W. R. Berkley (WRB) 10-Q 7 May 18 2018 Q1 Quarterly report Financial data

Document and Entity Informatio

Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2018	May 01, 2018
Document and Entity Information [Abstract]
Entity Registrant Name	BERKLEY W R CORP
Entity Central Index Key	11,544
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Document Type	10-Q
Document Period End Date	Mar. 31, 2018
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	Q1
Amendment Flag	false
Entity Common Stock, Shares Outstanding		121,669,098

Consolidated Balance Sheets Con

Consolidated Balance Sheets Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Investments:
Fixed maturity securities	$ 13,343,132	$ 13,551,250
Investment funds	1,161,127	1,155,677
Real estate	1,833,337	1,469,601
Arbitrage trading account	744,859	617,649
Equity securities	496,034	576,647
Loans receivable	75,902	79,684
Total investments	17,654,391	17,450,508
Cash and cash equivalents	956,603	950,471
Premiums and fees receivable	1,845,723	1,773,844
Due from reinsurers	1,868,667	1,783,200
Deferred policy acquisition costs	513,586	507,549
Prepaid reinsurance premiums	490,582	472,009
Trading account receivables from brokers and clearing organizations	26,667	189,280
Property, furniture and equipment	424,751	422,960
Goodwill	178,945	178,945
Accrued investment income	143,974	136,597
Other assets	483,943	434,554
Total assets	24,587,832	24,299,917
Liabilities:
Reserves for losses and loss expenses	11,784,895	11,670,408
Unearned premiums	3,404,003	3,290,180
Due to reinsurers	248,746	246,460
Trading account securities sold but not yet purchased	29,453	64,358
Federal and foreign income taxes	96,735	98,091
Other liabilities	852,255	981,987
Senior notes and other debt	1,782,139	1,769,052
Subordinated debentures	897,426	728,218
Total liabilities	19,095,652	18,848,754
Equity:
Preferred stock, par value $.10 per share: Authorized 5,000,000 shares; issued and outstanding - none	0	0
Common stock, par value $.20 per share: Authorized 500,000,000 shares, issued and outstanding, net of treasury shares, 121,769,109 and 121,193,599 shares, respectively	47,024	47,024
Additional paid-in capital	1,057,230	1,048,283
Retained earnings	7,322,201	6,956,882
Accumulated other comprehensive (loss) income	(258,982)	68,541
Treasury stock, at cost, 113,573,967 and 113,603,066 shares, respectively	2,715,697	2,709,386
Total stockholders’ equity	5,451,776	5,411,344
Noncontrolling interests	40,404	39,819
Total equity	5,492,180	5,451,163
Total liabilities and equity	$ 24,587,832	$ 24,299,917

Consolidated Balance Sheets Co3

Consolidated Balance Sheets Consolidated Balance Sheets (Parenthetical) - $ / shares	Mar. 31, 2018	Dec. 31, 2017
Statement of Financial Position [Abstract]
Preferred stock, par value (in dollar per share)	$ 0.1	$ 0.1
Preferred shares authorized	5,000,000	5,000,000
Preferred shares issued	0	0
Preferred shares outstanding	0	0
Common stock, par value (in dollar per share)	$ 0.2	$ 0.2
Common shares authorized	500,000,000	500,000,000
Common shares issued	121,543,951	121,514,852
Common shares outstanding	121,543,951	121,514,852
Treasury stock issued at cost	113,573,967	113,603,066

Consolidated Statements of Oper

Consolidated Statements of Operations (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
REVENUES:
Net premiums written	$ 1,665,338	$ 1,646,838
Change in net unearned premiums	(97,930)	(76,796)
Net premiums earned	1,567,408	1,570,042
Net investment income	174,518	148,858
Net realized and unrealized gains on investments	48,464	52,348
Revenues from non-insurance businesses	70,171	65,390
Insurance service fees	30,675	33,280
Other income	11	500
Total revenues	1,891,247	1,870,418
OPERATING COSTS AND EXPENSES:
Losses and loss expenses	963,219	979,603
Other operating costs and expenses	610,439	603,700
Expenses from non-insurance businesses	69,543	66,019
Interest expense	37,056	36,799
Total operating costs and expenses	1,680,257	1,686,121
Income before income taxes	210,990	184,297
Income tax expense	(43,417)	(59,623)
Net income before noncontrolling interests	167,573	124,674
Noncontrolling interests	(1,177)	(1,227)
Net income to common stockholders	$ 166,396	$ 123,447
NET INCOME PER SHARE:
Basic (in dollar per share)	$ 1.32	$ 1.01
Diluted (in dollar per share)	$ 1.30	$ 0.96

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Statement of Comprehensive Income [Abstract]
Net income before noncontrolling interests	$ 167,573	$ 124,674
Other comprehensive (loss) income:
Change in unrealized currency translation adjustments	12,799	22,735
Change in unrealized investment gains, net of taxes	(125,772)	(8,831)
Other comprehensive income (loss)	(112,973)	13,904
Comprehensive income	54,600	138,578
Noncontrolling interests	(1,188)	(1,208)
Comprehensive income to common stockholders	$ 53,412	$ 137,370

Consolidated Statements of Stoc

Consolidated Statements of Stockholders' Equity (Unaudited) - USD ($) $ in Thousands	Total	Common stock	Additional paid-in capital	Retained earnings	Accumulated Other Comprehensive Income (Loss)	Unrealized investment gain	Currency Translation Adjustments	Treasury stock	Noncontrolling interest
Beginning of period at Dec. 31, 2016		$ 47,024	$ 1,037,446	$ 6,595,987		$ 427,154	$ (371,586)	$ (2,688,817)	$ 33,926
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Restricted stock units issued			(667)
Restricted stock units expensed			10,810
Cumulative effect adjustment resulting from changes in accounting principles				0		0
Net income before noncontrolling interests	$ 124,674			123,447					1,227
Dividends				(15,759)
Unrealized losses on securities not other-than-temporarily impaired	(8,831)					(8,913)
Unrealized gains on other-than-temporarily impaired securities						101
Net change in period	22,735						22,735
Stock exercised/vested								644
Stock repurchased								0
(Distributions) contributions									3,801
Other comprehensive income (loss), net of tax	13,904				$ 13,904		22,735		(19)
End of period at Mar. 31, 2017			1,047,589	6,703,675	69,491	418,342	(348,851)	(2,688,173)	38,935
Beginning of period at Dec. 31, 2017	5,451,163	$ 47,024	1,048,283	6,956,882		375,421	(306,880)	(2,709,386)	39,819
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Restricted stock units issued			(487)
Restricted stock units expensed			9,434
Cumulative effect adjustment resulting from changes in accounting principles				215,939		(214,539)
Net income before noncontrolling interests	167,573			166,396					1,177
Dividends				(17,016)
Unrealized losses on securities not other-than-temporarily impaired	(125,772)					(125,796)
Unrealized gains on other-than-temporarily impaired securities						13
Net change in period	12,799						12,799
Stock exercised/vested								488
Stock repurchased								(6,799)
(Distributions) contributions									(603)
Other comprehensive income (loss), net of tax	(112,973)				(112,973)		12,799		11
End of period at Mar. 31, 2018	$ 5,492,180		$ 1,057,230	$ 7,322,201	$ (258,982)	$ 35,099	$ (294,081)	$ (2,715,697)	$ 40,404

Consolidated Statements of Cash

Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
CASH (USED IN) FROM OPERATING ACTIVITIES:
Net income to common stockholders	$ 166,396	$ 123,447
Adjustments to reconcile net income to net cash from operating activities:
Net realized and unrealized gains on investments	(48,464)	(52,348)
Depreciation and amortization	29,027	18,133
Noncontrolling interests	1,177	1,227
Investment funds	(40,354)	(26,649)
Stock incentive plans	9,434	10,780
Change in:
Arbitrage trading account	497	2,350
Premiums and fees receivable	(74,492)	(59,244)
Reinsurance accounts	(100,379)	67,205
Deferred policy acquisition costs	(6,851)	(6,126)
Income taxes	50,505	50,595
Reserves for losses and loss expenses	120,063	10,424
Unearned premiums	116,627	113,483
Other	(243,221)	(177,805)
Net cash (used in) from operating activities	(20,035)	75,472
CASH USED IN INVESTING ACTIVITIES:
Proceeds from sale of fixed maturity securities	2,004,008	719,969
Proceeds from sale of equity securities	152,949	51,854
Distributions from (contributions to) investment funds	33,695	(11,290)
Proceeds from maturities and prepayments of fixed maturity securities	97,911	888,423
Purchase of fixed maturity securities	(2,085,683)	(1,767,208)
Purchase of equity securities	(44,219)	(103)
Real estate purchased	(336,601)	(48,710)
Change in loans receivable	2,058	3,147
Net additions to property, furniture and equipment	(14,102)	(12,457)
Change in balances due to security brokers	58,500	(22,034)
Payment for business purchased net of cash acquired	0	(71,346)
Net cash used in investing activities	(131,484)	(269,755)
CASH FROM (USED IN) FINANCING ACTIVITIES:
Repayment of senior notes and other debt	(23)	(1,475)
Net proceeds from issuance of debt	181,792	0
Cash dividends to common stockholders	(17,016)	0
Purchase of common treasury shares	(6,799)	0
Other, net	(544)	(1,281)
Net cash from (used in) financing activities	157,410	(2,756)
Net impact on cash due to change in foreign exchange rates	241	10,147
Net change in cash and cash equivalents	6,132	(186,892)
Cash and cash equivalents at beginning of year	950,471	795,285
Cash and cash equivalents at end of period	$ 956,603	$ 608,393

General

General	3 Months Ended
	Mar. 31, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
General	General The unaudited consolidated financial statements, which include the accounts of W. R. Berkley Corporation and its subsidiaries (the “Company”) have been prepared on the basis of U.S. generally accepted accounting principles (“GAAP”) for interim financial information. Accordingly, they do not include all the information and notes required by GAAP for annual financial statements. The unaudited consolidated financial statements reflect all adjustments, consisting only of normal recurring items, which are necessary to present fairly the Company’s financial position and results of operations on a basis consistent with the prior audited consolidated financial statements. Operating results for interim periods are not necessarily indicative of the results that may be expected for the year. All significant intercompany accounts and transactions have been eliminated. The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosures of contingent assets and liabilities at the date of the financial statements and the revenues and expenses reflected during the reporting period. For further information related to a description of areas of judgment and estimates and other information necessary to understand the Company’s financial position and results of operations, refer to the audited consolidated financial statements and notes included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2017 . Reclassifications have been made in the 2017 financial statements as originally reported to conform to the presentation of the 2018 financial statements. The income tax provision has been computed based on the Company’s estimated annual effective tax rate. The effective tax rate for the quarter differs from the federal income tax rate of 21% principally because of tax-exempt investment income, as well as tax on income from foreign jurisdictions with different tax rates.

Per Share Data

Per Share Data	3 Months Ended
	Mar. 31, 2018
Earnings Per Share [Abstract]
Per Share Data	Per Share Data The Company presents both basic and diluted net income per share (“EPS”) amounts. Basic EPS is calculated by dividing net income by the weighted average number of common shares outstanding during the period (including 4,847,303 and 4,087,731 common shares held in a grantor trust as of March 31, 2018 and 2017, respectively). The common shares held in the grantor trust are for delivery upon settlement of vested but mandatorily deferred restricted stock units ("RSUs"). Shares held by the grantor trust do not affect diluted shares outstanding since the shares deliverable under vested RSUs were already included in diluted shares outstanding. Diluted EPS is based upon the weighted average number of basic and common equivalent shares outstanding during the period and is calculated using the treasury stock method for stock incentive plans. Common equivalent shares are excluded from the computation in periods in which they have an anti-dilutive effect. The weighted average number of common shares used in the computation of basic and diluted earnings per share was as follows: For the Three Months Ended March 31, (In thousands) 2018 2017 Basic 126,375 121,893 Diluted 128,125 128,453

Recent Accounting Pronouncement

Recent Accounting Pronouncements	3 Months Ended
	Mar. 31, 2018
Accounting Policies [Abstract]
Recent Accounting Pronouncements	Recent Accounting Pronouncements Recently adopted accounting pronouncements: In May 2014, the Financial Accounting Standards Board ("FASB") issued ASU 2014-09, Revenue from Customers. ASU 2014-09 clarifies the principles for recognizing revenue. While insurance contracts are not within the scope of this updated guidance, the Company’s insurance service fee revenue and non-insurance business revenue are subject to this updated guidance. The updated guidance requires an entity to recognize revenue as performance obligations are met, in order to reflect the transfer of promised goods or services to customers in an amount that reflects the consideration the entity is entitled to receive for those goods or services. The updated guidance, as amended by ASU 2015-14, was effective for public business entities for annual and interim reporting periods beginning after December 15, 2017. The Company adopted this guidance on January 1, 2018 on a prospective basis. The impact of applying this guidance prospectively was a cumulative effect adjustment that increased retained earnings, a component of stockholders' equity, by $1 million after-tax. In January 2016, the FASB issued ASU 2016-01, Financial Instruments. ASU 2016-01 amends the accounting guidance for financial instruments to require all equity investments with readily determinable fair values to be measured at fair value with changes in the fair value recognized in net income (other than those accounted for under equity method of accounting or those that result in consolidation of the investee). The updated guidance was effective for public business entities for annual reporting periods beginning after December 15, 2017 and interim periods within those years. The Company adopted this updated guidance on January 1, 2018 on a prospective basis. The impact of applying this guidance prospectively was a cumulative effect adjustment that increased retained earnings and decreased accumulated other comprehensive income ("AOCI") by offsetting amounts of $291 million , resulting in no net impact to total stockholders' equity. Following the adoption, the Company reported changes in fair value related to equity securities within net realized and unrealized gains on investments. In February 2018, the FASB issued ASU 2018-02, Reporting Comprehensive Income, which amends previous guidance to allow a reclassification to retained earnings for stranded tax effects resulting from the Tax Cuts and Jobs Act of 2017 (the “Tax Act”). The amount of the reclassification includes the effect of the change in the U.S. federal corporate income tax rate on the gross deferred tax amounts and related valuation allowances, if any, at the date of the enactment of the Tax Act related to items in AOCI. The updated guidance will be effective for reporting periods beginning after December 15, 2018, and is eligible for early adoption. The Company adopted this updated guidance on January 1, 2018. The impact of applying this guidance was a cumulative effect adjustment that decreased retained earnings and increased AOCI by offsetting amounts of $76 million , resulting in no net impact to total stockholders' equity. All other accounting and reporting standards that have become effective in 2018 were either not applicable to the Company or their adoption did not have a material impact on the Company. Accounting and reporting standards that are not yet effective: In February 2016, the FASB issued ASU 2016-02, Leases, which amends the accounting and disclosure guidance for leases. This guidance retains the two classifications of a lease, as either an operating or finance lease, both of which will require lessees to recognize a right-of-use asset and a lease liability for leases with terms of more than 12 months. The right-of-use asset and the lease liability will be determined based upon the present value of cash flows. Finance leases will reflect the financial arrangement by recognizing interest expense on the lease liability separately from the amortization expense of the right-of-use asset. Operating leases will recognize lease expense (with no separate recognition of interest expense) on a straight-line basis over the term of the lease. The accounting by lessors is not significantly changed by the updated guidance. The updated guidance is effective for reporting periods beginning after December 15, 2018, and can be adopted prospectively or will require that the earliest comparative period presented include the measurement and recognition of existing leases with an adjustment to equity as if the updated guidance had always been applied. The Company is currently evaluating the impact that the adoption of this guidance will have on its results of operations, financial position and liquidity. In June 2016, the FASB issued ASU 2016-13, Financial Instruments - Credit Losses, which amends the accounting guidance for credit losses on financial instruments. The updated guidance amends the current other-than-temporary impairment model for available-for-sale debt securities by requiring the recognition of impairments relating to credit losses through an allowance account and limits the amount of credit loss to the difference between a security’s amortized cost basis and its fair value. This guidance also applies a new current expected credit loss model for determining credit-related impairments for financial instruments measured at amortized cost. The updated guidance is effective for reporting periods beginning after December 15, 2019. The Company will not be able to determine the impact the adoption of this guidance will have on its results of operations, financial position or liquidity until the year the guidance becomes effective. All other recently issued but not yet effective accounting and reporting standards are either not applicable to the Company or are not expected to have a material impact on the Company.

Consolidated Statements of Co11

Consolidated Statements of Comprehensive Income	3 Months Ended
	Mar. 31, 2018
Equity [Abstract]
Consolidated Statements of Comprehensive Income	Consolidated Statement of Comprehensive (Loss) Income The following table presents the components of the changes in accumulated other comprehensive (loss) income ("AOCI"): (In thousands) Unrealized Investment Gains (Losses) Currency Translation Adjustments Accumulated Other Comprehensive (Loss) Income As of and for the three months ended March 31, 2018 Changes in AOCI Beginning of period $ 375,421 $ (306,880 ) $ 68,541 Cumulative effect adjustment resulting from changes in accounting principles (214,539 ) — (214,539 ) Restated beginning of period 160,882 (306,880 ) (145,998 ) Other comprehensive (loss) income before reclassifications (118,189 ) 12,799 (105,390 ) Amounts reclassified from AOCI (7,583 ) — (7,583 ) Other comprehensive (loss) income (125,772 ) 12,799 (112,973 ) Unrealized investment gain related to noncontrolling interest (11 ) — (11 ) End of period $ 35,099 $ (294,081 ) $ (258,982 ) Amounts reclassified from AOCI Pre-tax $ (9,599 ) (1) $ — $ (9,599 ) Tax effect 2,016 (2) — 2,016 After-tax amounts reclassified $ (7,583 ) $ — $ (7,583 ) Other comprehensive (loss) income Pre-tax $ (160,848 ) $ 12,799 $ (148,049 ) Tax effect 35,076 — 35,076 Other comprehensive (loss) income $ (125,772 ) $ 12,799 $ (112,973 ) As of and for the three months ended March 31, 2017: Changes in AOCI Beginning of period $ 427,154 $ (371,586 ) $ 55,568 Other comprehensive income before reclassifications 19,994 22,735 42,729 Amounts reclassified from AOCI (28,825 ) — (28,825 ) Other comprehensive (loss) income (8,831 ) 22,735 13,904 Unrealized investment loss related to noncontrolling interest 19 — 19 End of period $ 418,342 $ (348,851 ) $ 69,491 Amounts reclassified from AOCI Pre-tax $ (44,346 ) (1) $ — $ (44,346 ) Tax effect 15,521 (2) — 15,521 After-tax amounts reclassified $ (28,825 ) $ — $ (28,825 ) Other comprehensive (loss) income Pre-tax $ (9,571 ) $ 22,735 $ 13,164 Tax effect 740 — 740 Other comprehensive (loss) income $ (8,831 ) $ 22,735 $ 13,904 _________________________ (1) Net realized and unrealized gains on investments in the consolidated statements of income. (2) Income tax expense in the consolidated statements of income.

Statements of Cash Flow

Statements of Cash Flow	3 Months Ended
	Mar. 31, 2018
Supplemental Cash Flow Elements [Abstract]
Statements of Cash Flow	Statements of Cash Flow Interest payments were $61,890,000 and $61,782,000 and income taxes paid were none and $1,610,000 in the three months ended March 31, 2018 and 2017 , respectively.

Investments In Fixed Maturity S

Investments In Fixed Maturity Securities	3 Months Ended
	Mar. 31, 2018
Debt securities
Schedule of Available-for-sale Securities [Line Items]
Investments In Fixed Maturity Securities	Investments in Fixed Maturity Securities At March 31, 2018 and December 31, 2017 , investments in fixed maturity securities were as follows: (In thousands) Amortized Cost Gross Unrealized Fair Value Carrying Value Gains Losses March 31, 2018 Held to maturity: State and municipal $ 66,459 $ 12,185 $ — $ 78,644 $ 66,459 Residential mortgage-backed 12,772 988 — 13,760 12,772 Total held to maturity 79,231 13,173 — 92,404 79,231 Available for sale: U.S. government and government agency 479,330 6,692 (6,113 ) 479,909 479,909 State and municipal: Special revenue 2,644,248 36,059 (22,675 ) 2,657,632 2,657,632 State general obligation 404,710 12,113 (2,610 ) 414,213 414,213 Pre-refunded 443,852 18,131 (87 ) 461,896 461,896 Corporate backed 368,073 7,415 (1,610 ) 373,878 373,878 Local general obligation 389,887 17,227 (3,209 ) 403,905 403,905 Total state and municipal 4,250,770 90,945 (30,191 ) 4,311,524 4,311,524 Mortgage-backed securities: Residential (1) 1,067,814 6,233 (22,334 ) 1,051,713 1,051,713 Commercial 338,683 1,164 (4,563 ) 335,284 335,284 Total mortgage-backed securities 1,406,497 7,397 (26,897 ) 1,386,997 1,386,997 Asset-backed 2,101,896 11,435 (11,640 ) 2,101,691 2,101,691 Corporate: Industrial 2,378,793 27,145 (31,817 ) 2,374,121 2,374,121 Financial 1,411,529 22,100 (15,031 ) 1,418,598 1,418,598 Utilities 270,915 8,163 (4,546 ) 274,532 274,532 Other 43,682 1 (233 ) 43,450 43,450 Total corporate 4,104,919 57,409 (51,627 ) 4,110,701 4,110,701 Foreign 850,866 25,791 (3,578 ) 873,079 873,079 Total available for sale 13,194,278 199,669 (130,046 ) 13,263,901 13,263,901 Total investments in fixed maturity securities $ 13,273,509 $ 212,842 $ (130,046 ) $ 13,356,305 $ 13,343,132 (In thousands) Amortized Gross Unrealized Fair Carrying Gains Losses December 31, 2017 Held to maturity: State and municipal $ 65,882 $ 14,499 $ — $ 80,381 $ 65,882 Residential mortgage-backed 13,450 1,227 — 14,677 13,450 Total held to maturity 79,332 15,726 — 95,058 79,332 Available for sale: U.S. government and government agency 372,748 8,824 (3,832 ) 377,740 377,740 State and municipal: Special revenue 2,663,245 53,512 (10,027 ) 2,706,730 2,706,730 State general obligation 439,358 16,087 (711 ) 454,734 454,734 Pre-refunded 436,241 22,701 (9 ) 458,933 458,933 Corporate backed 375,268 10,059 (860 ) 384,467 384,467 Local general obligation 417,955 23,242 (967 ) 440,230 440,230 Total state and municipal 4,332,067 125,601 (12,574 ) 4,445,094 4,445,094 Mortgage-backed securities: Residential (1) 1,043,629 9,304 (13,547 ) 1,039,386 1,039,386 Commercial 261,652 1,521 (2,628 ) 260,545 260,545 Total mortgage-backed securities 1,305,281 10,825 (16,175 ) 1,299,931 1,299,931 Asset-backed 2,111,132 11,024 (10,612 ) 2,111,544 2,111,544 Corporate: Industrial 2,574,400 52,210 (7,718 ) 2,618,892 2,618,892 Financial 1,402,161 37,744 (5,138 ) 1,434,767 1,434,767 Utilities 284,886 11,316 (1,248 ) 294,954 294,954 Other 40,560 5 (66 ) 40,499 40,499 Total corporate 4,302,007 101,275 (14,170 ) 4,389,112 4,389,112 Foreign 819,345 32,018 (2,866 ) 848,497 848,497 Total available for sale 13,242,580 289,567 (60,229 ) 13,471,918 13,471,918 Total investments in fixed maturity securities $ 13,321,912 $ 305,293 $ (60,229 ) $ 13,566,976 $ 13,551,250 ____________ (1) Gross unrealized gains (losses) for residential mortgage-backed securities include $89,704 and $76,467 as of March 31, 2018 and December 31, 2017 , respectively, related to securities with the non-credit portion of other-than-temporary impairments (“OTTI”) recognized in accumulated other comprehensive income. The amortized cost and fair value of fixed maturity securities at March 31, 2018 , by contractual maturity, are shown below. Actual maturities may differ from contractual maturities because certain issuers may have the right to call or prepay obligations. (In thousands) Amortized Cost Fair Value Due in one year or less $ 813,191 $ 816,313 Due after one year through five years 4,580,074 4,621,880 Due after five years through ten years 3,110,432 3,158,810 Due after ten years 3,350,543 3,358,545 Mortgage-backed securities 1,419,269 1,400,757 Total $ 13,273,509 $ 13,356,305 At March 31, 2018 and December 31, 2017 , there were no investments that exceeded 10% of common stockholders' equity, other than investments in United States government and government agency securities.

Investments in Equity Securitie

Investments in Equity Securities Available for Sale	3 Months Ended
	Mar. 31, 2018
Equity securities
Schedule of Available-for-sale Securities [Line Items]
Investments in Equity Securities Available for Sale	Investments in Equity Securities At March 31, 2018 and December 31, 2017 , investments in equity securities were as follows: (In thousands) Cost Gross Unrealized (1) Fair Value Carrying Value Gains Losses March 31, 2018 Common stocks $ 95,447 $ 232,206 $ (7,218 ) $ 320,435 $ 320,435 Preferred stocks 124,150 53,423 (1,974 ) 175,599 175,599 Total $ 219,597 $ 285,629 $ (9,192 ) $ 496,034 $ 496,034 December 31, 2017 Common stocks $ 81,855 $ 272,309 $ (1,960 ) $ 352,204 $ 352,204 Preferred stocks 124,150 102,890 (2,597 ) 224,443 224,443 Total $ 206,005 $ 375,199 $ (4,557 ) $ 576,647 $ 576,647 ______________________ (1) Effective January 1, 2018, the Company adopted new accounting guidance that requires all equity investments with readily determinable fair values (subject to certain exceptions) to be measured at fair value with changes in the fair value recognized through net income. Refer to Note 3 for additional information.

Arbitrage Trading Account

Arbitrage Trading Account	3 Months Ended
	Mar. 31, 2018
Trading Securities [Abstract]
Arbitrage Trading Account	Arbitrage Trading Account At March 31, 2018 and December 31, 2017 , the fair and carrying values of the arbitrage trading account were $745 million and $618 million , respectively. The primary focus of the trading account is merger arbitrage. Merger arbitrage is the business of investing in the securities of publicly held companies which are the targets in announced tender offers and mergers. Arbitrage investing differs from other types of investing in its focus on transactions and events believed likely to bring about a change in value over a relatively short time period (usually four months or less). The Company uses put options, call options and swap contracts in order to mitigate the impact of potential changes in market conditions on the merger arbitrage trading account. These options and contracts are reported at fair value. As of March 31, 2018 , the fair value of long option contracts outstanding was $1.0 million (notional amount of $17.6 million ) and the fair value of short option contracts outstanding was $0.2 million (notional amount of $27.0 million ). Other than with respect to the use of these trading account securities, the Company does not make use of derivatives.

Net Investment Income

Net Investment Income	3 Months Ended
	Mar. 31, 2018
Net Investment Income [Abstract]
Net Investment Income	Net Investment Income Net investment income consists of the following: For the Three Months Ended March 31, (In thousands) 2018 2017 Investment income earned on: Fixed maturity securities, including cash and cash equivalents and loans receivable $ 123,246 $ 112,346 Investment funds 40,354 26,649 Arbitrage trading account 5,191 6,360 Real estate 6,568 4,566 Equity securities 646 639 Gross investment income 176,005 150,560 Investment expense (1,487 ) (1,702 ) Net investment income $ 174,518 $ 148,858

Investment Funds

Investment Funds	3 Months Ended
	Mar. 31, 2018
Equity Method Investments and Joint Ventures [Abstract]
Investment Funds	Investment Funds The Company evaluates whether it is an investor in a variable interest entity ("VIE"). Such entities do not have sufficient equity at risk to finance their activities without additional subordinated financial support, or the equity investors, as a group, do not have the characteristics of a controlling financial interest (primary beneficiary). The Company determines whether it is the primary beneficiary of an entity subject to consolidation based on a qualitative assessment of the VIE's capital structure, contractual terms, nature of the VIE's operations and purpose, and the Company's relative exposure to the related risks of the VIE on the date it becomes initially involved in the VIE and on an ongoing basis. The Company is not the primary beneficiary in any of its investment funds, and accordingly, carries its interests in investment funds under the equity method of accounting. The Company’s maximum exposure to loss with respect to these investments is limited to the carrying amount reported on the Company’s consolidated balance sheet and its unfunded commitments, which were $376 million as of March 31, 2018 . Investment funds consisted of the following: Carrying Value as of Income from Investment Funds March 31, December 31, For the Three Months Ended March 31, (In thousands) 2018 2017 2018 2017 Real estate $ 624,716 $ 606,995 $ 26,051 $ 4,532 Energy 80,833 82,882 74 3,245 Other funds 455,578 465,800 14,229 18,872 Total $ 1,161,127 $ 1,155,677 $ 40,354 $ 26,649 The Company's share of the earnings or losses of investment funds is generally reported on a one-quarter lag in order to facilitate the timely completion of the Company's consolidated financial statements.

Real Estate

Real Estate	3 Months Ended
	Mar. 31, 2018
Real Estate [Abstract]
Real Estate	Real Estate Investment in real estate represents directly owned property held for investment, as follows: Carrying Value March 31, December 31, (In thousands) 2018 2017 Properties in operation $ 739,405 $ 451,691 Properties under development 1,093,932 1,017,910 Total $ 1,833,337 $ 1,469,601 In 2018, properties in operation included a long-term ground lease in Washington, D.C., a hotel in Memphis, Tennessee, two office complexes in New York City and office buildings in West Palm Beach and Palm Beach, Florida. Properties in operation are net of accumulated depreciation and amortization of $29,477,000 and $25,646,000 as of March 31, 2018 and December 31, 2017, respectively. Related depreciation expense was $3,815,000 and $1,648,000 for the three months ended March 31, 2018 and 2017, respectively. Future minimum rental income expected on operating leases relating to properties in operation is $38,716,924 in 2018, $54,741,633 in 2019, $53,127,758 in 2020, $52,210,617 in 2021, $48,472,505 in 2022, $41,829,736 in 2023 and $498,985,951 thereafter. Properties under development include an office building in London and a mixed-use project in Washington, D.C.

Loans Receivable

Loans Receivable	3 Months Ended
	Mar. 31, 2018
Receivables [Abstract]
Loans Receivable	Loans Receivable Loans receivable are as follows: (In thousands) March 31, 2018 December 31, 2017 Amortized cost (net of valuation allowance): Real estate loans $ 63,191 $ 66,057 Commercial loans 12,711 13,627 Total $ 75,902 $ 79,684 Fair value: Real estate loans $ 64,026 $ 66,917 Commercial loans 14,212 15,130 Total $ 78,238 $ 82,047 Valuation allowance: Specific $ 1,200 $ 1,200 General 2,183 2,183 Total $ 3,383 $ 3,383 For the Three Months Ended March 31, 2018 2017 Decrease in valuation allowance $ — $ (14 ) Loans receivable in non-accrual status were $1.5 million and $4.3 million as of March 31, 2018 and December 31, 2017 , respectively. The Company monitors the performance of its loans receivable and assesses the ability of the borrower to pay principal and interest based upon loan structure, underlying property values, cash flow and related financial and operating performance of the property and market conditions. Loans receivable with a potential for default are further assessed using discounted cash flow analysis and comparable cost and sales methodologies, if appropriate. The real estate loans are secured by commercial real estate primarily located in New York. These loans generally earn interest at floating LIBOR-based interest rates and have maturities (inclusive of extension options) through August 2025. The commercial loans are with small business owners who have secured the related financing with the assets of the business. Commercial loans primarily earn interest on a fixed basis and have varying maturities generally not exceeding 10 years. In evaluating the real estate loans, the Company considers their credit quality indicators, including loan to value ratios, which compare the outstanding loan amount to the estimated value of the property, the borrower’s financial condition and performance with respect to loan terms, the position in the capital structure, the overall leverage in the capital structure and other market conditions. Based on these considerations, none of the real estate loans were considered to be impaired at March 31, 2018, and accordingly, the Company determined that a specific valuation allowance was not required.

Realized And Unrealized Investm

Realized And Unrealized Investment Gains (Losses)	3 Months Ended
	Mar. 31, 2018
Realized and Unrealized Investment Gains (Losses) [Abstract]
Realized and Unrealized Investment Gains (Losses)	Realized and Unrealized Gains (Losses) on Investments Net r ealized and unrealized gains (losses) on investments are as follows: For the Three Months Ended March 31, (In thousands) 2018 2017 Net realized and unrealized gains (losses) on investments in earnings Fixed maturity securities: Gains $ 13,339 $ 5,605 Losses (3,740 ) (3,965 ) Equity securities (1): Net realized gains on investment sales 122,321 42,707 Change in unrealized gains (94,205 ) — Investment funds 119 1,267 Real estate 7,998 3,300 Loans receivable 2,058 — Other 574 3,434 Net realized and unrealized gains on investments in earnings before OTTI 48,464 52,348 Other-than-temporary impairments (2) — — Net realized and unrealized gains on investments in earnings 48,464 52,348 Income tax expense (10,177 ) (18,322 ) After-tax net realized and unrealized gains on investments in earnings $ 38,287 $ 34,026 Change in unrealized investment gains of available for sale securities: Fixed maturity securities $ (159,727 ) $ 37,984 Previously impaired fixed maturity securities 13 101 Equity securities available for sale (3) — (48,862 ) Investment funds (1,134 ) 1,206 Total change in unrealized investment gains (160,848 ) (9,571 ) Income tax benefit 35,076 740 Noncontrolling interests (11 ) 19 After-tax change in unrealized investment gains of available for sale securities $ (125,783 ) $ (8,812 ) ______________________ (1) The net realized gains or losses on investment sales represent the total gains or losses from the purchase dates of the equity securities. The change in unrealized gains consists of two components: (i) the reversal of the gain or loss recognized in previous periods on equity securities sold and (ii) the change in unrealized gain or loss resulting from mark-to-market adjustments on equity securities still held. (2) There were no other than temporary impairments (OTTI) for the three months ended March 31, 2018 and 2017 . (3) Effective January 1, 2018, the Company adopted new accounting guidance that requires all equity investments with readily determinable fair values (subject to certain exceptions) to be measured at fair value with changes in the fair value recognized in net income. The Company recorded an adjustment of $291 million to opening AOCI net of tax as a result of this guidance. Refer to Note 3 for further information.

Securities In An Unrealized Los

Securities In An Unrealized Loss Position	3 Months Ended
	Mar. 31, 2018
Investments [Abstract]
Securities in Unrealized Loss Position	Securities in an Unrealized Loss Position The following tables summarize all fixed maturity securities in an unrealized loss position at March 31, 2018 and December 31, 2017 by the length of time those securities have been continuously in an unrealized loss position: Less Than 12 Months 12 Months or Greater Total (In thousands) Fair Value Gross Unrealized Losses Fair Value Gross Unrealized Losses Fair Value Gross Unrealized Losses March 31, 2018 U.S. government and government agency $ 138,917 $ 2,978 $ 71,224 $ 3,135 $ 210,141 $ 6,113 State and municipal 1,514,028 20,922 303,246 9,269 1,817,274 30,191 Mortgage-backed securities 754,800 12,603 362,331 14,294 1,117,131 26,897 Asset-backed securities 1,271,743 9,444 160,263 2,196 1,432,006 11,640 Corporate 1,912,850 42,874 168,813 8,753 2,081,663 51,627 Foreign government 216,681 3,301 25,541 277 242,222 3,578 Fixed maturity securities $ 5,809,019 $ 92,122 $ 1,091,418 $ 37,924 $ 6,900,437 $ 130,046 December 31, 2017 U.S. government and government agency $ 92,167 $ 1,491 $ 72,055 $ 2,341 $ 164,222 $ 3,832 State and municipal 735,972 5,944 345,755 6,630 1,081,727 12,574 Mortgage-backed securities 480,435 5,110 373,956 11,065 854,391 16,175 Asset-backed securities 1,127,309 8,298 167,412 2,314 1,294,721 10,612 Corporate 1,103,747 8,224 170,858 5,946 1,274,605 14,170 Foreign government 244,139 2,615 25,824 251 269,963 2,866 Fixed maturity securities $ 3,783,769 $ 31,682 $ 1,155,860 $ 28,547 $ 4,939,629 $ 60,229 A summary of the Company’s non-investment grade fixed maturity securities that were in an unrealized loss position at March 31, 2018 is presented in the table below: ($ in thousands) Number of Securities Aggregate Fair Value Gross Unrealized Loss Corporate 10 $ 86,345 $ 4,429 Foreign government 8 $ 30,997 $ 739 Asset-backed securities 3 370 140 Mortgage-backed securities 5 4,532 117 State and municipal 1 3,641 3 Total 27 $ 125,885 $ 5,428 For OTTI of fixed maturity securities that management does not intend to sell or to be required to sell, the portion of the decline in value that is considered to be due to credit factors is recognized in earnings, and the portion of the decline in value that is considered to be due to non-credit factors is recognized in other comprehensive income. The Company has evaluated its fixed maturity securities in an unrealized loss position and believes the unrealized losses are due primarily to temporary market and sector-related factors rather than to issuer-specific factors. None of these securities are delinquent or in default under financial covenants. Based on its assessment of these issuers, the Company expects them to continue to meet their contractual payment obligations as they become due and does not consider any of these securities to be OTTI.

Fair Value Measurements

Fair Value Measurements	3 Months Ended
	Mar. 31, 2018
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements The Company’s fixed maturity securities, equity securities and arbitrage trading account securities are carried at fair value. Fair value is defined as “the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date.” The Company utilizes a fair value hierarchy that prioritizes the inputs to valuation techniques used to measure fair value into three broad levels, as follows: Level 1 - Quoted prices (unadjusted) in active markets for identical assets or liabilities that the Company has the ability to access at the measurement date. Level 2 - Quoted prices for similar assets or valuations based on inputs that are observable. Level 3 - Estimates of fair value based on internal pricing methodologies using unobservable inputs. Unobservable inputs are only used to measure fair value to the extent that observable inputs are not available. Substantially, all of the Company’s fixed maturity securities were priced by independent pricing services. The prices provided by the independent pricing services are estimated based on observable market data in active markets utilizing pricing models and processes, which may include benchmark yields, reported trades, broker/dealer quotes, issuer spreads, two-sided markets, benchmark securities, bids, offers, sector groupings, matrix pricing and reference data. The pricing services may prioritize inputs differently on any given day for any security based on market conditions, and not all inputs are available for each security evaluation on any given day. The pricing services used by the Company have indicated that they will only produce an estimate of fair value if objectively verifiable information is available. The determination of whether markets are active or inactive is based upon the volume and level of activity for a particular asset class. The Company reviews the prices provided by pricing services for reasonableness and periodically performs independent price tests of a sample of securities to ensure proper valuation. If prices from independent pricing services are not available for fixed maturity securities, the Company estimates the fair value. For Level 2 securities, the Company utilizes pricing models and processes which may include benchmark yields, sector groupings, matrix pricing, reported trades, broker/dealer quotes, issuer spreads, two-sided markets, bids, offers and reference data. Where broker quotes are used, the Company generally requests two or more quotes and sets a price within the range of quotes received based on its assessment of the credibility of the quote and its own evaluation of the security. The Company generally does not adjust quotes received from brokers. For securities traded only in private negotiations, the Company determines fair value based primarily on the cost of such securities, which is adjusted to reflect prices of recent placements of securities of the same issuer, financial projections, credit quality and business developments of the issuer and other relevant information. For Level 3 securities, the Company generally uses a discounted cash flow model to estimate the fair value of fixed maturity securities. The cash flow models are based upon assumptions as to prevailing credit spreads, interest rate and interest rate volatility, time to maturity and subordination levels. Projected cash flows are discounted at rates that are adjusted to reflect illiquidity, where appropriate. The following tables present the assets and liabilities measured at fair value on a recurring basis as of March 31, 2018 and December 31, 2017 by level: (In thousands) Total Level 1 Level 2 Level 3 March 31, 2018 Assets: Fixed maturity securities available for sale: U.S. government and government agency $ 479,909 $ — $ 479,909 $ — State and municipal 4,311,524 — 4,311,524 — Mortgage-backed securities 1,386,997 — 1,386,997 — Asset-backed securities 2,101,691 — 2,101,528 163 Corporate 4,110,701 — 4,110,701 — Foreign government 873,079 — 873,079 — Total fixed maturity securities available for sale 13,263,901 — 13,263,738 163 Equity securities: Common stocks 320,435 311,329 — 9,106 Preferred stocks 175,599 — 164,756 10,843 Total equity securities 496,034 311,329 164,756 19,949 Arbitrage trading account 744,859 434,470 306,547 3,842 Total $ 14,504,794 $ 745,799 $ 13,735,041 $ 23,954 Liabilities: Trading account securities sold but not yet purchased $ 29,453 $ 29,444 $ 9 $ — December 31, 2017 Assets: Fixed maturity securities available for sale: U.S. government and government agency $ 377,740 $ — $ 377,740 $ — State and municipal 4,445,094 — 4,445,094 — Mortgage-backed securities 1,299,931 — 1,299,931 — Asset-backed securities 2,111,544 — 2,111,372 172 Corporate 4,389,112 — 4,389,112 — Foreign government 848,497 — 848,497 — Total fixed maturity securities available for sale 13,471,918 — 13,471,746 172 Equity securities: Common stocks 352,204 342,834 — 9,370 Preferred stocks 224,443 — 213,600 10,843 Total equity securities 576,647 342,834 213,600 20,213 Arbitrage trading account 617,649 471,420 146,229 — Total $ 14,666,214 $ 814,254 $ 13,831,575 $ 20,385 Liabilities: Trading account securities sold but not yet purchased $ 64,358 $ 64,358 $ — $ — There were no significant transfers between Levels 1 and 2 during the three months ended March 31, 2018 or during the year ended December 31, 2017 . The following tables summarize changes in Level 3 assets and liabilities for the three months ended March 31, 2018 and for the year ended December 31, 2017 : Gains (Losses) Included in: (In thousands) Beginning Balance Earnings (Losses) Other Comprehensive Income (Loss) Impairments Purchases (Sales) Paydowns / Maturities Transfers Ending Balance In / (Out) Three Months Ended March 31, 2018 Assets: Fixed maturities securities available for sale: Asset-backed securities $ 172 $ 2 $ 4 $ — $ — $ (15 ) $ — $ — $ 163 Total 172 2 4 — — (15 ) — — 163 Equity securities: Common stocks 9,370 (264 ) — — — — — — 9,106 Preferred stocks 10,843 — — — — — — — 10,843 Total 20,213 (264 ) — — — — — — 19,949 Arbitrage trading account — (40 ) — — 3,882 — — — 3,842 Total $ 20,385 $ (302 ) $ 4 $ — $ 3,882 $ (15 ) $ — $ — $ 23,954 Year ended December 31, 2017 Assets: Fixed maturities securities available for sale: Asset-backed securities $ 183 $ 3 $ 34 $ — $ — $ (48 ) $ — $ — $ 172 Total 183 3 34 — — (48 ) — — 172 Equity securities: Common stocks 8,754 — 616 — — — — — 9,370 Preferred stocks 3,662 8 — — 7,173 — — — 10,843 Total 12,416 8 616 — 7,173 — — — 20,213 Arbitrage trading account — 8 — — — (8 ) — — — Total $ 12,599 $ 19 $ 650 $ — $ 7,173 $ (56 ) $ — $ — $ 20,385 During the three months ended March 31, 2018 and for the year ended December 31, 2017 , there were no t ransfers out of Level 3. Fair Value of Financial Instruments The following table presents the carrying amounts and estimated fair values of the Company’s financial instruments: March 31, 2018 December 31, 2017 (In thousands) Carrying Value Fair Value Carrying Value Fair Value Assets: Fixed maturity securities $ 13,343,132 $ 13,356,305 $ 13,551,250 $ 13,566,976 Equity securities 496,034 496,034 576,647 576,647 Arbitrage trading account 744,859 744,859 617,649 617,649 Loans receivable 75,902 78,238 79,684 82,047 Cash and cash equivalents 956,603 956,603 950,471 950,471 Trading account receivables from brokers and clearing organizations 26,667 26,667 189,280 189,280 Liabilities: Due to broker 74,450 74,450 15,920 15,920 Trading account securities sold but not yet purchased 29,453 29,453 64,358 64,358 Subordinated debentures 897,426 929,948 728,218 769,060 Senior notes and other debt 1,782,139 1,921,635 1,769,052 1,945,313 The estimated fair values of the Company’s fixed maturity securities, equity securities and arbitrage trading account securities are based on various valuation techniques that rely on fair value measurements as described in Note 15 above. The fair value of loans receivable are estimated by using current institutional purchaser yield requirements for loans with similar credit characteristics, which is considered a Level 2 input. The fair value of the senior notes and other debt and the subordinated debentures is based on spreads for similar securities, which is considered a Level 2 input.

Reserves for Loss and Loss Expe

Reserves for Loss and Loss Expenses	3 Months Ended
	Mar. 31, 2018
Insurance [Abstract]
Reserves for Loss and Loss Expenses	Reserves for Loss and Loss Expenses The Company's reserves for losses and loss expenses are comprised of case reserves and incurred but not reported liabilities ("IBNR"). When a claim is reported, a case reserve is established for the estimated ultimate payment based upon known information about the claim. As more information about the claim becomes available over time, case reserves are adjusted up or down as appropriate. Reserves are also established on an aggregate basis to provide for IBNR liabilities and expected loss reserve development on reported claims. Loss reserves included in the Company’s financial statements represent management’s best estimates based upon an actuarially derived point estimate and other considerations. The Company uses a variety of actuarial techniques and methods to derive an actuarial point estimate for each operating unit. These methods include paid loss development, incurred loss development, paid and incurred Bornhuetter-Ferguson methods and frequency and severity methods. In circumstances where one actuarial method is considered more credible than the others, that method is used to set the point estimate. The actuarial point estimate may also be based on a judgmental weighting of estimates produced from each of the methods considered. Industry loss experience is used to supplement the Company’s own data in selecting “tail factors” in areas where the Company’s own data is limited. The actuarial data is analyzed by line of business, coverage and accident or policy year, as appropriate, for each operating unit. The establishment of the actuarially derived loss reserve point estimate also includes consideration of qualitative factors that may affect the ultimate losses. These qualitative considerations include, among others, the impact of re-underwriting initiatives, changes in the mix of business, changes in distribution sources and changes in policy terms and conditions. The key assumptions used to arrive at the best estimate of loss reserves are the expected loss ratios, rate of loss cost inflation, and reported and paid loss emergence patterns. Expected loss ratios represent management’s expectation of losses at the time the business is priced and written, before any actual claims experience has emerged. This expectation is a significant determinant of the estimate of loss reserves for recently written business where there is little paid or incurred loss data to consider. Expected loss ratios are generally derived from historical loss ratios adjusted for the impact of rate changes, loss cost trends and known changes in the type of risks underwritten. Expected loss ratios are estimated for each key line of business within each operating unit. Expected loss cost inflation is particularly important for the long-tail lines, such as excess casualty, and claims with a high medical component, such as workers’ compensation. Reported and paid loss emergence patterns are used to project current reported or paid loss amounts to their ultimate settlement value. Loss development factors are based on the historical emergence patterns of paid and incurred losses, and are derived from the Company’s own experience and industry data. The paid loss emergence pattern is also significant to excess and assumed workers’ compensation reserves because those reserves are discounted to their estimated present value based upon such estimated payout patterns. Loss frequency and severity are measures of loss activity that are considered in determining the key assumptions described in our discussion of loss and loss expense reserves, including expected loss ratios, rate of loss cost inflation and reported and paid loss emergence patterns. Loss frequency is a measure of the number of claims per unit of insured exposure, and loss severity is a measure of the average size of claims. Factors affecting loss frequency include the effectiveness of loss controls and safety programs and changes in economic activity or weather patterns. Factors affecting loss severity include changes in policy limits, retentions, rate of inflation and judicial interpretations. Another factor affecting estimates of loss frequency and severity is the loss reporting lag, which is the period of time between the occurrence of a loss and the date the loss is reported to the Company. The length of the loss reporting lag affects our ability to accurately predict loss frequency (loss frequencies are more predictable for lines with short reporting lags) as well as the amount of reserves needed for incurred but not reported losses (less IBNR is required for lines with short reporting lags). As a result, loss reserves for lines with short reporting lags are likely to have less variation from initial loss estimates. For lines with short reporting lags, which include commercial automobile, primary workers’ compensation, other liability (claims-made) and property business, the key assumption is the loss emergence pattern used to project ultimate loss estimates from known losses paid or reported to date. For lines of business with long reporting lags, which include other liability (occurrence), products liability, excess workers’ compensation and liability reinsurance, the key assumption is the expected loss ratio since there is often little paid or incurred loss data to consider. Historically, the Company has experienced less variation from its initial loss estimates for lines of businesses with short reporting lags than for lines of business with long reporting lags. The key assumptions used in calculating the most recent estimate of the loss reserves are reviewed each quarter and adjusted, to the extent necessary, to reflect the latest reported loss data, current trends and other factors observed. The table below provides a reconciliation of the beginning and ending reserve balances: March 31, (In thousands) 2018 2017 Net reserves at beginning of year $ 10,056,914 $ 9,590,265 Net provision for losses and loss expenses: Claims occurring during the current year (1) 956,181 958,684 (Decrease) increase in estimates for claims occurring in prior years (2) (3) (3,582 ) 8,727 Loss reserve discount accretion 10,620 12,192 Total 963,219 979,603 Net payments for claims: Current year 111,030 97,461 Prior year 810,709 773,571 Total 921,739 871,032 Foreign currency translation 2,501 23,204 Net reserves at end of period 10,100,895 9,722,040 Ceded reserve at end of period 1,684,000 1,502,284 Gross reserves at end of period $ 11,784,895 $ 11,224,324 _______________________________________ (1) Claims occurring during the current year are net of loss reserve discounts of $ 6,448,000 and $ 5,761,000 for the three months ended March 31, 2018 and 2017 , respectively. (2) The decrease or increase in estimates for claims occurring in prior years is net of loss reserve discount. On an undiscounted basis, the estimates for claims occurring in prior years decreased by $ 6,662,000 and increased by $ 4,841,000 for the three months ended March 31, 2018 and 2017 , respectively. (3) For certain retrospectively rated insurance policies and reinsurance agreements, reserve development is offset by additional or return premiums. Favorable development, net of additional and return premiums, was $12 million and $2 million for the three months ended March 31, 2018 and 2017 , respectively. During the three months ended March 31, 2018, favorable prior year development (net of additional and return premiums) of $12.2 million included $16.3 million of favorable development for the Insurance segment, offset by $4.1 million of adverse development for the Reinsurance segment. The favorable development for the Insurance segment was primarily attributable to workers’ compensation business. The favorable workers’ compensation development was spread across many accident years, including prior to 2008, but was most significant in accident years 2015 through 2017. The favorable workers’ compensation development reflects a continuation of the benign loss cost trends experienced during recent years, particularly the favorable claim frequency trends (i.e., number of reported claims per unit of exposure). The adverse development for the Reinsurance segment was mainly driven by US casualty facultative business from accident years 2008 and prior related to construction projects. During the three months ended March 31, 2017, favorable prior year development (net of additional and return premiums) of $2.4 million included $26.2 million of favorable development for the Insurance segment, largely offset by $23.8 million of adverse development for the Reinsurance segment. The favorable development for the Insurance segment was primarily attributable to workers' compensation business, including excess workers' compensation. The favorable workers' compensation development was spread across many accident years, including prior to 2008, but was most significant in accident years 2014 and 2015. The favorable workers' compensation development reflects a continuation of the benign loss cost trends experienced during 2016, particularly the favorable claim frequency trends ( i.e., number of reported claims per unit of exposure). The adverse development for the Reinsurance segment was almost entirely due to reserve strengthening associated with claims impacted by the change in the Ogden discount rate in the U.K. The Ogden rate is the discount rate used to calculate lump-sum bodily injury payouts in the U.K. and was recently reduced by the U.K. Ministry of Justice from +2.5% to -0.75% . The adverse development mostly related to U.K. motor bodily injury claims which we reinsured on an excess of loss basis in accident years 2012 through 2016.

Fair Value Of Financial Instrum

Fair Value Of Financial Instruments	3 Months Ended
	Mar. 31, 2018
Fair Value Disclosures [Abstract]
Fair Value Of Financial Instruments	Fair Value Measurements The Company’s fixed maturity securities, equity securities and arbitrage trading account securities are carried at fair value. Fair value is defined as “the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date.” The Company utilizes a fair value hierarchy that prioritizes the inputs to valuation techniques used to measure fair value into three broad levels, as follows: Level 1 - Quoted prices (unadjusted) in active markets for identical assets or liabilities that the Company has the ability to access at the measurement date. Level 2 - Quoted prices for similar assets or valuations based on inputs that are observable. Level 3 - Estimates of fair value based on internal pricing methodologies using unobservable inputs. Unobservable inputs are only used to measure fair value to the extent that observable inputs are not available. Substantially, all of the Company’s fixed maturity securities were priced by independent pricing services. The prices provided by the independent pricing services are estimated based on observable market data in active markets utilizing pricing models and processes, which may include benchmark yields, reported trades, broker/dealer quotes, issuer spreads, two-sided markets, benchmark securities, bids, offers, sector groupings, matrix pricing and reference data. The pricing services may prioritize inputs differently on any given day for any security based on market conditions, and not all inputs are available for each security evaluation on any given day. The pricing services used by the Company have indicated that they will only produce an estimate of fair value if objectively verifiable information is available. The determination of whether markets are active or inactive is based upon the volume and level of activity for a particular asset class. The Company reviews the prices provided by pricing services for reasonableness and periodically performs independent price tests of a sample of securities to ensure proper valuation. If prices from independent pricing services are not available for fixed maturity securities, the Company estimates the fair value. For Level 2 securities, the Company utilizes pricing models and processes which may include benchmark yields, sector groupings, matrix pricing, reported trades, broker/dealer quotes, issuer spreads, two-sided markets, bids, offers and reference data. Where broker quotes are used, the Company generally requests two or more quotes and sets a price within the range of quotes received based on its assessment of the credibility of the quote and its own evaluation of the security. The Company generally does not adjust quotes received from brokers. For securities traded only in private negotiations, the Company determines fair value based primarily on the cost of such securities, which is adjusted to reflect prices of recent placements of securities of the same issuer, financial projections, credit quality and business developments of the issuer and other relevant information. For Level 3 securities, the Company generally uses a discounted cash flow model to estimate the fair value of fixed maturity securities. The cash flow models are based upon assumptions as to prevailing credit spreads, interest rate and interest rate volatility, time to maturity and subordination levels. Projected cash flows are discounted at rates that are adjusted to reflect illiquidity, where appropriate. The following tables present the assets and liabilities measured at fair value on a recurring basis as of March 31, 2018 and December 31, 2017 by level: (In thousands) Total Level 1 Level 2 Level 3 March 31, 2018 Assets: Fixed maturity securities available for sale: U.S. government and government agency $ 479,909 $ — $ 479,909 $ — State and municipal 4,311,524 — 4,311,524 — Mortgage-backed securities 1,386,997 — 1,386,997 — Asset-backed securities 2,101,691 — 2,101,528 163 Corporate 4,110,701 — 4,110,701 — Foreign government 873,079 — 873,079 — Total fixed maturity securities available for sale 13,263,901 — 13,263,738 163 Equity securities: Common stocks 320,435 311,329 — 9,106 Preferred stocks 175,599 — 164,756 10,843 Total equity securities 496,034 311,329 164,756 19,949 Arbitrage trading account 744,859 434,470 306,547 3,842 Total $ 14,504,794 $ 745,799 $ 13,735,041 $ 23,954 Liabilities: Trading account securities sold but not yet purchased $ 29,453 $ 29,444 $ 9 $ — December 31, 2017 Assets: Fixed maturity securities available for sale: U.S. government and government agency $ 377,740 $ — $ 377,740 $ — State and municipal 4,445,094 — 4,445,094 — Mortgage-backed securities 1,299,931 — 1,299,931 — Asset-backed securities 2,111,544 — 2,111,372 172 Corporate 4,389,112 — 4,389,112 — Foreign government 848,497 — 848,497 — Total fixed maturity securities available for sale 13,471,918 — 13,471,746 172 Equity securities: Common stocks 352,204 342,834 — 9,370 Preferred stocks 224,443 — 213,600 10,843 Total equity securities 576,647 342,834 213,600 20,213 Arbitrage trading account 617,649 471,420 146,229 — Total $ 14,666,214 $ 814,254 $ 13,831,575 $ 20,385 Liabilities: Trading account securities sold but not yet purchased $ 64,358 $ 64,358 $ — $ — There were no significant transfers between Levels 1 and 2 during the three months ended March 31, 2018 or during the year ended December 31, 2017 . The following tables summarize changes in Level 3 assets and liabilities for the three months ended March 31, 2018 and for the year ended December 31, 2017 : Gains (Losses) Included in: (In thousands) Beginning Balance Earnings (Losses) Other Comprehensive Income (Loss) Impairments Purchases (Sales) Paydowns / Maturities Transfers Ending Balance In / (Out) Three Months Ended March 31, 2018 Assets: Fixed maturities securities available for sale: Asset-backed securities $ 172 $ 2 $ 4 $ — $ — $ (15 ) $ — $ — $ 163 Total 172 2 4 — — (15 ) — — 163 Equity securities: Common stocks 9,370 (264 ) — — — — — — 9,106 Preferred stocks 10,843 — — — — — — — 10,843 Total 20,213 (264 ) — — — — — — 19,949 Arbitrage trading account — (40 ) — — 3,882 — — — 3,842 Total $ 20,385 $ (302 ) $ 4 $ — $ 3,882 $ (15 ) $ — $ — $ 23,954 Year ended December 31, 2017 Assets: Fixed maturities securities available for sale: Asset-backed securities $ 183 $ 3 $ 34 $ — $ — $ (48 ) $ — $ — $ 172 Total 183 3 34 — — (48 ) — — 172 Equity securities: Common stocks 8,754 — 616 — — — — — 9,370 Preferred stocks 3,662 8 — — 7,173 — — — 10,843 Total 12,416 8 616 — 7,173 — — — 20,213 Arbitrage trading account — 8 — — — (8 ) — — — Total $ 12,599 $ 19 $ 650 $ — $ 7,173 $ (56 ) $ — $ — $ 20,385 During the three months ended March 31, 2018 and for the year ended December 31, 2017 , there were no t ransfers out of Level 3. Fair Value of Financial Instruments The following table presents the carrying amounts and estimated fair values of the Company’s financial instruments: March 31, 2018 December 31, 2017 (In thousands) Carrying Value Fair Value Carrying Value Fair Value Assets: Fixed maturity securities $ 13,343,132 $ 13,356,305 $ 13,551,250 $ 13,566,976 Equity securities 496,034 496,034 576,647 576,647 Arbitrage trading account 744,859 744,859 617,649 617,649 Loans receivable 75,902 78,238 79,684 82,047 Cash and cash equivalents 956,603 956,603 950,471 950,471 Trading account receivables from brokers and clearing organizations 26,667 26,667 189,280 189,280 Liabilities: Due to broker 74,450 74,450 15,920 15,920 Trading account securities sold but not yet purchased 29,453 29,453 64,358 64,358 Subordinated debentures 897,426 929,948 728,218 769,060 Senior notes and other debt 1,782,139 1,921,635 1,769,052 1,945,313 The estimated fair values of the Company’s fixed maturity securities, equity securities and arbitrage trading account securities are based on various valuation techniques that rely on fair value measurements as described in Note 15 above. The fair value of loans receivable are estimated by using current institutional purchaser yield requirements for loans with similar credit characteristics, which is considered a Level 2 input. The fair value of the senior notes and other debt and the subordinated debentures is based on spreads for similar securities, which is considered a Level 2 input.

Reinsurance

Reinsurance	3 Months Ended
	Mar. 31, 2018
Insurance [Abstract]
Reinsurance	Reinsurance The following is a summary of reinsurance financial information: For the Three Months Ended March 31, (In thousands) 2018 2017 Written premiums: Direct $ 1,787,235 $ 1,721,062 Assumed 192,187 215,145 Ceded (314,084 ) (289,369 ) Total net premiums written $ 1,665,338 $ 1,646,838 Earned premiums: Direct $ 1,674,550 $ 1,613,364 Assumed 188,866 208,626 Ceded (296,008 ) (251,948 ) Total net premiums earned $ 1,567,408 $ 1,570,042 Ceded losses and loss expenses incurred $ 238,995 $ 35,192 Ceded commissions earned $ 66,356 $ 56,550 The Company reinsures a portion of its insurance exposures in order to reduce its net liability on individual risks and catastrophe losses. The Company also cedes premiums to state assigned risk plans and captive insurance companies. Estimated amounts due from reinsurers are reported net of reserves for uncollectible reinsurance of $1 million as of both March 31, 2018 and December 31, 2017 .

Restricted Stock Units

Restricted Stock Units	3 Months Ended
	Mar. 31, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Restricted Stock Units	Restricted Stock Units Pursuant to its stock incentive plan, the Company may issue restricted stock units ("RSUs") to employees of the Company and its subsidiaries. The RSUs generally vest three to five years from the award date and are subject to other vesting and forfeiture provisions contained in the award agreement. RSUs are expensed pro-ratably over the vesting period. RSU expenses were $9 million and $11 million for the three months ended March 31, 2018 and 2017 , respectively. A summary of RSUs issued in the three months ended March 31, 2018 and 2017 follows: ($ in thousands) Units Fair Value 2018 4,174 $ 290 2017 1,853 $ 129

Litigation and Contingent Liabi

Litigation and Contingent Liabilities	3 Months Ended
	Mar. 31, 2018
Commitments and Contingencies Disclosure [Abstract]
Litigation and Contingent Liabilities	Litigation and Contingent Liabilities In the ordinary course of business, the Company is subject to disputes, litigation and arbitration arising from its insurance and reinsurance businesses. These matters are generally related to insurance and reinsurance claims and are considered in the establishment of loss and loss expense reserves. In addition, the Company may also become involved in legal actions which seek extra-contractual damages, punitive damages or penalties, including claims alleging bad faith in handling of insurance claims. The Company expects its ultimate liability with respect to such matters will not be material to its financial condition. However, adverse outcomes on such matters are possible, from time to time, and could be material to the Company’s results of operations in any particular financial reporting period.

Business Segments

Business Segments	3 Months Ended
	Mar. 31, 2018
Segment Reporting [Abstract]
Business Segments	Business Segments The Company’s reportable segments include the following two business segments, plus a corporate segment: • Insurance - predominantly commercial insurance business, including excess and surplus lines, admitted lines and specialty personal lines throughout the United States, as well as insurance business in the United Kingdom, Continental Europe, South America, Canada, Mexico, Scandinavia, Asia and Australia. • Reinsurance - reinsurance business on a facultative and treaty basis, primarily in the United States, the United Kingdom, Continental Europe, Australia, the Asia-Pacific Region and South Africa. The accounting policies of the segments are the same as those described in the summary of significant accounting policies. Income tax expense and benefits are calculated based upon the Company's overall effective tax rate. Summary financial information about the Company's reporting segments is presented in the following tables. Income (loss) before income taxes by segment includes allocated investment income. Identifiable assets by segment are those assets used in or allocated to the operation of each segment. Revenues (In thousands) Earned Premiums Investment Income Other Total (1) Pre-Tax Income (Loss) Net Income (Loss) to Common Stockholders Three months ended March 31, 2018 Insurance $ 1,432,337 $ 135,862 $ 18,968 $ 1,587,167 $ 229,028 $ 181,626 Reinsurance 135,071 24,650 — 159,721 14,592 11,654 Corporate, other and eliminations (2) — 14,006 81,889 95,895 (81,094 ) (65,170 ) Net realized and unrealized gains on investments — — 48,464 48,464 48,464 38,286 Total $ 1,567,408 $ 174,518 $ 149,321 $ 1,891,247 $ 210,990 $ 166,396 Three months ended March 31, 2017 Insurance $ 1,413,170 $ 111,909 $ 18,287 $ 1,543,366 $ 199,994 $ 134,095 Reinsurance 156,872 24,778 — 181,650 4,594 3,099 Corporate, other and eliminations (2) — 12,171 80,883 93,054 (72,639 ) (47,773 ) Net realized and unrealized gains on investments — — 52,348 52,348 52,348 34,026 Total $ 1,570,042 $ 148,858 $ 151,518 $ 1,870,418 $ 184,297 $ 123,447 _________________ (1) Revenues for Insurance from foreign countries for the three months ended March 31, 2018 and 2017 were $183 million and $184 million , respectively. Revenues for Reinsurance from foreign countries for the three months ended March 31, 2018 and 2017 were $56 million and $49 million , respectively. (2) Corporate, other and eliminations represent corporate revenues and expenses that are not allocated to business segments. Identifiable Assets (In thousands) March 31, 2018 December 31, 2017 Insurance $ 19,322,526 $ 19,263,193 Reinsurance 3,093,808 3,169,731 Corporate, other and eliminations 2,171,498 1,866,993 Consolidated $ 24,587,832 $ 24,299,917 Net premiums earned by major line of business are as follows: For the Three Months Ended March 31, (In thousands) 2018 2017 Insurance: Other liability $ 464,167 $ 451,830 Workers’ compensation 365,948 361,136 Short-tail lines (1) 295,105 296,790 Commercial automobile 175,199 170,571 Professional liability 131,918 132,843 Total Insurance 1,432,337 1,413,170 Reinsurance: Casualty 90,570 94,739 Property 44,501 62,133 Total Reinsurance 135,071 156,872 Total $ 1,567,408 $ 1,570,042 ______________ (1) Short-tail lines include commercial multi-peril (non-liability), inland marine, accident and health, fidelity and surety, boiler and machinery and other lines.

Recent Accounting Pronounceme29

Recent Accounting Pronouncements (Policies)	3 Months Ended
	Mar. 31, 2018
Accounting Policies [Abstract]
Per Share Data	Per Share Data The Company presents both basic and diluted net income per share (“EPS”) amounts. Basic EPS is calculated by dividing net income by the weighted average number of common shares outstanding during the period (including 4,847,303 and 4,087,731 common shares held in a grantor trust as of March 31, 2018 and 2017, respectively). The common shares held in the grantor trust are for delivery upon settlement of vested but mandatorily deferred restricted stock units ("RSUs"). Shares held by the grantor trust do not affect diluted shares outstanding since the shares deliverable under vested RSUs were already included in diluted shares outstanding. Diluted EPS is based upon the weighted average number of basic and common equivalent shares outstanding during the period and is calculated using the treasury stock method for stock incentive plans. Common equivalent shares are excluded from the computation in periods in which they have an anti-dilutive effect.
Recent Accounting Pronouncements	Recent Accounting Pronouncements Recently adopted accounting pronouncements: In May 2014, the Financial Accounting Standards Board ("FASB") issued ASU 2014-09, Revenue from Customers. ASU 2014-09 clarifies the principles for recognizing revenue. While insurance contracts are not within the scope of this updated guidance, the Company’s insurance service fee revenue and non-insurance business revenue are subject to this updated guidance. The updated guidance requires an entity to recognize revenue as performance obligations are met, in order to reflect the transfer of promised goods or services to customers in an amount that reflects the consideration the entity is entitled to receive for those goods or services. The updated guidance, as amended by ASU 2015-14, was effective for public business entities for annual and interim reporting periods beginning after December 15, 2017. The Company adopted this guidance on January 1, 2018 on a prospective basis. The impact of applying this guidance prospectively was a cumulative effect adjustment that increased retained earnings, a component of stockholders' equity, by $1 million after-tax. In January 2016, the FASB issued ASU 2016-01, Financial Instruments. ASU 2016-01 amends the accounting guidance for financial instruments to require all equity investments with readily determinable fair values to be measured at fair value with changes in the fair value recognized in net income (other than those accounted for under equity method of accounting or those that result in consolidation of the investee). The updated guidance was effective for public business entities for annual reporting periods beginning after December 15, 2017 and interim periods within those years. The Company adopted this updated guidance on January 1, 2018 on a prospective basis. The impact of applying this guidance prospectively was a cumulative effect adjustment that increased retained earnings and decreased accumulated other comprehensive income ("AOCI") by offsetting amounts of $291 million , resulting in no net impact to total stockholders' equity. Following the adoption, the Company reported changes in fair value related to equity securities within net realized and unrealized gains on investments. In February 2018, the FASB issued ASU 2018-02, Reporting Comprehensive Income, which amends previous guidance to allow a reclassification to retained earnings for stranded tax effects resulting from the Tax Cuts and Jobs Act of 2017 (the “Tax Act”). The amount of the reclassification includes the effect of the change in the U.S. federal corporate income tax rate on the gross deferred tax amounts and related valuation allowances, if any, at the date of the enactment of the Tax Act related to items in AOCI. The updated guidance will be effective for reporting periods beginning after December 15, 2018, and is eligible for early adoption. The Company adopted this updated guidance on January 1, 2018. The impact of applying this guidance was a cumulative effect adjustment that decreased retained earnings and increased AOCI by offsetting amounts of $76 million , resulting in no net impact to total stockholders' equity. All other accounting and reporting standards that have become effective in 2018 were either not applicable to the Company or their adoption did not have a material impact on the Company. Accounting and reporting standards that are not yet effective: In February 2016, the FASB issued ASU 2016-02, Leases, which amends the accounting and disclosure guidance for leases. This guidance retains the two classifications of a lease, as either an operating or finance lease, both of which will require lessees to recognize a right-of-use asset and a lease liability for leases with terms of more than 12 months. The right-of-use asset and the lease liability will be determined based upon the present value of cash flows. Finance leases will reflect the financial arrangement by recognizing interest expense on the lease liability separately from the amortization expense of the right-of-use asset. Operating leases will recognize lease expense (with no separate recognition of interest expense) on a straight-line basis over the term of the lease. The accounting by lessors is not significantly changed by the updated guidance. The updated guidance is effective for reporting periods beginning after December 15, 2018, and can be adopted prospectively or will require that the earliest comparative period presented include the measurement and recognition of existing leases with an adjustment to equity as if the updated guidance had always been applied. The Company is currently evaluating the impact that the adoption of this guidance will have on its results of operations, financial position and liquidity. In June 2016, the FASB issued ASU 2016-13, Financial Instruments - Credit Losses, which amends the accounting guidance for credit losses on financial instruments. The updated guidance amends the current other-than-temporary impairment model for available-for-sale debt securities by requiring the recognition of impairments relating to credit losses through an allowance account and limits the amount of credit loss to the difference between a security’s amortized cost basis and its fair value. This guidance also applies a new current expected credit loss model for determining credit-related impairments for financial instruments measured at amortized cost. The updated guidance is effective for reporting periods beginning after December 15, 2019. The Company will not be able to determine the impact the adoption of this guidance will have on its results of operations, financial position or liquidity until the year the guidance becomes effective. All other recently issued but not yet effective accounting and reporting standards are either not applicable to the Company or are not expected to have a material impact on the Company.

Per Share Data (Tables)

Per Share Data (Tables)	3 Months Ended
	Mar. 31, 2018
Earnings Per Share [Abstract]
Weighted average number of common shares	The weighted average number of common shares used in the computation of basic and diluted earnings per share was as follows: For the Three Months Ended March 31, (In thousands) 2018 2017 Basic 126,375 121,893 Diluted 128,125 128,453

Consolidated Statements of Co31

Consolidated Statements of Comprehensive Income (Tables)	3 Months Ended
	Mar. 31, 2018
Equity [Abstract]
Components of changes in accumulated other comprehensive income (loss)	The following table presents the components of the changes in accumulated other comprehensive (loss) income ("AOCI"): (In thousands) Unrealized Investment Gains (Losses) Currency Translation Adjustments Accumulated Other Comprehensive (Loss) Income As of and for the three months ended March 31, 2018 Changes in AOCI Beginning of period $ 375,421 $ (306,880 ) $ 68,541 Cumulative effect adjustment resulting from changes in accounting principles (214,539 ) — (214,539 ) Restated beginning of period 160,882 (306,880 ) (145,998 ) Other comprehensive (loss) income before reclassifications (118,189 ) 12,799 (105,390 ) Amounts reclassified from AOCI (7,583 ) — (7,583 ) Other comprehensive (loss) income (125,772 ) 12,799 (112,973 ) Unrealized investment gain related to noncontrolling interest (11 ) — (11 ) End of period $ 35,099 $ (294,081 ) $ (258,982 ) Amounts reclassified from AOCI Pre-tax $ (9,599 ) (1) $ — $ (9,599 ) Tax effect 2,016 (2) — 2,016 After-tax amounts reclassified $ (7,583 ) $ — $ (7,583 ) Other comprehensive (loss) income Pre-tax $ (160,848 ) $ 12,799 $ (148,049 ) Tax effect 35,076 — 35,076 Other comprehensive (loss) income $ (125,772 ) $ 12,799 $ (112,973 ) As of and for the three months ended March 31, 2017: Changes in AOCI Beginning of period $ 427,154 $ (371,586 ) $ 55,568 Other comprehensive income before reclassifications 19,994 22,735 42,729 Amounts reclassified from AOCI (28,825 ) — (28,825 ) Other comprehensive (loss) income (8,831 ) 22,735 13,904 Unrealized investment loss related to noncontrolling interest 19 — 19 End of period $ 418,342 $ (348,851 ) $ 69,491 Amounts reclassified from AOCI Pre-tax $ (44,346 ) (1) $ — $ (44,346 ) Tax effect 15,521 (2) — 15,521 After-tax amounts reclassified $ (28,825 ) $ — $ (28,825 ) Other comprehensive (loss) income Pre-tax $ (9,571 ) $ 22,735 $ 13,164 Tax effect 740 — 740 Other comprehensive (loss) income $ (8,831 ) $ 22,735 $ 13,904 _________________________ (1) Net realized and unrealized gains on investments in the consolidated statements of income. (2) Income tax expense in the consolidated statements of income.

Investments in Fixed Maturity32

Investments in Fixed Maturity Securities (Tables)	3 Months Ended
	Mar. 31, 2018
Investments, Debt and Equity Securities [Abstract]
Schedule of investments in fixed maturity securities	At March 31, 2018 and December 31, 2017 , investments in fixed maturity securities were as follows: (In thousands) Amortized Cost Gross Unrealized Fair Value Carrying Value Gains Losses March 31, 2018 Held to maturity: State and municipal $ 66,459 $ 12,185 $ — $ 78,644 $ 66,459 Residential mortgage-backed 12,772 988 — 13,760 12,772 Total held to maturity 79,231 13,173 — 92,404 79,231 Available for sale: U.S. government and government agency 479,330 6,692 (6,113 ) 479,909 479,909 State and municipal: Special revenue 2,644,248 36,059 (22,675 ) 2,657,632 2,657,632 State general obligation 404,710 12,113 (2,610 ) 414,213 414,213 Pre-refunded 443,852 18,131 (87 ) 461,896 461,896 Corporate backed 368,073 7,415 (1,610 ) 373,878 373,878 Local general obligation 389,887 17,227 (3,209 ) 403,905 403,905 Total state and municipal 4,250,770 90,945 (30,191 ) 4,311,524 4,311,524 Mortgage-backed securities: Residential (1) 1,067,814 6,233 (22,334 ) 1,051,713 1,051,713 Commercial 338,683 1,164 (4,563 ) 335,284 335,284 Total mortgage-backed securities 1,406,497 7,397 (26,897 ) 1,386,997 1,386,997 Asset-backed 2,101,896 11,435 (11,640 ) 2,101,691 2,101,691 Corporate: Industrial 2,378,793 27,145 (31,817 ) 2,374,121 2,374,121 Financial 1,411,529 22,100 (15,031 ) 1,418,598 1,418,598 Utilities 270,915 8,163 (4,546 ) 274,532 274,532 Other 43,682 1 (233 ) 43,450 43,450 Total corporate 4,104,919 57,409 (51,627 ) 4,110,701 4,110,701 Foreign 850,866 25,791 (3,578 ) 873,079 873,079 Total available for sale 13,194,278 199,669 (130,046 ) 13,263,901 13,263,901 Total investments in fixed maturity securities $ 13,273,509 $ 212,842 $ (130,046 ) $ 13,356,305 $ 13,343,132 (In thousands) Amortized Gross Unrealized Fair Carrying Gains Losses December 31, 2017 Held to maturity: State and municipal $ 65,882 $ 14,499 $ — $ 80,381 $ 65,882 Residential mortgage-backed 13,450 1,227 — 14,677 13,450 Total held to maturity 79,332 15,726 — 95,058 79,332 Available for sale: U.S. government and government agency 372,748 8,824 (3,832 ) 377,740 377,740 State and municipal: Special revenue 2,663,245 53,512 (10,027 ) 2,706,730 2,706,730 State general obligation 439,358 16,087 (711 ) 454,734 454,734 Pre-refunded 436,241 22,701 (9 ) 458,933 458,933 Corporate backed 375,268 10,059 (860 ) 384,467 384,467 Local general obligation 417,955 23,242 (967 ) 440,230 440,230 Total state and municipal 4,332,067 125,601 (12,574 ) 4,445,094 4,445,094 Mortgage-backed securities: Residential (1) 1,043,629 9,304 (13,547 ) 1,039,386 1,039,386 Commercial 261,652 1,521 (2,628 ) 260,545 260,545 Total mortgage-backed securities 1,305,281 10,825 (16,175 ) 1,299,931 1,299,931 Asset-backed 2,111,132 11,024 (10,612 ) 2,111,544 2,111,544 Corporate: Industrial 2,574,400 52,210 (7,718 ) 2,618,892 2,618,892 Financial 1,402,161 37,744 (5,138 ) 1,434,767 1,434,767 Utilities 284,886 11,316 (1,248 ) 294,954 294,954 Other 40,560 5 (66 ) 40,499 40,499 Total corporate 4,302,007 101,275 (14,170 ) 4,389,112 4,389,112 Foreign 819,345 32,018 (2,866 ) 848,497 848,497 Total available for sale 13,242,580 289,567 (60,229 ) 13,471,918 13,471,918 Total investments in fixed maturity securities $ 13,321,912 $ 305,293 $ (60,229 ) $ 13,566,976 $ 13,551,250 ____________ (1) Gross unrealized gains (losses) for residential mortgage-backed securities include $89,704 and $76,467 as of March 31, 2018 and December 31, 2017 , respectively, related to securities with the non-credit portion of other-than-temporary impairments (“OTTI”) recognized in accumulated other comprehensive income.
Amortized cost and fair value of fixed maturity securities by contractual maturity	The amortized cost and fair value of fixed maturity securities at March 31, 2018 , by contractual maturity, are shown below. Actual maturities may differ from contractual maturities because certain issuers may have the right to call or prepay obligations. (In thousands) Amortized Cost Fair Value Due in one year or less $ 813,191 $ 816,313 Due after one year through five years 4,580,074 4,621,880 Due after five years through ten years 3,110,432 3,158,810 Due after ten years 3,350,543 3,358,545 Mortgage-backed securities 1,419,269 1,400,757 Total $ 13,273,509 $ 13,356,305

Investments in Equity Securit33

Investments in Equity Securities Available for Sale (Tables)	3 Months Ended
	Mar. 31, 2018
Equity securities
Schedule of Available-for-sale Securities [Line Items]
Schedule of Investments in Equity Securities	At March 31, 2018 and December 31, 2017 , investments in equity securities were as follows: (In thousands) Cost Gross Unrealized (1) Fair Value Carrying Value Gains Losses March 31, 2018 Common stocks $ 95,447 $ 232,206 $ (7,218 ) $ 320,435 $ 320,435 Preferred stocks 124,150 53,423 (1,974 ) 175,599 175,599 Total $ 219,597 $ 285,629 $ (9,192 ) $ 496,034 $ 496,034 December 31, 2017 Common stocks $ 81,855 $ 272,309 $ (1,960 ) $ 352,204 $ 352,204 Preferred stocks 124,150 102,890 (2,597 ) 224,443 224,443 Total $ 206,005 $ 375,199 $ (4,557 ) $ 576,647 $ 576,647 ______________________ (1) Effective January 1, 2018, the Company adopted new accounting guidance that requires all equity investments with readily determinable fair values (subject to certain exceptions) to be measured at fair value with changes in the fair value recognized through net income. Refer to Note 3 for additional information.

Net Investment Income (Tables)

Net Investment Income (Tables)	3 Months Ended
	Mar. 31, 2018
Net Investment Income [Abstract]
Schedule of Net Investment Income	Net investment income consists of the following: For the Three Months Ended March 31, (In thousands) 2018 2017 Investment income earned on: Fixed maturity securities, including cash and cash equivalents and loans receivable $ 123,246 $ 112,346 Investment funds 40,354 26,649 Arbitrage trading account 5,191 6,360 Real estate 6,568 4,566 Equity securities 646 639 Gross investment income 176,005 150,560 Investment expense (1,487 ) (1,702 ) Net investment income $ 174,518 $ 148,858

Investment Funds (Tables)

Investment Funds (Tables)	3 Months Ended
	Mar. 31, 2018
Equity Method Investments and Joint Ventures [Abstract]
Schedule of Investment Funds	Investment funds consisted of the following: Carrying Value as of Income from Investment Funds March 31, December 31, For the Three Months Ended March 31, (In thousands) 2018 2017 2018 2017 Real estate $ 624,716 $ 606,995 $ 26,051 $ 4,532 Energy 80,833 82,882 74 3,245 Other funds 455,578 465,800 14,229 18,872 Total $ 1,161,127 $ 1,155,677 $ 40,354 $ 26,649

Real Estate Real Estate (Tables

Real Estate Real Estate (Tables)	3 Months Ended
	Mar. 31, 2018
Real Estate [Abstract]
Schedule of Real Estate Investments	Investment in real estate represents directly owned property held for investment, as follows: Carrying Value March 31, December 31, (In thousands) 2018 2017 Properties in operation $ 739,405 $ 451,691 Properties under development 1,093,932 1,017,910 Total $ 1,833,337 $ 1,469,601

Loans Receivable Loans Receivab

Loans Receivable Loans Receivable (Tables)	3 Months Ended
	Mar. 31, 2018
Receivables [Abstract]
Schedule of Loans Receivable	Loans receivable are as follows: (In thousands) March 31, 2018 December 31, 2017 Amortized cost (net of valuation allowance): Real estate loans $ 63,191 $ 66,057 Commercial loans 12,711 13,627 Total $ 75,902 $ 79,684 Fair value: Real estate loans $ 64,026 $ 66,917 Commercial loans 14,212 15,130 Total $ 78,238 $ 82,047 Valuation allowance: Specific $ 1,200 $ 1,200 General 2,183 2,183 Total $ 3,383 $ 3,383 For the Three Months Ended March 31, 2018 2017 Decrease in valuation allowance $ — $ (14 )

Realized And Unrealized Inves38

Realized And Unrealized Investment Gains (Losses) (Tables)	3 Months Ended
	Mar. 31, 2018
Realized and Unrealized Investment Gains (Losses) [Abstract]
Realized and Unrealized Investment Gains (Losses)	ealized and unrealized gains (losses) on investments are as follows: For the Three Months Ended March 31, (In thousands) 2018 2017 Net realized and unrealized gains (losses) on investments in earnings Fixed maturity securities: Gains $ 13,339 $ 5,605 Losses (3,740 ) (3,965 ) Equity securities (1): Net realized gains on investment sales 122,321 42,707 Change in unrealized gains (94,205 ) — Investment funds 119 1,267 Real estate 7,998 3,300 Loans receivable 2,058 — Other 574 3,434 Net realized and unrealized gains on investments in earnings before OTTI 48,464 52,348 Other-than-temporary impairments (2) — — Net realized and unrealized gains on investments in earnings 48,464 52,348 Income tax expense (10,177 ) (18,322 ) After-tax net realized and unrealized gains on investments in earnings $ 38,287 $ 34,026
Unrealized Gain (Loss) on Investments	Change in unrealized investment gains of available for sale securities: Fixed maturity securities $ (159,727 ) $ 37,984 Previously impaired fixed maturity securities 13 101 Equity securities available for sale (3) — (48,862 ) Investment funds (1,134 ) 1,206 Total change in unrealized investment gains (160,848 ) (9,571 ) Income tax benefit 35,076 740 Noncontrolling interests (11 ) 19 After-tax change in unrealized investment gains of available for sale securities $ (125,783 ) $ (8,812 ) ______________________ (1) The net realized gains or losses on investment sales represent the total gains or losses from the purchase dates of the equity securities. The change in unrealized gains consists of two components: (i) the reversal of the gain or loss recognized in previous periods on equity securities sold and (ii) the change in unrealized gain or loss resulting from mark-to-market adjustments on equity securities still held. (2) There were no other than temporary impairments (OTTI) for the three months ended March 31, 2018 and 2017 . (3) Effective January 1, 2018, the Company adopted new accounting guidance that requires all equity investments with readily determinable fair values (subject to certain exceptions) to be measured at fair value with changes in the fair value recognized in net income. The Company recorded an adjustment of $291 million to opening AOCI net of tax as a result of this guidance. Refer to Note 3 for further information.

Fixed Maturity Securities In An

Fixed Maturity Securities In An Unrealized Loss Position Securities In An Unrealized Loss Position (Tables)	3 Months Ended
	Mar. 31, 2018
Statement of Financial Position [Abstract]
Securities in an unrealized loss position	The following tables summarize all fixed maturity securities in an unrealized loss position at March 31, 2018 and December 31, 2017 by the length of time those securities have been continuously in an unrealized loss position: Less Than 12 Months 12 Months or Greater Total (In thousands) Fair Value Gross Unrealized Losses Fair Value Gross Unrealized Losses Fair Value Gross Unrealized Losses March 31, 2018 U.S. government and government agency $ 138,917 $ 2,978 $ 71,224 $ 3,135 $ 210,141 $ 6,113 State and municipal 1,514,028 20,922 303,246 9,269 1,817,274 30,191 Mortgage-backed securities 754,800 12,603 362,331 14,294 1,117,131 26,897 Asset-backed securities 1,271,743 9,444 160,263 2,196 1,432,006 11,640 Corporate 1,912,850 42,874 168,813 8,753 2,081,663 51,627 Foreign government 216,681 3,301 25,541 277 242,222 3,578 Fixed maturity securities $ 5,809,019 $ 92,122 $ 1,091,418 $ 37,924 $ 6,900,437 $ 130,046 December 31, 2017 U.S. government and government agency $ 92,167 $ 1,491 $ 72,055 $ 2,341 $ 164,222 $ 3,832 State and municipal 735,972 5,944 345,755 6,630 1,081,727 12,574 Mortgage-backed securities 480,435 5,110 373,956 11,065 854,391 16,175 Asset-backed securities 1,127,309 8,298 167,412 2,314 1,294,721 10,612 Corporate 1,103,747 8,224 170,858 5,946 1,274,605 14,170 Foreign government 244,139 2,615 25,824 251 269,963 2,866 Fixed maturity securities $ 3,783,769 $ 31,682 $ 1,155,860 $ 28,547 $ 4,939,629 $ 60,229
Non-Investment Grade Fixed Maturity Securities	A summary of the Company’s non-investment grade fixed maturity securities that were in an unrealized loss position at March 31, 2018 is presented in the table below: ($ in thousands) Number of Securities Aggregate Fair Value Gross Unrealized Loss Corporate 10 $ 86,345 $ 4,429 Foreign government 8 $ 30,997 $ 739 Asset-backed securities 3 370 140 Mortgage-backed securities 5 4,532 117 State and municipal 1 3,641 3 Total 27 $ 125,885 $ 5,428

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	3 Months Ended
	Mar. 31, 2018
Fair Value Disclosures [Abstract]
Assets And Liabilities Measured At Fair value, On A Recurring Basis	The following tables present the assets and liabilities measured at fair value on a recurring basis as of March 31, 2018 and December 31, 2017 by level: (In thousands) Total Level 1 Level 2 Level 3 March 31, 2018 Assets: Fixed maturity securities available for sale: U.S. government and government agency $ 479,909 $ — $ 479,909 $ — State and municipal 4,311,524 — 4,311,524 — Mortgage-backed securities 1,386,997 — 1,386,997 — Asset-backed securities 2,101,691 — 2,101,528 163 Corporate 4,110,701 — 4,110,701 — Foreign government 873,079 — 873,079 — Total fixed maturity securities available for sale 13,263,901 — 13,263,738 163 Equity securities: Common stocks 320,435 311,329 — 9,106 Preferred stocks 175,599 — 164,756 10,843 Total equity securities 496,034 311,329 164,756 19,949 Arbitrage trading account 744,859 434,470 306,547 3,842 Total $ 14,504,794 $ 745,799 $ 13,735,041 $ 23,954 Liabilities: Trading account securities sold but not yet purchased $ 29,453 $ 29,444 $ 9 $ — December 31, 2017 Assets: Fixed maturity securities available for sale: U.S. government and government agency $ 377,740 $ — $ 377,740 $ — State and municipal 4,445,094 — 4,445,094 — Mortgage-backed securities 1,299,931 — 1,299,931 — Asset-backed securities 2,111,544 — 2,111,372 172 Corporate 4,389,112 — 4,389,112 — Foreign government 848,497 — 848,497 — Total fixed maturity securities available for sale 13,471,918 — 13,471,746 172 Equity securities: Common stocks 352,204 342,834 — 9,370 Preferred stocks 224,443 — 213,600 10,843 Total equity securities 576,647 342,834 213,600 20,213 Arbitrage trading account 617,649 471,420 146,229 — Total $ 14,666,214 $ 814,254 $ 13,831,575 $ 20,385 Liabilities: Trading account securities sold but not yet purchased $ 64,358 $ 64,358 $ — $ —
Summarize Changes In Level 3 Assets	The following tables summarize changes in Level 3 assets and liabilities for the three months ended March 31, 2018 and for the year ended December 31, 2017 : Gains (Losses) Included in: (In thousands) Beginning Balance Earnings (Losses) Other Comprehensive Income (Loss) Impairments Purchases (Sales) Paydowns / Maturities Transfers Ending Balance In / (Out) Three Months Ended March 31, 2018 Assets: Fixed maturities securities available for sale: Asset-backed securities $ 172 $ 2 $ 4 $ — $ — $ (15 ) $ — $ — $ 163 Total 172 2 4 — — (15 ) — — 163 Equity securities: Common stocks 9,370 (264 ) — — — — — — 9,106 Preferred stocks 10,843 — — — — — — — 10,843 Total 20,213 (264 ) — — — — — — 19,949 Arbitrage trading account — (40 ) — — 3,882 — — — 3,842 Total $ 20,385 $ (302 ) $ 4 $ — $ 3,882 $ (15 ) $ — $ — $ 23,954 Year ended December 31, 2017 Assets: Fixed maturities securities available for sale: Asset-backed securities $ 183 $ 3 $ 34 $ — $ — $ (48 ) $ — $ — $ 172 Total 183 3 34 — — (48 ) — — 172 Equity securities: Common stocks 8,754 — 616 — — — — — 9,370 Preferred stocks 3,662 8 — — 7,173 — — — 10,843 Total 12,416 8 616 — 7,173 — — — 20,213 Arbitrage trading account — 8 — — — (8 ) — — — Total $ 12,599 $ 19 $ 650 $ — $ 7,173 $ (56 ) $ — $ — $ 20,385

Reserves for Loss and Loss Ex41

Reserves for Loss and Loss Expenses (Tables)	3 Months Ended
	Mar. 31, 2018
Insurance [Abstract]
Reserve Balances	The table below provides a reconciliation of the beginning and ending reserve balances: March 31, (In thousands) 2018 2017 Net reserves at beginning of year $ 10,056,914 $ 9,590,265 Net provision for losses and loss expenses: Claims occurring during the current year (1) 956,181 958,684 (Decrease) increase in estimates for claims occurring in prior years (2) (3) (3,582 ) 8,727 Loss reserve discount accretion 10,620 12,192 Total 963,219 979,603 Net payments for claims: Current year 111,030 97,461 Prior year 810,709 773,571 Total 921,739 871,032 Foreign currency translation 2,501 23,204 Net reserves at end of period 10,100,895 9,722,040 Ceded reserve at end of period 1,684,000 1,502,284 Gross reserves at end of period $ 11,784,895 $ 11,224,324 _______________________________________ (1) Claims occurring during the current year are net of loss reserve discounts of $ 6,448,000 and $ 5,761,000 for the three months ended March 31, 2018 and 2017 , respectively. (2) The decrease or increase in estimates for claims occurring in prior years is net of loss reserve discount. On an undiscounted basis, the estimates for claims occurring in prior years decreased by $ 6,662,000 and increased by $ 4,841,000 for the three months ended March 31, 2018 and 2017 , respectively. (3) For certain retrospectively rated insurance policies and reinsurance agreements, reserve development is offset by additional or return premiums. Favorable development, net of additional and return premiums, was $12 million and $2 million for the three months ended March 31, 2018 and 2017 , respectively.

Fair Value of Financial Instr42

Fair Value of Financial Instruments (Tables)	3 Months Ended
	Mar. 31, 2018
Fair Value Disclosures [Abstract]
Carrying Amounts And Estimated Fair Values Of Financial Instruments	The following table presents the carrying amounts and estimated fair values of the Company’s financial instruments: March 31, 2018 December 31, 2017 (In thousands) Carrying Value Fair Value Carrying Value Fair Value Assets: Fixed maturity securities $ 13,343,132 $ 13,356,305 $ 13,551,250 $ 13,566,976 Equity securities 496,034 496,034 576,647 576,647 Arbitrage trading account 744,859 744,859 617,649 617,649 Loans receivable 75,902 78,238 79,684 82,047 Cash and cash equivalents 956,603 956,603 950,471 950,471 Trading account receivables from brokers and clearing organizations 26,667 26,667 189,280 189,280 Liabilities: Due to broker 74,450 74,450 15,920 15,920 Trading account securities sold but not yet purchased 29,453 29,453 64,358 64,358 Subordinated debentures 897,426 929,948 728,218 769,060 Senior notes and other debt 1,782,139 1,921,635 1,769,052 1,945,313

Reinsurance (Tables)

Reinsurance (Tables)	3 Months Ended
	Mar. 31, 2018
Insurance [Abstract]
Reinsurance Financial Information	The following is a summary of reinsurance financial information: For the Three Months Ended March 31, (In thousands) 2018 2017 Written premiums: Direct $ 1,787,235 $ 1,721,062 Assumed 192,187 215,145 Ceded (314,084 ) (289,369 ) Total net premiums written $ 1,665,338 $ 1,646,838 Earned premiums: Direct $ 1,674,550 $ 1,613,364 Assumed 188,866 208,626 Ceded (296,008 ) (251,948 ) Total net premiums earned $ 1,567,408 $ 1,570,042 Ceded losses and loss expenses incurred $ 238,995 $ 35,192 Ceded commissions earned $ 66,356 $ 56,550

Restricted Stock Units (Tables)

Restricted Stock Units (Tables)	3 Months Ended
	Mar. 31, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Summary Of Restricted Stock Units Issued	A summary of RSUs issued in the three months ended March 31, 2018 and 2017 follows: ($ in thousands) Units Fair Value 2018 4,174 $ 290 2017 1,853 $ 129

Business Segments (Tables)

Business Segments (Tables)	3 Months Ended
	Mar. 31, 2018
Segment Reporting [Abstract]
Financial Information Of Company Operating Segments	Summary financial information about the Company's reporting segments is presented in the following tables. Income (loss) before income taxes by segment includes allocated investment income. Identifiable assets by segment are those assets used in or allocated to the operation of each segment. Revenues (In thousands) Earned Premiums Investment Income Other Total (1) Pre-Tax Income (Loss) Net Income (Loss) to Common Stockholders Three months ended March 31, 2018 Insurance $ 1,432,337 $ 135,862 $ 18,968 $ 1,587,167 $ 229,028 $ 181,626 Reinsurance 135,071 24,650 — 159,721 14,592 11,654 Corporate, other and eliminations (2) — 14,006 81,889 95,895 (81,094 ) (65,170 ) Net realized and unrealized gains on investments — — 48,464 48,464 48,464 38,286 Total $ 1,567,408 $ 174,518 $ 149,321 $ 1,891,247 $ 210,990 $ 166,396 Three months ended March 31, 2017 Insurance $ 1,413,170 $ 111,909 $ 18,287 $ 1,543,366 $ 199,994 $ 134,095 Reinsurance 156,872 24,778 — 181,650 4,594 3,099 Corporate, other and eliminations (2) — 12,171 80,883 93,054 (72,639 ) (47,773 ) Net realized and unrealized gains on investments — — 52,348 52,348 52,348 34,026 Total $ 1,570,042 $ 148,858 $ 151,518 $ 1,870,418 $ 184,297 $ 123,447 _________________ (1) Revenues for Insurance from foreign countries for the three months ended March 31, 2018 and 2017 were $183 million and $184 million , respectively. Revenues for Reinsurance from foreign countries for the three months ended March 31, 2018 and 2017 were $56 million and $49 million , respectively. (2) Corporate, other and eliminations represent corporate revenues and expenses that are not allocated to business segments.
Identifiable Assets By Segment	Identifiable Assets (In thousands) March 31, 2018 December 31, 2017 Insurance $ 19,322,526 $ 19,263,193 Reinsurance 3,093,808 3,169,731 Corporate, other and eliminations 2,171,498 1,866,993 Consolidated $ 24,587,832 $ 24,299,917
Net Premiums Earned By Major Line Of Business	Net premiums earned by major line of business are as follows: For the Three Months Ended March 31, (In thousands) 2018 2017 Insurance: Other liability $ 464,167 $ 451,830 Workers’ compensation 365,948 361,136 Short-tail lines (1) 295,105 296,790 Commercial automobile 175,199 170,571 Professional liability 131,918 132,843 Total Insurance 1,432,337 1,413,170 Reinsurance: Casualty 90,570 94,739 Property 44,501 62,133 Total Reinsurance 135,071 156,872 Total $ 1,567,408 $ 1,570,042 ______________ (1) Short-tail lines include commercial multi-peril (non-liability), inland marine, accident and health, fidelity and surety, boiler and machinery and other lines.

General (Details)

General (Details)	3 Months Ended
	Mar. 31, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Federal Income Tax Rate	21.00%

Per Share Data (Narrative) (Det

Per Share Data (Narrative) (Details) - shares	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Earnings Per Share [Abstract]
Weighted average number of shares held in grantor trust	4,847,303	4,087,731

Per Share Data (Weighted Averag

Per Share Data (Weighted Average Number of Common Shares Used In the Computation of Basic and Diluted Earnings per Share) (Details) - shares shares in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Earnings Per Share [Abstract]
Basic (shares)	126,375	121,893
Diluted (shares)	128,125	128,453

Recent Accounting Pronounceme49

Recent Accounting Pronouncements (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Jan. 01, 2018	Dec. 31, 2017
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Increase in retained earnings	$ 7,322,201		$ 6,956,882
Increase (decrease) in accumulated other comprehensive income	$ (258,982)		$ 68,541
Accounting Standards Update 2014-09 | Difference Between Revenue Guidance In Effect Before And After Topic 606
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Increase in retained earnings		$ 1,000
Retained earnings | Accounting Standards Update 2016-01
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Cumulative effect adjustment resulting from changes in accounting principles		291,000
Retained earnings | Accounting Standards Update 2018-02
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Cumulative effect adjustment resulting from changes in accounting principles		(76,000)
AOCI Including Portion Attributable to Noncontrolling Interest | Accounting Standards Update 2016-01
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Increase (decrease) in accumulated other comprehensive income		(291,000)
AOCI Including Portion Attributable to Noncontrolling Interest | Accounting Standards Update 2018-02
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Increase (decrease) in accumulated other comprehensive income		$ 76,000

Consolidated Statements of Co50

Consolidated Statements of Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning of period	$ 68,541
Other comprehensive income (loss)	(112,973)	$ 13,904
End of period	(258,982)
Net realized and unrealized gains on investments	48,464	52,348
Income before income taxes	210,990	184,297
Tax effect	(43,417)	(59,623)
Net income before noncontrolling interests	167,573	124,674
Net change in period	12,799	22,735
Other comprehensive income (loss), pre-tax	(148,049)	13,164
Other comprehensive income (loss), tax effect	35,076	740
Accumulated Other Comprehensive Income (Loss)
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning of period	(145,998)	55,568
Other comprehensive income (loss) before reclassifications	(105,390)	42,729
Amounts reclassified from AOCI	(7,583)	(28,825)
Other comprehensive income (loss)	(112,973)	13,904
Unrealized investment gain related to noncontrolling interest	(11)	19
End of period	(258,982)	69,491
Accumulated Other Comprehensive Income (Loss) | Amounts reclassified from AOCI
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Income before income taxes	(9,599)	(44,346)
Tax effect	2,016	15,521
Net income before noncontrolling interests	(7,583)	(28,825)
Unrealized Investment Gains (Losses)
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning of period	160,882	427,154
Other comprehensive income (loss) before reclassifications	(118,189)	19,994
Amounts reclassified from AOCI	(7,583)	(28,825)
Other comprehensive income (loss)	(125,772)	(8,831)
Unrealized investment gain related to noncontrolling interest	(11)	19
End of period	35,099	418,342
Unrealized investment gains, pre-tax	(160,848)	(9,571)
Unrealized investment gains, tax effect	35,076	740
Unrealized investment gains (losses), after-tax amounts	(125,772)	(8,831)
Unrealized Investment Gains (Losses) | Amounts reclassified from AOCI
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Net realized and unrealized gains on investments	(9,599)	(44,346)
Tax effect	2,016	15,521
Net income before noncontrolling interests	(7,583)	(28,825)
Currency Translation Adjustments
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning of period	(306,880)	(371,586)
Other comprehensive income (loss) before reclassifications	12,799	22,735
Amounts reclassified from AOCI	0	0
Other comprehensive income (loss)	12,799	22,735
Unrealized investment gain related to noncontrolling interest	0	0
End of period	(294,081)	(348,851)
Currency translation adjustment, pre-tax	12,799	22,735
Currency translation adjustment, tax effect	0	0
Net change in period	12,799	22,735
Currency Translation Adjustments | Amounts reclassified from AOCI
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Income before income taxes	0	0
Tax effect	0	0
Net income before noncontrolling interests	0	$ 0
Scenario, Previously Reported | Accumulated Other Comprehensive Income (Loss)
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning of period	68,541
Scenario, Previously Reported | Unrealized Investment Gains (Losses)
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning of period	375,421
Scenario, Previously Reported | Currency Translation Adjustments
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning of period	(306,880)
Restatement Adjustment | Accumulated Other Comprehensive Income (Loss)
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning of period	(214,539)
Restatement Adjustment | Unrealized Investment Gains (Losses)
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning of period	(214,539)
Restatement Adjustment | Currency Translation Adjustments
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning of period	$ 0

Statements of Cash Flow (Detail

Statements of Cash Flow (Details) - USD ($)	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Supplemental Cash Flow Elements [Abstract]
Interest payments	$ 61,890,000	$ 61,782,000
Income taxes paid	$ 0	$ 1,610,000

Investments in Fixed Maturity52

Investments in Fixed Maturity Securities (Investments in fixed maturity securities) (Details) - USD ($)	Mar. 31, 2018	Dec. 31, 2017
Schedule of Available-for-sale Securities [Line Items]
Total held to maturity, Amortized Cost	$ 79,231,000	$ 79,332,000
Held to Maturity Securities Accumulated Unrecognized Holding Gain	13,173,000	15,726,000
Held to Maturity Securities Accumulated Unrecognized Holding Loss	0	0
Total held to maturity, Fair Value	92,404,000	95,058,000
Total held to maturity, Carrying Value	79,231,000	79,332,000
Total available for sale, Amortized Cost	13,194,278,000	13,242,580,000
Total available for sale, Gross Unrealized Gains	199,669,000	289,567,000
Total available for sale, Gross Unrealized Losses	(130,046,000)	(60,229,000)
Total available for sale, Fair Value	13,263,901,000	13,471,918,000
Total available for sale, Carrying Value	13,263,901,000	13,471,918,000
Total investments in fixed maturity securities, Amortized Value	13,273,509,000	13,321,912,000
Total investments in fixed maturity securities, Gross Unrealized Gains	212,842,000	305,293,000
Total investments in fixed maturity securities, Gross Unrealized Losses	(130,046,000)	(60,229,000)
Total investments in fixed maturity securities, Fair Value	13,356,305,000	13,566,976,000
Total investments in fixed maturity securities, Carrying Value	13,343,132,000	13,551,250,000
U.S. government and government agency
Schedule of Available-for-sale Securities [Line Items]
Total available for sale, Amortized Cost	479,330,000	372,748,000
Total available for sale, Gross Unrealized Gains	6,692,000	8,824,000
Total available for sale, Gross Unrealized Losses	(6,113,000)	(3,832,000)
Total available for sale, Fair Value	479,909,000	377,740,000
Total available for sale, Carrying Value	479,909,000	377,740,000
Special revenue
Schedule of Available-for-sale Securities [Line Items]
Total available for sale, Amortized Cost	2,644,248,000	2,663,245,000
Total available for sale, Gross Unrealized Gains	36,059,000	53,512,000
Total available for sale, Gross Unrealized Losses	(22,675,000)	(10,027,000)
Total available for sale, Fair Value	2,657,632,000	2,706,730,000
Total available for sale, Carrying Value	2,657,632,000	2,706,730,000
State general obligation
Schedule of Available-for-sale Securities [Line Items]
Total available for sale, Amortized Cost	404,710,000	439,358,000
Total available for sale, Gross Unrealized Gains	12,113,000	16,087,000
Total available for sale, Gross Unrealized Losses	(2,610,000)	(711,000)
Total available for sale, Fair Value	414,213,000	454,734,000
Total available for sale, Carrying Value	414,213,000	454,734,000
Pre-refunded
Schedule of Available-for-sale Securities [Line Items]
Total available for sale, Amortized Cost	443,852,000	436,241,000
Total available for sale, Gross Unrealized Gains	18,131,000	22,701,000
Total available for sale, Gross Unrealized Losses	(87,000)	(9,000)
Total available for sale, Fair Value	461,896,000	458,933,000
Total available for sale, Carrying Value	461,896,000	458,933,000
Corporate backed
Schedule of Available-for-sale Securities [Line Items]
Total available for sale, Amortized Cost	368,073,000	375,268,000
Total available for sale, Gross Unrealized Gains	7,415,000	10,059,000
Total available for sale, Gross Unrealized Losses	(1,610,000)	(860,000)
Total available for sale, Fair Value	373,878,000	384,467,000
Total available for sale, Carrying Value	373,878,000	384,467,000
Local general obligation
Schedule of Available-for-sale Securities [Line Items]
Total available for sale, Amortized Cost	389,887,000	417,955,000
Total available for sale, Gross Unrealized Gains	17,227,000	23,242,000
Total available for sale, Gross Unrealized Losses	(3,209,000)	(967,000)
Total available for sale, Fair Value	403,905,000	440,230,000
Total available for sale, Carrying Value	403,905,000	440,230,000
State and municipal
Schedule of Available-for-sale Securities [Line Items]
Total available for sale, Amortized Cost	4,250,770,000	4,332,067,000
Total available for sale, Gross Unrealized Gains	90,945,000	125,601,000
Total available for sale, Gross Unrealized Losses	(30,191,000)	(12,574,000)
Total available for sale, Fair Value	4,311,524,000	4,445,094,000
Total available for sale, Carrying Value	4,311,524,000	4,445,094,000
Mortgage-backed securities
Schedule of Available-for-sale Securities [Line Items]
Total available for sale, Amortized Cost	1,406,497,000	1,305,281,000
Total available for sale, Gross Unrealized Gains	7,397,000	10,825,000
Total available for sale, Gross Unrealized Losses	(26,897,000)	(16,175,000)
Total available for sale, Fair Value	1,386,997,000	1,299,931,000
Total available for sale, Carrying Value	1,386,997,000	1,299,931,000
Residential
Schedule of Available-for-sale Securities [Line Items]
Total available for sale, Amortized Cost	1,067,814,000	1,043,629,000
Total available for sale, Gross Unrealized Gains	6,233,000	9,304,000
Total available for sale, Gross Unrealized Losses	(22,334,000)	(13,547,000)
Total available for sale, Fair Value	1,051,713,000	1,039,386,000
Total available for sale, Carrying Value	1,051,713,000	1,039,386,000
Gross unrealized gains (losses) related to securities	89,704	76,467
Commercial
Schedule of Available-for-sale Securities [Line Items]
Total available for sale, Amortized Cost	338,683,000	261,652,000
Total available for sale, Gross Unrealized Gains	1,164,000	1,521,000
Total available for sale, Gross Unrealized Losses	(4,563,000)	(2,628,000)
Total available for sale, Fair Value	335,284,000	260,545,000
Total available for sale, Carrying Value	335,284,000	260,545,000
Asset-backed
Schedule of Available-for-sale Securities [Line Items]
Total available for sale, Amortized Cost	2,101,896,000	2,111,132,000
Total available for sale, Gross Unrealized Gains	11,435,000	11,024,000
Total available for sale, Gross Unrealized Losses	(11,640,000)	(10,612,000)
Total available for sale, Fair Value	2,101,691,000	2,111,544,000
Total available for sale, Carrying Value	2,101,691,000	2,111,544,000
Corporate
Schedule of Available-for-sale Securities [Line Items]
Total available for sale, Amortized Cost	4,104,919,000	4,302,007,000
Total available for sale, Gross Unrealized Gains	57,409,000	101,275,000
Total available for sale, Gross Unrealized Losses	(51,627,000)	(14,170,000)
Total available for sale, Fair Value	4,110,701,000	4,389,112,000
Total available for sale, Carrying Value	4,110,701,000	4,389,112,000
Industrial
Schedule of Available-for-sale Securities [Line Items]
Total available for sale, Amortized Cost	2,378,793,000	2,574,400,000
Total available for sale, Gross Unrealized Gains	27,145,000	52,210,000
Total available for sale, Gross Unrealized Losses	(31,817,000)	(7,718,000)
Total available for sale, Fair Value	2,374,121,000	2,618,892,000
Total available for sale, Carrying Value	2,374,121,000	2,618,892,000
Financial
Schedule of Available-for-sale Securities [Line Items]
Total available for sale, Amortized Cost	1,411,529,000	1,402,161,000
Total available for sale, Gross Unrealized Gains	22,100,000	37,744,000
Total available for sale, Gross Unrealized Losses	(15,031,000)	(5,138,000)
Total available for sale, Fair Value	1,418,598,000	1,434,767,000
Total available for sale, Carrying Value	1,418,598,000	1,434,767,000
Utilities
Schedule of Available-for-sale Securities [Line Items]
Total available for sale, Amortized Cost	270,915,000	284,886,000
Total available for sale, Gross Unrealized Gains	8,163,000	11,316,000
Total available for sale, Gross Unrealized Losses	(4,546,000)	(1,248,000)
Total available for sale, Fair Value	274,532,000	294,954,000
Total available for sale, Carrying Value	274,532,000	294,954,000
Other
Schedule of Available-for-sale Securities [Line Items]
Total available for sale, Amortized Cost	43,682,000	40,560,000
Total available for sale, Gross Unrealized Gains	1,000	5,000
Total available for sale, Gross Unrealized Losses	(233,000)	(66,000)
Total available for sale, Fair Value	43,450,000	40,499,000
Total available for sale, Carrying Value	43,450,000	40,499,000
Foreign
Schedule of Available-for-sale Securities [Line Items]
Total available for sale, Amortized Cost	850,866,000	819,345,000
Total available for sale, Gross Unrealized Gains	25,791,000	32,018,000
Total available for sale, Gross Unrealized Losses	(3,578,000)	(2,866,000)
Total available for sale, Fair Value	873,079,000	848,497,000
Total available for sale, Carrying Value	873,079,000	848,497,000
State and municipal
Schedule of Available-for-sale Securities [Line Items]
Total held to maturity, Amortized Cost	66,459,000	65,882,000
Held to Maturity Securities Accumulated Unrecognized Holding Gain	12,185,000	14,499,000
Held to Maturity Securities Accumulated Unrecognized Holding Loss	0	0
Total held to maturity, Fair Value	78,644,000	80,381,000
Total held to maturity, Carrying Value	66,459,000	65,882,000
Residential
Schedule of Available-for-sale Securities [Line Items]
Total held to maturity, Amortized Cost	12,772,000	13,450,000
Held to Maturity Securities Accumulated Unrecognized Holding Gain	988,000	1,227,000
Held to Maturity Securities Accumulated Unrecognized Holding Loss	0	0
Total held to maturity, Fair Value	13,760,000	14,677,000
Total held to maturity, Carrying Value	$ 12,772,000	$ 13,450,000

Investments In Fixed Maturity53

Investments In Fixed Maturity Securities Investments in Fixed Maturity Securities (Amortized cost and fair value of fixed maturity securities) (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Investments, Debt and Equity Securities [Abstract]
Amortized Cost, Due in one year or less	$ 813,191
Amortized Cost, Due after one year through five years	4,580,074
Amortized Cost, Due after five years through ten years	3,110,432
Amortized Cost, Due after ten years	3,350,543
Amortized Cost, Mortgaged-backed securities	1,419,269
Total investments in fixed maturity securities, Amortized Value	13,273,509	$ 13,321,912
Fair Value, Due in one year or less	816,313
Fair Value, Due after one year through five years	4,621,880
Fair Value, Due after five years through ten years	3,158,810
Fair Value, Due after ten years	3,358,545
Fair Value, Mortgage-backed securities	1,400,757
Total investments in fixed maturity securities, Fair Value	$ 13,356,305	$ 13,566,976

Investments in Equity Securit54

Investments in Equity Securities Available for Sale (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Schedule of Available-for-sale Securities [Line Items]
Equity securities	$ 496,034	$ 576,647
Fair Value
Schedule of Available-for-sale Securities [Line Items]
Cost	219,597	206,005
Gross Unrealized, Gains	285,629	375,199
Gross Unrealized, Losses	(9,192)	(4,557)
Equity securities	496,034	576,647
Fair Value | Common stock
Schedule of Available-for-sale Securities [Line Items]
Cost	95,447	81,855
Gross Unrealized, Gains	232,206	272,309
Gross Unrealized, Losses	(7,218)	(1,960)
Equity securities	320,435	352,204
Fair Value | Preferred stocks
Schedule of Available-for-sale Securities [Line Items]
Cost	124,150	124,150
Gross Unrealized, Gains	53,423	102,890
Gross Unrealized, Losses	(1,974)	(2,597)
Equity securities	175,599	224,443
Carrying Value
Schedule of Available-for-sale Securities [Line Items]
Equity securities	496,034	576,647
Carrying Value | Common stock
Schedule of Available-for-sale Securities [Line Items]
Equity securities	320,435	352,204
Carrying Value | Preferred stocks
Schedule of Available-for-sale Securities [Line Items]
Equity securities	$ 175,599	$ 224,443

Arbitrage Trading Account (Deta

Arbitrage Trading Account (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Derivative [Line Items]
Arbitrage trading account	$ 744,859	$ 617,649
Long | Options held
Derivative [Line Items]
Fair value of derivative	1,000
Notional amount of derivative	17,600
Short | Options held
Derivative [Line Items]
Fair value of derivative	200
Notional amount of derivative	$ 27,000

Net Investment Income (Details)

Net Investment Income (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Net Investment Income [Line Items]
Gross investment income	$ 176,005	$ 150,560
Investment expense	(1,487)	(1,702)
Net investment income	174,518	148,858
Fixed maturity securities, including cash and cash equivalents and loans receivable
Net Investment Income [Line Items]
Gross investment income	123,246	112,346
Investment funds
Net Investment Income [Line Items]
Gross investment income	40,354	26,649
Arbitrage trading account
Net Investment Income [Line Items]
Gross investment income	5,191	6,360
Real estate
Net Investment Income [Line Items]
Gross investment income	6,568	4,566
Equity securities
Net Investment Income [Line Items]
Gross investment income	$ 646	$ 639

Investment Funds Investment Fun

Investment Funds Investment Funds (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Schedule of Equity Method Investments [Line Items]
Unfunded commitments	$ 376,000
Investment funds	1,161,127		$ 1,155,677
Income from Investment Funds	40,354	$ 26,649
Real estate
Schedule of Equity Method Investments [Line Items]
Investment funds	624,716		606,995
Income from Investment Funds	26,051	4,532
Energy
Schedule of Equity Method Investments [Line Items]
Investment funds	80,833		82,882
Income from Investment Funds	74	3,245
Other funds
Schedule of Equity Method Investments [Line Items]
Investment funds	455,578		$ 465,800
Income from Investment Funds	$ 14,229	$ 18,872

Real Estate Real Estate (Detail

Real Estate Real Estate (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Real Estate [Abstract]
Properties in operation	$ 739,405	$ 451,691
Properties under development	1,093,932	1,017,910
Total	$ 1,833,337	$ 1,469,601

Real Estate Real Estate (Narrat

Real Estate Real Estate (Narrative) (Details) - USD ($)	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Real Estate [Abstract]
Accumulated depreciation and amortization on properties	$ 29,477,000		$ 25,646,000
Real estate depreciation expense	3,815,000	$ 1,648,000
Lease future minimum payments 2017	38,716,924
Lease future minimum payments 2018	54,741,633
Lease future minimum payments 2019	53,127,758
Lease future minimum payments 2020	52,210,617
Lease future minimum payments 2021	48,472,505
Lease future minimum payments 2022	41,829,736
Lease future minimum payments there after	$ 498,985,951

Loans Receivable (Details)

Loans Receivable (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans receivable, gross	$ 75,902		$ 79,684
Loans receivable	78,238		82,047
Valuation allowance, specific	1,200		1,200
Valuation allowance, general	2,183		2,183
Valuation allowance of loans receivable	3,383		3,383
(Decrease) increase in valuation allowance	0	$ (14)
Loans in nonaccrual status	1,500		4,300
Real estate loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans receivable, gross	63,191		66,057
Loans receivable	64,026		66,917
Commercial loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans receivable, gross	12,711		13,627
Loans receivable	$ 14,212		$ 15,130

Realized and Unrealized Inves61

Realized and Unrealized Investment Gains (Losses) (Realized and unrealized investmetns gains(losses)) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Realized and Unrealized Investment Gains Losses [Line Items]
Fixed maturity securities, gains	$ 13,339	$ 5,605
Fixed maturity securities, losses	(3,740)	(3,965)
Net realized gains on investment sales	122,321	42,707
Change in unrealized gains	(94,205)	0
Investment funds	119	1,267
Real estate	7,998	3,300
Loans receivable	2,058	0
Other	574	3,434
Net realized and unrealized gains on investments in earnings before OTTI	48,464	52,348
Other-than-temporary impairments	0	0
Net realized and unrealized gains on investments in earnings	48,464	52,348
Income tax expense	(10,177)	(18,322)
After-tax net realized and unrealized gains on investments in earnings	$ 38,287	$ 34,026

Realized and Unrealized Inves62

Realized and Unrealized Investment Gains (Losses) (Change in Unrealized Gains (Losses) of Available For Sales Securities) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Jan. 01, 2018	Dec. 31, 2017
Realized and Unrealized Investment Gains Losses [Line Items]
Total change in unrealized investment gains	$ (160,848)	$ (9,571)
Income tax benefit	35,076	740
Noncontrolling interests	(11)	19
Total change in unrealized gains	(125,783)	(8,812)
Increase (decrease) in accumulated other comprehensive income	(258,982)			$ 68,541
Debt securities
Realized and Unrealized Investment Gains Losses [Line Items]
Total change in unrealized investment gains	(159,727)	37,984
Previously impaired fixed maturity securities
Realized and Unrealized Investment Gains Losses [Line Items]
Total change in unrealized investment gains	13	101
Equity securities
Realized and Unrealized Investment Gains Losses [Line Items]
Total change in unrealized investment gains	0	(48,862)
Investment funds
Realized and Unrealized Investment Gains Losses [Line Items]
Total change in unrealized investment gains	$ (1,134)	$ 1,206
AOCI Including Portion Attributable to Noncontrolling Interest | Accounting Standards Update 2016-01
Realized and Unrealized Investment Gains Losses [Line Items]
Increase (decrease) in accumulated other comprehensive income			$ (291,000)

Securities in an Unrealized L63

Securities in an Unrealized Loss Position (Securities in an Unrealized Loss Position) (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Debt securities
Schedule of Available-for-sale Securities [Line Items]
Fair Value, Less than 12 Months	$ 5,809,019	$ 3,783,769
Gross Unrealized Losses, Less than 12 Months	92,122	31,682
Fair Value, 12 Months or Greater	1,091,418	1,155,860
Gross Unrealized Losses, 12 Months or Greater	37,924	28,547
Fair Value, Total	6,900,437	4,939,629
Gross Unrealized Losses, Total	130,046	60,229
U.S. government and government agency
Schedule of Available-for-sale Securities [Line Items]
Fair Value, Less than 12 Months	138,917	92,167
Gross Unrealized Losses, Less than 12 Months	2,978	1,491
Fair Value, 12 Months or Greater	71,224	72,055
Gross Unrealized Losses, 12 Months or Greater	3,135	2,341
Fair Value, Total	210,141	164,222
Gross Unrealized Losses, Total	6,113	3,832
State and municipal
Schedule of Available-for-sale Securities [Line Items]
Fair Value, Less than 12 Months	1,514,028	735,972
Gross Unrealized Losses, Less than 12 Months	20,922	5,944
Fair Value, 12 Months or Greater	303,246	345,755
Gross Unrealized Losses, 12 Months or Greater	9,269	6,630
Fair Value, Total	1,817,274	1,081,727
Gross Unrealized Losses, Total	30,191	12,574
Mortgage-backed securities
Schedule of Available-for-sale Securities [Line Items]
Fair Value, Less than 12 Months	754,800	480,435
Gross Unrealized Losses, Less than 12 Months	12,603	5,110
Fair Value, 12 Months or Greater	362,331	373,956
Gross Unrealized Losses, 12 Months or Greater	14,294	11,065
Fair Value, Total	1,117,131	854,391
Gross Unrealized Losses, Total	26,897	16,175
Asset-backed
Schedule of Available-for-sale Securities [Line Items]
Fair Value, Less than 12 Months	1,271,743	1,127,309
Gross Unrealized Losses, Less than 12 Months	9,444	8,298
Fair Value, 12 Months or Greater	160,263	167,412
Gross Unrealized Losses, 12 Months or Greater	2,196	2,314
Fair Value, Total	1,432,006	1,294,721
Gross Unrealized Losses, Total	11,640	10,612
Corporate
Schedule of Available-for-sale Securities [Line Items]
Fair Value, Less than 12 Months	1,912,850	1,103,747
Gross Unrealized Losses, Less than 12 Months	42,874	8,224
Fair Value, 12 Months or Greater	168,813	170,858
Gross Unrealized Losses, 12 Months or Greater	8,753	5,946
Fair Value, Total	2,081,663	1,274,605
Gross Unrealized Losses, Total	51,627	14,170
Foreign government
Schedule of Available-for-sale Securities [Line Items]
Fair Value, Less than 12 Months	216,681	244,139
Gross Unrealized Losses, Less than 12 Months	3,301	2,615
Fair Value, 12 Months or Greater	25,541	25,824
Gross Unrealized Losses, 12 Months or Greater	277	251
Fair Value, Total	242,222	269,963
Gross Unrealized Losses, Total	$ 3,578	$ 2,866

Securities In An Unrealized L64

Securities In An Unrealized Loss Position (Non-Investment Grade Fixed Maturity Securities) (Details) $ in Thousands	Mar. 31, 2018USD ($)position	Dec. 31, 2017USD ($)
Mortgage-backed securities
Schedule of Available-for-sale Securities [Line Items]
Aggregate Fair Value	$ 1,117,131	$ 854,391
Corporate
Schedule of Available-for-sale Securities [Line Items]
Aggregate Fair Value	2,081,663	1,274,605
Asset-backed securities
Schedule of Available-for-sale Securities [Line Items]
Aggregate Fair Value	$ 1,432,006	$ 1,294,721
Noninvestment Grade Investments at Loss Position
Schedule of Available-for-sale Securities [Line Items]
Number of Securities	27
Aggregate Fair Value	$ 125,885
Gross Unrealized Loss	$ 5,428
Noninvestment Grade Investments at Loss Position | Foreign government
Schedule of Available-for-sale Securities [Line Items]
Number of Securities	8
Aggregate Fair Value	$ 30,997
Gross Unrealized Loss	$ 739
Noninvestment Grade Investments at Loss Position | Mortgage-backed securities
Schedule of Available-for-sale Securities [Line Items]
Number of Securities	5
Aggregate Fair Value	$ 4,532
Gross Unrealized Loss	$ 117
Noninvestment Grade Investments at Loss Position | Corporate
Schedule of Available-for-sale Securities [Line Items]
Number of Securities	10
Aggregate Fair Value	$ 86,345
Gross Unrealized Loss	$ 4,429
Noninvestment Grade Investments at Loss Position | Asset-backed securities
Schedule of Available-for-sale Securities [Line Items]
Number of Securities | position	3
Aggregate Fair Value	$ 370
Gross Unrealized Loss	$ 140
Noninvestment Grade Investments at Loss Position | State and municipal
Schedule of Available-for-sale Securities [Line Items]
Number of Securities	1
Aggregate Fair Value	$ 3,641
Gross Unrealized Loss	$ 3

Fair Value Measurements (Assets

Fair Value Measurements (Assets and Liabilities Measured At Fair Value, On a Recurring Basis) (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Assets:
Total fixed maturity securities available for sale	$ 13,263,901	$ 13,471,918
Equity securities	496,034	576,647
Arbitrage trading account	744,859	617,649
Fair Value, Measurements, Recurring
Assets:
Total fixed maturity securities available for sale	13,263,901	13,471,918
Equity securities	496,034	576,647
Arbitrage trading account	744,859	617,649
Assets, fair value disclosure	14,504,794	14,666,214
Liabilities:
Securities sold but not yet purchased	29,453	64,358
Fair Value, Measurements, Recurring | U.S. government and government agency
Assets:
Total fixed maturity securities available for sale	479,909	377,740
Fair Value, Measurements, Recurring | State and municipal
Assets:
Total fixed maturity securities available for sale	4,311,524	4,445,094
Fair Value, Measurements, Recurring | Mortgage-backed securities
Assets:
Total fixed maturity securities available for sale	1,386,997	1,299,931
Fair Value, Measurements, Recurring | Asset-backed
Assets:
Total fixed maturity securities available for sale	2,101,691	2,111,544
Fair Value, Measurements, Recurring | Corporate
Assets:
Total fixed maturity securities available for sale	4,110,701	4,389,112
Fair Value, Measurements, Recurring | Foreign government
Assets:
Total fixed maturity securities available for sale	873,079	848,497
Fair Value, Measurements, Recurring | Common stocks
Assets:
Equity securities	320,435	352,204
Fair Value, Measurements, Recurring | Preferred stocks
Assets:
Equity securities	175,599	224,443
Level 1 | Fair Value, Measurements, Recurring
Assets:
Total fixed maturity securities available for sale	0	0
Equity securities	311,329	342,834
Arbitrage trading account	434,470	471,420
Assets, fair value disclosure	745,799	814,254
Liabilities:
Securities sold but not yet purchased	29,444	64,358
Level 1 | Fair Value, Measurements, Recurring | U.S. government and government agency
Assets:
Total fixed maturity securities available for sale	0	0
Level 1 | Fair Value, Measurements, Recurring | State and municipal
Assets:
Total fixed maturity securities available for sale	0	0
Level 1 | Fair Value, Measurements, Recurring | Mortgage-backed securities
Assets:
Total fixed maturity securities available for sale	0	0
Level 1 | Fair Value, Measurements, Recurring | Asset-backed
Assets:
Total fixed maturity securities available for sale	0	0
Level 1 | Fair Value, Measurements, Recurring | Corporate
Assets:
Total fixed maturity securities available for sale	0	0
Level 1 | Fair Value, Measurements, Recurring | Foreign government
Assets:
Total fixed maturity securities available for sale	0	0
Level 1 | Fair Value, Measurements, Recurring | Common stocks
Assets:
Equity securities	311,329	342,834
Level 1 | Fair Value, Measurements, Recurring | Preferred stocks
Assets:
Equity securities	0	0
Level 2 | Fair Value, Measurements, Recurring
Assets:
Total fixed maturity securities available for sale	13,263,738	13,471,746
Equity securities	164,756	213,600
Arbitrage trading account	306,547	146,229
Assets, fair value disclosure	13,735,041	13,831,575
Liabilities:
Securities sold but not yet purchased	9	0
Level 2 | Fair Value, Measurements, Recurring | U.S. government and government agency
Assets:
Total fixed maturity securities available for sale	479,909	377,740
Level 2 | Fair Value, Measurements, Recurring | State and municipal
Assets:
Total fixed maturity securities available for sale	4,311,524	4,445,094
Level 2 | Fair Value, Measurements, Recurring | Mortgage-backed securities
Assets:
Total fixed maturity securities available for sale	1,386,997	1,299,931
Level 2 | Fair Value, Measurements, Recurring | Asset-backed
Assets:
Total fixed maturity securities available for sale	2,101,528	2,111,372
Level 2 | Fair Value, Measurements, Recurring | Corporate
Assets:
Total fixed maturity securities available for sale	4,110,701	4,389,112
Level 2 | Fair Value, Measurements, Recurring | Foreign government
Assets:
Total fixed maturity securities available for sale	873,079	848,497
Level 2 | Fair Value, Measurements, Recurring | Common stocks
Assets:
Equity securities	0	0
Level 2 | Fair Value, Measurements, Recurring | Preferred stocks
Assets:
Equity securities	164,756	213,600
Level 3 | Fair Value, Measurements, Recurring
Assets:
Total fixed maturity securities available for sale	163	172
Equity securities	19,949	20,213
Arbitrage trading account	3,842	0
Assets, fair value disclosure	23,954	20,385
Liabilities:
Securities sold but not yet purchased	0	0
Level 3 | Fair Value, Measurements, Recurring | U.S. government and government agency
Assets:
Total fixed maturity securities available for sale	0	0
Level 3 | Fair Value, Measurements, Recurring | State and municipal
Assets:
Total fixed maturity securities available for sale	0	0
Level 3 | Fair Value, Measurements, Recurring | Mortgage-backed securities
Assets:
Total fixed maturity securities available for sale	0	0
Level 3 | Fair Value, Measurements, Recurring | Asset-backed
Assets:
Total fixed maturity securities available for sale	163	172
Level 3 | Fair Value, Measurements, Recurring | Corporate
Assets:
Total fixed maturity securities available for sale	0	0
Level 3 | Fair Value, Measurements, Recurring | Foreign government
Assets:
Total fixed maturity securities available for sale	0	0
Level 3 | Fair Value, Measurements, Recurring | Common stocks
Assets:
Equity securities	9,106	9,370
Level 3 | Fair Value, Measurements, Recurring | Preferred stocks
Assets:
Equity securities	$ 10,843	$ 10,843

Fair Value Measurements (Summar

Fair Value Measurements (Summarize Changes in Level 3 Assets) (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2018	Dec. 31, 2017
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Assets, impairments	$ 0	$ 0
Level 3
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Assets, beginning balance	20,385	12,599
Assets, earnings	(302)	19
Assets, other comprehensive income	4	650
Assets, purchases	3,882	7,173
Assets, (sales)	(15)	(56)
Assets. transfers out		0
Assets, ending balance	23,954	20,385
Level 3 | Debt securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Assets, beginning balance	172	183
Assets, earnings	2	3
Assets, other comprehensive income	4	34
Assets, impairments	0	0
Assets, purchases	0	0
Assets, (sales)	(15)	(48)
Assets. transfers out	0	0
Assets, ending balance	163	172
Level 3 | Asset-backed
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Assets, beginning balance	172	183
Assets, earnings	2	3
Assets, other comprehensive income	4	34
Assets, impairments	0	0
Assets, purchases	0	0
Assets, (sales)	(15)	(48)
Assets, maturities	0	0
Assets. transfers out	0	0
Assets, ending balance	163	172
Level 3 | Equity securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Assets, beginning balance	20,213	12,416
Assets, earnings	(264)	8
Assets, other comprehensive income	0	616
Assets, impairments	0	0
Assets, purchases	0	7,173
Assets, (sales)	0	0
Assets. transfers out	0	0
Assets, ending balance	19,949	20,213
Level 3 | Common stock
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Assets, beginning balance	9,370	8,754
Assets, earnings	(264)	0
Assets, other comprehensive income	0	616
Assets, impairments	0	0
Assets, purchases	0	0
Assets, (sales)	0	0
Assets. transfers out	0	0
Assets, ending balance	9,106	9,370
Level 3 | Preferred stocks
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Assets, beginning balance	10,843	3,662
Assets, earnings	0	8
Assets, other comprehensive income	0	0
Assets, impairments	0	0
Assets, purchases	0	7,173
Assets, (sales)	0	0
Assets. transfers out	0	0
Assets, ending balance	10,843	10,843
Level 3 | Arbitrage trading account
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Assets, beginning balance	0	0
Assets, earnings	(40)	8
Assets, other comprehensive income	0	0
Assets, impairments	0	0
Assets, purchases	3,882	0
Assets, (sales)	0	(8)
Assets. transfers out	0	0
Assets, ending balance	$ 3,842	$ 0

Reserves for Loss and Loss Ex67

Reserves for Loss and Loss Expenses (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Net reserves at beginning of year	$ 10,056,914	$ 9,590,265
Net provision for losses and loss expenses:
Claims occurring during the current year	956,181	958,684
Decrease in estimates for claims occurring in prior years	(3,582)	8,727
Loss reserve discount accretion	10,620	12,192
Liability for Unpaid Claims and Claims Adjustment Expense, Incurred Claims	963,219	979,603
Net payments for claims:
Current year	111,030	97,461
Prior year	810,709	773,571
Total	921,739	871,032
Foreign currency translation	2,501	23,204
Net reserves at end of period	10,100,895	9,722,040
Ceded reserve at end of period	1,684,000	1,502,284
Gross reserves at end of period	$ 11,784,895	$ 11,224,324	$ 11,670,408

Reserves for Loss and Loss Ex68

Reserves for Loss and Loss Expenses (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017	Dec. 31, 2016
Liability for Claims and Claims Adjustment Expense [Line Items]
Net of loss reserve discounts	$ 6,448	$ 5,761
Decrease in estimates for claims	6,662	4,841
Adjustment expense	12,000	2,000
Insurance
Liability for Claims and Claims Adjustment Expense [Line Items]
Adjustment expense	12,200	2,400
Favorable reserve development net of premium offsets	16,300	26,200
Reinsurance
Liability for Claims and Claims Adjustment Expense [Line Items]
Unfavorable reserve development net of premium offsets	$ 4,100	$ 23,800
Reinsurance reserves ogden discount rate			(0.75%)	2.50%

Fair Value of Financial Instr69

Fair Value of Financial Instruments (Carrying Amounts and Estimated Fair Values of Financial Instruments) (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Assets:
Arbitrage trading account	$ 744,859	$ 617,649
Loans receivable	78,238	82,047
Carrying Value
Assets:
Fixed maturity securities	13,343,132	13,551,250
Equity securities	496,034	576,647
Arbitrage trading account	744,859	617,649
Loans receivable	75,902	79,684
Cash and cash equivalents	956,603	950,471
Trading account receivables from brokers and clearing organizations	26,667	189,280
Liabilities:
Due to broker	74,450	15,920
Trading account securities sold but not yet purchased	29,453	64,358
Subordinated debentures	897,426	728,218
Senior notes and other debt	1,782,139	1,769,052
Fair Value
Assets:
Fixed maturity securities	13,356,305	13,566,976
Equity securities	496,034	576,647
Arbitrage trading account	744,859	617,649
Loans receivable	78,238	82,047
Cash and cash equivalents	956,603	950,471
Trading account receivables from brokers and clearing organizations	26,667	189,280
Liabilities:
Due to broker	74,450	15,920
Trading account securities sold but not yet purchased	29,453	64,358
Subordinated debentures	929,948	769,060
Senior notes and other debt	$ 1,921,635	$ 1,945,313

Reinsurance (Details)

Reinsurance (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Written premiums:
Written premiums, direct	$ 1,787,235	$ 1,721,062
Written premiums, assumed	192,187	215,145
Written premiums, ceded	(314,084)	(289,369)
Total net premiums written	1,665,338	1,646,838
Earned premiums:
Earned premiums, direct	1,674,550	1,613,364
Earned premiums, assumed	188,866	208,626
Earned premiums, ceded	(296,008)	(251,948)
Net premiums earned	1,567,408	1,570,042
Ceded losses and loss expenses incurred	238,995	35,192
Ceded commissions earned	66,356	$ 56,550
Uncollectible reinsurance	$ 1,000		$ 1,000

Restricted Stock Units (Summary

Restricted Stock Units (Summary of Restricted Stock Units Issued) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Share-Based Compensation Arrangement by Share-based Payment Award [Line Item]
Share based compensation expense	$ 9,000	$ 11,000
Restricted stock
Share-Based Compensation Arrangement by Share-based Payment Award [Line Item]
Restricted stock units (in units)	4,174	1,853,000
Fair Value	$ 290	$ 129
Minimum | Restricted stock
Share-Based Compensation Arrangement by Share-based Payment Award [Line Item]
Award vesting period	3 years
Maximum | Restricted stock
Share-Based Compensation Arrangement by Share-based Payment Award [Line Item]
Award vesting period	5 years

Business Segments (Financial In

Business Segments (Financial Information of Company Operating Segments) (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2018USD ($)segment	Mar. 31, 2017USD ($)
Segment Reporting Information [Line Items]
Number of reportable segments | segment	2
Earned Premiums	$ 1,567,408	$ 1,570,042
Investment Income	174,518	148,858
Other	149,321	151,518
Total revenues	1,891,247	1,870,418
Pre-Tax Income (Loss)	210,990	184,297
Net Income (Loss) to Common Stockholders	166,396	123,447
Net investment gains	48,464	52,348
Net investment gains, net of tax	38,286	34,026
Corporate, other and eliminations
Segment Reporting Information [Line Items]
Earned Premiums	0	0
Investment Income	14,006	12,171
Other	81,889	80,883
Total revenues	95,895	93,054
Pre-Tax Income (Loss)	(81,094)	(72,639)
Net Income (Loss) to Common Stockholders	(65,170)	(47,773)
Insurance
Segment Reporting Information [Line Items]
Earned Premiums	1,432,337	1,413,170
Insurance | Operating Segments
Segment Reporting Information [Line Items]
Earned Premiums	1,432,337	1,413,170
Investment Income	135,862	111,909
Other	18,968	18,287
Total revenues	1,587,167	1,543,366
Pre-Tax Income (Loss)	229,028	199,994
Net Income (Loss) to Common Stockholders	181,626	134,095
Reinsurance
Segment Reporting Information [Line Items]
Earned Premiums	135,071	156,872
Reinsurance | Operating Segments
Segment Reporting Information [Line Items]
Earned Premiums	135,071	156,872
Investment Income	24,650	24,778
Other	0	0
Total revenues	159,721	181,650
Pre-Tax Income (Loss)	14,592	4,594
Net Income (Loss) to Common Stockholders	11,654	3,099
Re-insurance - International | Operating Segments
Segment Reporting Information [Line Items]
Total revenues	56,000	49,000
Net investment gains
Segment Reporting Information [Line Items]
Earned Premiums	0	0
Investment Income	0	0
Insurance-International Segment | Operating Segments
Segment Reporting Information [Line Items]
Total revenues	$ 183,000	$ 184,000

Business Segments (Identifiable

Business Segments (Identifiable Assets by Segment) (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Segment Reporting, Asset Reconciling Item [Line Items]
Consolidated Assets	$ 24,587,832	$ 24,299,917
Operating Segments | Insurance
Segment Reporting, Asset Reconciling Item [Line Items]
Consolidated Assets	19,322,526	19,263,193
Operating Segments | Reinsurance
Segment Reporting, Asset Reconciling Item [Line Items]
Consolidated Assets	3,093,808	3,169,731
Corporate, other and eliminations
Segment Reporting, Asset Reconciling Item [Line Items]
Consolidated Assets	$ 2,171,498	$ 1,866,993

Business Segments (Net Premiums

Business Segments (Net Premiums Earned By Major Line of Business) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Revenue from External Customer [Line Items]
Net premiums earned	$ 1,567,408	$ 1,570,042
Insurance
Revenue from External Customer [Line Items]
Net premiums earned	1,432,337	1,413,170
Insurance | Other liability
Revenue from External Customer [Line Items]
Net premiums earned	464,167	451,830
Insurance | Workers’ compensation
Revenue from External Customer [Line Items]
Net premiums earned	365,948	361,136
Insurance | Property
Revenue from External Customer [Line Items]
Net premiums earned	295,105	296,790
Insurance | Commercial automobile
Revenue from External Customer [Line Items]
Net premiums earned	175,199	170,571
Insurance | Professional liability
Revenue from External Customer [Line Items]
Net premiums earned	131,918	132,843
Reinsurance
Revenue from External Customer [Line Items]
Net premiums earned	135,071	156,872
Reinsurance | Property
Revenue from External Customer [Line Items]
Net premiums earned	44,501	62,133
Reinsurance | Casualty
Revenue from External Customer [Line Items]
Net premiums earned	$ 90,570	$ 94,739