W. R. Berkley (WRB) 10-Q 4 May 20 2020 Q1 Quarterly report Financial data

Cover Page

Cover Page - shares	3 Months Ended
	Mar. 31, 2020	Apr. 30, 2020
Entity Information [Line Items]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Mar. 31, 2020
Document Transition Report	false
Entity File Number	1-15202
Entity Registrant Name	W. R. BERKLEY CORP
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	22-1867895
Entity Address, Address Line One	475 Steamboat Road
Entity Address, City or Town	Greenwich
Entity Address, State or Province	CT
Entity Address, Postal Zip Code	06830
City Area Code	(203)
Local Phone Number	629-3000
Title of 12(b) Security	Common Stock, par value $.20 per share
Trading Symbol	WRB
Security Exchange Name	NYSE
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		178,724,311
Entity Central Index Key	0000011544
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q1
Amendment Flag	false
5.625% Subordinated Debentures due 2053
Entity Information [Line Items]
Title of 12(b) Security	5.625% Subordinated Debentures due 2053
Trading Symbol	WRB-PB
Security Exchange Name	NYSE
5.90% Subordinated Debentures due 2056
Entity Information [Line Items]
Title of 12(b) Security	5.90% Subordinated Debentures due 2056
Trading Symbol	WRB-PC
Security Exchange Name	NYSE
5.75% Subordinated Debentures due 2056
Entity Information [Line Items]
Title of 12(b) Security	5.75% Subordinated Debentures due 2056
Trading Symbol	WRB-PD
Security Exchange Name	NYSE
5.70% Subordinated Debentures due 2058
Entity Information [Line Items]
Title of 12(b) Security	5.70% Subordinated Debentures due 2058
Trading Symbol	WRB-PE
Security Exchange Name	NYSE

Consolidated Balance Sheets Con

Consolidated Balance Sheets Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Investments:
Fixed maturity securities (allowance for expected credit losses of $67,463 at March 31, 2020)	$ 13,666,067	$ 14,180,961
Real estate	2,084,387	2,105,950
Investment funds	1,178,858	1,213,535
Arbitrage trading account	666,829	400,809
Equity securities	356,102	480,620
Loans receivable (allowance for expected credit losses of $3,928 at March 31, 2020)	87,058	91,799
Total investments	18,039,301	18,473,674
Cash and cash equivalents	965,012	1,023,710
Premiums and fees receivable (allowance for expected credit losses of $21,524 at March 31, 2020)	2,075,685	1,997,186
Due from reinsurers (allowance for expected credit losses of $6,800 at March 31, 2020)	2,178,092	2,133,683
Deferred policy acquisition costs	542,013	517,364
Prepaid reinsurance premiums	576,646	567,595
Trading account receivables from brokers and clearing organizations	132,928	423,543
Property, furniture and equipment	422,012	422,091
Goodwill	169,652	169,652
Accrued investment income	140,843	138,789
Federal and foreign income taxes	83,677	0
Other assets	764,068	762,743
Total assets	26,089,929	26,630,030
Liabilities:
Reserves for losses and loss expenses	12,732,515	12,583,249
Unearned premiums	3,800,642	3,656,507
Due to reinsurers	368,724	360,314
Trading account securities sold but not yet purchased	14,003	36,143
Federal and foreign income taxes	0	4,308
Other liabilities	1,005,433	1,244,888
Senior notes and other debt	1,432,117	1,427,575
Subordinated debentures	1,198,951	1,198,704
Total liabilities	20,552,385	20,511,688
Equity:
Perferred 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, 179,836,714 and 183,411,907 shares, respectively	70,535	70,535
Additional paid-in capital	1,063,084	1,056,042
Retained earnings	7,877,371	7,932,372
Accumulated other comprehensive loss	(589,521)	(257,299)
Treasury stock, at cost, 172,840,050 and 169,264,857 shares, respectively	(2,927,994)	(2,726,711)
Total stockholders’ equity	5,493,475	6,074,939
Noncontrolling interests	44,069	43,403
Total equity	5,537,544	6,118,342
Total liabilities and equity	$ 26,089,929	$ 26,630,030

Consolidated Balance Sheets C_2

Consolidated Balance Sheets Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Statement of Financial Position [Abstract]
Fixed maturity securities, allowance for credit loss	$ 67,463
Debt Securities, Available-for-sale and Held-to-maturity, Amortized Cost	13,818,447	$ 13,976,647
Cumulative effect adjustment resulting from changes in accounting principles	3,928	2,146
Cumulative effect adjustment resulting from changes in accounting principles	21,524	19,823
Reinsurance recoverable, allowance for credit loss	$ 6,800	$ 690
Preferred stock, par value (in dollars per share)	$ 0.10	$ 0.10
Preferred stock issued (in shares)	5,000,000	5,000,000
Preferred stock outstanding (in shares)	0	0
Common stock, par value (in dollar per share)	$ 0.2	$ 0.2
Common shares authorized (in shares)	500,000,000	500,000,000
Common shares issued (in shares)	179,836,714	183,411,907
Common shares outstanding (in shares)	179,836,714	183,411,907
Treasury stock issued at cost (in shares)	172,840,050	169,264,857

Consolidated Statements of (Los

Consolidated Statements of (Loss) Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
REVENUES:
Net premiums written	$ 1,845,846	$ 1,709,601
Change in net unearned premiums	(154,428)	(116,745)
Net premiums earned	1,691,418	1,592,856
Net investment income	174,763	158,254
Net realized and unrealized (losses) gains on investments	(143,285)	68,653
Change in allowance for expected credit losses on investments	(33,889)	0
Net investment (losses) gains	(177,174)	68,653
Revenues from non-insurance businesses	93,729	91,827
Insurance service fees	25,751	25,312
Other income	2,123	120
Total revenues	1,810,610	1,937,022
OPERATING COSTS AND EXPENSES:
Losses and loss expenses	1,107,253	988,650
Other operating costs and expenses	578,334	588,087
Expenses from non-insurance businesses	94,757	90,125
Interest expense	36,734	40,721
Total operating costs and expenses	1,817,078	1,707,583
(Loss) income before income taxes	(6,468)	229,439
Income tax benefit (expense)	2,942	(47,825)
Net (loss) income before noncontrolling interests	(3,526)	181,614
Noncontrolling interests	(892)	(892)
Net (loss) income to common stockholders	$ (4,418)	$ 180,722
NET (LOSS) INCOME PER SHARE:
Basic (in dollar per share)	$ (0.02)	$ 0.95
Diluted (in dollar per share)	$ (0.02)	$ 0.94

Consolidated Statements of Comp

Consolidated Statements of Comprehensive (Loss) Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Statement of Comprehensive Income [Abstract]
Net (loss) income before noncontrolling interests	$ (3,526)	$ 181,614
Other comprehensive (loss) income:
Change in unrealized currency translation adjustments	(98,194)	19,760
Change in unrealized investment (losses) gains, net of taxes	(258,981)	125,774
Other comprehensive income (loss)	(357,175)	145,534
Comprehensive (loss) income	(360,701)	327,148
Noncontrolling interests	(893)	(845)
Comprehensive (loss) income to common stockholders	$ (361,594)	$ 326,303

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	Cumulative effect adjustment resulting from changes in accounting principlesRetained earnings	Cumulative effect adjustment resulting from changes in accounting principlesAccumulated Other Comprehensive Income (Loss)	Cumulative effect adjustment resulting from changes in accounting principlesUnrealized investment gain	Cumulative effect adjustment resulting from changes in accounting principlesCurrency Translation Adjustments
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect adjustment resulting from changes in accounting principles		$ 70,535	$ 1,039,633	$ 7,558,619	$ (510,470)	$ (91,491)	$ (418,979)	$ (2,720,466)	$ 41,947	$ 0		$ 0
Beginning of period at Dec. 31, 2018		70,535	1,039,633	7,558,619	(510,470)	(91,491)	(418,979)	(2,720,466)	41,947	0		0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Restricted stock units issued			(455)
Restricted stock units expensed			14,194
Cumulative effect adjustment resulting from changes in accounting principles		70,535	1,053,372	7,721,039	(510,470)	34,236	(399,219)	(2,720,011)	42,844	0		0
Net (loss) income before noncontrolling interests	$ 181,614			180,722					892
Dividends ($0.11 and $0.10 per share, respectively)				(18,302)
Change in unrealized (losses) gains on securities without an allowance for expected credit losses	125,774					125,796
Change in unrealized gains (losses) on securities with an allowance for expected credit losses						(69)
Net change in period	19,760						19,760
Stock exercised/vested								455
Stock repurchased								0
(Distributions) contributions									52
Other comprehensive income (loss), net of tax	$ 145,534				145,534		19,760		(47)
End of period at Mar. 31, 2019			1,053,372	7,721,039	(364,983)	34,236	(399,219)	(2,720,011)	42,844
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock dividends, per share, cash paid (in dollars per share)	$ 0.10
Cumulative effect adjustment resulting from changes in accounting principles			1,053,372	7,721,039	(364,983)	34,236	(399,219)	(2,720,011)	42,844
Cumulative effect adjustment resulting from changes in accounting principles	$ 6,118,342	70,535	1,056,042	7,932,372	(257,299)	124,514	(381,813)	(2,726,711)	43,403	(30,514)	$ 24,952	24,952	$ 0
Beginning of period at Dec. 31, 2019	6,118,342	70,535	1,056,042	7,932,372	(257,299)	124,514	(381,813)	(2,726,711)	43,403	(30,514)	24,952	24,952	0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Restricted stock units issued			(4,590)
Restricted stock units expensed			11,632
Cumulative effect adjustment resulting from changes in accounting principles	6,118,342	$ 70,535	1,063,084	7,877,371	(589,521)	(109,514)	(480,007)	(2,927,994)	44,069	$ (30,514)	$ 24,952	$ 24,952	$ 0
Net (loss) income before noncontrolling interests	(3,526)			(4,418)					892
Dividends ($0.11 and $0.10 per share, respectively)				(20,069)
Change in unrealized (losses) gains on securities without an allowance for expected credit losses	(258,981)					(260,521)
Change in unrealized gains (losses) on securities with an allowance for expected credit losses						1,541
Net change in period	(98,194)						(98,194)
Stock exercised/vested								1,338
Stock repurchased								(202,621)
(Distributions) contributions									(227)
Other comprehensive income (loss), net of tax	(357,175)				(357,175)		(98,194)		1
End of period at Mar. 31, 2020	$ 5,537,544		1,063,084	7,877,371	(589,521)	(109,514)	(480,007)	(2,927,994)	44,069
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock dividends, per share, cash paid (in dollars per share)	$ 0.11
Cumulative effect adjustment resulting from changes in accounting principles	$ 5,537,544		$ 1,063,084	$ 7,877,371	$ (589,521)	$ (109,514)	$ (480,007)	$ (2,927,994)	$ 44,069

Consolidated Statements of Cash

Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
CASH FROM OPERATING ACTIVITIES:
Net (loss) income to common stockholders	$ (4,418)	$ 180,722
Adjustments to reconcile net income to net cash from (used in) operating activities:
Net investment losses (gains)	177,174	(68,653)
Depreciation and amortization	25,063	27,424
Noncontrolling interests	892	892
Investment funds	(40,576)	(11,411)
Stock incentive plans	11,683	14,828
Change in:
Arbitrage trading account	2,455	(7,753)
Premiums and fees receivable	(97,169)	(156,450)
Reinsurance accounts	(43,104)	(20,272)
Deferred policy acquisition costs	(26,139)	(17,732)
Income taxes	(12,500)	36,180
Reserves for losses and loss expenses	200,294	119,780
Unearned premiums	163,793	135,184
Other	(204,878)	(154,409)
Net cash from operating activities	152,570	78,330
CASH FROM INVESTING ACTIVITIES:
Proceeds from sale of fixed maturity securities	1,574,232	973,626
Proceeds from sale of equity securities	5,311	37,762
Distributions from (contributions to) investment funds	99,194	(13,874)
Proceeds from maturities and prepayments of fixed maturity securities	1,055,722	686,795
Purchase of fixed maturity securities	(2,598,076)	(1,528,267)
Purchase of equity securities	(35,260)	(35,314)
Real estate purchased	(24,249)	(52,901)
Change in loans receivable	2,877	(726)
Net purchases of property, furniture and equipment	(14,637)	(3,299)
Change in balances due to security brokers	(34,378)	(22,011)
Other	86	0
Net cash from investing activities	30,822	41,791
CASH USED IN FINANCING ACTIVITIES:
Net payments for stock options exercised	(3,321)	0
Net proceeds from issuance of debt	4,259	0
Cash dividends to common stockholders	(20,069)	0
Purchase of common treasury shares	(202,621)	0
Other, net	(204)	(976)
Net cash used in financing activities	(221,956)	(976)
Net impact on cash due to change in foreign exchange rates	(20,134)	681
Net change in cash and cash equivalents	(58,698)	119,826
Cash and cash equivalents at beginning of year	1,023,710	817,602
Cash and cash equivalents at end of period	$ 965,012	$ 937,428

General

General	3 Months Ended
	Mar. 31, 2020
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 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, 2019 . 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 U.S. federal income tax rate of 21% principally because of tax-exempt investment income, tax benefits related to equity-based compensation, and tax on income from foreign jurisdictions with different tax rates.

Per Share Data

Per Share Data	3 Months Ended
	Mar. 31, 2020
Earnings Per Share [Abstract]
Per Share Data	Per Share Data The Company presents both basic and diluted net (loss) income per share (“EPS”) amounts. Basic EPS is calculated by dividing net (loss) income by the weighted average number of common shares outstanding during the period (including 7,575,168 and 7,389,781 common shares held in a grantor trust as of March 31, 2020 and 2019 , 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. For the period ended March 31, 2020 , diluted shares have been reduced by 2.0 million to reflect the anti-dilutive effect of common equivalent shares. The weighted average number of common shares used in the computation of basic and diluted (losses) earnings per share was as follows: For the Three Months (In thousands) 2020 2019 Basic 190,287 190,400 Diluted 190,287 192,669

Recent Accounting Pronouncement

Recent Accounting Pronouncements	3 Months Ended
	Mar. 31, 2020
Accounting Policies [Abstract]
Recent Accounting Pronouncements	Recent Accounting Pronouncements and Accounting Policies Recently adopted accounting pronouncements: In June 2016, the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update ("ASU") 2016-13, Financial Instruments - Credit Losses, which amended the accounting guidance for credit losses on financial instruments. The updated guidance amended 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, such as reinsurance recoverables. The updated guidance was effective for reporting periods beginning after December 15, 2019. The adoption of this guidance on January 1, 2020 resulted in the recognition of an allowance for expected credit loss in connection with operating assets (premiums and fees receivable and due from reinsurers) of $5.7 million (net of tax) and a corresponding cumulative effect adjustment that decreased common stockholders' equity. Certain investments (primarily fixed maturity securities available for sale) established an allowance for expected credit loss of $24.8 million (net of tax), with a cumulative effect adjustment decreasing retained earnings by $24.8 million (net of tax) and increasing accumulated other comprehensive (loss) income ("AOCI") by $25.0 million (net of tax), resulting in $0.2 million net impact to total common stockholders' equity. All other accounting and reporting standards that have become effective in 2020 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: All 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. Accounting policies: The following accounting policies have been updated to reflect the Company's adoption of Financial Instruments - Credit Losses as described above. Revenue recognition (related to premiums and fees receivable) Insurance premiums are recognized as written at the inception of the policy. Reinsurance premiums are estimated based upon information received from ceding companies, and subsequent differences from such estimates are recorded in the period they are determined. Insurance and reinsurance premiums are primarily earned on a pro rata basis over the policy term. Fees for services are earned over the period that the services are provided. Premiums and fees receivable are reported net of an allowance for expected credit losses with the allowance being estimated based on current and future expected conditions, historical loss data and specific identification of collectability concerns where applicable. Changes in the allowance are reported within other operating costs and expenses. Reinsurance ceded (related to due from reinsurers) The unearned portion of premiums ceded to reinsurers is reported as prepaid reinsurance premiums and earned ratably over the policy term. The estimated amounts of reinsurance recoverable on unpaid losses are reported as due from reinsurers. To the extent any reinsurer does not meet its obligations under reinsurance agreements, the Company must discharge its liability. Amounts due from reinsurers are reflected net of funds held where the right of offset is present. The Company has provided an allowance for expected credit losses for estimated uncollectible reinsurance. The allowance is estimated based on the composition of the recoverable balance, considering reinsurer credit ratings, collateral received from financial institutions and funds withheld arrangements, length of collection periods, probability of default methodology, and specific identification of collectability concerns. Changes in the allowance are reported within losses and loss expenses. Investments For available for sale securities in an unrealized loss position where the Company intends to sell, or it is more likely than not that it will be required to sell the security before recovery in value, the amortized cost basis is written down to fair value through net investment (losses) gains. For available for sale securities in an unrealized loss position where the Company does not intend to sell, or it is more likely than not that it will not be required to sell the security before recovery in value, the Company evaluates whether the decline in fair value has resulted from credit losses or all other factors (non-credit factors). In making this assessment, the Company considers the extent to which fair value is less than amortized cost, changes to the rating of the security by a rating agency, and adverse conditions specifically related to the security, among other factors. If this assessment indicates that a credit loss exists, the present value of cash flows expected to be collected from the security are compared to the amortized cost basis of the security. If the present value of cash flows expected to be collected is less than the amortized cost basis, an allowance for expected credit losses is recorded for the credit loss through net investment (losses) gains, limited by the amount that the fair value is less than the amortized cost basis. The allowance is adjusted for any change in expected credit losses and subsequent recoveries through net investment (losses) gains. The impairment related to non-credit factors is recognized in other comprehensive income. For financial assets carried at amortized cost, which includes held to maturity securities and loans receivable, the Company estimates an allowance for expected credit losses based on relevant information about past events, including historical loss experience, current conditions and forecasts that affect the expected collectability of the amortized cost of the financial asset. The allowance for expected credit losses is presented as a reduction to amortized cost of the financial asset in the consolidated balance sheet and changes to the estimate for expected credit losses are recognized through net investment (losses) gains. The Company’s credit assessment of allowance for expected credit losses uses a third party model for available for sale and held to maturity securities, as well as loans receivable. The allowance for expected credit losses is generally based on the performance of the underlying collateral under various economic and default scenarios that involve subjective judgments and estimates by management. Modeling these securities involves various factors, such as projected default rates, the nature and realizable value of the collateral, if any, the ability of the issuer to make scheduled payments, historical performance and other relevant economic and performance factors. A discounted cash flow analysis is used to ascertain the amount of the allowance for expected credit losses, if any. In general, the model reverts to the rating-level long-term average marginal default rates based on 10 years of historical data, beyond the forecast period. For other inputs, the model in most cases reverts to the baseline long-term assumptions linearly over 5 years beyond the forecast period. The long-term assumptions are based on the historical averages. The Company reports accrued investment income separately from fixed maturity securities, and has elected not to measure an allowance for expected credit losses for accrued investment income. Accrued investment income is written off through net investment income at the time the issuer of the bond defaults or is expected to default on payments.

Consolidated Statements of Co_2

Consolidated Statements of Comprehensive Income (Loss)	3 Months Ended
	Mar. 31, 2020
Equity [Abstract]
Consolidated Statements of Comprehensive Income (Loss)	Consolidated Statements of Comprehensive (Loss) Income The following table presents the components of the changes in accumulated other comprehensive (loss) income ("AOCI"): (In thousands) Unrealized Investment (Losses) Gains Currency Translation Adjustments Accumulated Other Comprehensive (Loss) Income As of and for the three months ended March 31, 2020 Changes in AOCI Beginning of period $ 124,514 $ (381,813 ) $ (257,299 ) Cumulative effect adjustment resulting from changes in accounting principles 24,952 — 24,952 Restated beginning of period 149,466 (381,813 ) (232,347 ) Other comprehensive loss before reclassifications (298,531 ) (98,194 ) (396,725 ) Amounts reclassified from AOCI 39,550 — 39,550 Other comprehensive loss (258,981 ) (98,194 ) (357,175 ) Unrealized investment losses related to noncontrolling interest 1 — 1 Ending balance $ (109,514 ) $ (480,007 ) $ (589,521 ) Amounts reclassified from AOCI Pre-tax $ 50,063 (1) $ — $ 50,063 Tax effect (10,513 ) (2) — (10,513 ) After-tax amounts reclassified $ 39,550 $ — $ 39,550 Other comprehensive loss Pre-tax $ (332,850 ) $ (98,194 ) $ (431,044 ) Tax effect 73,869 — 73,869 Other comprehensive loss $ (258,981 ) $ (98,194 ) $ (357,175 ) As of and for the three months ended March 31, 2019 Changes in AOCI Beginning of period $ (91,491 ) $ (418,979 ) $ (510,470 ) Other comprehensive income before reclassifications 127,139 19,760 146,899 Amounts reclassified from AOCI (1,365 ) — (1,365 ) Other comprehensive income 125,774 19,760 145,534 Unrealized investment gain related to noncontrolling interest (47 ) — (47 ) Ending balance $ 34,236 $ (399,219 ) $ (364,983 ) Amounts reclassified from AOCI Pre-tax $ (1,728 ) (1) $ — $ (1,728 ) Tax effect 363 (2) — 363 After-tax amounts reclassified $ (1,365 ) $ — $ (1,365 ) Other comprehensive income Pre-tax $ 169,260 $ 19,760 $ 189,020 Tax effect (43,486 ) — (43,486 ) Other comprehensive income $ 125,774 $ 19,760 $ 145,534 _________________________ (1) Net investment (losses) gains in the consolidated statements of income. (2) Income tax benefit (expense) in the consolidated statements of income.

Statements of Cash Flow

Statements of Cash Flow	3 Months Ended
	Mar. 31, 2020
Supplemental Cash Flow Elements [Abstract]
Statements of Cash Flow	Statements of Cash Flows Interest payments were $54,582,000 and $62,981,000 for the three months ended March 31, 2020 and 2019 , respectively. No

Investments In Fixed Maturity S

Investments In Fixed Maturity Securities	3 Months Ended
	Mar. 31, 2020
Investments, Debt and Equity Securities [Abstract]
Investments In Fixed Maturity Securities	Investments in Fixed Maturity Securities At March 31, 2020 and December 31, 2019 , investments in fixed maturity securities were as follows: (In thousands) Amortized Cost Allowance for Expected Credit Losses (1) Gross Unrealized Fair Value Carrying Value Gains Losses March 31, 2020 Held to maturity: State and municipal $ 70,971 $ (107 ) $ 11,516 $ — $ 82,380 $ 70,864 Residential mortgage-backed 7,888 — 808 — 8,696 7,888 Total held to maturity 78,859 (107 ) 12,324 — 91,076 78,752 Available for sale: U.S. government and government agency 715,890 — 23,830 (58 ) 739,662 739,662 State and municipal: Special revenue 2,283,655 — 53,529 (9,043 ) 2,328,141 2,328,141 State general obligation 365,109 — 22,440 (1,592 ) 385,957 385,957 Pre-refunded 311,077 — 18,281 (128 ) 329,230 329,230 Corporate backed 254,887 — 4,880 (1,705 ) 258,062 258,062 Local general obligation 412,291 — 34,985 (511 ) 446,765 446,765 Total state and municipal 3,627,019 — 134,115 (12,979 ) 3,748,155 3,748,155 Mortgage-backed securities: Residential 1,169,144 — 26,039 (15,480 ) 1,179,703 1,179,703 Commercial 284,584 — 841 (9,688 ) 275,737 275,737 Total mortgage-backed securities 1,453,728 — 26,880 (25,168 ) 1,455,440 1,455,440 Asset-backed 3,123,627 — 2,415 (187,990 ) 2,938,052 2,938,052 Corporate: Industrial 2,175,423 (3,513 ) 42,215 (62,365 ) 2,151,760 2,151,760 Financial 1,482,371 (2,923 ) 16,083 (28,128 ) 1,467,403 1,467,403 Utilities 327,101 — 9,315 (1,838 ) 334,578 334,578 Other 24,560 — 230 (14 ) 24,776 24,776 Total corporate 4,009,455 (6,436 ) 67,843 (92,345 ) 3,978,517 3,978,517 Foreign government 809,869 (60,920 ) 21,377 (42,837 ) 727,489 727,489 Total available for sale 13,739,588 (67,356 ) 276,460 (361,377 ) 13,587,315 13,587,315 Total investments in fixed maturity securities $ 13,818,447 $ (67,463 ) $ 288,784 $ (361,377 ) $ 13,678,391 $ 13,666,067 ____________ (1) Represents the amount of impairment that has resulted from credit-related factors. The change in the allowance for expected credit losses, excluding the cumulative effect adjustment resulting from changes in accounting principles, is recognized in the consolidated statements of (loss) income. Amount excludes unrealized losses relating to non-credit factors. (In thousands) Amortized Gross Unrealized Fair Carrying Gains Losses December 31, 2019 Held to maturity: State and municipal $ 70,312 $ 13,000 $ — $ 83,312 $ 70,312 Residential mortgage-backed 8,371 994 — 9,365 8,371 Total held to maturity 78,683 13,994 — 92,677 78,683 Available for sale: U.S. government and government agency 775,157 13,249 (1,475 ) 786,931 786,931 State and municipal: Special revenue 2,343,209 64,586 (4,152 ) 2,403,643 2,403,643 State general obligation 359,298 22,074 (97 ) 381,275 381,275 Pre-refunded 364,571 20,342 (128 ) 384,785 384,785 Corporate backed 255,230 7,232 (903 ) 261,559 261,559 Local general obligation 432,333 32,684 (647 ) 464,370 464,370 Total state and municipal 3,754,641 146,918 (5,927 ) 3,895,632 3,895,632 Mortgage-backed securities: Residential 1,298,145 23,230 (5,155 ) 1,316,220 1,316,220 Commercial 304,506 5,214 (346 ) 309,374 309,374 Total mortgage-backed securities 1,602,651 28,444 (5,501 ) 1,625,594 1,625,594 Asset-backed 2,802,588 9,532 (21,490 ) 2,790,630 2,790,630 Corporate: Industrial 2,260,073 72,900 (3,800 ) 2,329,173 2,329,173 Financial 1,447,589 37,681 (4,118 ) 1,481,152 1,481,152 Utilities 325,762 15,281 (402 ) 340,641 340,641 Other 5,219 230 — 5,449 5,449 Total corporate 4,038,643 126,092 (8,320 ) 4,156,415 4,156,415 Foreign government 924,284 16,465 (93,673 ) 847,076 847,076 Total available for sale 13,897,964 340,700 (136,386 ) 14,102,278 14,102,278 Total investments in fixed maturity securities $ 13,976,647 $ 354,694 $ (136,386 ) $ 14,194,955 $ 14,180,961 The following table presents the rollforward of the allowance for expected credit losses for held to maturity securities for the period ended March 31, 2020 : State and Municipal (In thousands) Allowance for expected credit losses at January 1, 2020 $ — Cumulative effect adjustment resulting from changes in accounting principles 69 Provision for expected credit losses 38 Allowance for expected credit losses at March 31, 2020 $ 107 The following table presents the rollforward of the allowance for expected credit losses for available for sale securities for the period ended March 31, 2020 : Foreign Government Corporate Total (In thousands) Allowance for expected credit losses at January 1, 2020 $ — $ — $ — Cumulative effect adjustment resulting from changes in accounting principles 35,645 — 35,645 Expected credit losses on securities for which credit losses were not previously recorded 12,494 6,436 18,930 Expected credit losses on securities for which credit losses were previously recorded 16,369 — 16,369 Reduction due to disposals (3,588 ) — (3,588 ) Allowance for expected credit losses at March 31, 2020 $ 60,920 $ 6,436 $ 67,356 During the three months ended March 31, 2020, the Company increased the allowance for expected credit losses utilizing its credit loss assessment process and inputs used in its credit loss model, primarily due to the negative impact to the financial markets caused by COVID-19. As a result, the Company recognized an initial allowance for expected credit losses on securities that previously did not have an allowance, and increased the allowance for expected credit losses on existing securities due to higher default rate and lower recovery rate assumptions. The amortized cost and fair value of fixed maturity securities at March 31, 2020 , 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 Fair Due in one year or less $ 867,594 $ 845,806 Due after one year through five years 4,927,863 4,921,159 Due after five years through ten years 3,366,555 3,369,995 Due after ten years 3,194,713 3,077,295 Mortgage-backed securities 1,461,616 1,464,136 Total $ 13,818,341 $ 13,678,391 ____________ (1) Amortized cost includes the allowance for expected credit losses of $107 thousand related to held to maturity securities. At March 31, 2020 and December 31, 2019 , there were no investments that exceeded 10%

Investments in Equity Securitie

Investments in Equity Securities	3 Months Ended
	Mar. 31, 2020
Debt Securities, Available-for-sale [Line Items]
Investments in Equity Securities	Investments in Fixed Maturity Securities At March 31, 2020 and December 31, 2019 , investments in fixed maturity securities were as follows: (In thousands) Amortized Cost Allowance for Expected Credit Losses (1) Gross Unrealized Fair Value Carrying Value Gains Losses March 31, 2020 Held to maturity: State and municipal $ 70,971 $ (107 ) $ 11,516 $ — $ 82,380 $ 70,864 Residential mortgage-backed 7,888 — 808 — 8,696 7,888 Total held to maturity 78,859 (107 ) 12,324 — 91,076 78,752 Available for sale: U.S. government and government agency 715,890 — 23,830 (58 ) 739,662 739,662 State and municipal: Special revenue 2,283,655 — 53,529 (9,043 ) 2,328,141 2,328,141 State general obligation 365,109 — 22,440 (1,592 ) 385,957 385,957 Pre-refunded 311,077 — 18,281 (128 ) 329,230 329,230 Corporate backed 254,887 — 4,880 (1,705 ) 258,062 258,062 Local general obligation 412,291 — 34,985 (511 ) 446,765 446,765 Total state and municipal 3,627,019 — 134,115 (12,979 ) 3,748,155 3,748,155 Mortgage-backed securities: Residential 1,169,144 — 26,039 (15,480 ) 1,179,703 1,179,703 Commercial 284,584 — 841 (9,688 ) 275,737 275,737 Total mortgage-backed securities 1,453,728 — 26,880 (25,168 ) 1,455,440 1,455,440 Asset-backed 3,123,627 — 2,415 (187,990 ) 2,938,052 2,938,052 Corporate: Industrial 2,175,423 (3,513 ) 42,215 (62,365 ) 2,151,760 2,151,760 Financial 1,482,371 (2,923 ) 16,083 (28,128 ) 1,467,403 1,467,403 Utilities 327,101 — 9,315 (1,838 ) 334,578 334,578 Other 24,560 — 230 (14 ) 24,776 24,776 Total corporate 4,009,455 (6,436 ) 67,843 (92,345 ) 3,978,517 3,978,517 Foreign government 809,869 (60,920 ) 21,377 (42,837 ) 727,489 727,489 Total available for sale 13,739,588 (67,356 ) 276,460 (361,377 ) 13,587,315 13,587,315 Total investments in fixed maturity securities $ 13,818,447 $ (67,463 ) $ 288,784 $ (361,377 ) $ 13,678,391 $ 13,666,067 ____________ (1) Represents the amount of impairment that has resulted from credit-related factors. The change in the allowance for expected credit losses, excluding the cumulative effect adjustment resulting from changes in accounting principles, is recognized in the consolidated statements of (loss) income. Amount excludes unrealized losses relating to non-credit factors. (In thousands) Amortized Gross Unrealized Fair Carrying Gains Losses December 31, 2019 Held to maturity: State and municipal $ 70,312 $ 13,000 $ — $ 83,312 $ 70,312 Residential mortgage-backed 8,371 994 — 9,365 8,371 Total held to maturity 78,683 13,994 — 92,677 78,683 Available for sale: U.S. government and government agency 775,157 13,249 (1,475 ) 786,931 786,931 State and municipal: Special revenue 2,343,209 64,586 (4,152 ) 2,403,643 2,403,643 State general obligation 359,298 22,074 (97 ) 381,275 381,275 Pre-refunded 364,571 20,342 (128 ) 384,785 384,785 Corporate backed 255,230 7,232 (903 ) 261,559 261,559 Local general obligation 432,333 32,684 (647 ) 464,370 464,370 Total state and municipal 3,754,641 146,918 (5,927 ) 3,895,632 3,895,632 Mortgage-backed securities: Residential 1,298,145 23,230 (5,155 ) 1,316,220 1,316,220 Commercial 304,506 5,214 (346 ) 309,374 309,374 Total mortgage-backed securities 1,602,651 28,444 (5,501 ) 1,625,594 1,625,594 Asset-backed 2,802,588 9,532 (21,490 ) 2,790,630 2,790,630 Corporate: Industrial 2,260,073 72,900 (3,800 ) 2,329,173 2,329,173 Financial 1,447,589 37,681 (4,118 ) 1,481,152 1,481,152 Utilities 325,762 15,281 (402 ) 340,641 340,641 Other 5,219 230 — 5,449 5,449 Total corporate 4,038,643 126,092 (8,320 ) 4,156,415 4,156,415 Foreign government 924,284 16,465 (93,673 ) 847,076 847,076 Total available for sale 13,897,964 340,700 (136,386 ) 14,102,278 14,102,278 Total investments in fixed maturity securities $ 13,976,647 $ 354,694 $ (136,386 ) $ 14,194,955 $ 14,180,961 The following table presents the rollforward of the allowance for expected credit losses for held to maturity securities for the period ended March 31, 2020 : State and Municipal (In thousands) Allowance for expected credit losses at January 1, 2020 $ — Cumulative effect adjustment resulting from changes in accounting principles 69 Provision for expected credit losses 38 Allowance for expected credit losses at March 31, 2020 $ 107 The following table presents the rollforward of the allowance for expected credit losses for available for sale securities for the period ended March 31, 2020 : Foreign Government Corporate Total (In thousands) Allowance for expected credit losses at January 1, 2020 $ — $ — $ — Cumulative effect adjustment resulting from changes in accounting principles 35,645 — 35,645 Expected credit losses on securities for which credit losses were not previously recorded 12,494 6,436 18,930 Expected credit losses on securities for which credit losses were previously recorded 16,369 — 16,369 Reduction due to disposals (3,588 ) — (3,588 ) Allowance for expected credit losses at March 31, 2020 $ 60,920 $ 6,436 $ 67,356 During the three months ended March 31, 2020, the Company increased the allowance for expected credit losses utilizing its credit loss assessment process and inputs used in its credit loss model, primarily due to the negative impact to the financial markets caused by COVID-19. As a result, the Company recognized an initial allowance for expected credit losses on securities that previously did not have an allowance, and increased the allowance for expected credit losses on existing securities due to higher default rate and lower recovery rate assumptions. The amortized cost and fair value of fixed maturity securities at March 31, 2020 , 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 Fair Due in one year or less $ 867,594 $ 845,806 Due after one year through five years 4,927,863 4,921,159 Due after five years through ten years 3,366,555 3,369,995 Due after ten years 3,194,713 3,077,295 Mortgage-backed securities 1,461,616 1,464,136 Total $ 13,818,341 $ 13,678,391 ____________ (1) Amortized cost includes the allowance for expected credit losses of $107 thousand related to held to maturity securities. At March 31, 2020 and December 31, 2019 , there were no investments that exceeded 10%
Equity securities
Debt Securities, Available-for-sale [Line Items]
Investments in Equity Securities	Investments in Equity Securities At March 31, 2020 and December 31, 2019 , investments in equity securities were as follows: (In thousands) Cost Gross Unrealized Fair Value Carrying Value Gains Losses March 31, 2020 Common stocks $ 200,427 $ 6,718 $ (60,487 ) $ 146,658 $ 146,658 Preferred stocks 174,621 45,516 (10,693 ) 209,444 209,444 Total $ 375,048 $ 52,234 $ (71,180 ) $ 356,102 $ 356,102 December 31, 2019 Common stocks $ 175,928 $ 16,967 $ (26,090 ) $ 166,805 $ 166,805 Preferred stocks 169,171 148,243 (3,599 ) 313,815 313,815 Total $ 345,099 $ 165,210 $ (29,689 ) $ 480,620 $ 480,620

Arbitrage Trading Account

Arbitrage Trading Account	3 Months Ended
	Mar. 31, 2020
Debt Securities, Trading, and Equity Securities, FV-NI [Abstract]
Arbitrage Trading Account	Arbitrage Trading Account At March 31, 2020 and December 31, 2019 , the fair and carrying values of the arbitrage trading account were $667 million and $401 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 and call options in order to mitigate the impact of potential changes in market conditions on the merger arbitrage trading account. These options are reported at fair value. As of March 31, 2020 , the fair value of long option contracts outstanding was $917 thousand (notional amount of $23.5 million ) and the fair value of short option contracts outstanding was $545 thousand (notional amount of $29.8 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, 2020
Net Investment Income [Abstract]
Net Investment Income	Net Investment Income Net investment income consisted of the following: For the Three Months (In thousands) 2020 2019 Investment income earned on: Fixed maturity securities, including cash and cash equivalents and loans receivable $ 128,018 $ 132,119 Investment funds 40,577 11,411 Arbitrage trading account 1,138 10,585 Real estate 6,096 4,307 Equity securities 1,563 1,288 Gross investment income 177,392 159,710 Investment expense (2,629 ) (1,456 ) Net investment income $ 174,763 $ 158,254

Investment Funds

Investment Funds	3 Months Ended
	Mar. 31, 2020
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 $225 million as of March 31, 2020 . Investment funds consisted of the following: Carrying Value as of Income (Loss) from Investment Funds March 31, December 31, For the Three Months (In thousands) 2020 2019 2020 2019 Real estate $ 328,053 $ 412,275 $ 6,790 $ 10,476 Financial services 318,084 280,705 15,209 1,528 Energy 152,658 156,869 4,413 (11,793 ) Transportation 150,353 147,034 2,646 8,602 Other funds 229,710 216,652 11,519 2,598 Total $ 1,178,858 $ 1,213,535 $ 40,577 $ 11,411 The Company's share of the earnings or losses from investment funds is generally reported on a one-quarter lag in order to facilitate the timely completion of the Company's consolidated financial statements. Accordingly, income from investment funds for the first quarter of 2020 does not reflect the adverse impact from the recent disruption in global financial markets associated with COVID-19.

Real Estate

Real Estate	3 Months Ended
	Mar. 31, 2020
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) 2020 2019 Properties in operation $ 1,637,162 $ 1,351,249 Properties under development 447,225 754,701 Total $ 2,084,387 $ 2,105,950 In 2020, 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, office buildings in West Palm Beach and Palm Beach, Florida, an office building in London, and the completed portion of a mixed-use project in Washington D.C.. Properties in operation are net of accumulated depreciation and amortization of $66,160,000 and $59,832,000 as of March 31, 2020 and December 31, 2019 , respectively. Related depreciation expense was $6,620,000 and $3,427,000 for the three months ended March 31, 2020 and 2019 , respectively. Future minimum rental income expected on operating leases relating to properties in operation is $44,198,185 in 2020, $60,669,125 in 2021, $60,719,260 in 2022, $54,301,460 in 2023, $52,053,044 in 2024, $48,299,498 in 2025 and $522,531,742 thereafter. The Company borrowed $101,750,000 through a non-recourse loan secured by the West Palm Beach office building in 2018. The loan matures in November 2028 and carries a fixed interest rate of 4.21% . The carrying value does not reflect the outstanding financing, which is reflected within senior notes and other debt on the Company's consolidated balance sheet. A mixed-use project in Washington, D.C. has been under development in 2020 and 2019, with the completed portion reported in properties in operation as of March 31, 2020

Loans Receivable

Loans Receivable	3 Months Ended
	Mar. 31, 2020
Receivables [Abstract]
Loans Receivable	Loans Receivable At March 31, 2020 and December 31, 2019 , loans receivable are as follows: (In thousands) March 31, 2020 December 31, 2019 Amortized cost (net of allowance for expected credit losses): Real estate loans $ 52,890 $ 58,541 Commercial loans 34,168 33,258 Total $ 87,058 $ 91,799 Fair value: Real estate loans $ 56,906 $ 59,853 Commercial loans 34,168 34,760 Total $ 91,074 $ 94,613 The following table presents the rollforward of the allowance for expected credit losses for loans receivable for the period ended March 31, 2020 : Real Estate Loans Commercial Loans Total (In thousands) Allowance for expected credit losses at January 1, 2020 $ 1,502 $ 644 $ 2,146 Cumulative effect adjustment resulting from changes in accounting principles (905 ) 548 (357 ) Provision for expected credit losses 838 1,301 2,139 Allowance for expected credit losses at March 31, 2020 $ 1,435 $ 2,493 $ 3,928 Loans receivable in non-accrual status were both $0.2 million as of March 31, 2020 and December 31, 2019 . 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. 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 .

Realized And Unrealized Investm

Realized And Unrealized Investment Gains (Losses) on Investments	3 Months Ended
	Mar. 31, 2020
Realized and Unrealized Investment Gains (Losses) [Abstract]
Realized And Unrealized Investment Gains (Losses) on Investments	Net Investment (Losses) Gains Net investment (losses) gains are as follows: For the Three Months (In thousands) 2020 2019 Net investment (losses) gains: Fixed maturity securities: Gains $ 4,931 $ 5,246 Losses (4,847 ) (3,518 ) Equity securities (1): Net realized gains on investment sales — 23,345 Change in unrealized (losses) gains (154,467 ) 42,078 Investment funds 30,183 17 Real estate (687 ) 2,746 Loans receivable — (970 ) Other (18,398 ) (291 ) Net realized and unrealized (losses) gains on investments in earnings before allowance for expected credit losses (143,285 ) 68,653 Change in allowance for expected credit losses on investments (2): Fixed maturity securities (31,750 ) — Loans receivable (2,139 ) — Change in allowance for expected credit losses on investments (33,889 ) — Net investment (losses) gains (177,174 ) 68,653 Income tax benefit (expense) 37,207 (14,417 ) After-tax net investment (losses) gains $ (139,967 ) $ 54,236 Change in unrealized investment (losses) gains on available for sale securities: Fixed maturity securities without allowance for expected credit losses $ (326,416 ) $ 174,494 Fixed maturity securities with allowance for expected credit losses 1,541 (69 ) Investment funds (7,646 ) 1,790 Other (329 ) (6,955 ) Total change in unrealized investment (losses) gains (332,850 ) 169,260 Income tax benefit (expense) 73,869 (43,486 ) Noncontrolling interests 1 (47 ) After-tax change in unrealized investment (losses) gains of available for sale securities $ (258,980 ) $ 125,727 ______________________ (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) The inclusion of the allowance for expected credit losses on investments commenced January 1, 2020 due to the adoption of ASU 2016-13. See Note 3 for more details.

Fixed Maturity Securities In An

Fixed Maturity Securities In An Unrealized Loss Position	3 Months Ended
	Mar. 31, 2020
Investments, Debt and Equity Securities [Abstract]
Fixed Maturity Securities In An Unrealized Loss Position	Fixed Maturity Securities in an Unrealized Loss Position The following tables summarize all fixed maturity securities in an unrealized loss position at March 31, 2020 and December 31, 2019 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, 2020 U.S. government and government agency $ 13,308 $ 13 $ 7,145 $ 45 $ 20,453 $ 58 State and municipal 640,570 11,306 74,998 1,673 715,568 12,979 Mortgage-backed securities 609,582 24,143 86,569 1,025 696,151 25,168 Asset-backed securities 2,014,456 108,100 614,876 79,890 2,629,332 187,990 Corporate 1,886,894 85,902 54,226 6,443 1,941,120 92,345 Foreign government 114,439 7,257 24,647 35,580 139,086 42,837 Fixed maturity securities $ 5,279,249 $ 236,721 $ 862,461 $ 124,656 $ 6,141,710 $ 361,377 December 31, 2019 U.S. government and government agency $ 83,837 $ 618 $ 53,089 $ 857 $ 136,926 $ 1,475 State and municipal 365,184 4,245 127,210 1,682 492,394 5,927 Mortgage-backed securities 301,358 2,281 180,148 3,220 481,506 5,501 Asset-backed securities 755,259 2,307 774,508 19,183 1,529,767 21,490 Corporate 307,367 3,148 121,470 5,172 428,837 8,320 Foreign government 164,536 32,028 107,266 61,645 271,802 93,673 Fixed maturity securities $ 1,977,541 $ 44,627 $ 1,363,691 $ 91,759 $ 3,341,232 $ 136,386 Substantially all of the securities in an unrealized loss position are rated investment grade, except for the securities in the foreign government classification. In general, fair value in all classifications were negatively affected by market disruptions caused by COVID-19. A significant amount of the unrealized loss on foreign government securities is the result of changes in currency exchange rates. A summary of the Company’s non-investment grade fixed maturity securities that were in an unrealized loss position at March 31, 2020 is presented in the table below: ($ in thousands) Number of Securities Aggregate Fair Value Gross Unrealized Loss Foreign government 17 $ 46,834 $ 38,867 Corporate 15 55,989 7,293 Asset-backed securities 4 361 67 Mortgage-backed securities 13 14,213 1,484 Total 49 $ 117,397 $ 47,711 For 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 (loss) income.

Fair Value Measurements

Fair Value Measurements	3 Months Ended
	Mar. 31, 2020
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements The Company’s fixed maturity available for sale securities, equity securities and its 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, 2020 and December 31, 2019 by level: (In thousands) Total Level 1 Level 2 Level 3 March 31, 2020 Assets: Fixed maturity securities available for sale: U.S. government and government agency $ 739,662 $ — $ 739,662 $ — State and municipal 3,748,155 — 3,748,155 — Mortgage-backed securities 1,455,440 — 1,455,440 — Asset-backed securities 2,938,052 — 2,938,052 — Corporate 3,978,517 — 3,978,517 — Foreign government 727,489 — 727,489 — Total fixed maturity securities available for sale 13,587,315 — 13,587,315 — Equity securities: Common stocks 146,658 137,791 — 8,867 Preferred stocks 209,444 — 202,939 6,505 Total equity securities 356,102 137,791 202,939 15,372 Arbitrage trading account 666,829 480,495 186,334 — Total $ 14,610,246 $ 618,286 $ 13,976,588 $ 15,372 Liabilities: Trading account securities sold but not yet purchased $ 14,003 $ 14,003 $ — $ — December 31, 2019 Assets: Fixed maturity securities available for sale: U.S. government and government agency $ 786,931 $ — $ 786,931 $ — State and municipal 3,895,632 — 3,895,632 — Mortgage-backed securities 1,625,594 — 1,625,594 — Asset-backed securities 2,790,630 — 2,790,630 — Corporate 4,156,415 — 4,156,415 — Foreign government 847,076 — 847,076 — Total fixed maturity securities available for sale 14,102,278 — 14,102,278 — Equity securities: Common stocks 166,805 157,752 — 9,053 Preferred stocks 313,815 — 307,310 6,505 Total equity securities 480,620 157,752 307,310 15,558 Arbitrage trading account 400,809 381,061 19,748 — Total $ 14,983,707 $ 538,813 $ 14,429,336 $ 15,558 Liabilities: Trading account securities sold but not yet purchased $ 36,143 $ 36,143 $ — $ — The following tables summarize changes in Level 3 assets and liabilities for the three months ended March 31, 2020 and for the year ended December 31, 2019 : Gains (Losses) Included in: (In thousands) Beginning Balance Earnings (Losses) Other Comprehensive Income (Loss) Impairments Purchases (Sales) Paydowns / Maturities Transfers In / (Out) Ending Balance Three Months Ended March 31, 2020 Assets: Equity securities: Common stocks $ 9,053 $ 880 $ — $ — $ — $ (1,066 ) $ — $ — $ 8,867 Preferred stocks 6,505 — — — — — — — 6,505 Total $ 15,558 $ 880 $ — $ — $ — $ (1,066 ) $ — $ — $ 15,372 Year Ended Assets: Fixed maturities securities available for sale: Asset-backed securities $ 99 $ (26 ) $ 61 $ — $ — $ (134 ) $ — $ — $ — Total 99 (26 ) 61 — — (134 ) — — — Equity securities: Common stocks 8,596 2,005 — — (1,548 ) — — 9,053 Preferred stocks 3,945 (42 ) — — 2,602 — — — 6,505 Total 12,541 1,963 — — 2,602 (1,548 ) — — 15,558 Arbitrage trading account 17,308 (8,731 ) — — 14,767 (38,233 ) — 14,889 — Total $ 29,948 $ (6,794 ) $ 61 $ — $ 17,369 $ (39,915 ) $ — $ 14,889 $ 15,558 Liabilities: Trading account securities sold but not yet purchased $ 793 $ 133 $ — $ — $ 7,609 $ (8,535 ) $ — $ — $ — For the quarter ended March 31, 2020 , there were no securities transferred into or out of Level 3. For the year ended December 31, 2019, there were two common stocks transferred into Level 3 in the arbitrage trading account where publicly traded prices were no longer available, and both were sold by year end. The following table presents the carrying amounts and estimated fair values of the Company’s financial instruments: March 31, 2020 December 31, 2019 (In thousands) Carrying Value Fair Value Carrying Value Fair Value Assets: Fixed maturity securities $ 13,666,067 $ 13,678,391 $ 14,180,961 $ 14,194,955 Equity securities 356,102 356,102 480,620 480,620 Arbitrage trading account 666,829 666,829 400,809 400,809 Loans receivable 87,058 91,074 91,799 94,613 Cash and cash equivalents 965,012 965,012 1,023,710 1,023,710 Trading account receivables from brokers and clearing organizations 132,928 132,928 423,543 423,543 Due from broker 11,476 11,476 — — Liabilities: Due to broker — — 27,116 27,116 Trading account securities sold but not yet purchased 14,003 14,003 36,143 36,143 Subordinated debentures 1,198,951 1,092,780 1,198,704 1,274,088 Senior notes and other debt 1,432,117 1,454,081 1,427,575 1,582,290

Reserves for Loss and Loss Expe

Reserves for Loss and Loss Expenses	3 Months Ended
	Mar. 31, 2020
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) 2020 2019 Net reserves at beginning of period $ 10,697,998 $ 10,248,883 Cumulative effect adjustment resulting from changes in accounting principles 5,927 — Restated net reserves at beginning of period 10,703,925 10,248,883 Net provision for losses and loss expenses: Claims occurring during the current year (1) 1,097,523 971,806 Increase in estimates for claims occurring in prior years (2) (3) 433 6,481 Loss reserve discount accretion 9,297 10,363 Total 1,107,253 988,650 Net payments for claims: Current year 84,310 295,873 Prior years 864,064 567,756 Total 948,374 863,629 Foreign currency translation (77,167 ) (163 ) Net reserves at end of period 10,785,637 10,373,741 Ceded reserves at end of period 1,946,878 1,719,369 Gross reserves at end of period $ 12,732,515 $ 12,093,110 _______________________________________ (1) Claims occurring during the current year are net of loss reserve discounts of $ 3 million and $6 million for the three months ended March 31, 2020 and 2019 , respectively. (2) The change 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 $ 4 million and increased by $ 3 million for the three months ended March 31, 2020 and 2019 , 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 $4 million and $7 million for the three months ended March 31, 2020 and 2019 , respectively. One of the many ways in which the ongoing COVID-19 global pandemic may impact the Company’s results is through its impact on claim frequency and severity. Loss cost trends will be impacted directly by COVID-19 related claims filed in certain lines of business, as well as indirectly due to other impacts of COVID-19 associated with economic conditions, inflation, and social distancing and work from home rules, for example. These impacts could act to increase or decrease the overall loss cost trends and could have differing impacts on the Company's different lines of business. For certain lines of business, such as contingency and event cancellation, the Company has received reported claims related to COVID-19, and we expect additional claims to be reported in the future. Further, for workers’ compensation, several States have enacted rules, legislation or administrative orders creating the presumption that certain “essential” workers who contract COVID-19 did so through the course of their employment. Other States are considering similar actions, including with varying definitions of “essential” workers. The Company believes that such State actions will likely lead to increased workers’ compensation loss frequency and severity. As a result of these developments, the Company has estimated the potential COVID-19 impact to its workers’ compensation, contingency and event cancellation lines of business under a number of possible scenarios. Due to the rapidly evolving COVID-19 situation and the limited amount of available data, there is a high degree of uncertainty around these COVID-19 reserves. In addition, several States, through regulation, legislation and/or judicial action, are seeking to expand policy coverage terms beyond the policy’s intended coverage, including, for example, but not limited to, property coverages, where there are attempts to extend business interruption coverage where there is no physical damage or loss to property, and attempts to disregard policy exclusions for communicable disease. Policyholder losses arising from these State actions could exceed the reserves we have established for those related policies. For the three months ended March 31, 2020 , the Company has recognized a best estimate preliminary reserve for COVID-19 related claims activity, net of reinsurance and inclusive of reinstatement premium, of approximately $67 million , of which $47 million relates to the Insurance segment and $20 million relates to the Reinsurance & Monoline Excess segment. During the three months ended March 31, 2020 , favorable prior year development (net of additional and return premiums) of $4.0 million included $7.0 million of favorable development for the Insurance segment, partially offset by $3.0 million of adverse development for the Reinsurance & Monoline Excess segment. The overall favorable development for the Insurance segment was primarily attributable to favorable development on workers’ compensation business, partially offset by adverse development on professional liability business. The favorable workers’ compensation development was spread across many accident years, including prior to 2010, and was especially significant in accident years 2018 and 2019. 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). In addition, ongoing workers’ compensation claims management efforts, including active medical case management and use of networks and specialty vendors to control medical and pharmaceutical benefit costs, have added to the Company’s favorable workers’ compensation prior year development. The adverse professional liability development was mainly concentrated in accident years 2016 and 2017, but was also spread to a lesser degree across other accident years. The development mainly relates to directors and officers and lawyers professional liability lines of business, and was driven by a higher than expected number of large losses being reported in the period. The Company also experienced a small amount of adverse prior year development during the first quarter 2020 on general liability business stemming from large losses in its excess and surplus lines book of business, mainly in accident years 2016 and 2017. The adverse development for the Reinsurance & Monoline Excess segment was mainly driven by non-proportional reinsurance assumed liability business written in the U.K., primarily from accident years 2015 through 2019. The development was driven by a higher than expected number of reported large losses. During the three months ended March 31, 2019 , favorable prior year development (net of additional and return premiums) of $6.7 million included $9.6 million of favorable development for the Insurance segment, offset by $2.9 million of adverse development for the Reinsurance & Monoline Excess segment. The overall favorable development for the Insurance segment was primarily attributable to favorable development on workers’ compensation business, partially offset by adverse development on other liability business and professional liability business. The favorable workers’ compensation development was spread across many accident years, including prior to 2009, 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 other liability development was mainly related to accident years 2014 through 2018. It was driven by a higher than expected number of large losses being reported in the period, including both general liability and professional liability losses. The adverse development for the Reinsurance & Monoline Excess segment was mainly driven by U.S. casualty facultative business from accident years 2009 and prior related to construction projects.

Fair Value Of Financial Instrum

Fair Value Of Financial Instruments	3 Months Ended
	Mar. 31, 2020
Fair Value Disclosures [Abstract]
Fair Value Of Financial Instruments	Fair Value Measurements The Company’s fixed maturity available for sale securities, equity securities and its 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, 2020 and December 31, 2019 by level: (In thousands) Total Level 1 Level 2 Level 3 March 31, 2020 Assets: Fixed maturity securities available for sale: U.S. government and government agency $ 739,662 $ — $ 739,662 $ — State and municipal 3,748,155 — 3,748,155 — Mortgage-backed securities 1,455,440 — 1,455,440 — Asset-backed securities 2,938,052 — 2,938,052 — Corporate 3,978,517 — 3,978,517 — Foreign government 727,489 — 727,489 — Total fixed maturity securities available for sale 13,587,315 — 13,587,315 — Equity securities: Common stocks 146,658 137,791 — 8,867 Preferred stocks 209,444 — 202,939 6,505 Total equity securities 356,102 137,791 202,939 15,372 Arbitrage trading account 666,829 480,495 186,334 — Total $ 14,610,246 $ 618,286 $ 13,976,588 $ 15,372 Liabilities: Trading account securities sold but not yet purchased $ 14,003 $ 14,003 $ — $ — December 31, 2019 Assets: Fixed maturity securities available for sale: U.S. government and government agency $ 786,931 $ — $ 786,931 $ — State and municipal 3,895,632 — 3,895,632 — Mortgage-backed securities 1,625,594 — 1,625,594 — Asset-backed securities 2,790,630 — 2,790,630 — Corporate 4,156,415 — 4,156,415 — Foreign government 847,076 — 847,076 — Total fixed maturity securities available for sale 14,102,278 — 14,102,278 — Equity securities: Common stocks 166,805 157,752 — 9,053 Preferred stocks 313,815 — 307,310 6,505 Total equity securities 480,620 157,752 307,310 15,558 Arbitrage trading account 400,809 381,061 19,748 — Total $ 14,983,707 $ 538,813 $ 14,429,336 $ 15,558 Liabilities: Trading account securities sold but not yet purchased $ 36,143 $ 36,143 $ — $ — The following tables summarize changes in Level 3 assets and liabilities for the three months ended March 31, 2020 and for the year ended December 31, 2019 : Gains (Losses) Included in: (In thousands) Beginning Balance Earnings (Losses) Other Comprehensive Income (Loss) Impairments Purchases (Sales) Paydowns / Maturities Transfers In / (Out) Ending Balance Three Months Ended March 31, 2020 Assets: Equity securities: Common stocks $ 9,053 $ 880 $ — $ — $ — $ (1,066 ) $ — $ — $ 8,867 Preferred stocks 6,505 — — — — — — — 6,505 Total $ 15,558 $ 880 $ — $ — $ — $ (1,066 ) $ — $ — $ 15,372 Year Ended Assets: Fixed maturities securities available for sale: Asset-backed securities $ 99 $ (26 ) $ 61 $ — $ — $ (134 ) $ — $ — $ — Total 99 (26 ) 61 — — (134 ) — — — Equity securities: Common stocks 8,596 2,005 — — (1,548 ) — — 9,053 Preferred stocks 3,945 (42 ) — — 2,602 — — — 6,505 Total 12,541 1,963 — — 2,602 (1,548 ) — — 15,558 Arbitrage trading account 17,308 (8,731 ) — — 14,767 (38,233 ) — 14,889 — Total $ 29,948 $ (6,794 ) $ 61 $ — $ 17,369 $ (39,915 ) $ — $ 14,889 $ 15,558 Liabilities: Trading account securities sold but not yet purchased $ 793 $ 133 $ — $ — $ 7,609 $ (8,535 ) $ — $ — $ — For the quarter ended March 31, 2020 , there were no securities transferred into or out of Level 3. For the year ended December 31, 2019, there were two common stocks transferred into Level 3 in the arbitrage trading account where publicly traded prices were no longer available, and both were sold by year end. The following table presents the carrying amounts and estimated fair values of the Company’s financial instruments: March 31, 2020 December 31, 2019 (In thousands) Carrying Value Fair Value Carrying Value Fair Value Assets: Fixed maturity securities $ 13,666,067 $ 13,678,391 $ 14,180,961 $ 14,194,955 Equity securities 356,102 356,102 480,620 480,620 Arbitrage trading account 666,829 666,829 400,809 400,809 Loans receivable 87,058 91,074 91,799 94,613 Cash and cash equivalents 965,012 965,012 1,023,710 1,023,710 Trading account receivables from brokers and clearing organizations 132,928 132,928 423,543 423,543 Due from broker 11,476 11,476 — — Liabilities: Due to broker — — 27,116 27,116 Trading account securities sold but not yet purchased 14,003 14,003 36,143 36,143 Subordinated debentures 1,198,951 1,092,780 1,198,704 1,274,088 Senior notes and other debt 1,432,117 1,454,081 1,427,575 1,582,290

Reinsurance

Reinsurance	3 Months Ended
	Mar. 31, 2020
Insurance [Abstract]
Reinsurance	Premiums and Reinsurance Related Information The following is a summary of insurance and reinsurance financial information: For the Three Months (In thousands) 2020 2019 Written premiums: Direct $ 1,964,490 $ 1,829,815 Assumed 266,882 216,415 Ceded (385,526 ) (336,629 ) Total net premiums written $ 1,845,846 $ 1,709,601 Earned premiums: Direct $ 1,829,713 $ 1,723,610 Assumed 228,214 188,191 Ceded (366,509 ) (318,945 ) Total net premiums earned $ 1,691,418 $ 1,592,856 Ceded losses and loss expenses incurred $ 235,183 $ 173,046 Ceded commissions earned $ 81,045 $ 71,017 The following table presents the rollforward of the allowance for expected credit losses for premiums and fees receivable for the period ended March 31, 2020 : (In thousands) Allowance for expected credit losses at January 1, 2020 $ 19,823 Cumulative effect adjustment resulting from changes in accounting principles 1,270 Provision for expected credit losses 431 Allowance for expected credit losses at March 31, 2020 $ 21,524 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 an allowance for expected credit losses. The following table presents the rollforward of the allowance for expected credit losses associated with due from reinsurers for the period ended March 31, 2020 : (In thousands) Allowance for expected credit losses at January 1, 2020 $ 690 Cumulative effect adjustment resulting from changes in accounting principles 5,927 Provision for expected credit losses 183 Allowance for expected credit losses at March 31, 2020 $ 6,800

Restricted Stock Units

Restricted Stock Units	3 Months Ended
	Mar. 31, 2020
Share-based Payment Arrangement [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 $12 million and $15 million for the three months ended March 31, 2020 and 2019 , respectively. A summary of RSUs issued in the three months ended March 31, 2020 and 2019 follows: ($ in thousands) Units Fair Value 2020 724 $ 57 2019 1,106 $ 60

Litigation and Contingent Liabi

Litigation and Contingent Liabilities	3 Months Ended
	Mar. 31, 2020
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.

Leases

Leases	3 Months Ended
	Mar. 31, 2020
Leases [Abstract]
Leases	Leases Lessees are required to recognize a right-of-use asset and a lease liability for leases with terms of more than 12 months on the balance sheet. All leases disclosed within this footnote are classified as operating leases. Recognized right-of-use asset and lease liability are reported within other assets and other liabilities, respectively, in the consolidated balance sheet. Lease expense is reported in other operating costs and expenses in the consolidated statement of income and accounted for on a straight-line basis over the lease term. To determine the discount rate used to calculate present value of future minimum lease payments, the Company uses its incremental borrowing rate during the lease commencement period in line with the respective lease duration. In certain cases, the Company has the option to renew the lease. Lease renewal future payments are included in the present value of the future minimum lease payments when the Company determines it is reasonably certain to renew. The main leases entered into by the Company are for office space used by the Company’s operating units across the world. Additionally, the Company, to a lesser extent, has equipment leases mainly for office equipment. Further information relating to operating lease expense and other operating lease information are as follows: For the Three Months Ended (In thousands) 2020 2019 Leases: Lease cost $ 11,236 $ 11,555 Cash paid for amounts included in the measurement of lease liabilities reported in operating cash flows $ 10,830 $ 11,657 Right-of-use assets obtained in exchange for new lease liabilities $ 1,612 $ 4,966 As of March 31, ($ in thousands) 2020 2019 Right-of-use assets $ 184,544 $ 185,012 Lease liabilities $ 224,189 $ 215,008 Weighted-average remaining lease term 6.95 years 6.8 years Weighted-average discount rate 5.95 % 5.95 % Contractual maturities of the Company’s future minimum lease payments are as follows: (In thousands) March 31, 2020 Contractual Maturities: 2020 $ 36,912 2021 45,262 2022 41,267 2023 37,602 2024 31,357 Thereafter 78,532 Total undiscounted future minimum lease payments 270,932 Less: Discount impact (46,743 ) Total lease liability $ 224,189

Business Segments

Business Segments	3 Months Ended
	Mar. 31, 2020
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 & Monoline Excess - 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, as well as operations that solely retain risk on an excess basis. 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 (1) Investment Income Other Total (2) Pre-Tax (Loss) Income Net (Loss) Income to Common Stockholders Three months ended March 31, 2020 Insurance $ 1,484,955 $ 123,458 $ 8,473 $ 1,616,886 $ 175,947 $ 140,117 Reinsurance & Monoline Excess 206,463 37,710 — 244,173 36,514 29,187 Corporate, other and eliminations (3) — 13,595 113,130 126,725 (41,755 ) (33,755 ) Net investment losses — — (177,174 ) (177,174 ) (177,174 ) (139,967 ) Total $ 1,691,418 $ 174,763 $ (55,571 ) $ 1,810,610 $ (6,468 ) $ (4,418 ) Three months ended March 31, 2019 Insurance $ 1,427,034 $ 100,041 $ 13,244 $ 1,540,319 $ 184,516 $ 145,993 Reinsurance & Monoline Excess 165,822 39,574 — 205,396 44,855 35,525 Corporate, other and eliminations (3) — 18,639 104,015 122,654 (68,585 ) (55,032 ) Net investment gains — — 68,653 68,653 68,653 54,236 Total $ 1,592,856 $ 158,254 $ 185,912 $ 1,937,022 $ 229,439 $ 180,722 _________________ (1) Certain amounts included in earned premiums of each segment are related to inter-segment transactions. (2) Revenues for Insurance from foreign countries for the three months ended March 31, 2020 and 2019 were $168 million and $170 million , respectively. Revenues for Reinsurance & Monoline Excess from foreign countries for the three months ended March 31, 2020 and 2019 were $69 million and $59 million , respectively. (3) Corporate, other and eliminations represent corporate revenues and expenses that are not allocated to business segments. Identifiable Assets (In thousands) March 31, December 31, Insurance $ 19,485,407 $ 20,005,802 Reinsurance & Monoline Excess 4,405,637 4,710,819 Corporate, other and eliminations 2,198,885 1,913,409 Consolidated $ 26,089,929 $ 26,630,030 Net premiums earned by major line of business are as follows: For the Three Months (In thousands) 2020 2019 Insurance: Other liability $ 547,129 $ 490,661 Workers’ compensation 301,600 326,676 Short-tail lines (1) 295,478 289,091 Commercial automobile 189,643 180,925 Professional liability 151,105 139,681 Total Insurance 1,484,955 1,427,034 Reinsurance & Monoline Excess: Casualty reinsurance 122,731 90,830 Monoline excess (2) 42,161 38,981 Property reinsurance 41,571 36,011 Total Reinsurance & Monoline Excess 206,463 165,822 Total $ 1,691,418 $ 1,592,856 ______________ (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 Pronounceme_2

Recent Accounting Pronouncements (Policies)	3 Months Ended
	Mar. 31, 2020
Accounting Policies [Abstract]
Per Share Data	Per Share Data The Company presents both basic and diluted net (loss) income per share (“EPS”) amounts. Basic EPS is calculated by dividing net (loss) income by the weighted average number of common shares outstanding during the period (including 7,575,168 and 7,389,781 common shares held in a grantor trust as of March 31, 2020 and 2019
Recent Accounting Pronouncements	Recent Accounting Pronouncements and Accounting Policies Recently adopted accounting pronouncements: In June 2016, the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update ("ASU") 2016-13, Financial Instruments - Credit Losses, which amended the accounting guidance for credit losses on financial instruments. The updated guidance amended 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, such as reinsurance recoverables. The updated guidance was effective for reporting periods beginning after December 15, 2019. The adoption of this guidance on January 1, 2020 resulted in the recognition of an allowance for expected credit loss in connection with operating assets (premiums and fees receivable and due from reinsurers) of $5.7 million (net of tax) and a corresponding cumulative effect adjustment that decreased common stockholders' equity. Certain investments (primarily fixed maturity securities available for sale) established an allowance for expected credit loss of $24.8 million (net of tax), with a cumulative effect adjustment decreasing retained earnings by $24.8 million (net of tax) and increasing accumulated other comprehensive (loss) income ("AOCI") by $25.0 million (net of tax), resulting in $0.2 million net impact to total common stockholders' equity. All other accounting and reporting standards that have become effective in 2020 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: All 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, 2020
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 (losses) earnings per share was as follows: For the Three Months (In thousands) 2020 2019 Basic 190,287 190,400 Diluted 190,287 192,669

Consolidated Statements of Co_3

Consolidated Statements of Comprehensive Income (Loss) (Tables)	3 Months Ended
	Mar. 31, 2020
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 (Losses) Gains Currency Translation Adjustments Accumulated Other Comprehensive (Loss) Income As of and for the three months ended March 31, 2020 Changes in AOCI Beginning of period $ 124,514 $ (381,813 ) $ (257,299 ) Cumulative effect adjustment resulting from changes in accounting principles 24,952 — 24,952 Restated beginning of period 149,466 (381,813 ) (232,347 ) Other comprehensive loss before reclassifications (298,531 ) (98,194 ) (396,725 ) Amounts reclassified from AOCI 39,550 — 39,550 Other comprehensive loss (258,981 ) (98,194 ) (357,175 ) Unrealized investment losses related to noncontrolling interest 1 — 1 Ending balance $ (109,514 ) $ (480,007 ) $ (589,521 ) Amounts reclassified from AOCI Pre-tax $ 50,063 (1) $ — $ 50,063 Tax effect (10,513 ) (2) — (10,513 ) After-tax amounts reclassified $ 39,550 $ — $ 39,550 Other comprehensive loss Pre-tax $ (332,850 ) $ (98,194 ) $ (431,044 ) Tax effect 73,869 — 73,869 Other comprehensive loss $ (258,981 ) $ (98,194 ) $ (357,175 ) As of and for the three months ended March 31, 2019 Changes in AOCI Beginning of period $ (91,491 ) $ (418,979 ) $ (510,470 ) Other comprehensive income before reclassifications 127,139 19,760 146,899 Amounts reclassified from AOCI (1,365 ) — (1,365 ) Other comprehensive income 125,774 19,760 145,534 Unrealized investment gain related to noncontrolling interest (47 ) — (47 ) Ending balance $ 34,236 $ (399,219 ) $ (364,983 ) Amounts reclassified from AOCI Pre-tax $ (1,728 ) (1) $ — $ (1,728 ) Tax effect 363 (2) — 363 After-tax amounts reclassified $ (1,365 ) $ — $ (1,365 ) Other comprehensive income Pre-tax $ 169,260 $ 19,760 $ 189,020 Tax effect (43,486 ) — (43,486 ) Other comprehensive income $ 125,774 $ 19,760 $ 145,534 _________________________ (1) Net investment (losses) gains in the consolidated statements of income. (2) Income tax benefit (expense) in the consolidated statements of income.

Investments in Fixed Maturity_2

Investments in Fixed Maturity Securities (Tables)	3 Months Ended
	Mar. 31, 2020
Investments, Debt and Equity Securities [Abstract]
Schedule of investments in fixed maturity securities	At March 31, 2020 and December 31, 2019 , investments in fixed maturity securities were as follows: (In thousands) Amortized Cost Allowance for Expected Credit Losses (1) Gross Unrealized Fair Value Carrying Value Gains Losses March 31, 2020 Held to maturity: State and municipal $ 70,971 $ (107 ) $ 11,516 $ — $ 82,380 $ 70,864 Residential mortgage-backed 7,888 — 808 — 8,696 7,888 Total held to maturity 78,859 (107 ) 12,324 — 91,076 78,752 Available for sale: U.S. government and government agency 715,890 — 23,830 (58 ) 739,662 739,662 State and municipal: Special revenue 2,283,655 — 53,529 (9,043 ) 2,328,141 2,328,141 State general obligation 365,109 — 22,440 (1,592 ) 385,957 385,957 Pre-refunded 311,077 — 18,281 (128 ) 329,230 329,230 Corporate backed 254,887 — 4,880 (1,705 ) 258,062 258,062 Local general obligation 412,291 — 34,985 (511 ) 446,765 446,765 Total state and municipal 3,627,019 — 134,115 (12,979 ) 3,748,155 3,748,155 Mortgage-backed securities: Residential 1,169,144 — 26,039 (15,480 ) 1,179,703 1,179,703 Commercial 284,584 — 841 (9,688 ) 275,737 275,737 Total mortgage-backed securities 1,453,728 — 26,880 (25,168 ) 1,455,440 1,455,440 Asset-backed 3,123,627 — 2,415 (187,990 ) 2,938,052 2,938,052 Corporate: Industrial 2,175,423 (3,513 ) 42,215 (62,365 ) 2,151,760 2,151,760 Financial 1,482,371 (2,923 ) 16,083 (28,128 ) 1,467,403 1,467,403 Utilities 327,101 — 9,315 (1,838 ) 334,578 334,578 Other 24,560 — 230 (14 ) 24,776 24,776 Total corporate 4,009,455 (6,436 ) 67,843 (92,345 ) 3,978,517 3,978,517 Foreign government 809,869 (60,920 ) 21,377 (42,837 ) 727,489 727,489 Total available for sale 13,739,588 (67,356 ) 276,460 (361,377 ) 13,587,315 13,587,315 Total investments in fixed maturity securities $ 13,818,447 $ (67,463 ) $ 288,784 $ (361,377 ) $ 13,678,391 $ 13,666,067 ____________ (1) Represents the amount of impairment that has resulted from credit-related factors. The change in the allowance for expected credit losses, excluding the cumulative effect adjustment resulting from changes in accounting principles, is recognized in the consolidated statements of (loss) income. Amount excludes unrealized losses relating to non-credit factors. (In thousands) Amortized Gross Unrealized Fair Carrying Gains Losses December 31, 2019 Held to maturity: State and municipal $ 70,312 $ 13,000 $ — $ 83,312 $ 70,312 Residential mortgage-backed 8,371 994 — 9,365 8,371 Total held to maturity 78,683 13,994 — 92,677 78,683 Available for sale: U.S. government and government agency 775,157 13,249 (1,475 ) 786,931 786,931 State and municipal: Special revenue 2,343,209 64,586 (4,152 ) 2,403,643 2,403,643 State general obligation 359,298 22,074 (97 ) 381,275 381,275 Pre-refunded 364,571 20,342 (128 ) 384,785 384,785 Corporate backed 255,230 7,232 (903 ) 261,559 261,559 Local general obligation 432,333 32,684 (647 ) 464,370 464,370 Total state and municipal 3,754,641 146,918 (5,927 ) 3,895,632 3,895,632 Mortgage-backed securities: Residential 1,298,145 23,230 (5,155 ) 1,316,220 1,316,220 Commercial 304,506 5,214 (346 ) 309,374 309,374 Total mortgage-backed securities 1,602,651 28,444 (5,501 ) 1,625,594 1,625,594 Asset-backed 2,802,588 9,532 (21,490 ) 2,790,630 2,790,630 Corporate: Industrial 2,260,073 72,900 (3,800 ) 2,329,173 2,329,173 Financial 1,447,589 37,681 (4,118 ) 1,481,152 1,481,152 Utilities 325,762 15,281 (402 ) 340,641 340,641 Other 5,219 230 — 5,449 5,449 Total corporate 4,038,643 126,092 (8,320 ) 4,156,415 4,156,415 Foreign government 924,284 16,465 (93,673 ) 847,076 847,076 Total available for sale 13,897,964 340,700 (136,386 ) 14,102,278 14,102,278 Total investments in fixed maturity securities $ 13,976,647 $ 354,694 $ (136,386 ) $ 14,194,955 $ 14,180,961
Debt Securities, Held-to-maturity, Allowance for Credit Loss	The following table presents the rollforward of the allowance for expected credit losses for held to maturity securities for the period ended March 31, 2020 : State and Municipal (In thousands) Allowance for expected credit losses at January 1, 2020 $ — Cumulative effect adjustment resulting from changes in accounting principles 69 Provision for expected credit losses 38 Allowance for expected credit losses at March 31, 2020 $ 107
Debt Securities, Available-for-sale, Allowance for Credit Loss	The following table presents the rollforward of the allowance for expected credit losses for available for sale securities for the period ended March 31, 2020 : Foreign Government Corporate Total (In thousands) Allowance for expected credit losses at January 1, 2020 $ — $ — $ — Cumulative effect adjustment resulting from changes in accounting principles 35,645 — 35,645 Expected credit losses on securities for which credit losses were not previously recorded 12,494 6,436 18,930 Expected credit losses on securities for which credit losses were previously recorded 16,369 — 16,369 Reduction due to disposals (3,588 ) — (3,588 ) Allowance for expected credit losses at March 31, 2020 $ 60,920 $ 6,436 $ 67,356
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, 2020 , 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 Fair Due in one year or less $ 867,594 $ 845,806 Due after one year through five years 4,927,863 4,921,159 Due after five years through ten years 3,366,555 3,369,995 Due after ten years 3,194,713 3,077,295 Mortgage-backed securities 1,461,616 1,464,136 Total $ 13,818,341 $ 13,678,391 ____________ (1) Amortized cost includes the allowance for expected credit losses of $107 thousand

Investments in Equity Securit_2

Investments in Equity Securities (Tables)	3 Months Ended
	Mar. 31, 2020
Equity securities
Debt Securities, Available-for-sale [Line Items]
Schedule of Investments in Equity Securities	At March 31, 2020 and December 31, 2019 , investments in equity securities were as follows: (In thousands) Cost Gross Unrealized Fair Value Carrying Value Gains Losses March 31, 2020 Common stocks $ 200,427 $ 6,718 $ (60,487 ) $ 146,658 $ 146,658 Preferred stocks 174,621 45,516 (10,693 ) 209,444 209,444 Total $ 375,048 $ 52,234 $ (71,180 ) $ 356,102 $ 356,102 December 31, 2019 Common stocks $ 175,928 $ 16,967 $ (26,090 ) $ 166,805 $ 166,805 Preferred stocks 169,171 148,243 (3,599 ) 313,815 313,815 Total $ 345,099 $ 165,210 $ (29,689 ) $ 480,620 $ 480,620

Net Investment Income (Tables)

Net Investment Income (Tables)	3 Months Ended
	Mar. 31, 2020
Net Investment Income [Abstract]
Schedule of Net Investment Income	Net investment income consisted of the following: For the Three Months (In thousands) 2020 2019 Investment income earned on: Fixed maturity securities, including cash and cash equivalents and loans receivable $ 128,018 $ 132,119 Investment funds 40,577 11,411 Arbitrage trading account 1,138 10,585 Real estate 6,096 4,307 Equity securities 1,563 1,288 Gross investment income 177,392 159,710 Investment expense (2,629 ) (1,456 ) Net investment income $ 174,763 $ 158,254

Investment Funds (Tables)

Investment Funds (Tables)	3 Months Ended
	Mar. 31, 2020
Equity Method Investments and Joint Ventures [Abstract]
Schedule of Investment Funds	Investment funds consisted of the following: Carrying Value as of Income (Loss) from Investment Funds March 31, December 31, For the Three Months (In thousands) 2020 2019 2020 2019 Real estate $ 328,053 $ 412,275 $ 6,790 $ 10,476 Financial services 318,084 280,705 15,209 1,528 Energy 152,658 156,869 4,413 (11,793 ) Transportation 150,353 147,034 2,646 8,602 Other funds 229,710 216,652 11,519 2,598 Total $ 1,178,858 $ 1,213,535 $ 40,577 $ 11,411

Real Estate (Tables)

Real Estate (Tables)	3 Months Ended
	Mar. 31, 2020
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) 2020 2019 Properties in operation $ 1,637,162 $ 1,351,249 Properties under development 447,225 754,701 Total $ 2,084,387 $ 2,105,950

Loans Receivable Loans Receivab

Loans Receivable Loans Receivable (Tables)	3 Months Ended
	Mar. 31, 2020
Receivables [Abstract]
Schedule of Loans Receivable	oans receivable are as follows: (In thousands) March 31, 2020 December 31, 2019 Amortized cost (net of allowance for expected credit losses): Real estate loans $ 52,890 $ 58,541 Commercial loans 34,168 33,258 Total $ 87,058 $ 91,799 Fair value: Real estate loans $ 56,906 $ 59,853 Commercial loans 34,168 34,760 Total $ 91,074 $ 94,613
Financing Receivable, Allowance for Credit Loss	The following table presents the rollforward of the allowance for expected credit losses for loans receivable for the period ended March 31, 2020 : Real Estate Loans Commercial Loans Total (In thousands) Allowance for expected credit losses at January 1, 2020 $ 1,502 $ 644 $ 2,146 Cumulative effect adjustment resulting from changes in accounting principles (905 ) 548 (357 ) Provision for expected credit losses 838 1,301 2,139 Allowance for expected credit losses at March 31, 2020 $ 1,435 $ 2,493 $ 3,928

Realized And Unrealized Inves_2

Realized And Unrealized Investment Gains (Losses) on Investments (Tables)	3 Months Ended
	Mar. 31, 2020
Realized and Unrealized Investment Gains (Losses) [Abstract]
Realized And Unrealized Investment Gains (Losses)	Net investment (losses) gains are as follows: For the Three Months (In thousands) 2020 2019 Net investment (losses) gains: Fixed maturity securities: Gains $ 4,931 $ 5,246 Losses (4,847 ) (3,518 ) Equity securities (1): Net realized gains on investment sales — 23,345 Change in unrealized (losses) gains (154,467 ) 42,078 Investment funds 30,183 17 Real estate (687 ) 2,746 Loans receivable — (970 ) Other (18,398 ) (291 ) Net realized and unrealized (losses) gains on investments in earnings before allowance for expected credit losses (143,285 ) 68,653 Change in allowance for expected credit losses on investments (2): Fixed maturity securities (31,750 ) — Loans receivable (2,139 ) — Change in allowance for expected credit losses on investments (33,889 ) — Net investment (losses) gains (177,174 ) 68,653 Income tax benefit (expense) 37,207 (14,417 ) After-tax net investment (losses) gains $ (139,967 ) $ 54,236 Change in unrealized investment (losses) gains on available for sale securities: Fixed maturity securities without allowance for expected credit losses $ (326,416 ) $ 174,494 Fixed maturity securities with allowance for expected credit losses 1,541 (69 ) Investment funds (7,646 ) 1,790 Other (329 ) (6,955 ) Total change in unrealized investment (losses) gains (332,850 ) 169,260 Income tax benefit (expense) 73,869 (43,486 ) Noncontrolling interests 1 (47 ) After-tax change in unrealized investment (losses) gains of available for sale securities $ (258,980 ) $ 125,727 ______________________ (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) The inclusion of the allowance for expected credit losses on investments commenced January 1, 2020 due to the adoption of ASU 2016-13. See Note 3 for more details.

Fixed Maturity Securities In _2

Fixed Maturity Securities In An Unrealized Loss Position (Tables)	3 Months Ended
	Mar. 31, 2020
Investments, Debt and Equity Securities [Abstract]
Securities in an unrealized loss position	The following tables summarize all fixed maturity securities in an unrealized loss position at March 31, 2020 and December 31, 2019 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, 2020 U.S. government and government agency $ 13,308 $ 13 $ 7,145 $ 45 $ 20,453 $ 58 State and municipal 640,570 11,306 74,998 1,673 715,568 12,979 Mortgage-backed securities 609,582 24,143 86,569 1,025 696,151 25,168 Asset-backed securities 2,014,456 108,100 614,876 79,890 2,629,332 187,990 Corporate 1,886,894 85,902 54,226 6,443 1,941,120 92,345 Foreign government 114,439 7,257 24,647 35,580 139,086 42,837 Fixed maturity securities $ 5,279,249 $ 236,721 $ 862,461 $ 124,656 $ 6,141,710 $ 361,377 December 31, 2019 U.S. government and government agency $ 83,837 $ 618 $ 53,089 $ 857 $ 136,926 $ 1,475 State and municipal 365,184 4,245 127,210 1,682 492,394 5,927 Mortgage-backed securities 301,358 2,281 180,148 3,220 481,506 5,501 Asset-backed securities 755,259 2,307 774,508 19,183 1,529,767 21,490 Corporate 307,367 3,148 121,470 5,172 428,837 8,320 Foreign government 164,536 32,028 107,266 61,645 271,802 93,673 Fixed maturity securities $ 1,977,541 $ 44,627 $ 1,363,691 $ 91,759 $ 3,341,232 $ 136,386
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, 2020 is presented in the table below: ($ in thousands) Number of Securities Aggregate Fair Value Gross Unrealized Loss Foreign government 17 $ 46,834 $ 38,867 Corporate 15 55,989 7,293 Asset-backed securities 4 361 67 Mortgage-backed securities 13 14,213 1,484 Total 49 $ 117,397 $ 47,711

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	3 Months Ended
	Mar. 31, 2020
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, 2020 and December 31, 2019 by level: (In thousands) Total Level 1 Level 2 Level 3 March 31, 2020 Assets: Fixed maturity securities available for sale: U.S. government and government agency $ 739,662 $ — $ 739,662 $ — State and municipal 3,748,155 — 3,748,155 — Mortgage-backed securities 1,455,440 — 1,455,440 — Asset-backed securities 2,938,052 — 2,938,052 — Corporate 3,978,517 — 3,978,517 — Foreign government 727,489 — 727,489 — Total fixed maturity securities available for sale 13,587,315 — 13,587,315 — Equity securities: Common stocks 146,658 137,791 — 8,867 Preferred stocks 209,444 — 202,939 6,505 Total equity securities 356,102 137,791 202,939 15,372 Arbitrage trading account 666,829 480,495 186,334 — Total $ 14,610,246 $ 618,286 $ 13,976,588 $ 15,372 Liabilities: Trading account securities sold but not yet purchased $ 14,003 $ 14,003 $ — $ — December 31, 2019 Assets: Fixed maturity securities available for sale: U.S. government and government agency $ 786,931 $ — $ 786,931 $ — State and municipal 3,895,632 — 3,895,632 — Mortgage-backed securities 1,625,594 — 1,625,594 — Asset-backed securities 2,790,630 — 2,790,630 — Corporate 4,156,415 — 4,156,415 — Foreign government 847,076 — 847,076 — Total fixed maturity securities available for sale 14,102,278 — 14,102,278 — Equity securities: Common stocks 166,805 157,752 — 9,053 Preferred stocks 313,815 — 307,310 6,505 Total equity securities 480,620 157,752 307,310 15,558 Arbitrage trading account 400,809 381,061 19,748 — Total $ 14,983,707 $ 538,813 $ 14,429,336 $ 15,558 Liabilities: Trading account securities sold but not yet purchased $ 36,143 $ 36,143 $ — $ —
Summarize Changes In Level 3 Assets	The following tables summarize changes in Level 3 assets and liabilities for the three months ended March 31, 2020 and for the year ended December 31, 2019 : Gains (Losses) Included in: (In thousands) Beginning Balance Earnings (Losses) Other Comprehensive Income (Loss) Impairments Purchases (Sales) Paydowns / Maturities Transfers In / (Out) Ending Balance Three Months Ended March 31, 2020 Assets: Equity securities: Common stocks $ 9,053 $ 880 $ — $ — $ — $ (1,066 ) $ — $ — $ 8,867 Preferred stocks 6,505 — — — — — — — 6,505 Total $ 15,558 $ 880 $ — $ — $ — $ (1,066 ) $ — $ — $ 15,372 Year Ended Assets: Fixed maturities securities available for sale: Asset-backed securities $ 99 $ (26 ) $ 61 $ — $ — $ (134 ) $ — $ — $ — Total 99 (26 ) 61 — — (134 ) — — — Equity securities: Common stocks 8,596 2,005 — — (1,548 ) — — 9,053 Preferred stocks 3,945 (42 ) — — 2,602 — — — 6,505 Total 12,541 1,963 — — 2,602 (1,548 ) — — 15,558 Arbitrage trading account 17,308 (8,731 ) — — 14,767 (38,233 ) — 14,889 — Total $ 29,948 $ (6,794 ) $ 61 $ — $ 17,369 $ (39,915 ) $ — $ 14,889 $ 15,558 Liabilities: Trading account securities sold but not yet purchased $ 793 $ 133 $ — $ — $ 7,609 $ (8,535 ) $ — $ — $ —

Reserves for Loss and Loss Ex_2

Reserves for Loss and Loss Expenses (Tables)	3 Months Ended
	Mar. 31, 2020
Insurance [Abstract]
Reserve Balances	The table below provides a reconciliation of the beginning and ending reserve balances: March 31, (In thousands) 2020 2019 Net reserves at beginning of period $ 10,697,998 $ 10,248,883 Cumulative effect adjustment resulting from changes in accounting principles 5,927 — Restated net reserves at beginning of period 10,703,925 10,248,883 Net provision for losses and loss expenses: Claims occurring during the current year (1) 1,097,523 971,806 Increase in estimates for claims occurring in prior years (2) (3) 433 6,481 Loss reserve discount accretion 9,297 10,363 Total 1,107,253 988,650 Net payments for claims: Current year 84,310 295,873 Prior years 864,064 567,756 Total 948,374 863,629 Foreign currency translation (77,167 ) (163 ) Net reserves at end of period 10,785,637 10,373,741 Ceded reserves at end of period 1,946,878 1,719,369 Gross reserves at end of period $ 12,732,515 $ 12,093,110 _______________________________________ (1) Claims occurring during the current year are net of loss reserve discounts of $ 3 million and $6 million for the three months ended March 31, 2020 and 2019 , respectively. (2) The change 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 $ 4 million and increased by $ 3 million for the three months ended March 31, 2020 and 2019 , 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 $4 million and $7 million for the three months ended March 31, 2020 and 2019 , respectively.

Fair Value of Financial Instr_2

Fair Value of Financial Instruments (Tables)	3 Months Ended
	Mar. 31, 2020
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, 2020 December 31, 2019 (In thousands) Carrying Value Fair Value Carrying Value Fair Value Assets: Fixed maturity securities $ 13,666,067 $ 13,678,391 $ 14,180,961 $ 14,194,955 Equity securities 356,102 356,102 480,620 480,620 Arbitrage trading account 666,829 666,829 400,809 400,809 Loans receivable 87,058 91,074 91,799 94,613 Cash and cash equivalents 965,012 965,012 1,023,710 1,023,710 Trading account receivables from brokers and clearing organizations 132,928 132,928 423,543 423,543 Due from broker 11,476 11,476 — — Liabilities: Due to broker — — 27,116 27,116 Trading account securities sold but not yet purchased 14,003 14,003 36,143 36,143 Subordinated debentures 1,198,951 1,092,780 1,198,704 1,274,088 Senior notes and other debt 1,432,117 1,454,081 1,427,575 1,582,290

Reinsurance (Tables)

Reinsurance (Tables)	3 Months Ended
	Mar. 31, 2020
Insurance [Abstract]
Reinsurance Financial Information	The following is a summary of insurance and reinsurance financial information: For the Three Months (In thousands) 2020 2019 Written premiums: Direct $ 1,964,490 $ 1,829,815 Assumed 266,882 216,415 Ceded (385,526 ) (336,629 ) Total net premiums written $ 1,845,846 $ 1,709,601 Earned premiums: Direct $ 1,829,713 $ 1,723,610 Assumed 228,214 188,191 Ceded (366,509 ) (318,945 ) Total net premiums earned $ 1,691,418 $ 1,592,856 Ceded losses and loss expenses incurred $ 235,183 $ 173,046 Ceded commissions earned $ 81,045 $ 71,017
Premium receivable, allowance for credit loss	The following table presents the rollforward of the allowance for expected credit losses for premiums and fees receivable for the period ended March 31, 2020 : (In thousands) Allowance for expected credit losses at January 1, 2020 $ 19,823 Cumulative effect adjustment resulting from changes in accounting principles 1,270 Provision for expected credit losses 431 Allowance for expected credit losses at March 31, 2020 $ 21,524
Reinsurance Recoverable, Allowance for Credit Loss [Table Text Block]	The following table presents the rollforward of the allowance for expected credit losses associated with due from reinsurers for the period ended March 31, 2020 : (In thousands) Allowance for expected credit losses at January 1, 2020 $ 690 Cumulative effect adjustment resulting from changes in accounting principles 5,927 Provision for expected credit losses 183 Allowance for expected credit losses at March 31, 2020 $ 6,800

Restricted Stock Units (Tables)

Restricted Stock Units (Tables)	3 Months Ended
	Mar. 31, 2020
Share-based Payment Arrangement [Abstract]
Summary Of Restricted Stock Units Issued	A summary of RSUs issued in the three months ended March 31, 2020 and 2019 follows: ($ in thousands) Units Fair Value 2020 724 $ 57 2019 1,106 $ 60

Leases (Tables)

Leases (Tables)	3 Months Ended
	Mar. 31, 2020
Leases [Abstract]
Lease, Cost	Further information relating to operating lease expense and other operating lease information are as follows: For the Three Months Ended (In thousands) 2020 2019 Leases: Lease cost $ 11,236 $ 11,555 Cash paid for amounts included in the measurement of lease liabilities reported in operating cash flows $ 10,830 $ 11,657 Right-of-use assets obtained in exchange for new lease liabilities $ 1,612 $ 4,966
Supplemental Balance Sheet Information	As of March 31, ($ in thousands) 2020 2019 Right-of-use assets $ 184,544 $ 185,012 Lease liabilities $ 224,189 $ 215,008 Weighted-average remaining lease term 6.95 years 6.8 years Weighted-average discount rate 5.95 % 5.95 %
Maturities of Operating Lease Liabilities	Contractual maturities of the Company’s future minimum lease payments are as follows: (In thousands) March 31, 2020 Contractual Maturities: 2020 $ 36,912 2021 45,262 2022 41,267 2023 37,602 2024 31,357 Thereafter 78,532 Total undiscounted future minimum lease payments 270,932 Less: Discount impact (46,743 ) Total lease liability $ 224,189

Business Segments (Tables)

Business Segments (Tables)	3 Months Ended
	Mar. 31, 2020
Segment Reporting [Abstract]
Financial Information Of Company Operating Segments	Revenues (In thousands) Earned Premiums (1) Investment Income Other Total (2) Pre-Tax (Loss) Income Net (Loss) Income to Common Stockholders Three months ended March 31, 2020 Insurance $ 1,484,955 $ 123,458 $ 8,473 $ 1,616,886 $ 175,947 $ 140,117 Reinsurance & Monoline Excess 206,463 37,710 — 244,173 36,514 29,187 Corporate, other and eliminations (3) — 13,595 113,130 126,725 (41,755 ) (33,755 ) Net investment losses — — (177,174 ) (177,174 ) (177,174 ) (139,967 ) Total $ 1,691,418 $ 174,763 $ (55,571 ) $ 1,810,610 $ (6,468 ) $ (4,418 ) Three months ended March 31, 2019 Insurance $ 1,427,034 $ 100,041 $ 13,244 $ 1,540,319 $ 184,516 $ 145,993 Reinsurance & Monoline Excess 165,822 39,574 — 205,396 44,855 35,525 Corporate, other and eliminations (3) — 18,639 104,015 122,654 (68,585 ) (55,032 ) Net investment gains — — 68,653 68,653 68,653 54,236 Total $ 1,592,856 $ 158,254 $ 185,912 $ 1,937,022 $ 229,439 $ 180,722 _________________ (1) Certain amounts included in earned premiums of each segment are related to inter-segment transactions. (2) Revenues for Insurance from foreign countries for the three months ended March 31, 2020 and 2019 were $168 million and $170 million , respectively. Revenues for Reinsurance & Monoline Excess from foreign countries for the three months ended March 31, 2020 and 2019 were $69 million and $59 million , respectively. (3)
Identifiable Assets By Segment	(In thousands) March 31, December 31, Insurance $ 19,485,407 $ 20,005,802 Reinsurance & Monoline Excess 4,405,637 4,710,819 Corporate, other and eliminations 2,198,885 1,913,409 Consolidated $ 26,089,929 $ 26,630,030
Net Premiums Earned By Major Line Of Business	Net premiums earned by major line of business are as follows: For the Three Months (In thousands) 2020 2019 Insurance: Other liability $ 547,129 $ 490,661 Workers’ compensation 301,600 326,676 Short-tail lines (1) 295,478 289,091 Commercial automobile 189,643 180,925 Professional liability 151,105 139,681 Total Insurance 1,484,955 1,427,034 Reinsurance & Monoline Excess: Casualty reinsurance 122,731 90,830 Monoline excess (2) 42,161 38,981 Property reinsurance 41,571 36,011 Total Reinsurance & Monoline Excess 206,463 165,822 Total $ 1,691,418 $ 1,592,856 ______________ (1) Short-tail lines include commercial multi-peril (non-liability), inland marine, accident and health, fidelity and surety, boiler and machinery and other lines. (2) Monoline excess includes operations that solely retain risk on an excess basis.

General (Details)

General (Details)	3 Months Ended
	Mar. 31, 2020
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, 2020	Mar. 31, 2019
Earnings Per Share [Abstract]
Weighted average number of shares held in grantor trust	7,575,168	7,389,781
Antidilutive securities excluded from computation of earnings per share, amount (in shares)	2,000,000

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, 2020	Mar. 31, 2019
Earnings Per Share [Abstract]
Basic (shares)	190,287	190,400
Diluted (shares)	190,287	192,669

Recent Accounting Pronounceme_3

Recent Accounting Pronouncements (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Jan. 01, 2020	Dec. 31, 2019	Mar. 31, 2019	Dec. 31, 2018
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Fixed maturity securities, allowance for credit loss	$ 67,463
Cumulative effect adjustment resulting from changes in accounting principles	5,537,544		$ 6,118,342
Cumulative effect adjustment resulting from changes in accounting principles | Accounting Standards Update 2016-13
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Premium receivable and reinsurance recoverable, allowance for credit loss		$ 5,700
Fixed maturity securities, allowance for credit loss		24,800
Retained earnings
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect adjustment resulting from changes in accounting principles	7,877,371		7,932,372	$ 7,721,039	$ 7,558,619
Retained earnings | Cumulative effect adjustment resulting from changes in accounting principles
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect adjustment resulting from changes in accounting principles			(30,514)		0
Retained earnings | Cumulative effect adjustment resulting from changes in accounting principles | Accounting Standards Update 2016-13
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect adjustment resulting from changes in accounting principles		(5,700)
Accumulated Other Comprehensive Income (Loss)
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect adjustment resulting from changes in accounting principles	$ (109,514)		124,514	$ 34,236	(91,491)
Accumulated Other Comprehensive Income (Loss) | Cumulative effect adjustment resulting from changes in accounting principles
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect adjustment resulting from changes in accounting principles			$ 24,952		$ 0
Investments | Cumulative effect adjustment resulting from changes in accounting principles | Accounting Standards Update 2016-13
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect adjustment resulting from changes in accounting principles		200
Investments | Retained earnings | Cumulative effect adjustment resulting from changes in accounting principles | Accounting Standards Update 2016-13
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect adjustment resulting from changes in accounting principles		(24,800)
Investments | Accumulated Other Comprehensive Income (Loss) | Cumulative effect adjustment resulting from changes in accounting principles | Accounting Standards Update 2016-13
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect adjustment resulting from changes in accounting principles		$ 25,000

Consolidated Statements of Co_4

Consolidated Statements of Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning of period	$ 6,118,342
Other comprehensive income (loss)	(357,175)	$ 145,534
End of period	5,537,544
Net realized and unrealized (losses) gains on investments	(143,285)	68,653
(Loss) income before income taxes	(6,468)	229,439
Tax effect	2,942	(47,825)
Net (loss) income before noncontrolling interests	(3,526)	181,614
Total change in unrealized investment (losses) gains	(332,850)	169,260
Net change in period	(98,194)	19,760
Other comprehensive income (loss), pre-tax	(431,044)	189,020
Other comprehensive income (loss), tax effect	73,869	(43,486)
Accumulated Other Comprehensive Income (Loss)
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning of period	(257,299)	(510,470)
Other comprehensive income (loss) before reclassifications	(396,725)	146,899
Amounts reclassified from AOCI	39,550	(1,365)
Other comprehensive income (loss)	(357,175)	145,534
End of period	(589,521)	(364,983)
Unrealized investment loss related to noncontrolling interest	1	(47)
Accumulated Other Comprehensive Income (Loss) | Amounts reclassified from AOCI
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
(Loss) income before income taxes	50,063	(1,728)
Tax effect	(10,513)	363
Net (loss) income before noncontrolling interests	39,550	(1,365)
Unrealized Investment Gains (Losses)
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning of period	124,514	(91,491)
Other comprehensive income (loss) before reclassifications	(298,531)	127,139
Amounts reclassified from AOCI	39,550	(1,365)
Other comprehensive income (loss)	(258,981)	125,774
End of period	(109,514)	34,236
Unrealized investment loss related to noncontrolling interest	1	(47)
Total change in unrealized investment (losses) gains	(332,850)	169,260
Unrealized investment gains, tax effect	73,869	(43,486)
Unrealized investment gains (losses), after-tax amounts	(258,981)	125,774
Unrealized Investment Gains (Losses) | Amounts reclassified from AOCI
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Net realized and unrealized (losses) gains on investments	50,063	(1,728)
Tax effect	(10,513)	363
Net (loss) income before noncontrolling interests	39,550	(1,365)
Currency Translation Adjustments
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning of period	(381,813)	(418,979)
Other comprehensive income (loss) before reclassifications	(98,194)	19,760
Amounts reclassified from AOCI	0	0
Other comprehensive income (loss)	(98,194)	19,760
End of period	(480,007)	(399,219)
Unrealized investment loss related to noncontrolling interest	0	0
Currency translation adjustment, pre-tax	(98,194)	19,760
Currency translation adjustment, tax effect	0	0
Net change in period	(98,194)	19,760
Currency Translation Adjustments | Amounts reclassified from AOCI
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
(Loss) income before income taxes	0	0
Tax effect	0	0
Net (loss) income before noncontrolling interests	0	$ 0
Cumulative effect adjustment resulting from changes in accounting principles | Accumulated Other Comprehensive Income (Loss)
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning of period	24,952
Cumulative effect adjustment resulting from changes in accounting principles | Unrealized Investment Gains (Losses)
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning of period	24,952
Cumulative effect adjustment resulting from changes in accounting principles | Currency Translation Adjustments
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning of period	0
Cumulative Effect, Period Of Adoption, Adjusted Balance | Accumulated Other Comprehensive Income (Loss)
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning of period	(232,347)
Cumulative Effect, Period Of Adoption, Adjusted Balance | Unrealized Investment Gains (Losses)
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning of period	149,466
Cumulative Effect, Period Of Adoption, Adjusted Balance | Currency Translation Adjustments
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning of period	$ (381,813)

Statements of Cash Flow (Detail

Statements of Cash Flow (Details) - USD ($)	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Supplemental Cash Flow Elements [Abstract]
Interest payments	$ 54,582,000	$ 62,981,000
Income taxes paid	$ 0	$ 0

Investments in Fixed Maturity_3

Investments in Fixed Maturity Securities (Investments in fixed maturity securities) (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Debt Securities, Available-for-sale [Line Items]
Total held to maturity, Amortized Cost	$ 78,859	$ 78,683
Held-to-maturity, Allowance for Credit Loss	(107)	0
Held to maturity, Gross Unrealized Gains	12,324	13,994
Held to maturity, Gross Unrealized Losses	0	0
Total held to maturity, Fair Value	91,076	92,677
Total held to maturity, Carrying Value	78,752	78,683
Total available for sale, Amortized Cost	13,739,588	13,897,964
Available-for-sale, Allowance for Credit Loss	(67,356)	0
Total available for sale, Gross Unrealized Gains	276,460	340,700
Total available for sale, Gross Unrealized Losses	(361,377)	(136,386)
Total available for sale, Fair Value	13,587,315	14,102,278
Total available for sale, Carrying Value	13,587,315	14,102,278
Total investments in fixed maturity securities, Amortized Value	13,818,447	13,976,647
Fixed maturity securities, allowance for credit loss	(67,463)
Total investments in fixed maturity securities, Gross Unrealized Gains	288,784	354,694
Total investments in fixed maturity securities, Gross Unrealized Losses	(361,377)	(136,386)
Total investments in fixed maturity securities, Fair Value	13,678,391	14,194,955
Total investments in fixed maturity securities, Carrying Value	13,666,067	14,180,961
State and municipal
Debt Securities, Available-for-sale [Line Items]
Total held to maturity, Amortized Cost	70,971	70,312
Held-to-maturity, Allowance for Credit Loss	(107)
Held to maturity, Gross Unrealized Gains	11,516	13,000
Held to maturity, Gross Unrealized Losses	0	0
Total held to maturity, Fair Value	82,380	83,312
Total held to maturity, Carrying Value	70,864	70,312
Total available for sale, Amortized Cost	3,627,019	3,754,641
Available-for-sale, Allowance for Credit Loss	0
Total available for sale, Gross Unrealized Gains	134,115	146,918
Total available for sale, Gross Unrealized Losses	(12,979)	(5,927)
Total available for sale, Fair Value	3,748,155	3,895,632
Total available for sale, Carrying Value	3,748,155	3,895,632
Residential mortgage-backed
Debt Securities, Available-for-sale [Line Items]
Total held to maturity, Amortized Cost	7,888	8,371
Held-to-maturity, Allowance for Credit Loss	0
Held to maturity, Gross Unrealized Gains	808	994
Held to maturity, Gross Unrealized Losses	0	0
Total held to maturity, Fair Value	8,696	9,365
Total held to maturity, Carrying Value	7,888	8,371
Total available for sale, Amortized Cost	1,169,144	1,298,145
Available-for-sale, Allowance for Credit Loss	0
Total available for sale, Gross Unrealized Gains	26,039	23,230
Total available for sale, Gross Unrealized Losses	(15,480)	(5,155)
Total available for sale, Fair Value	1,179,703	1,316,220
Total available for sale, Carrying Value	1,179,703	1,316,220
U.S. government and government agency
Debt Securities, Available-for-sale [Line Items]
Total available for sale, Amortized Cost	715,890	775,157
Available-for-sale, Allowance for Credit Loss	0
Total available for sale, Gross Unrealized Gains	23,830	13,249
Total available for sale, Gross Unrealized Losses	(58)	(1,475)
Total available for sale, Fair Value	739,662	786,931
Total available for sale, Carrying Value	739,662	786,931
Special revenue
Debt Securities, Available-for-sale [Line Items]
Total available for sale, Amortized Cost	2,283,655	2,343,209
Available-for-sale, Allowance for Credit Loss	0
Total available for sale, Gross Unrealized Gains	53,529	64,586
Total available for sale, Gross Unrealized Losses	(9,043)	(4,152)
Total available for sale, Fair Value	2,328,141	2,403,643
Total available for sale, Carrying Value	2,328,141	2,403,643
State general obligation
Debt Securities, Available-for-sale [Line Items]
Total available for sale, Amortized Cost	365,109	359,298
Available-for-sale, Allowance for Credit Loss	0
Total available for sale, Gross Unrealized Gains	22,440	22,074
Total available for sale, Gross Unrealized Losses	(1,592)	(97)
Total available for sale, Fair Value	385,957	381,275
Total available for sale, Carrying Value	385,957	381,275
Pre-refunded
Debt Securities, Available-for-sale [Line Items]
Total available for sale, Amortized Cost	311,077	364,571
Available-for-sale, Allowance for Credit Loss	0
Total available for sale, Gross Unrealized Gains	18,281	20,342
Total available for sale, Gross Unrealized Losses	(128)	(128)
Total available for sale, Fair Value	329,230	384,785
Total available for sale, Carrying Value	329,230	384,785
Corporate backed
Debt Securities, Available-for-sale [Line Items]
Total available for sale, Amortized Cost	254,887	255,230
Available-for-sale, Allowance for Credit Loss	0
Total available for sale, Gross Unrealized Gains	4,880	7,232
Total available for sale, Gross Unrealized Losses	(1,705)	(903)
Total available for sale, Fair Value	258,062	261,559
Total available for sale, Carrying Value	258,062	261,559
Local general obligation
Debt Securities, Available-for-sale [Line Items]
Total available for sale, Amortized Cost	412,291	432,333
Available-for-sale, Allowance for Credit Loss	0
Total available for sale, Gross Unrealized Gains	34,985	32,684
Total available for sale, Gross Unrealized Losses	(511)	(647)
Total available for sale, Fair Value	446,765	464,370
Total available for sale, Carrying Value	446,765	464,370
Commercial mortgage-backed
Debt Securities, Available-for-sale [Line Items]
Total available for sale, Amortized Cost	284,584	304,506
Available-for-sale, Allowance for Credit Loss	0
Total available for sale, Gross Unrealized Gains	841	5,214
Total available for sale, Gross Unrealized Losses	(9,688)	(346)
Total available for sale, Fair Value	275,737	309,374
Total available for sale, Carrying Value	275,737	309,374
Mortgage-backed securities
Debt Securities, Available-for-sale [Line Items]
Total available for sale, Amortized Cost	1,453,728	1,602,651
Available-for-sale, Allowance for Credit Loss	0
Total available for sale, Gross Unrealized Gains	26,880	28,444
Total available for sale, Gross Unrealized Losses	(25,168)	(5,501)
Total available for sale, Fair Value	1,455,440	1,625,594
Total available for sale, Carrying Value	1,455,440	1,625,594
Asset-backed
Debt Securities, Available-for-sale [Line Items]
Total available for sale, Amortized Cost	3,123,627	2,802,588
Available-for-sale, Allowance for Credit Loss	0
Total available for sale, Gross Unrealized Gains	2,415	9,532
Total available for sale, Gross Unrealized Losses	(187,990)	(21,490)
Total available for sale, Fair Value	2,938,052	2,790,630
Total available for sale, Carrying Value	2,938,052	2,790,630
Industrial
Debt Securities, Available-for-sale [Line Items]
Total available for sale, Amortized Cost	2,175,423	2,260,073
Available-for-sale, Allowance for Credit Loss	(3,513)
Total available for sale, Gross Unrealized Gains	42,215	72,900
Total available for sale, Gross Unrealized Losses	(62,365)	(3,800)
Total available for sale, Fair Value	2,151,760	2,329,173
Total available for sale, Carrying Value	2,151,760	2,329,173
Financial
Debt Securities, Available-for-sale [Line Items]
Total available for sale, Amortized Cost	1,482,371	1,447,589
Available-for-sale, Allowance for Credit Loss	(2,923)
Total available for sale, Gross Unrealized Gains	16,083	37,681
Total available for sale, Gross Unrealized Losses	(28,128)	(4,118)
Total available for sale, Fair Value	1,467,403	1,481,152
Total available for sale, Carrying Value	1,467,403	1,481,152
Utilities
Debt Securities, Available-for-sale [Line Items]
Total available for sale, Amortized Cost	327,101	325,762
Available-for-sale, Allowance for Credit Loss	0
Total available for sale, Gross Unrealized Gains	9,315	15,281
Total available for sale, Gross Unrealized Losses	(1,838)	(402)
Total available for sale, Fair Value	334,578	340,641
Total available for sale, Carrying Value	334,578	340,641
Other
Debt Securities, Available-for-sale [Line Items]
Total available for sale, Amortized Cost	24,560	5,219
Available-for-sale, Allowance for Credit Loss	0
Total available for sale, Gross Unrealized Gains	230	230
Total available for sale, Gross Unrealized Losses	(14)	0
Total available for sale, Fair Value	24,776	5,449
Total available for sale, Carrying Value	24,776	5,449
Corporate
Debt Securities, Available-for-sale [Line Items]
Total available for sale, Amortized Cost	4,009,455	4,038,643
Available-for-sale, Allowance for Credit Loss	(6,436)	0
Total available for sale, Gross Unrealized Gains	67,843	126,092
Total available for sale, Gross Unrealized Losses	(92,345)	(8,320)
Total available for sale, Fair Value	3,978,517	4,156,415
Total available for sale, Carrying Value	3,978,517	4,156,415
Foreign government
Debt Securities, Available-for-sale [Line Items]
Total available for sale, Amortized Cost	809,869	924,284
Available-for-sale, Allowance for Credit Loss	(60,920)	0
Total available for sale, Gross Unrealized Gains	21,377	16,465
Total available for sale, Gross Unrealized Losses	(42,837)	(93,673)
Total available for sale, Fair Value	727,489	847,076
Total available for sale, Carrying Value	$ 727,489	$ 847,076

Investments in Fixed Maturity_4

Investments in Fixed Maturity Securities (HTM Allowance for Credit Loss) (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2020USD ($)
Debt Securities, Held-to-maturity, Allowance for Credit Loss [Roll Forward]
Allowance for expected credit losses at January 1, 2020	$ 0
Cumulative effect adjustment resulting from changes in accounting principles	107
Provision for expected credit losses	38
Allowance for expected credit losses at March 31, 2020	107
Cumulative effect adjustment resulting from changes in accounting principles
Debt Securities, Held-to-maturity, Allowance for Credit Loss [Roll Forward]
Allowance for expected credit losses at January 1, 2020	69
Cumulative effect adjustment resulting from changes in accounting principles	$ 69

Investments in Fixed Maturity_5

Investments in Fixed Maturity Securities (AFS Allowance for Credit Loss) (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2020USD ($)
Debt Securities, Available-for-sale, Allowance for Credit Loss [Roll Forward]
Allowance for expected credit losses at January 1, 2020	$ 0
Cumulative effect adjustment resulting from changes in accounting principles	67,356
Expected credit losses on securities for which credit losses were not previously recorded	18,930
Expected credit losses on securities for which credit losses were previously recorded	16,369
Reduction due to disposals	(3,588)
Allowance for expected credit losses at March 31, 2020	67,356
Cumulative effect adjustment resulting from changes in accounting principles
Debt Securities, Available-for-sale, Allowance for Credit Loss [Roll Forward]
Allowance for expected credit losses at January 1, 2020	35,645
Cumulative effect adjustment resulting from changes in accounting principles	35,645
Foreign government
Debt Securities, Available-for-sale, Allowance for Credit Loss [Roll Forward]
Allowance for expected credit losses at January 1, 2020	0
Cumulative effect adjustment resulting from changes in accounting principles	60,920
Expected credit losses on securities for which credit losses were not previously recorded	12,494
Expected credit losses on securities for which credit losses were previously recorded	16,369
Reduction due to disposals	(3,588)
Allowance for expected credit losses at March 31, 2020	60,920
Foreign government | Cumulative effect adjustment resulting from changes in accounting principles
Debt Securities, Available-for-sale, Allowance for Credit Loss [Roll Forward]
Allowance for expected credit losses at January 1, 2020	35,645
Cumulative effect adjustment resulting from changes in accounting principles	35,645
Corporate
Debt Securities, Available-for-sale, Allowance for Credit Loss [Roll Forward]
Allowance for expected credit losses at January 1, 2020	0
Cumulative effect adjustment resulting from changes in accounting principles	6,436
Expected credit losses on securities for which credit losses were not previously recorded	6,436
Expected credit losses on securities for which credit losses were previously recorded	0
Reduction due to disposals	0
Allowance for expected credit losses at March 31, 2020	6,436
Corporate | Cumulative effect adjustment resulting from changes in accounting principles
Debt Securities, Available-for-sale, Allowance for Credit Loss [Roll Forward]
Allowance for expected credit losses at January 1, 2020	0
Cumulative effect adjustment resulting from changes in accounting principles	$ 0

Investments in Fixed Maturity_6

Investments in Fixed Maturity Securities (Amortized cost and fair value of fixed maturity securities) (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Investments, Debt and Equity Securities [Abstract]
Amortized Cost, Due in one year or less	$ 867,594
Amortized Cost, Due after one year through five years	4,927,863
Amortized Cost, Due after five years through ten years	3,366,555
Amortized Cost, Due after ten years	3,194,713
Amortized Cost, Mortgaged-backed securities	1,461,616
Total investments in fixed maturity securities, Amortized Value	13,818,341
Fair Value, Due in one year or less	845,806
Fair Value, Due after one year through five years	4,921,159
Fair Value, Due after five years through ten years	3,369,995
Fair Value, Due after ten years	3,077,295
Fair Value, Mortgage-backed securities	1,464,136
Total investments in fixed maturity securities, Fair Value	13,678,391	$ 14,194,955
Cumulative effect adjustment resulting from changes in accounting principles	$ 107	$ 0

Investments in Equity Securit_3

Investments in Equity Securities (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Debt Securities, Available-for-sale [Line Items]
Equity securities	$ 356,102	$ 480,620
Fair Value
Debt Securities, Available-for-sale [Line Items]
Cost	375,048	345,099
Gross Unrealized, Gains	52,234	165,210
Gross Unrealized, Losses	(71,180)	(29,689)
Equity securities	356,102	480,620
Fair Value | Common stock
Debt Securities, Available-for-sale [Line Items]
Cost	200,427	175,928
Gross Unrealized, Gains	6,718	16,967
Gross Unrealized, Losses	(60,487)	(26,090)
Equity securities	146,658	166,805
Fair Value | Preferred stocks
Debt Securities, Available-for-sale [Line Items]
Cost	174,621	169,171
Gross Unrealized, Gains	45,516	148,243
Gross Unrealized, Losses	(10,693)	(3,599)
Equity securities	209,444	313,815
Carrying Value
Debt Securities, Available-for-sale [Line Items]
Equity securities	356,102	480,620
Carrying Value | Common stock
Debt Securities, Available-for-sale [Line Items]
Equity securities	146,658	166,805
Carrying Value | Preferred stocks
Debt Securities, Available-for-sale [Line Items]
Equity securities	$ 209,444	$ 313,815

Arbitrage Trading Account (Deta

Arbitrage Trading Account (Details) - USD ($)	Mar. 31, 2020	Dec. 31, 2019
Derivative [Line Items]
Arbitrage trading account	$ 666,829,000	$ 400,809,000
Long | Options held
Derivative [Line Items]
Fair value of derivative	917,000
Notional amount of derivative	23,500,000
Short | Options held
Derivative [Line Items]
Fair value of derivative	545,000
Notional amount of derivative	$ 29,800,000

Net Investment Income (Details)

Net Investment Income (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Net Investment Income [Line Items]
Gross investment income	$ 177,392	$ 159,710
Investment expense	(2,629)	(1,456)
Net investment income	174,763	158,254
Fixed maturity securities, including cash and cash equivalents and loans receivable
Net Investment Income [Line Items]
Gross investment income	128,018	132,119
Investment funds
Net Investment Income [Line Items]
Gross investment income	40,577	11,411
Arbitrage trading account
Net Investment Income [Line Items]
Gross investment income	1,138	10,585
Real estate
Net Investment Income [Line Items]
Gross investment income	6,096	4,307
Equity securities
Net Investment Income [Line Items]
Gross investment income	$ 1,563	$ 1,288

Investment Funds (Details)

Investment Funds (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Schedule of Equity Method Investments [Line Items]
Unfunded commitments	$ 225,000
Investment funds	1,178,858		$ 1,213,535
Income (Loss) from Investment Funds	40,577	$ 11,411
Real estate
Schedule of Equity Method Investments [Line Items]
Investment funds	328,053		412,275
Income (Loss) from Investment Funds	6,790	10,476
Financial services
Schedule of Equity Method Investments [Line Items]
Investment funds	318,084		280,705
Income (Loss) from Investment Funds	15,209	1,528
Energy
Schedule of Equity Method Investments [Line Items]
Investment funds	152,658		156,869
Income (Loss) from Investment Funds	4,413	(11,793)
Transportation
Schedule of Equity Method Investments [Line Items]
Investment funds	150,353		147,034
Income (Loss) from Investment Funds	2,646	8,602
Other funds
Schedule of Equity Method Investments [Line Items]
Investment funds	229,710		$ 216,652
Income (Loss) from Investment Funds	$ 11,519	$ 2,598

Real Estate (Details)

Real Estate (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Real Estate [Abstract]
Properties in operation	$ 1,637,162	$ 1,351,249
Properties under development	447,225	754,701
Total	$ 2,084,387	$ 2,105,950

Real Estate (Narrative) (Detail

Real Estate (Narrative) (Details) - USD ($)	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Debt Instrument [Line Items]
Accumulated depreciation and amortization on properties	$ 66,160,000		$ 59,832,000
Real estate depreciation expense	6,620,000	$ 3,427,000
Lease future minimum payments 2019	44,198,185
Lease future minimum payments 2020	60,669,125
Lease future minimum payments 2021	60,719,260
Lease future minimum payments 2022	54,301,460
Lease future minimum payments 2023	52,053,044
Lease future minimum payments 2024	48,299,498
Lease future minimum payments there after	$ 522,531,742
Secured Debt
Debt Instrument [Line Items]
Fae value of debt			$ 101,750,000,000
Interest rate, percent			4.21%

Loans Receivable (Details)

Loans Receivable (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Dec. 31, 2019
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans receivable, gross	$ 87,058	$ 91,799
Loans receivable	91,074	94,613
Loans in nonaccrual status	200	200
Real estate loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans receivable, gross	52,890	58,541
Loans receivable	56,906	59,853
Commercial loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans receivable, gross	34,168	33,258
Loans receivable	$ 34,168	$ 34,760
Loans receivable maturity term	10 years

Loans Receivable - Allowance Fo

Loans Receivable - Allowance For Credit Loss (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2020USD ($)
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for expected credit losses at January 1, 2020	$ 2,146
Cumulative effect adjustment resulting from changes in accounting principles	3,928
Provision for expected credit losses	2,139
Allowance for expected credit losses at March 31, 2020	3,928
Real estate loans
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for expected credit losses at January 1, 2020	1,502
Cumulative effect adjustment resulting from changes in accounting principles	1,435
Provision for expected credit losses	838
Allowance for expected credit losses at March 31, 2020	1,435
Commercial loans
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for expected credit losses at January 1, 2020	644
Cumulative effect adjustment resulting from changes in accounting principles	2,493
Provision for expected credit losses	1,301
Allowance for expected credit losses at March 31, 2020	2,493
Cumulative effect adjustment resulting from changes in accounting principles
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for expected credit losses at January 1, 2020	(357)
Cumulative effect adjustment resulting from changes in accounting principles	(357)
Cumulative effect adjustment resulting from changes in accounting principles | Real estate loans
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for expected credit losses at January 1, 2020	(905)
Cumulative effect adjustment resulting from changes in accounting principles	(905)
Cumulative effect adjustment resulting from changes in accounting principles | Commercial loans
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for expected credit losses at January 1, 2020	548
Cumulative effect adjustment resulting from changes in accounting principles	$ 548

Realized And Unrealized Inves_3

Realized And Unrealized Investment Gains (Losses) on Investments (Realized and Unrealized Investments Gains (Losses)) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Investments, Debt and Equity Securities [Abstract]
Fixed maturity securities, gains	$ 4,931	$ 5,246
Fixed maturity securities, losses	(4,847)	(3,518)
Net realized gains on investment sales	0	23,345
Change in unrealized (losses) gains	(154,467)	42,078
Investment funds	30,183	17
Real estate	(687)	2,746
Loans receivable	0	(970)
Other	(18,398)	(291)
Net realized and unrealized (losses) gains on investments in earnings before allowance for expected credit losses	(143,285)	68,653
Fixed maturity securities	(31,750)	0
Loans receivable	(2,139)	0
Change in allowance for expected credit losses on investments	(33,889)	0
Net investment (losses) gains	(177,174)	68,653
Income tax benefit (expense)	37,207	(14,417)
After-tax net investment (losses) gains	$ (139,967)	$ 54,236

Realized And Unrealized Inves_4

Realized And Unrealized Investment Gains (Losses) on Investments (Change in Unrealized Gains (Losses) of Available For Sales Securities) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Realized and Unrealized Investment Gains Losses [Line Items]
Total change in unrealized investment (losses) gains	$ (332,850)	$ 169,260
Income tax benefit (expense)	73,869	(43,486)
Noncontrolling interests	1	(47)
Total change in unrealized gains	(258,980)	125,727
Debt securities
Realized and Unrealized Investment Gains Losses [Line Items]
Total change in unrealized investment (losses) gains	(326,416)	174,494
Fixed maturity securities with allowance for expected credit losses
Realized and Unrealized Investment Gains Losses [Line Items]
Total change in unrealized investment (losses) gains	1,541	(69)
Investment funds
Realized and Unrealized Investment Gains Losses [Line Items]
Total change in unrealized investment (losses) gains	(7,646)	1,790
Other
Realized and Unrealized Investment Gains Losses [Line Items]
Total change in unrealized investment (losses) gains	$ (329)	$ (6,955)

Fixed Maturity Securities In _3

Fixed Maturity Securities In An Unrealized Loss Position (Securities in an Unrealized Loss Position) (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Debt securities
Debt Securities, Available-for-sale [Line Items]
Fair Value, Less than 12 Months	$ 5,279,249	$ 1,977,541
Gross Unrealized Losses, Less than 12 Months	236,721	44,627
Fair Value, 12 Months or Greater	862,461	1,363,691
Gross Unrealized Losses, 12 Months or Greater	124,656	91,759
Fair Value, Total	6,141,710	3,341,232
Gross Unrealized Losses, Total	361,377	136,386
U.S. government and government agency
Debt Securities, Available-for-sale [Line Items]
Fair Value, Less than 12 Months	13,308	83,837
Gross Unrealized Losses, Less than 12 Months	13	618
Fair Value, 12 Months or Greater	7,145	53,089
Gross Unrealized Losses, 12 Months or Greater	45	857
Fair Value, Total	20,453	136,926
Gross Unrealized Losses, Total	58	1,475
State and municipal
Debt Securities, Available-for-sale [Line Items]
Fair Value, Less than 12 Months	640,570	365,184
Gross Unrealized Losses, Less than 12 Months	11,306	4,245
Fair Value, 12 Months or Greater	74,998	127,210
Gross Unrealized Losses, 12 Months or Greater	1,673	1,682
Fair Value, Total	715,568	492,394
Gross Unrealized Losses, Total	12,979	5,927
Mortgage-backed securities
Debt Securities, Available-for-sale [Line Items]
Fair Value, Less than 12 Months	609,582	301,358
Gross Unrealized Losses, Less than 12 Months	24,143	2,281
Fair Value, 12 Months or Greater	86,569	180,148
Gross Unrealized Losses, 12 Months or Greater	1,025	3,220
Fair Value, Total	696,151	481,506
Gross Unrealized Losses, Total	25,168	5,501
Asset-backed
Debt Securities, Available-for-sale [Line Items]
Fair Value, Less than 12 Months	2,014,456	755,259
Gross Unrealized Losses, Less than 12 Months	108,100	2,307
Fair Value, 12 Months or Greater	614,876	774,508
Gross Unrealized Losses, 12 Months or Greater	79,890	19,183
Fair Value, Total	2,629,332	1,529,767
Gross Unrealized Losses, Total	187,990	21,490
Corporate
Debt Securities, Available-for-sale [Line Items]
Fair Value, Less than 12 Months	1,886,894	307,367
Gross Unrealized Losses, Less than 12 Months	85,902	3,148
Fair Value, 12 Months or Greater	54,226	121,470
Gross Unrealized Losses, 12 Months or Greater	6,443	5,172
Fair Value, Total	1,941,120	428,837
Gross Unrealized Losses, Total	92,345	8,320
Foreign government
Debt Securities, Available-for-sale [Line Items]
Fair Value, Less than 12 Months	114,439	164,536
Gross Unrealized Losses, Less than 12 Months	7,257	32,028
Fair Value, 12 Months or Greater	24,647	107,266
Gross Unrealized Losses, 12 Months or Greater	35,580	61,645
Fair Value, Total	139,086	271,802
Gross Unrealized Losses, Total	$ 42,837	$ 93,673

Fixed Maturity Securities In _4

Fixed Maturity Securities In An Unrealized Loss Position (Non-Investment Grade Fixed Maturity Securities) (Details) $ in Thousands	Mar. 31, 2020USD ($)position	Dec. 31, 2019USD ($)
Mortgage-backed securities
Debt Securities, Available-for-sale [Line Items]
Aggregate Fair Value	$ 696,151	$ 481,506
Corporate
Debt Securities, Available-for-sale [Line Items]
Aggregate Fair Value	1,941,120	428,837
Asset-backed securities
Debt Securities, Available-for-sale [Line Items]
Aggregate Fair Value	$ 2,629,332	$ 1,529,767
Noninvestment Grade Investments at Loss Position
Debt Securities, Available-for-sale [Line Items]
Number of Securities | position	49
Aggregate Fair Value	$ 117,397
Gross Unrealized Loss	$ 47,711
Noninvestment Grade Investments at Loss Position | Foreign government
Debt Securities, Available-for-sale [Line Items]
Number of Securities | position	17
Aggregate Fair Value	$ 46,834
Gross Unrealized Loss	$ 38,867
Noninvestment Grade Investments at Loss Position | Mortgage-backed securities
Debt Securities, Available-for-sale [Line Items]
Number of Securities | position	13
Aggregate Fair Value	$ 14,213
Gross Unrealized Loss	$ 1,484
Noninvestment Grade Investments at Loss Position | Corporate
Debt Securities, Available-for-sale [Line Items]
Number of Securities | position	15
Aggregate Fair Value	$ 55,989
Gross Unrealized Loss	$ 7,293
Noninvestment Grade Investments at Loss Position | Asset-backed securities
Debt Securities, Available-for-sale [Line Items]
Number of Securities | position	4
Aggregate Fair Value	$ 361
Gross Unrealized Loss	$ 67

Fair Value Measurements (Assets

Fair Value Measurements (Assets and Liabilities Measured At Fair Value, On a Recurring Basis) (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Assets:
Total fixed maturity securities available for sale	$ 13,587,315	$ 14,102,278
Equity securities	356,102	480,620
Arbitrage trading account	666,829	400,809
Fair Value, Measurements, Recurring
Assets:
Total fixed maturity securities available for sale	13,587,315	14,102,278
Equity securities	356,102	480,620
Arbitrage trading account	666,829	400,809
Assets, fair value disclosure	14,610,246	14,983,707
Liabilities:
Securities sold but not yet purchased	14,003	36,143
Fair Value, Measurements, Recurring | U.S. government and government agency
Assets:
Total fixed maturity securities available for sale	739,662	786,931
Fair Value, Measurements, Recurring | State and municipal
Assets:
Total fixed maturity securities available for sale	3,748,155	3,895,632
Fair Value, Measurements, Recurring | Mortgage-backed securities
Assets:
Total fixed maturity securities available for sale	1,455,440	1,625,594
Fair Value, Measurements, Recurring | Asset-backed
Assets:
Total fixed maturity securities available for sale	2,938,052	2,790,630
Fair Value, Measurements, Recurring | Corporate
Assets:
Total fixed maturity securities available for sale	3,978,517	4,156,415
Fair Value, Measurements, Recurring | Foreign government
Assets:
Total fixed maturity securities available for sale	727,489	847,076
Fair Value, Measurements, Recurring | Common stocks
Assets:
Equity securities	146,658	166,805
Fair Value, Measurements, Recurring | Preferred stocks
Assets:
Equity securities	209,444	313,815
Level 1 | Fair Value, Measurements, Recurring
Assets:
Total fixed maturity securities available for sale	0	0
Equity securities	137,791	157,752
Arbitrage trading account	480,495	381,061
Assets, fair value disclosure	618,286	538,813
Liabilities:
Securities sold but not yet purchased	14,003	36,143
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	137,791	157,752
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	13,587,315	14,102,278
Equity securities	202,939	307,310
Arbitrage trading account	186,334	19,748
Assets, fair value disclosure	13,976,588	14,429,336
Liabilities:
Securities sold but not yet purchased	0	0
Level 2 | Fair Value, Measurements, Recurring | U.S. government and government agency
Assets:
Total fixed maturity securities available for sale	739,662	786,931
Level 2 | Fair Value, Measurements, Recurring | State and municipal
Assets:
Total fixed maturity securities available for sale	3,748,155	3,895,632
Level 2 | Fair Value, Measurements, Recurring | Mortgage-backed securities
Assets:
Total fixed maturity securities available for sale	1,455,440	1,625,594
Level 2 | Fair Value, Measurements, Recurring | Asset-backed
Assets:
Total fixed maturity securities available for sale	2,938,052	2,790,630
Level 2 | Fair Value, Measurements, Recurring | Corporate
Assets:
Total fixed maturity securities available for sale	3,978,517	4,156,415
Level 2 | Fair Value, Measurements, Recurring | Foreign government
Assets:
Total fixed maturity securities available for sale	727,489	847,076
Level 2 | Fair Value, Measurements, Recurring | Common stocks
Assets:
Equity securities	0	0
Level 2 | Fair Value, Measurements, Recurring | Preferred stocks
Assets:
Equity securities	202,939	307,310
Level 3 | Fair Value, Measurements, Recurring
Assets:
Total fixed maturity securities available for sale	0	0
Equity securities	15,372	15,558
Arbitrage trading account	0	0
Assets, fair value disclosure	15,372	15,558
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	0	0
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	8,867	9,053
Level 3 | Fair Value, Measurements, Recurring | Preferred stocks
Assets:
Equity securities	$ 6,505	$ 6,505

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, 2020	Mar. 31, 2019	Dec. 31, 2019
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Assets, impairments		$ 0
Level 3
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Assets, beginning balance	$ 15,558	29,948	$ 29,948
Assets, earnings		(6,794)
Assets, other comprehensive income		61
Assets, purchases		17,369
Assets, (sales)		(39,915)
Assets. transfers out		14,889
Assets, ending balance			15,558
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Liabilities, beginning balance	0	793	793
Liabilities, earnings			133
Liabilities, other comprehensive income			0
Liabilities, impairments			0
Liabilities, purchases			7,609
Liabilities, (sales)			(8,535)
Liabilities, maturities			0
Liabilities, ending balance			0
Level 3 | Debt securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Assets, beginning balance	0	99	99
Assets, earnings		(26)
Assets, other comprehensive income		61
Assets, impairments		0
Assets, purchases		0
Assets, (sales)		(134)
Assets. transfers out		0
Assets, ending balance			0
Level 3 | Asset-backed
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Assets, beginning balance	0	99	99
Assets, earnings		(26)
Assets, other comprehensive income		61
Assets, impairments		0
Assets, purchases		0
Assets, (sales)		(134)
Assets, maturities		0
Assets. transfers out		0
Assets, ending balance			0
Level 3 | Equity securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Assets, beginning balance	15,558	12,541	12,541
Assets, earnings	880	1,963
Assets, other comprehensive income	0	0
Assets, impairments	0	0
Assets, purchases	0	2,602
Assets, (sales)	(1,066)	(1,548)
Assets, maturities		0
Assets. transfers out	0	0
Assets, ending balance	15,372		15,558
Level 3 | Common stock
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Assets, beginning balance	9,053	8,596	8,596
Assets, earnings	880	2,005
Assets, other comprehensive income	0
Assets, impairments	0	0
Assets, purchases	0	0
Assets, (sales)	(1,066)	(1,548)
Assets. transfers out	0	0
Assets, ending balance	8,867		9,053
Level 3 | Preferred stocks
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Assets, beginning balance	6,505	3,945	3,945
Assets, earnings	0	(42)
Assets, other comprehensive income	0	0
Assets, impairments	0	0
Assets, purchases	0	2,602
Assets, (sales)	0	0
Assets. transfers out	0	0
Assets, ending balance	6,505		6,505
Level 3 | Arbitrage trading account
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Assets, beginning balance	$ 0	17,308	17,308
Assets, earnings		(8,731)
Assets, other comprehensive income		0
Assets, impairments		0
Assets, purchases		14,767
Assets, (sales)		(38,233)
Assets. transfers out		$ 14,889
Assets, ending balance			0
Level 3 | Securities Sold, Not yet Purchased [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Liabilities, transfers out			$ 0

Reserves for Loss and Loss Ex_3

Reserves for Loss and Loss Expenses (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2020	Dec. 31, 2019	Mar. 31, 2019
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Net reserves at beginning of period	$ 10,697,998	$ 10,248,883
Net provision for losses and loss expenses:
Claims occurring during the current year	1,097,523	971,806
Decrease in estimates for claims occurring in prior years	433	6,481
Loss reserve discount accretion	9,297	10,363
Liability for Unpaid Claims and Claims Adjustment Expense, Incurred Claims	1,107,253	988,650
Net payments for claims:
Current year	84,310	295,873
Prior years	864,064	567,756
Total	948,374	863,629
Foreign currency translation	(77,167)	(163)
Net reserves at end of period	10,697,998	10,248,883	$ 10,785,637	$ 10,697,998	$ 10,373,741
Ceded reserves at end of period			1,946,878		1,719,369
Gross reserves at end of period			$ 12,732,515	12,583,249	$ 12,093,110
Cumulative effect adjustment resulting from changes in accounting principles
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Net reserves at beginning of period	5,927	0
Net payments for claims:
Net reserves at end of period	5,927	0		5,927
Cumulative Effect, Period Of Adoption, Adjusted Balance
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Net reserves at beginning of period	10,703,925	10,248,883
Net payments for claims:
Net reserves at end of period	$ 10,703,925	$ 10,248,883		$ 10,703,925

Reserves for Loss and Loss Ex_4

Reserves for Loss and Loss Expenses (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Liability for Claims and Claims Adjustment Expense [Line Items]
Net of loss reserve discounts	$ 3	$ 6
Increase (decrease) in estimates for claims	4	(3)
Adjustment expense	4	6.7
Liability recognized for best estimate net of reinsurance	67
Insurance
Liability for Claims and Claims Adjustment Expense [Line Items]
Favorable reserve development net of premium offsets	7	9.6
Liability recognized for best estimate net of reinsurance	47
Reinsurance & Monoline Excess
Liability for Claims and Claims Adjustment Expense [Line Items]
Unfavorable reserve development net of premium offsets	3	$ 2.9
Liability recognized for best estimate net of reinsurance	$ 20

Fair Value of Financial Instr_3

Fair Value of Financial Instruments (Carrying Amounts and Estimated Fair Values of Financial Instruments) (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Assets:
Arbitrage trading account	$ 666,829	$ 400,809
Loans receivable	91,074	94,613
Carrying Value
Assets:
Fixed maturity securities	13,666,067	14,180,961
Equity securities	356,102	480,620
Arbitrage trading account	666,829	400,809
Loans receivable	87,058	91,799
Cash and cash equivalents	965,012	1,023,710
Trading account receivables from brokers and clearing organizations	132,928	423,543
Due from broker	11,476	0
Liabilities:
Due to broker	0	27,116
Trading account securities sold but not yet purchased	14,003	36,143
Subordinated debentures	1,198,951	1,198,704
Senior notes and other debt	1,432,117	1,427,575
Fair Value
Assets:
Fixed maturity securities	13,678,391	14,194,955
Equity securities	356,102	480,620
Arbitrage trading account	666,829	400,809
Loans receivable	91,074	94,613
Cash and cash equivalents	965,012	1,023,710
Trading account receivables from brokers and clearing organizations	132,928	423,543
Due from broker	11,476	0
Liabilities:
Due to broker	0	27,116
Trading account securities sold but not yet purchased	14,003	36,143
Subordinated debentures	1,092,780	1,274,088
Senior notes and other debt	$ 1,454,081	$ 1,582,290

Reinsurance (Details)

Reinsurance (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Written premiums:
Written premiums, direct	$ 1,964,490	$ 1,829,815
Written premiums, assumed	266,882	216,415
Written premiums, ceded	(385,526)	(336,629)
Total net premiums written	1,845,846	1,709,601
Earned premiums:
Earned premiums, direct	1,829,713	1,723,610
Earned premiums, assumed	228,214	188,191
Earned premiums, ceded	(366,509)	(318,945)
Net premiums earned	1,691,418	1,592,856
Ceded losses and loss expenses incurred	235,183	173,046
Ceded commissions earned	81,045	$ 71,017
Cumulative effect adjustment resulting from changes in accounting principles	$ 6,800		$ 690

Reinsurance - Premiums and Rein

Reinsurance - Premiums and Reinsurance, Allowance For Credit Loss (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2020USD ($)
Premium Receivable, Allowance for Credit Loss [Roll Forward]
Allowance for expected credit losses at January 1, 2020	$ 19,823
Cumulative effect adjustment resulting from changes in accounting principles	21,524
Provision for expected credit losses	431
Allowance for expected credit losses at March 31, 2020	21,524
Reinsurance Recoverable, Allowance for Credit Loss [Roll Forward]
Allowance for expected credit losses at January 1, 2020	690
Cumulative effect adjustment resulting from changes in accounting principles	6,800
Reinsurance Recoverable, Credit Loss Expense (Reversal)	183
Allowance for expected credit losses at March 31, 2020	6,800
Cumulative effect adjustment resulting from changes in accounting principles
Premium Receivable, Allowance for Credit Loss [Roll Forward]
Allowance for expected credit losses at January 1, 2020	1,270
Cumulative effect adjustment resulting from changes in accounting principles	1,270
Reinsurance Recoverable, Allowance for Credit Loss [Roll Forward]
Allowance for expected credit losses at January 1, 2020	5,927
Cumulative effect adjustment resulting from changes in accounting principles	$ 5,927

Restricted Stock Units (Summary

Restricted Stock Units (Summary of Restricted Stock Units Issued) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Share-Based Compensation Arrangement by Share-based Payment Award [Line Item]
Share based compensation expense	$ 12,000	$ 15,000
Restricted stock
Share-Based Compensation Arrangement by Share-based Payment Award [Line Item]
Restricted stock units (in units)	724	1,106
Fair Value	$ 57	$ 60
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

Leases (Lease Cost) (Details)

Leases (Lease Cost) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Leases [Abstract]
Lease cost	$ 11,236	$ 11,555
Cash paid for amounts included in the measurement of lease liabilities reported in operating cash flows	10,830	11,657
Right-of-use assets obtained in exchange for new lease liabilities	$ 1,612	$ 4,966

Leases (Supplemental Balance Sh

Leases (Supplemental Balance Sheet Information) (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Mar. 31, 2019
Leases [Abstract]
Operating lease, right-of-use asset	$ 184,544	$ 185,012
Operating lease, liability	$ 224,189	$ 215,008
Weighted-average remaining lease term	6 years 11 months 12 days	6 years 9 months 18 days
Weighted-average discount rate	5.95%	5.95%

Leases (Maturities of Operating

Leases (Maturities of Operating Lease Liabilities) (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Mar. 31, 2019
Leases [Abstract]
Remainder of 2019	$ 36,912
2021	45,262
2022	41,267
2023	37,602
2024	31,357
Thereafter	78,532
Total undiscounted future minimum lease payments	270,932
Less: Discount impact	(46,743)
Total lease liability	$ 224,189	$ 215,008

Business Segments (Financial In

Business Segments (Financial Information of Company Operating Segments) (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2020USD ($)segment	Mar. 31, 2019USD ($)
Segment Reporting Information [Line Items]
Number of reportable segments | segment	2
Earned Premiums (1)	$ 1,691,418	$ 1,592,856
Investment Income	174,763	158,254
Other	(55,571)	185,912
Total revenues	1,810,610	1,937,022
Pre-Tax (Loss) Income	(6,468)	229,439
Net (Loss) Income to Common Stockholders	(4,418)	180,722
Net investment gains	(177,174)	68,653
Net investment gains, net of tax	(139,967)	54,236
Corporate, other and eliminations
Segment Reporting Information [Line Items]
Earned Premiums (1)	0	0
Investment Income	13,595	18,639
Other	113,130	104,015
Total revenues	126,725	122,654
Pre-Tax (Loss) Income	(41,755)	(68,585)
Net (Loss) Income to Common Stockholders	(33,755)	(55,032)
Insurance
Segment Reporting Information [Line Items]
Earned Premiums (1)		1,427,034
Insurance | Operating Segments
Segment Reporting Information [Line Items]
Earned Premiums (1)	1,484,955	1,427,034
Investment Income	123,458	100,041
Other	8,473	13,244
Total revenues	1,616,886	1,540,319
Pre-Tax (Loss) Income	175,947	184,516
Net (Loss) Income to Common Stockholders	140,117	145,993
Reinsurance & Monoline Excess
Segment Reporting Information [Line Items]
Earned Premiums (1)		165,822
Reinsurance & Monoline Excess | Operating Segments
Segment Reporting Information [Line Items]
Earned Premiums (1)	206,463	165,822
Investment Income	37,710	39,574
Other	0	0
Total revenues	244,173	205,396
Pre-Tax (Loss) Income	36,514	44,855
Net (Loss) Income to Common Stockholders	29,187	35,525
Re-insurance - International | Operating Segments
Segment Reporting Information [Line Items]
Total revenues	69,000	59,000
Net investment gains
Segment Reporting Information [Line Items]
Earned Premiums (1)	0	0
Investment Income	0	0
Insurance-International Segment | Operating Segments
Segment Reporting Information [Line Items]
Total revenues	$ 168,000	$ 170,000

Business Segments (Identifiable

Business Segments (Identifiable Assets by Segment) (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Segment Reporting, Asset Reconciling Item [Line Items]
Consolidated Assets	$ 26,089,929	$ 26,630,030
Operating Segments | Insurance
Segment Reporting, Asset Reconciling Item [Line Items]
Consolidated Assets	19,485,407	20,005,802
Operating Segments | Reinsurance & Monoline Excess
Segment Reporting, Asset Reconciling Item [Line Items]
Consolidated Assets	4,405,637	4,710,819
Corporate, other and eliminations
Segment Reporting, Asset Reconciling Item [Line Items]
Consolidated Assets	$ 2,198,885	$ 1,913,409

Business Segments (Net Premiums

Business Segments (Net Premiums Earned By Major Line of Business) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Revenue from External Customer [Line Items]
Net premiums earned	$ 1,691,418	$ 1,592,856
Insurance
Revenue from External Customer [Line Items]
Net premiums earned		1,427,034
Insurance | Other liability
Revenue from External Customer [Line Items]
Net premiums earned	547,129	490,661
Insurance | Workers’ compensation
Revenue from External Customer [Line Items]
Net premiums earned	301,600	326,676
Insurance | Property reinsurance
Revenue from External Customer [Line Items]
Net premiums earned	295,478	289,091
Insurance | Commercial automobile
Revenue from External Customer [Line Items]
Net premiums earned	189,643	180,925
Insurance | Professional liability
Revenue from External Customer [Line Items]
Net premiums earned	151,105	139,681
Reinsurance & Monoline Excess
Revenue from External Customer [Line Items]
Net premiums earned		165,822
Reinsurance & Monoline Excess | Property reinsurance
Revenue from External Customer [Line Items]
Net premiums earned	41,571	36,011
Reinsurance & Monoline Excess | Casualty reinsurance
Revenue from External Customer [Line Items]
Net premiums earned	122,731	90,830
Reinsurance & Monoline Excess | Monoline Excess
Revenue from External Customer [Line Items]
Net premiums earned	$ 42,161	$ 38,981