnings period used in determining the expected average rate of earnings	20 years
Discretionary profit sharing contribution as a percentage of participant's eligible compensation (in hundredths)	5.00%
Matching contribution rate on employees' contributions (in hundredths)	100.00%
Employee contributions subject to employer match (in hundredths)	4.00%
Profit sharing and 401(k) savings plan expenses	$ 8	$ 7.4	$ 6
Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Lump sum pension plan benefit payments	$ 27.5	$ 18.5
Pension Plan | Equity securities | Maximum
Defined Benefit Plan Disclosure [Line Items]
Target asset allocations (in hundredths)	40.00%
Other Postretirement Benefit Plan
Defined Benefit Plan Disclosure [Line Items]
Minimum percentage return should exceed growth in consumer price index annually (in hundredths)	5.75%
Maximum investment in international mutual funds (in hundredths)	30.00%
Percent of international mutual funds equity allocation in emerging markets (in hundredths)	3.00%
Percent of international mutual funds equity allocation in companies primarily based in Europe and the Pacific Basin (in hundredths)	20.00%
Other Postretirement Benefit Plan | Equity securities | Maximum
Defined Benefit Plan Disclosure [Line Items]
Target asset allocations (in hundredths)	100.00%

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Net deferred tax assets and liabilities [Abstract]
Total deferred tax assets	$ 38,443				$ 63,533				$ 38,443	$ 63,533
Total deferred tax liabilities	(98,485)				(57,791)				(98,485)	(57,791)
Net deferred tax (liability) asset					5,742					5,742
Deferred Tax Liabilities, Net	(60,042)								(60,042)
Components of net deferred tax asset [Abstract]
Unearned premium reserves	23,163				30,487				23,163	30,487
Benefit plans	(13,977)				(10,790)				(13,977)	(10,790)
Loss reserves	3,542				2,175				3,542	2,175
Unrealized appreciation in investments	(72,341)				(36,822)				(72,341)	(36,822)
Mortgage investments	0				8,359				0	8,359
Deferred compensation	6,776				9,270				6,776	9,270
AMT credit carryforward	0				8,303				0	8,303
Other, net	(7,205)				(5,240)				(7,205)	(5,240)
Components of provisions for (benefit from) income taxes [Abstract]
Current Federal									85,574	162,911	$ (16,272)
Deferred Federal									28,244	11,860	185,598
Other									(648)	(557)	4,727
Provision for income taxes	38,782	$ 33,518	$ 2,436	$ 38,434	45,599	$ 46,186	$ 43,433	$ 38,996	113,170	174,214	174,053
Income taxes paid									79,600	$ 158,300	$ 12,200
Amount of tax and loss bonds held	271,000								$ 271,000
Reconciliation of effective income tax rate [Abstract]
Federal statutory income tax rate (in hundredths)									21.00%	21.00%	21.00%
Additional income tax provision related to IRS litigation (in hundredths)									0.00%	0.00%	(0.30%)
Tax exempt municipal bond interest (in hundredths)									(0.90%)	(0.60%)	(0.70%)
Other, net (in hundredths)									0.10%	0.10%	0.60%
Effective income tax provision rate (in hundredths)									20.20%	20.50%	20.60%
Unrecognized tax benefits	$ 0				$ 0				$ 0	$ 0
IRS
Reconciliation of effective income tax rate [Abstract]
Tax and interest payments for IRS settlement											$ 14,800
State tax authorities
Reconciliation of effective income tax rate [Abstract]
Tax and interest payments for IRS settlement											$ 36,800

Shareholders' Equity (Details)

Shareholders' Equity (Details) - USD ($) $ / shares in Units, $ in Thousands, shares in Millions	Jan. 26, 2021	Mar. 31, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Class of Stock [Line Items]
Shares repurchased during period (in shares)		9.6		8.7	16
Shares repurchased, weighted average price per share (in dollars per share)		$ 12.47		$ 13.13	$ 10.95
Remaining authorized repurchase amount			$ 291,000	$ 111,000	$ 25,000
Common stock, dividends, per share, cash paid (in dollars per share)			$ 0.06
Cash dividends			$ 82,600
Subsequent Event
Class of Stock [Line Items]
Common stock, dividends, per share, declared (in dollars per share)	$ 0.06

Statutory Information - Narrati

Statutory Information - Narrative (Details)	3 Months Ended	12 Months Ended
	Sep. 30, 2020USD ($)	Dec. 31, 2020USD ($)jurisdiction	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)
Statutory capital requirements [Abstract]
Percentage of premiums earned required to be maintained as contingency loss reserves (in hundredths)		50.00%
Period that contingency loss reserves must be held (in years)		10 years
Percentage of net premiums earned that incurred losses must exceed to enable early withdrawals from contingency loss reserves (in hundredths)		35.00%
Number of jurisdictions with risk-to-capital requirements | jurisdiction		16
Maximum permitted risk-to-capital ratio commonly applied		25 to 1
Risk to capital ratio of combined insurance operations at end of period		9.1 to 1
Risk-to-capital ratio on combined insurance operations		9.1
Statutory net income (loss)		$ 65,201,000	$ 305,857,000	$ 375,484,000
Statutory policyholders' surplus		$ 1,339,509,000	1,619,069,000	1,683,058,000
Maximum
Statutory capital requirements [Abstract]
Risk to capital ratio		25
Mortgage Guaranty Insurance Corporation
Statutory capital requirements [Abstract]
Contingency reserve withdrawal		$ 30,400,000
Risk to capital ratio at end of period		9.2 to 1
Risk to capital ratio		9.2
Amount of policyholders position above or below required MPP		$ 3,200,000,000
Amount of required MPP		1,700,000,000
Dividends paid to the parent company		$ 390,000,000	$ 280,000,000	$ 220,000,000
Dividend to parent, distribution of interest in 9% Debentures	$ 139,500,000
Percentage of statutory policyholders surplus used to determine maximum allowable dividends		10.00%
Adjusted statutory net income measurement period		3 years
Adjusted statutory net income dividend payment measurement period		2 years
Reduction in statutory net income due to increase in contingency reserve		$ 559,000,000
Statutory net income (loss)		(643,000,000)
Statutory policyholders' surplus		1,336,000,000
Realized statutory loss on merger of affiliate, eliminated in consolidation		$ 692,000,000

Statutory Information - Statuto

Statutory Information - Statutory financial information of insurance subsidiaries (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Statutory Capital [Abstract]
Statutory net income (loss)	$ 65,201	$ 305,857	$ 375,484
Statutory policyholders' surplus	1,339,509	1,619,069	1,683,058
Contingency reserve	$ 3,585,864	$ 3,021,055	$ 2,442,996

Statutory Information - Surplus

Statutory Information - Surplus contributions and dividends of insurance subsidiaries (Details) - Mortgage Guaranty Insurance Corporation - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Sep. 30, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Related Party Transaction [Line Items]
Dividends paid to the parent company		$ 390,000	$ 280,000	$ 220,000
Dividend to parent, distribution of interest in 9% Debentures	$ 139,500

Share-based Compensation Plan_2

Share-based Compensation Plans (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation cost	$ 13.8	$ 18.9	$ 20.9
Income tax benefit from compensation cost	$ 1.7	$ 2.7	$ 3
Shares [Roll Forward]
Restricted stock outstanding at end of period (in shares)	4,100,000
Restricted Stock/Restricted Stock Units
Weighted average grant date fair market value [Abstract]
Restricted stock outstanding at end of period (in dollars per share)	$ 12.81
Granted (in dollars per share)	13.62	$ 11.92	$ 15.69
Vested (in dollars per share)	11.67
Forfeited (in dollars per share)	13.24
Restricted stock outstanding at end of period (in dollars per share)	$ 13.57	$ 12.81
Shares [Roll Forward]
Restricted stock outstanding at beginning of period (in shares)	4,150,394
Granted (in shares)	1,672,060
Vested (in shares)	(1,564,843)
Forfeited (in shares)	(118,368)
Restricted stock outstanding at end of period (in shares)	4,139,243	4,150,394
Additional disclosures [Abstract]
Total fair value of restricted stock vested	$ 20.4	$ 13.7	$ 19.1
Unrecognized compensation cost	$ 25.8
RSUs subject to performance conditions
Shares [Roll Forward]
Restricted stock outstanding at end of period (in shares)	3,100,000
Additional disclosures [Abstract]
Unrecognized compensation cost	$ 19.8
RSUs subject only to service conditions
Shares [Roll Forward]
Restricted stock outstanding at end of period (in shares)	1,000,000
Additional disclosures [Abstract]
Unrecognized compensation cost	$ 5.9
Weighted-average period for recognition of compensation cost	1 year 8 months 12 days
2020 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Maximum number of shares can be awarded under the plan (in shares)	11,000,000
Shares available for future grants (in shares)	11,100,000
Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period	1 year
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period	3 years

Leases (Details)

Leases (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Leases [Abstract]
Remaining term of operating leases (in years)	4 years
Lessee, Operating Lease, Liability, Payment, Due [Abstract]
2021	$ 836
2022	687
2023	311
2024	81
2025 and thereafter	0
Total	1,915
Operating lease, expense	$ 1,900	$ 2,100
Total rental expense under operating leases			$ 1,900

Litigation and Contingencies (D

Litigation and Contingencies (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Commitments and Contingencies Disclosure [Abstract]
Average paid claim reduction due to curtailments (in hundredths)	3.60%	5.00%
Maximum exposure to loss	$ 40

Unaudited Quarterly Financial_3

Unaudited Quarterly Financial Data (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Quarterly Financial Information Disclosure [Abstract]
Net premiums earned	$ 261,367	$ 256,113	$ 243,562	$ 260,901	$ 266,267	$ 267,857	$ 247,102	$ 249,762	$ 1,021,943	$ 1,030,988	$ 975,162
Investment income, net of expenses	36,118	37,252	39,679	41,347	41,322	42,715	42,423	40,585	154,396	167,045	141,331
Realized gains (losses)	2,901	2,259	6,701	1,891	1,320	4,205	307	(526)	13,752	5,306	(1,353)
Other revenue	1,895	380	4,026	2,754	2,717	3,606	2,485	1,830	9,055	10,638	8,708
Loss incurred, net	45,758	40,686	217,374	60,956	23,690	33,985	21,836	39,064	364,774	118,575	36,562
Underwriting and other expenses, net	66,311	64,253	60,111	57,698	65,227	61,278	59,270	61,650	248,373	247,425
Loss on debt extinguishment	0	26,736	0	0					26,736	0	0
Provision for income tax	38,782	33,518	2,436	38,434	45,599	46,186	43,433	38,996	113,170	174,214	174,053
Net income	$ 151,430	$ 130,811	$ 14,047	$ 149,805	$ 177,110	$ 176,934	$ 167,778	$ 151,941	$ 446,093	$ 673,763	$ 670,097
Earnings per Share [Abstract]
Basic (in dollars per share)	$ 0.45	$ 0.39	$ 0.04	$ 0.44	$ 0.51	$ 0.50	$ 0.47	$ 0.43	$ 1.31	$ 1.91	$ 1.83
Diluted (in dollars per share)	$ 0.44	$ 0.38	$ 0.04	$ 0.42	$ 0.49	$ 0.49	$ 0.46	$ 0.42	$ 1.29	$ 1.85	$ 1.78

SCHEDULE I - SUMMARY OF INVES_2

SCHEDULE I - SUMMARY OF INVESTMENTS - OTHER THAN INVESTMENTS IN RELATED PARTIES (Details) $ in Thousands	Dec. 31, 2020USD ($)
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Amortized Cost	$ 6,334,686
Fair Value	6,679,811
Amount at which shown in the balance sheet	6,679,811
Fixed income
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Amortized Cost	6,317,164
Fair Value	6,661,596
Amount at which shown in the balance sheet	6,661,596
Fixed income | U.S. Treasury securities and obligations of U.S. government corporations and agencies
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Amortized Cost	264,531
Fair Value	265,693
Amount at which shown in the balance sheet	265,693
Fixed income | Obligations of U.S. states and political subdivisions
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Amortized Cost	2,083,568
Fair Value	2,249,869
Amount at which shown in the balance sheet	2,249,869
Fixed income | Debt securities issued by foreign sovereign governments
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Amortized Cost	4,485
Fair Value	4,709
Amount at which shown in the balance sheet	4,709
Fixed income | Public utilities
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Amortized Cost	303,285
Fair Value	303,011
Amount at which shown in the balance sheet	303,011
Fixed income | ABS
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Amortized Cost	203,807
Fair Value	206,686
Amount at which shown in the balance sheet	206,686
Fixed income | Collateralized loan obligations
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Amortized Cost	310,616
Fair Value	310,490
Amount at which shown in the balance sheet	310,490
Fixed income | Mortgage-backed
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Amortized Cost	738,104
Fair Value	758,668
Amount at which shown in the balance sheet	758,668
Fixed income | All other corporate bonds
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Amortized Cost	2,387,575
Fair Value	2,541,277
Amount at which shown in the balance sheet	2,541,277
Fixed income | Other investments
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Amortized Cost	21,193
Fair Value	21,193
Amount at which shown in the balance sheet	21,193
Equity Securities
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Amortized Cost	17,522
Fair Value	18,215
Amount at which shown in the balance sheet	18,215
Equity Securities | Industrial, miscellaneous and all other
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Amortized Cost	17,522
Fair Value	18,215
Amount at which shown in the balance sheet	$ 18,215

SCHEDULE II - CONDENSED FINAN_2

SCHEDULE II - CONDENSED FINANCIAL INFORMATION OF REGISTRANT (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Assets
Fixed income, available-for-sale, at fair value (amortized cost, 2020 – $773,881; 2019 – $287,489)	$ 6,661,596				$ 5,737,892				$ 6,661,596	$ 5,737,892
Cash and cash equivalents	287,953				161,847				287,953	161,847
Accrued investment income	49,997				49,705				49,997	49,705
Other assets	104,478				105,089				104,478	105,089
Total assets	7,354,526				6,229,571				7,354,526	6,229,571
Liabilities:
Senior notes	879,379				420,867				879,379	420,867
Convertible junior subordinated debentures	208,814				256,872				208,814	256,872
Other liabilities	244,711				151,962				244,711	151,962
Total liabilities	2,655,540				1,920,337				2,655,540	1,920,337
Shareholders’ equity:
Common stock (one dollar par value, shares authorized 1,000,000; shares issued 2020 - 371,353; 2019 - 371,353; outstanding 2020 - 338,573; 2019 - 347,308)	371,353				371,353				371,353	371,353
Paid-in capital	1,862,042				1,869,719				1,862,042	1,869,719
Treasury stock (shares at cost 2020 – 32,779; 2019 – 24,045)	(393,326)				(283,196)				(393,326)	(283,196)
Accumulated other comprehensive income, net of tax	216,821				72,708				216,821	72,708
Retained earnings	2,642,096				2,278,650				2,642,096	2,278,650
Total shareholders' equity	4,698,986				4,309,234				4,698,986	4,309,234	$ 3,581,891
Total liabilities and shareholders' equity	7,354,526				6,229,571				7,354,526	6,229,571
Parenthetical information [Abstract]
Fixed income, amortized cost	$ 6,317,164				$ 5,562,550				$ 6,317,164	$ 5,562,550
Common stock, par value (in dollars per share)	$ 1				$ 1				$ 1	$ 1
Common stock, shares authorized (in shares)	1,000,000,000				1,000,000,000				1,000,000,000	1,000,000,000
Common stock, shares issued (in shares)	371,353,000				371,353,000				371,353,000	371,353,000
Common stock, shares outstanding (in shares)	338,573,000				347,308,000				338,573,000	347,308,000
Treasury stock, shares at cost (in shares)	32,779,000				24,045,000				32,779,000	24,045,000
Revenues:
Investment income, net of expenses	$ 36,118	$ 37,252	$ 39,679	$ 41,347	$ 41,322	$ 42,715	$ 42,423	$ 40,585	$ 154,396	$ 167,045	141,331
Realized gains (losses)	2,901	2,259	6,701	1,891	1,320	4,205	307	(526)	13,752	5,306	(1,353)
Total revenues									1,199,146	1,213,977	1,123,848
Expenses:
Interest expense									59,595	52,656	52,993
Loss on debt extinguishment	0	26,736	0	0					26,736	0	0
Total losses and expenses									639,883	366,000	279,698
Income before tax									559,263	847,977	844,150
Provision for income taxes	38,782	33,518	2,436	38,434	45,599	46,186	43,433	38,996	113,170	174,214	174,053
Net income	151,430	130,811	14,047	149,805	177,110	176,934	167,778	151,941	446,093	673,763	670,097
Other comprehensive income (loss), net of tax									144,113	196,922	(80,413)
Comprehensive income									590,206	870,685	589,684
Cash flows from operating activities:
Net income	151,430	130,811	14,047	149,805	177,110	$ 176,934	$ 167,778	151,941	446,093	673,763	670,097
Adjustments to reconcile net income to net cash provided by operating activities:
Deferred Federal									28,244	11,860	185,598
Loss on debt extinguishment	0	$ 26,736	$ 0	0					26,736	0	0
Change in certain assets and liabilities:
Accrued investment income									(292)	(1,704)	(1,941)
Net cash provided by operating activities									732,309	609,532	544,517
Cash flows from investing activities:
Purchases of investments									(2,636,972)	(1,394,126)	(1,459,473)
Proceeds from sales of investments									836,851	229,796	370,449
Net cash used in investing activities									(772,506)	(422,108)	(317,780)
Cash flows from financing activities:
Proceeds from issuance of senior notes									640,250	0	0
Purchase of senior notes									(179,735)	0	0
Payment of original issue discount - senior notes									(2,969)	0	0
Purchase of convertible junior subordinated debentures									(36,392)	0	0
Payment of original issue discount- convertible junior subordinated debentures									(15,049)	0	0
Cash portion of loss on debt extinguishment									(25,266)	0	0
Repurchase of common stock									(119,997)	(125,766)	(163,419)
Dividends paid									(82,061)	(41,914)	0
Payment of debt issuance costs									(2,020)	0	0
Payment of withholding taxes related to share-based compensation net share settlement									(8,940)	(5,726)	(8,131)
Net cash provided by (used in) financing activities									167,821	(173,406)	(171,550)
Net increase in cash and cash equivalents and restricted cash and cash equivalents									127,624	14,018	55,187
Cash and cash equivalents and restricted cash and cash equivalents at beginning of year				169,056				155,038	169,056	155,038	99,851
Cash and cash equivalents and restricted cash and cash equivalents at end of year	296,680				169,056				296,680	169,056	155,038
Parent Company
Assets
Fixed income, available-for-sale, at fair value (amortized cost, 2020 – $773,881; 2019 – $287,489)	773,995				288,362				773,995	288,362
Cash and cash equivalents	73,000				36,621				73,000	36,621
Investment in subsidiaries, at equity in net assets	4,740,074				4,611,356				4,740,074	4,611,356
Accounts receivable - affiliates	1,450				2,129				1,450	2,129
Income taxes -current and deferred	219,059				196,978				219,059	196,978
Accrued investment income	3,760				2,498				3,760	2,498
Other assets	0				81				0	81
Total assets	5,811,338				5,138,025				5,811,338	5,138,025
Liabilities:
Senior notes	879,379				420,867				879,379	420,867
Convertible junior subordinated debentures	208,814				389,522				208,814	389,522
Accrued interest	23,004				17,928				23,004	17,928
Other liabilities	1,155				474				1,155	474
Total liabilities	1,112,352				828,791				1,112,352	828,791
Shareholders’ equity:
Common stock (one dollar par value, shares authorized 1,000,000; shares issued 2020 - 371,353; 2019 - 371,353; outstanding 2020 - 338,573; 2019 - 347,308)	371,353				371,353				371,353	371,353
Paid-in capital	1,862,042				1,869,719				1,862,042	1,869,719
Treasury stock (shares at cost 2020 – 32,779; 2019 – 24,045)	(393,326)				(283,196)				(393,326)	(283,196)
Accumulated other comprehensive income, net of tax	216,821				72,708				216,821	72,708
Retained earnings	2,642,096				2,278,650				2,642,096	2,278,650
Total shareholders' equity	4,698,986				4,309,234				4,698,986	4,309,234
Total liabilities and shareholders' equity	5,811,338				5,138,025				5,811,338	5,138,025
Parenthetical information [Abstract]
Fixed income, amortized cost	$ 773,881				$ 287,489				$ 773,881	$ 287,489
Common stock, par value (in dollars per share)	$ 1				$ 1				$ 1	$ 1
Common stock, shares authorized (in shares)	1,000,000,000				1,000,000,000				1,000,000,000	1,000,000,000
Common stock, shares issued (in shares)	371,353,000				371,353,000				371,353,000	371,353,000
Common stock, shares outstanding (in shares)	338,573,000				347,308,000				338,573,000	347,308,000
Treasury stock, shares at cost (in shares)	32,779,000				24,045,000				32,779,000	24,045,000
Revenues:
Investment income, net of expenses									$ 7,090	$ 7,695	4,685
Realized gains (losses)									1,454	(311)	(532)
Total revenues									8,544	7,384	4,153
Expenses:
Operating expenses									719	793	637
Interest expense									65,472	61,593	61,930
Loss on debt extinguishment									35,033	0	0
Total losses and expenses									101,224	62,386	62,567
Income before tax									(92,680)	(55,002)	(58,414)
Provision for income taxes									(18,431)	(12,263)	(13,517)
Equity in net income of subsidiaries									520,342	716,502	714,994
Net income									446,093	673,763	670,097
Other comprehensive income (loss), net of tax									144,113	196,922	(80,413)
Comprehensive income									590,206	870,685	589,684
Cash flows from operating activities:
Net income									446,093	673,763	670,097
Adjustments to reconcile net income to net cash provided by operating activities:
Equity in net income of subsidiaries									(520,342)	(716,502)	(714,994)
Dividends received from subsidiaries									221,024	154,413	199,692
Deferred Federal									(18,252)	(10,416)	(11,756)
Loss on debt extinguishment									35,033	0	0
Other									19,088	21,104	24,303
Change in certain assets and liabilities:
Accounts receivable - affiliates									972	(735)	18
Income taxes receivable									0	1	17,859
Accrued investment income									(1,262)	(478)	112
Accrued interest									5,076	(2)	(4)
Net cash provided by operating activities									187,430	121,148	185,327
Cash flows from investing activities:
Purchases of investments									(1,131,060)	(117,663)	(83,003)
Proceeds from sales of investments									812,188	160,040	93,481
Net cash used in investing activities									(318,872)	42,377	10,478
Cash flows from financing activities:
Proceeds from issuance of senior notes									640,250	0	0
Purchase of senior notes									(179,735)	0	0
Payment of original issue discount - senior notes									(2,969)	0	0
Purchase of convertible junior subordinated debentures									(36,392)	0	0
Payment of original issue discount- convertible junior subordinated debentures									(15,049)	0	0
Cash portion of loss on debt extinguishment									(25,266)	0	0
Repurchase of common stock									(119,997)	(125,766)	(163,419)
Dividends paid									(82,061)	(41,914)	0
Payment of debt issuance costs									(2,020)	0	0
Payment of withholding taxes related to share-based compensation net share settlement									(8,940)	(5,726)	(8,131)
Net cash provided by (used in) financing activities									167,821	(173,406)	(171,550)
Net increase in cash and cash equivalents and restricted cash and cash equivalents									36,379	(9,881)	24,255
Cash and cash equivalents and restricted cash and cash equivalents at beginning of year				$ 36,621				$ 46,502	36,621	46,502	22,247
Cash and cash equivalents and restricted cash and cash equivalents at end of year	$ 73,000				$ 36,621				$ 73,000	$ 36,621	$ 46,502

SCHEDULE II - CONDENSED FINAN_3

SCHEDULE II - CONDENSED FINANCIAL INFORMATION OF REGISTRANT - SUPPLEMENTARY NOTES (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Insurance Subsidiaries
SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information [Line Items]
Adjusted statutory net income measurement period	3 years
Adjusted statutory net income dividend payment measurement period	2 years
Proceeds from contribution from parent	$ 0	$ 0	$ 0
Convertible Junior Subordinated Debentures, at 9% per annum, Due 2063
SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information [Line Items]
Stated interest rate (in hundredths)	9.00%
Mortgage Guaranty Insurance Corporation
SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information [Line Items]
Percentage of statutory policyholders surplus used to determine maximum allowable dividends	10.00%
Adjusted statutory net income measurement period	3 years
Adjusted statutory net income dividend payment measurement period	2 years
Dividends paid to the parent company	$ 390,000,000	280,000,000	$ 220,000,000
Mortgage Guaranty Insurance Corporation | Convertible Junior Subordinated Debentures, at 9% per annum, Due 2063
SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information [Line Items]
Investment in holding company debt		$ 132,700,000

SCHEDULE IV - REINSURANCE (Deta

SCHEDULE IV - REINSURANCE (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
SEC Schedule, 12-17, Insurance Companies, Reinsurance [Abstract]
Gross Amount	$ 1,199,824	$ 1,155,240	$ 1,084,748
Ceded to Other Companies	188,729	129,337	111,391
Assumed From Other Companies	10,848	5,085	1,805
Net Amount	$ 1,021,943	$ 1,030,988	$ 975,162
Percentage of Amount Assumed to Net	1.10%	0.50%	0.20%