W. R. Berkley (WRB) 10-Q 2 Aug 21 2021 Q2 Quarterly report Financial data

Cover Page

Cover Page - shares	6 Months Ended
	Jun. 30, 2021	Jul. 28, 2021
Entity Information [Line Items]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Jun. 30, 2021
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		177,529,889
Entity Central Index Key	0000011544
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q2
Amendment Flag	false
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
5.10% Subordinated Debentures due 2059
Entity Information [Line Items]
Title of 12(b) Security	5.10% Subordinated Debentures due 2059
Trading Symbol	WRB-PF
Security Exchange Name	NYSE
4.25% Subordinated Debentures due 2060
Entity Information [Line Items]
Title of 12(b) Security	4.25% Subordinated Debentures due 2060
Trading Symbol	WRB-PG
Security Exchange Name	NYSE
4.125% Subordinated Debentures due 2061
Entity Information [Line Items]
Title of 12(b) Security	4.125% Subordinated Debentures due 2061
Trading Symbol	WRB-PH
Security Exchange Name	NYSE

Consolidated Balance Sheets Con

Consolidated Balance Sheets Consolidated Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Investments:
Fixed maturity securities (amortized cost of $15,350,553 and $13,755,858; allowance for expected credit losses of $19,364 and $2,580 at June 30, 2021 and December 31, 2020, respectively)	$ 15,653,508	$ 14,159,369
Real estate	1,811,263	1,960,914
Investment funds	1,369,453	1,309,430
Arbitrage trading account	634,276	341,473
Equity securities	642,993	625,667
Loans receivable (net of allowance for expected credit losses of $1,970 and $5,437 at June 30, 2021 and December 31, 2020, respectively)	116,009	84,913
Total investments	20,227,502	18,481,766
Cash and cash equivalents	1,790,199	2,372,366
Premiums and fees receivable (net of allowance for expected credit losses of $24,808 and $22,883 at June 30, 2021 and December 31, 2020, respectively)	2,487,649	2,167,799
Due from reinsurers (net of allowance for expected credit losses of $7,283 and $7,801 at June 30, 2021 and December 31, 2020, respectively)	2,681,266	2,424,502
Deferred policy acquisition costs	627,647	556,168
Prepaid reinsurance premiums	680,773	648,376
Trading account receivables from brokers and clearing organizations	361,586	524,727
Property, furniture and equipment	428,723	405,930
Goodwill	169,652	169,652
Accrued investment income	122,524	120,464
Current and deferred federal and foreign income taxes	44,659
Other assets	675,737	700,215
Total assets	30,297,917	28,571,965
Liabilities:
Reserves for losses and loss expenses	14,480,947	13,784,430
Unearned premiums	4,544,524	4,073,191
Due to reinsurers	535,286	426,124
Trading account securities sold but not yet purchased	190	10,048
Current and deferred federal and foreign income taxes	0	48,495
Other liabilities	1,229,970	1,178,546
Senior notes and other debt	1,911,753	1,623,025
Subordinated debentures	1,007,293	1,102,309
Total liabilities	23,709,963	22,246,168
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, 177,930,502 and 183,411,907 shares, respectively	70,535	70,535
Additional paid-in capital	1,035,166	1,012,483
Retained earnings	8,682,088	8,348,381
Accumulated other comprehensive loss	(122,444)	(62,172)
Treasury stock, at cost, 175,262,530 and 174,851,350 shares, respectively	(3,087,069)	(3,058,425)
Total stockholders’ equity	6,578,276	6,310,802
Noncontrolling interests	9,678	14,995
Total equity	6,587,954	6,325,797
Total liabilities and equity	$ 30,297,917	$ 28,571,965

Consolidated Balance Sheets C_2

Consolidated Balance Sheets Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Statement of Financial Position [Abstract]
Fixed maturity securities, allowance for credit loss	$ 19,364	$ 2,580
Fixed maturity securities, amortized cost	15,350,553	13,755,858
Cumulative effect adjustment resulting from changes in accounting principles	1,970	5,437
Cumulative effect adjustment resulting from changes in accounting principles	24,808	22,883
Reinsurance recoverable, allowance for credit loss	$ 7,283	$ 7,801
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)	$ 0.20	$ 0.20
Common shares authorized (in shares)	750,000,000	750,000,000
Common shares issued (in shares)	177,413,970	177,825,150
Common shares outstanding (in shares)	177,413,970	177,825,150
Treasury stock issued at cost (in shares)	175,262,530	174,851,350

Consolidated Statements Income

Consolidated Statements Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
REVENUES:
Net premiums written	$ 2,212,181	$ 1,739,818	$ 4,262,219	$ 3,585,664
Change in net unearned premiums	(240,557)	(62,903)	(440,639)	(217,331)
Net premiums earned	1,971,624	1,676,915	3,821,580	3,368,333
Net investment income	168,187	85,431	326,764	260,194
Net realized and unrealized gains (losses) on investments	20,461	61,653	72,219	(81,632)
Change in allowance for expected credit losses on investments	3,603	16,232	(13,316)	(17,657)
Net investment gains (losses)	24,064	77,885	58,903	(99,289)
Revenues from non-insurance businesses	109,122	75,742	196,552	169,471
Insurance service fees	22,256	19,870	48,064	45,621
Other income	833	183	1,092	2,305
Total revenues	2,296,086	1,936,026	4,452,955	3,746,635
OPERATING COSTS AND EXPENSES:
Losses and loss expenses	1,203,647	1,135,126	2,325,238	2,242,379
Other operating costs and expenses	647,705	580,840	1,263,973	1,159,173
Expenses from non-insurance businesses	106,698	76,238	192,989	170,996
Interest expense	38,096	38,373	74,747	75,105
Total operating costs and expenses	1,996,146	1,830,577	3,856,947	3,647,653
Income before income taxes	299,940	105,449	596,008	98,982
Income tax expense	(62,262)	(33,793)	(126,614)	(30,852)
Net income before noncontrolling interests	237,678	71,656	469,394	68,130
Noncontrolling interests	(440)	(396)	(2,631)	(1,288)
Net income to common stockholders	$ 237,238	$ 71,260	$ 466,763	$ 66,842
NET INCOME PER SHARE:
Basic (in dollar per share)	$ 1.28	$ 0.38	$ 2.52	$ 0.36
Diluted (in dollar per share)	$ 1.27	$ 0.38	$ 2.50	$ 0.35

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Statement of Comprehensive Income [Abstract]
Net income before noncontrolling interests	$ 237,678	$ 71,656	$ 469,394	$ 68,130
Other comprehensive income (loss):
Change in unrealized currency translation adjustments	2,537	21,447	6,587	(76,747)
Change in unrealized investment gains (losses), net of taxes	23,272	318,725	(66,858)	59,743
Other comprehensive income (loss)	25,809	340,172	(60,271)	(17,004)
Comprehensive income	263,487	411,828	409,123	51,126
Noncontrolling interests	(439)	(395)	(2,630)	(1,289)
Comprehensive income to common stockholders	$ 263,048	$ 411,433	$ 406,493	$ 49,837

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	$ 1,056,042	$ 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		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			(3,386)
Restricted stock units expensed			23,387
Net income before noncontrolling interests	$ 68,130			66,842					1,288
Dividends ( $0.63, $0.12, $0.75 and $0.23 per share, respectively)				(41,420)
Change in unrealized gains (losses) on securities without an allowance for expected credit losses	59,743					34,753
Change in unrealized (losses) gains on securities with an allowance for expected credit losses						24,991
Net change in period	(76,747)						(76,747)
Stock exercised/vested								2,221
Stock repurchased								(298,902)
Distributions									(417)
Other comprehensive income (loss), net of tax	(17,004)				(17,004)		(76,747)		1
End of period at Jun. 30, 2020			1,076,043	7,927,280	(249,350)	209,210	(458,560)	(3,023,392)	44,275
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect adjustment resulting from changes in accounting principles		70,535	1,063,084	7,877,371	(589,521)	(109,514)	(480,007)	(2,927,994)	44,069	0		0
Beginning of period at Mar. 31, 2020		70,535	1,063,084	7,877,371	(589,521)	(109,514)	(480,007)	(2,927,994)	44,069	0		0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Restricted stock units issued			1,204
Restricted stock units expensed			11,755
Net income before noncontrolling interests	71,656			71,260					396
Dividends ( $0.63, $0.12, $0.75 and $0.23 per share, respectively)				(21,351)
Change in unrealized gains (losses) on securities without an allowance for expected credit losses	318,725					295,274
Change in unrealized (losses) gains on securities with an allowance for expected credit losses						23,450
Net change in period	21,447						21,447
Stock exercised/vested								883
Stock repurchased								(96,281)
Distributions									(189)
Other comprehensive income (loss), net of tax	$ 340,172				340,172		21,447		(1)
End of period at Jun. 30, 2020			1,076,043	7,927,280	(249,350)	209,210	(458,560)	(3,023,392)	44,275
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock dividends, per share, cash paid (in dollars per share)	$ 0.23
Cumulative effect adjustment resulting from changes in accounting principles			1,076,043	7,927,280	(249,350)	209,210	(458,560)	(3,023,392)	44,275
Cumulative effect adjustment resulting from changes in accounting principles	$ 6,325,797	70,535	1,012,483	8,348,381	(62,172)	289,714	(351,886)	(3,058,425)	14,995	0		0
Beginning of period at Dec. 31, 2020	6,325,797	70,535	1,012,483	8,348,381	(62,172)	289,714	(351,886)	(3,058,425)	14,995	0		0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Restricted stock units issued			72
Restricted stock units expensed			22,611
Net income before noncontrolling interests	469,394			466,763					2,631
Dividends ( $0.63, $0.12, $0.75 and $0.23 per share, respectively)				(133,056)
Change in unrealized gains (losses) on securities without an allowance for expected credit losses	(66,858)					(77,145)
Change in unrealized (losses) gains on securities with an allowance for expected credit losses						10,286
Net change in period	6,587						6,587
Stock exercised/vested								1,039
Stock repurchased								(29,683)
Distributions									(7,947)
Other comprehensive income (loss), net of tax	(60,271)				(60,271)		6,587		(1)
End of period at Jun. 30, 2021	6,587,954		1,035,166	8,682,088	(122,444)	222,855	(345,299)	(3,087,069)	9,678
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect adjustment resulting from changes in accounting principles		70,535	1,023,556	8,556,621	(148,252)	199,584	(347,836)	(3,087,860)	15,684	0		0
Beginning of period at Mar. 31, 2021		$ 70,535	1,023,556	8,556,621	(148,252)	199,584	(347,836)	(3,087,860)	15,684	$ 0		$ 0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Restricted stock units issued			597
Restricted stock units expensed			11,013
Net income before noncontrolling interests	237,678			237,238					440
Dividends ( $0.63, $0.12, $0.75 and $0.23 per share, respectively)				(111,771)
Change in unrealized gains (losses) on securities without an allowance for expected credit losses	23,272					23,340
Change in unrealized (losses) gains on securities with an allowance for expected credit losses						(69)
Net change in period	2,537						2,537
Stock exercised/vested								791
Stock repurchased								0
Distributions									(6,445)
Other comprehensive income (loss), net of tax	25,809				25,809		2,537		(1)
End of period at Jun. 30, 2021	$ 6,587,954		1,035,166	8,682,088	(122,444)	222,855	(345,299)	(3,087,069)	9,678
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock dividends, per share, cash paid (in dollars per share)	$ 0.12
Cumulative effect adjustment resulting from changes in accounting principles	$ 6,587,954		$ 1,035,166	$ 8,682,088	$ (122,444)	$ 222,855	$ (345,299)	$ (3,087,069)	$ 9,678

Consolidated Statements of Cash

Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
CASH FROM OPERATING ACTIVITIES:
Net income to common stockholders	$ 466,763	$ 66,842
Adjustments to reconcile net income to net cash from operating activities:
Net investment (gains) losses	(58,903)	99,289
Depreciation and amortization	70,597	64,065
Noncontrolling interests	2,631	1,288
Investment funds	(100,246)	16,975
Stock incentive plans	23,122	25,731
Change in:
Arbitrage trading account	(139,520)	(26,158)
Premiums and fees receivable	(321,718)	(204,203)
Reinsurance accounts	(178,442)	(118,849)
Deferred policy acquisition costs	(72,125)	(31,478)
Income taxes	(71,205)	9,387
Reserves for losses and loss expenses	705,454	525,785
Unearned premiums	473,395	259,237
Other	(103,994)	(108,060)
Net cash from operating activities	695,809	579,851
CASH (USED IN) FROM INVESTING ACTIVITIES:
Proceeds from sale of fixed maturity securities	1,474,054	3,194,333
Proceeds from sale of equity securities	98,765	67,122
Distributions from investment funds	88,363	67,234
Proceeds from maturities and prepayments of fixed maturity securities	3,156,861	1,859,392
Purchase of fixed maturity securities	(6,266,934)	(4,189,664)
Purchase of equity securities	(143,836)	(35,591)
Real estate sold (purchased)	202,115	(30,178)
Change in loans receivable	(28,510)	963
Net purchases of property, furniture and equipment	(48,273)	(23,006)
Change in balances due to security brokers	65,751	(24,382)
Other	2	85
Net cash (used in) from investing activities	(1,401,642)	886,308
CASH FROM (USED IN) FINANCING ACTIVITIES:
Repayment of senior notes and other debt	(505,230)	(1,160)
Net proceeds from issuance of debt	686,893	298,447
Cash dividends to common stockholders	(21,285)	(41,420)
Purchase of common treasury shares	(29,683)	(298,902)
Other, net	(6,725)	(4,140)
Net cash from (used in) financing activities	123,970	(47,175)
Net impact on cash due to change in foreign exchange rates	(304)	(11,868)
Net change in cash and cash equivalents	(582,167)	1,407,116
Cash and cash equivalents at beginning of year	2,372,366	1,023,710
Cash and cash equivalents at end of period	$ 1,790,199	$ 2,430,826

Statements of Cash Flows

Statements of Cash Flows	6 Months Ended
	Jun. 30, 2021
Supplemental Cash Flow Elements [Abstract]
Statements of Cash Flows	Statements of Cash Flows    Interest payments were $71,781,000 and $73,056,000 for the six months ended June 30, 2021 and 2020, respectively. Income taxes were $177,000,000 paid for the six months ended June 30, 2021. No income tax was paid for such period in 2020.

General

General	6 Months Ended
	Jun. 30, 2021
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. Reclassifications have been made in the 2020 financial statements as originally reported to conform to the presentation of the 2021 financial statements. 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, 2020. The income tax provision has been computed based on the Company’s estimated annual effective tax rate. The effective income tax rate differs from the federal income tax rate of 21% principally because of state and foreign income taxes, which was partially offset by tax-exempt investment income and tax benefits related to equity-based compensation.

Per Share Data

Per Share Data	6 Months Ended
	Jun. 30, 2021
Earnings Per Share [Abstract]
Per Share Data	Per Share Data The Company presents both basic and diluted net income per share (“EPS”) amounts. Basic EPS is calculated by dividing net income by the weighted average number of common shares outstanding during the period (including 7,767,874 and 7,575,168 common shares held in a grantor trust as of June 30, 2021 and 2020, respectively). The common shares held in the grantor trust are for delivery upon settlement of vested but mandatorily deferred restricted stock units ("RSUs"). Shares held by the grantor trust do not affect diluted shares outstanding since the shares deliverable under vested RSUs were already included in diluted shares outstanding. Diluted EPS is based upon the weighted average number of basic and common equivalent shares outstanding during the period and is calculated using the treasury stock method for stock incentive plans. Common equivalent shares are excluded from the computation in periods in which they have an anti-dilutive effect. The weighted average number of common shares used in the computation of basic and diluted earnings per share was as follows: For the Three Months For the Six Months (In thousands) 2021 2020 2021 2020 Basic 185,155 185,979 185,175 188,133 Diluted 187,106 187,862 186,985 190,078

Recent Accounting Pronouncement

Recent Accounting Pronouncements and Accounting Policies	6 Months Ended
	Jun. 30, 2021
Accounting Policies [Abstract]
Recent Accounting Pronouncements and Accounting Policies	Recent Accounting Pronouncements and Accounting Policies Recently adopted accounting pronouncements: All accounting and reporting standards that have become effective in 2021 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.

Consolidated Statements of Co_2

Consolidated Statements of Comprehensive Income	6 Months Ended
	Jun. 30, 2021
Equity [Abstract]
Consolidated Statements of Comprehensive Income	Consolidated Statements of Comprehensive Income The following table presents the components of the changes in accumulated other comprehensive (loss) income ("AOCI"): (In thousands) Unrealized Investment Gains (Losses) Currency Translation Adjustments Accumulated Other Comprehensive As of and for the six months ended June 30, 2021 Changes in AOCI Beginning of period $ 289,714 $ (351,886) $ (62,172) Other comprehensive (loss) income before reclassifications (87,168) 6,587 (80,581) Amounts reclassified from AOCI 20,310 — 20,310 Other comprehensive (loss) income (66,858) 6,587 (60,271) Unrealized investment gain related to noncontrolling interest (1) — (1) End of period $ 222,855 $ (345,299) $ (122,444) Amounts reclassified from AOCI Pre-tax $ 25,709 (1) $ — $ 25,709 Tax effect (5,399) (2) — (5,399) After-tax amounts reclassified $ 20,310 $ — $ 20,310 Other comprehensive (loss) income Pre-tax $ (84,931) $ 6,587 $ (78,344) Tax effect 18,073 — 18,073 Other comprehensive (loss) income $ (66,858) $ 6,587 $ (60,271) As of and for the three months ended June 30, 2021 Changes in AOCI Beginning of period $ 199,584 $ (347,836) $ (148,252) Other comprehensive income before reclassifications 11,823 2,537 14,360 Amounts reclassified from AOCI 11,449 — 11,449 Other comprehensive income 23,272 2,537 25,809 Unrealized investment gain related to noncontrolling interest (1) — (1) Ending balance $ 222,855 $ (345,299) $ (122,444) Amounts reclassified from AOCI Pre-tax $ 14,493 (1) $ — $ 14,493 Tax effect (3,044) (2) — (3,044) After-tax amounts reclassified $ 11,449 $ — $ 11,449 Other comprehensive income Pre-tax $ 28,804 $ 2,537 $ 31,341 Tax effect (5,532) — (5,532) Other comprehensive income $ 23,272 $ 2,537 $ 25,809 As of and for the six months ended June 30, 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 income (loss) before reclassifications 36,986 (76,747) (39,761) Amounts reclassified from AOCI 22,757 — 22,757 Other comprehensive income (loss) 59,743 (76,747) (17,004) Unrealized investment loss related to noncontrolling interest 1 — 1 End of period $ 209,210 $ (458,560) $ (249,350) Amounts reclassified from AOCI Pre-tax $ 28,806 (1) $ — $ 28,806 Tax effect (6,049) (2) — (6,049) After-tax amounts reclassified $ 22,757 $ — $ 22,757 Other comprehensive income (loss) Pre-tax $ 62,777 $ (76,747) $ (13,970) Tax effect (3,034) — (3,034) Other comprehensive income (loss) $ 59,743 $ (76,747) $ (17,004) As of and for the three months ended June 30, 2020 Changes in AOCI Beginning of period $ (109,514) $ (480,007) $ (589,521) Other comprehensive income before reclassifications 335,518 21,447 356,965 Amounts reclassified from AOCI (16,793) — (16,793) Other comprehensive income 318,725 21,447 340,172 Unrealized investment gain related to noncontrolling interest (1) — (1) Ending balance $ 209,210 $ (458,560) $ (249,350) Amounts reclassified from AOCI Pre-tax $ (21,257) (1) $ — $ (21,257) Tax effect 4,464 (2) — 4,464 After-tax amounts reclassified $ (16,793) $ — $ (16,793) Other comprehensive income Pre-tax $ 395,624 $ 21,447 $ 417,071 Tax effect (76,899) — (76,899) Other comprehensive income $ 318,725 $ 21,447 $ 340,172 ____________ (1) Net investment gains (losses) in the consolidated statements of income. (2) Income tax (expense) benefit in the consolidated statements of income.

Investments In Fixed Maturity S

Investments In Fixed Maturity Securities	6 Months Ended
	Jun. 30, 2021
Investments, Debt and Equity Securities [Abstract]
Investments In Fixed Maturity Securities	Investments in Fixed Maturity Securities At June 30, 2021 and December 31, 2020, investments in fixed maturity securities were as follows: (In thousands) Amortized Allowance for Expected Credit Losses (1) Gross Unrealized Fair Carrying Gains Losses June 30, 2021 Held to maturity: State and municipal $ 68,310 $ (453) $ 12,069 $ — $ 79,926 $ 67,857 Residential mortgage-backed 5,724 — 859 — 6,583 5,724 Total held to maturity 74,034 (453) 12,928 — 86,509 73,581 Available for sale: U.S. government and government agency 488,196 — 14,890 (461) 502,625 502,625 State and municipal: Special revenue 2,074,036 — 85,037 (1,433) 2,157,640 2,157,640 State general obligation 378,596 — 29,413 (250) 407,759 407,759 Pre-refunded 225,787 — 17,677 (607) 242,857 242,857 Corporate backed 156,970 — 9,082 (862) 165,190 165,190 Local general obligation 419,506 — 33,630 (426) 452,710 452,710 Total state and municipal 3,254,895 — 174,839 (3,578) 3,426,156 3,426,156 Mortgage-backed: Residential 771,507 — 16,798 (8,189) 780,116 780,116 Commercial 137,996 — 5,740 (150) 143,586 143,586 Total mortgage-backed 909,503 — 22,538 (8,339) 923,702 923,702 Asset-backed 4,333,543 — 8,449 (24,129) 4,317,863 4,317,863 Corporate: Industrial 3,019,720 (12) 94,056 (7,761) 3,106,003 3,106,003 Financial 1,583,291 — 51,103 (1,076) 1,633,318 1,633,318 Utilities 406,423 — 18,531 (1,106) 423,848 423,848 Other 177,445 — 416 (367) 177,494 177,494 Total corporate 5,186,879 (12) 164,106 (10,310) 5,340,663 5,340,663 Foreign government 1,103,503 (18,899) 17,176 (32,862) 1,068,918 1,068,918 Total available for sale 15,276,519 (18,911) 401,998 (79,679) 15,579,927 15,579,927 Total investments in fixed maturity securities $ 15,350,553 $ (19,364) $ 414,926 $ (79,679) $ 15,666,436 $ 15,653,508 ____________ (1) Represents the amount of impairment that has resulted from credit-related factors. The change in the allowance for expected credit losses is recognized in the consolidated statements of income. Amount excludes unrealized losses relating to non-credit factors. (In thousands) Amortized Allowance for Expected Credit Losses (1) Gross Unrealized Fair Carrying Gains Losses December 31, 2020 Held to maturity: State and municipal $ 67,117 $ (798) $ 13,217 $ — $ 79,536 $ 66,319 Residential mortgage-backed 6,455 — 1,043 — 7,498 6,455 Total held to maturity 73,572 (798) 14,260 — 87,034 72,774 Available for sale: U.S. government and government agency 586,020 — 18,198 (347) 603,871 603,871 State and municipal: Special revenue 2,137,162 — 96,924 (714) 2,233,372 2,233,372 State general obligation 417,397 — 33,407 — 450,804 450,804 Pre-refunded 250,081 — 21,472 (162) 271,391 271,391 Corporate backed 206,356 — 8,755 (638) 214,473 214,473 Local general obligation 410,583 — 40,596 (555) 450,624 450,624 Total state and municipal 3,421,579 — 201,154 (2,069) 3,620,664 3,620,664 Mortgage-backed: Residential 813,187 — 24,664 (5,238) 832,613 832,613 Commercial 181,105 — 6,725 (113) 187,717 187,717 Total mortgage-backed securities 994,292 — 31,389 (5,351) 1,020,330 1,020,330 Asset-backed 3,218,048 — 10,035 (33,497) 3,194,586 3,194,586 Corporate: Industrial 2,456,516 (518) 115,926 (7,449) 2,564,475 2,564,475 Financial 1,513,943 — 62,947 (987) 1,575,903 1,575,903 Utilities 389,267 — 31,931 (33) 421,165 421,165 Other 109,353 — 696 (11) 110,038 110,038 Total corporate 4,469,079 (518) 211,500 (8,480) 4,671,581 4,671,581 Foreign government 993,268 (1,264) 28,007 (44,448) 975,563 975,563 Total available for sale 13,682,286 (1,782) 500,283 (94,192) 14,086,595 14,086,595 Total investments in fixed maturity securities $ 13,755,858 $ (2,580) $ 514,543 $ (94,192) $ 14,173,629 $ 14,159,369 ____________ (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 income. Amount excludes unrealized losses relating to non-credit factors. The following table presents the rollforward of the allowance for expected credit losses for state and municipal held to maturity securities for the six months ended June 30, 2021 and 2020: (In thousands) 2021 2020 Allowance for expected credit losses, beginning of period $ 798 $ — Cumulative effect adjustment resulting from changes in accounting principles — 69 Provision for expected credit losses (345) 879 Allowance for expected credit losses, end of period $ 453 $ 948 The following table presents the rollforward of the allowance for expected credit losses for state and municipal held to maturity securities for the three months ended June 30, 2021 and 2020: (In thousands) 2021 2020 Allowance for expected credit losses, beginning of period $ 730 $ 107 Provision for expected credit losses (277) 841 Allowance for expected credit losses, end of period $ 453 $ 948 The following table presents the rollforward of the allowance for expected credit losses for available for sale securities for the six months ended June 30, 2021 and 2020: 2021 2020 (In thousands) Foreign Government Corporate Total Foreign Government Corporate Total Allowance for expected credit losses, beginning of period $ 1,264 $ 518 $ 1,782 $ — $ — $ — 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 18,990 16 19,006 12,494 6,797 19,291 Expected credit losses on securities for which credit losses were previously recorded (861) (517) (1,378) 547 (3,758) (3,211) Reduction due to disposals (494) (5) (499) (3,917) (2,315) (6,232) Allowance for expected credit losses, end of period $ 18,899 $ 12 $ 18,911 $ 44,769 $ 724 $ 45,493 The following table presents the rollforward of the allowance for expected credit losses for available for sale securities for the three months ended June 30, 2021 and 2020: 2021 2020 (In thousands) Foreign Government Corporate Total Foreign Government Corporate Total Allowance for expected credit losses, beginning of period $ 19,993 $ 16 $ 20,009 $ 60,920 $ 6,436 $ 67,356 Expected credit losses on securities for which credit losses were not previously recorded — — — — 361 361 Expected credit losses on securities for which credit losses were previously recorded (600) (4) (604) (15,822) (3,758) (19,580) Reduction due to disposals (494) — (494) (329) (2,315) (2,644) Allowance for expected credit losses, end of period $ 18,899 $ 12 $ 18,911 $ 44,769 $ 724 $ 45,493 During the six months ended June 30, 2021, the Company increased the allowance for expected credit losses for available for sale securities utilizing its credit loss assessment process and inputs used in its credit loss model, primarily due to foreign government securities that had no reserve in prior periods. During the six months ended June 30, 2020, the Company increased the allowance for expected credit losses for available for sale securities primarily due to the negative impact to the financial markets caused by COVID-19. The amortized cost and fair value of fixed maturity securities at June 30, 2021, 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 $ 1,735,412 $ 1,739,369 Due after one year through five years 6,570,612 6,726,040 Due after five years through ten years 3,888,420 3,993,735 Due after ten years 2,240,429 2,277,007 Mortgage-backed securities 915,227 930,285 Total $ 15,350,100 $ 15,666,436 ________________ (1) Amortized cost is reduced by the allowance for expected credit losses of $453 thousand related to held to maturity securities.

Investments in Equity Securitie

Investments in Equity Securities	6 Months Ended
	Jun. 30, 2021
Debt Securities, Available-for-sale [Line Items]
Investments in Equity Securities	Investments in Fixed Maturity Securities At June 30, 2021 and December 31, 2020, investments in fixed maturity securities were as follows: (In thousands) Amortized Allowance for Expected Credit Losses (1) Gross Unrealized Fair Carrying Gains Losses June 30, 2021 Held to maturity: State and municipal $ 68,310 $ (453) $ 12,069 $ — $ 79,926 $ 67,857 Residential mortgage-backed 5,724 — 859 — 6,583 5,724 Total held to maturity 74,034 (453) 12,928 — 86,509 73,581 Available for sale: U.S. government and government agency 488,196 — 14,890 (461) 502,625 502,625 State and municipal: Special revenue 2,074,036 — 85,037 (1,433) 2,157,640 2,157,640 State general obligation 378,596 — 29,413 (250) 407,759 407,759 Pre-refunded 225,787 — 17,677 (607) 242,857 242,857 Corporate backed 156,970 — 9,082 (862) 165,190 165,190 Local general obligation 419,506 — 33,630 (426) 452,710 452,710 Total state and municipal 3,254,895 — 174,839 (3,578) 3,426,156 3,426,156 Mortgage-backed: Residential 771,507 — 16,798 (8,189) 780,116 780,116 Commercial 137,996 — 5,740 (150) 143,586 143,586 Total mortgage-backed 909,503 — 22,538 (8,339) 923,702 923,702 Asset-backed 4,333,543 — 8,449 (24,129) 4,317,863 4,317,863 Corporate: Industrial 3,019,720 (12) 94,056 (7,761) 3,106,003 3,106,003 Financial 1,583,291 — 51,103 (1,076) 1,633,318 1,633,318 Utilities 406,423 — 18,531 (1,106) 423,848 423,848 Other 177,445 — 416 (367) 177,494 177,494 Total corporate 5,186,879 (12) 164,106 (10,310) 5,340,663 5,340,663 Foreign government 1,103,503 (18,899) 17,176 (32,862) 1,068,918 1,068,918 Total available for sale 15,276,519 (18,911) 401,998 (79,679) 15,579,927 15,579,927 Total investments in fixed maturity securities $ 15,350,553 $ (19,364) $ 414,926 $ (79,679) $ 15,666,436 $ 15,653,508 ____________ (1) Represents the amount of impairment that has resulted from credit-related factors. The change in the allowance for expected credit losses is recognized in the consolidated statements of income. Amount excludes unrealized losses relating to non-credit factors. (In thousands) Amortized Allowance for Expected Credit Losses (1) Gross Unrealized Fair Carrying Gains Losses December 31, 2020 Held to maturity: State and municipal $ 67,117 $ (798) $ 13,217 $ — $ 79,536 $ 66,319 Residential mortgage-backed 6,455 — 1,043 — 7,498 6,455 Total held to maturity 73,572 (798) 14,260 — 87,034 72,774 Available for sale: U.S. government and government agency 586,020 — 18,198 (347) 603,871 603,871 State and municipal: Special revenue 2,137,162 — 96,924 (714) 2,233,372 2,233,372 State general obligation 417,397 — 33,407 — 450,804 450,804 Pre-refunded 250,081 — 21,472 (162) 271,391 271,391 Corporate backed 206,356 — 8,755 (638) 214,473 214,473 Local general obligation 410,583 — 40,596 (555) 450,624 450,624 Total state and municipal 3,421,579 — 201,154 (2,069) 3,620,664 3,620,664 Mortgage-backed: Residential 813,187 — 24,664 (5,238) 832,613 832,613 Commercial 181,105 — 6,725 (113) 187,717 187,717 Total mortgage-backed securities 994,292 — 31,389 (5,351) 1,020,330 1,020,330 Asset-backed 3,218,048 — 10,035 (33,497) 3,194,586 3,194,586 Corporate: Industrial 2,456,516 (518) 115,926 (7,449) 2,564,475 2,564,475 Financial 1,513,943 — 62,947 (987) 1,575,903 1,575,903 Utilities 389,267 — 31,931 (33) 421,165 421,165 Other 109,353 — 696 (11) 110,038 110,038 Total corporate 4,469,079 (518) 211,500 (8,480) 4,671,581 4,671,581 Foreign government 993,268 (1,264) 28,007 (44,448) 975,563 975,563 Total available for sale 13,682,286 (1,782) 500,283 (94,192) 14,086,595 14,086,595 Total investments in fixed maturity securities $ 13,755,858 $ (2,580) $ 514,543 $ (94,192) $ 14,173,629 $ 14,159,369 ____________ (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 income. Amount excludes unrealized losses relating to non-credit factors. The following table presents the rollforward of the allowance for expected credit losses for state and municipal held to maturity securities for the six months ended June 30, 2021 and 2020: (In thousands) 2021 2020 Allowance for expected credit losses, beginning of period $ 798 $ — Cumulative effect adjustment resulting from changes in accounting principles — 69 Provision for expected credit losses (345) 879 Allowance for expected credit losses, end of period $ 453 $ 948 The following table presents the rollforward of the allowance for expected credit losses for state and municipal held to maturity securities for the three months ended June 30, 2021 and 2020: (In thousands) 2021 2020 Allowance for expected credit losses, beginning of period $ 730 $ 107 Provision for expected credit losses (277) 841 Allowance for expected credit losses, end of period $ 453 $ 948 The following table presents the rollforward of the allowance for expected credit losses for available for sale securities for the six months ended June 30, 2021 and 2020: 2021 2020 (In thousands) Foreign Government Corporate Total Foreign Government Corporate Total Allowance for expected credit losses, beginning of period $ 1,264 $ 518 $ 1,782 $ — $ — $ — 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 18,990 16 19,006 12,494 6,797 19,291 Expected credit losses on securities for which credit losses were previously recorded (861) (517) (1,378) 547 (3,758) (3,211) Reduction due to disposals (494) (5) (499) (3,917) (2,315) (6,232) Allowance for expected credit losses, end of period $ 18,899 $ 12 $ 18,911 $ 44,769 $ 724 $ 45,493 The following table presents the rollforward of the allowance for expected credit losses for available for sale securities for the three months ended June 30, 2021 and 2020: 2021 2020 (In thousands) Foreign Government Corporate Total Foreign Government Corporate Total Allowance for expected credit losses, beginning of period $ 19,993 $ 16 $ 20,009 $ 60,920 $ 6,436 $ 67,356 Expected credit losses on securities for which credit losses were not previously recorded — — — — 361 361 Expected credit losses on securities for which credit losses were previously recorded (600) (4) (604) (15,822) (3,758) (19,580) Reduction due to disposals (494) — (494) (329) (2,315) (2,644) Allowance for expected credit losses, end of period $ 18,899 $ 12 $ 18,911 $ 44,769 $ 724 $ 45,493 During the six months ended June 30, 2021, the Company increased the allowance for expected credit losses for available for sale securities utilizing its credit loss assessment process and inputs used in its credit loss model, primarily due to foreign government securities that had no reserve in prior periods. During the six months ended June 30, 2020, the Company increased the allowance for expected credit losses for available for sale securities primarily due to the negative impact to the financial markets caused by COVID-19. The amortized cost and fair value of fixed maturity securities at June 30, 2021, 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 $ 1,735,412 $ 1,739,369 Due after one year through five years 6,570,612 6,726,040 Due after five years through ten years 3,888,420 3,993,735 Due after ten years 2,240,429 2,277,007 Mortgage-backed securities 915,227 930,285 Total $ 15,350,100 $ 15,666,436 ________________ (1) Amortized cost is reduced by the allowance for expected credit losses of $453 thousand related to held to maturity securities.
Real estate
Debt Securities, Available-for-sale [Line Items]
Investments in Equity Securities	Investments in Equity Securities At June 30, 2021 and December 31, 2020, investments in equity securities were as follows: (In thousands) Cost Gross Unrealized Fair Carrying Gains Losses June 30, 2021 Common stocks $ 367,228 $ 88,228 $ (5,956) $ 449,500 $ 449,500 Preferred stocks 208,685 8,398 (23,590) 193,493 193,493 Total $ 575,913 $ 96,626 $ (29,546) $ 642,993 $ 642,993 December 31, 2020 Common stocks $ 335,617 $ 28,742 $ (14,178) $ 350,181 $ 350,181 Preferred stocks 180,397 95,581 (492) 275,486 275,486 Total $ 516,014 $ 124,323 $ (14,670) $ 625,667 $ 625,667

Arbitrage Trading Account

Arbitrage Trading Account	6 Months Ended
	Jun. 30, 2021
Debt Securities, Trading, and Equity Securities, FV-NI [Abstract]
Arbitrage Trading Account	Arbitrage Trading Account At June 30, 2021 and December 31, 2020, the fair and carrying values of the arbitrage trading account were $634 million and $341 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 June 30, 2021, the fair value of long option contracts outstanding was $3 thousand (notional amount of $741 thousand) and the fair value of short option contracts outstanding was $183 thousand (notional amount of $9.8 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	6 Months Ended
	Jun. 30, 2021
Net Investment Income [Abstract]
Net Investment Income	Net Investment Income Net investment income consisted of the following: For the Three Months For the Six Months (In thousands) 2021 2020 2021 2020 Investment income (loss) earned on: Fixed maturity securities, including cash and cash equivalents and loans receivable $ 96,996 $ 105,843 $ 191,673 $ 233,861 Investment funds 61,311 (57,552) 100,246 (16,975) Arbitrage trading account 3,914 31,304 22,989 32,442 Equity securities 7,212 2,726 13,392 4,288 Real estate 872 5,045 2,032 11,141 Gross investment income 170,305 87,366 330,332 264,757 Investment expense (2,118) (1,935) (3,568) (4,563) Net investment income $ 168,187 $ 85,431 $ 326,764 $ 260,194

Investment Funds

Investment Funds	6 Months Ended
	Jun. 30, 2021
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 $166 million as of June 30, 2021. Investment funds consisted of the following: Carrying Value as of Income (Loss) from June 30, December 31, For the Six Months (In thousands) 2021 2020 2021 2020 Financial services $ 452,233 $ 434,437 $ 48,990 $ (6,881) Real Estate 262,889 310,783 10,506 4,021 Transportation 271,536 190,125 17,177 (4,627) Energy 149,008 140,935 9,492 (20,968) Other funds 233,787 233,150 14,081 11,480 Total $ 1,369,453 $ 1,309,430 $ 100,246 $ (16,975) 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. Financial services investment funds include the Company’s minority investment in Lifson Re, a Bermuda reinsurance company. Effective January 1, 2021, Lifson Re participates on a fully collateralized basis in a majority of the Company’s reinsurance placements for a 22.5% share of placed amounts. This pertains to all traditional reinsurance/retrocessional placements for both property and casualty business where there is more than one open market reinsurer participating. As of June 30, 2021, the Company has ceded approximately $139 million of written premiums to Lifson Re.

Real Estate

Real Estate	6 Months Ended
	Jun. 30, 2021
Real Estate [Abstract]
Real Estate	Real Estate Investment in real estate represents directly owned property held for investment, as follows: Carrying Value June 30, December 31, (In thousands) 2021 2020 Properties in operation $ 1,586,911 $ 1,738,144 Properties under development 224,352 222,770 Total $ 1,811,263 $ 1,960,914 As of June 30, 2021, properties in operation included a long-term ground lease in Washington, D.C., an office complex in New York City, an office building in London, U.K., and the completed portion of a mixed-use project in Washington D.C. Properties in operation are net of accumulated depreciation and amortization of $64,226,000 and $86,970,000 as of June 30, 2021 and December 31, 2020, respectively. Related depreciation expense was $9,622,000 and $13,776,000 for the six months ended June 30, 2021 and 2020, respectively. Future minimum rental income expected on operating leases relating to properties in operation is $29,265,862 in 2021, $59,450,838 in 2022, $53,607,393 in 2023, $52,500,378 in 2024, $50,115,697 in 2025, $47,602,823 in 2026 and $597,389,153 thereafter. During the three months ended June 30, 2021, the Company sold two office buildings in Palm Beach and West Palm Beach, Florida. One of these sales also resulted in a $102 million reduction of the Company's debt that was supporting the property.

Loans Receivable

Loans Receivable	6 Months Ended
	Jun. 30, 2021
Receivables [Abstract]
Loans Receivable	Loans Receivable At June 30, 2021 and December 31, 2020, loans receivable were as follows: (In thousands) June 30, December 31, Amortized cost (net of allowance for expected credit losses): Real estate loans $ 89,821 $ 51,910 Commercial loans 26,188 33,003 Total $ 116,009 $ 84,913 Fair value: Real estate loans $ 91,322 $ 53,593 Commercial loans 26,188 33,003 Total $ 117,510 $ 86,596 The real estate loans are secured by commercial and residential real estate primarily located in New York. These loans generally earn interest at fixed or stepped interest rates and have maturities through 2026. 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. Loans receivable in non-accrual status were both $0.2 million as of June 30, 2021 and December 31, 2020. The following table presents the rollforward of the allowance for expected credit losses for loans receivable for the six months ended June 30, 2021 and 2020: 2021 2020 (In thousands) Real Estate Loans Commercial Loans Total Real Estate Loans Commercial Loans Total Allowance for expected credit losses, beginning of period $ 1,683 $ 3,754 $ 5,437 $ 1,502 $ 644 $ 2,146 Cumulative effect adjustment resulting from changes in accounting principles — — — (905) 548 (357) Provision for expected credit losses (182) (3,285) (3,467) 3,721 3,209 6,930 Allowance for expected credit losses, end of period $ 1,501 $ 469 $ 1,970 $ 4,318 $ 4,401 $ 8,719 The following table presents the rollforward of the allowance for expected credit losses for loans receivable for the three months ended June 30, 2021 and 2020: 2021 2020 (In thousands) Real Estate Loans Commercial Loans Total Real Estate Loans Commercial Loans Total Allowance for expected credit losses, beginning of period $ 1,608 $ 2,590 $ 4,198 $ 1,435 $ 2,493 $ 3,928 Provision for expected credit losses (107) (2,121) (2,228) 2,883 1,908 4,791 Allowance for expected credit losses, end of period $ 1,501 $ 469 $ 1,970 $ 4,318 $ 4,401 $ 8,719 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.

Net Investment Gains (Losses)

Net Investment Gains (Losses)	6 Months Ended
	Jun. 30, 2021
Realized and Unrealized Investment Gains (Losses) [Abstract]
Net Investment Gains (Losses)	Net Investment Gains (Losses) Net investment gains (losses) were as follows: For the Three Months For the Six Months (In thousands) 2021 2020 2021 2020 Net investment gains (losses): Fixed maturity securities: Gains $ 5,440 $ 14,844 $ 13,680 $ 19,775 Losses (2,236) (9,234) (4,307) (14,081) Equity securities (1): Net realized gains on investment sales 6,256 5,727 14,828 5,727 Change in unrealized (losses) gains (18,239) 61,914 (42,574) (92,552) Investment funds (300) 913 47,371 31,096 Real estate 49,492 (7,137) 62,401 (7,824) Loans receivable (881) — (881) — Other (19,071) (5,374) (18,299) (23,773) Net realized and unrealized gains (losses) on investments in earnings before allowance for expected credit losses 20,461 61,653 72,219 (81,632) Change in allowance for expected credit losses on investments: Fixed maturity securities 1,375 21,023 (16,783) (10,727) Loans receivable 2,228 (4,791) 3,467 (6,930) Change in allowance for expected credit losses on investments 3,603 16,232 (13,316) (17,657) Net investment gains (losses) 24,064 77,885 58,903 (99,289) Income tax (expense) benefit (5,264) (18,098) (11,151) 22,476 After-tax net investment gains (losses) $ 18,800 $ 59,787 $ 47,752 $ (76,813) Change in unrealized investment gains (losses) on available for sale securities: Fixed maturity securities without allowance for expected credit losses $ 28,511 $ 369,615 $ (94,058) $ 43,199 Fixed maturity securities with allowance for expected credit losses (69) 23,450 10,286 24,991 Investment funds 762 4,212 (257) (3,434) Other (400) (1,653) (902) (1,979) Total change in unrealized investment gains (losses) 28,804 395,624 (84,931) 62,777 Income tax (expense) benefit (5,532) (76,899) 18,073 (3,034) Noncontrolling interests (1) (1) (1) 1 After-tax change in unrealized investment gains (losses) of available for sale securities $ 23,271 $ 318,724 $ (66,859) $ 59,744 ______________________ (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 (losses) 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.

Fixed Maturity Securities In An

Fixed Maturity Securities In An Unrealized Loss Position	6 Months Ended
	Jun. 30, 2021
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 June 30, 2021 and December 31, 2020 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 Gross Fair Gross Fair Gross June 30, 2021 U.S. government and government agency $ 38,752 $ 458 $ 524 $ 3 $ 39,276 $ 461 State and municipal 205,730 2,222 22,655 1,356 228,385 3,578 Mortgage-backed 266,963 7,799 29,570 540 296,533 8,339 Asset-backed 2,581,697 6,817 606,663 17,312 3,188,360 24,129 Corporate 972,383 8,212 44,055 2,098 1,016,438 10,310 Foreign government 376,746 11,433 11,921 21,429 388,667 32,862 Fixed maturity securities $ 4,442,271 $ 36,941 $ 715,388 $ 42,738 $ 5,157,659 $ 79,679 December 31, 2020 U.S. government and government agency $ 47,649 $ 347 $ 17 $ — $ 47,666 $ 347 State and municipal 147,754 1,165 20,528 904 168,282 2,069 Mortgage-backed 212,388 5,121 23,943 230 236,331 5,351 Asset-backed 1,389,133 6,563 656,877 26,934 2,046,010 33,497 Corporate 612,177 6,721 39,985 1,759 652,162 8,480 Foreign government 143,729 22,871 6,218 21,577 149,947 44,448 Fixed maturity securities $ 2,552,830 $ 42,788 $ 747,568 $ 51,404 $ 3,300,398 $ 94,192 Substantially all of the securities in an unrealized loss position are rated investment grade, except for the securities in the foreign government classification. 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 June 30, 2021 is presented in the table below: ($ in thousands) Number of Aggregate Gross Foreign government 27 $ 108,910 $ 30,171 Corporate 10 36,482 2,058 Mortgage-backed 4 276 19 Asset-backed 1 113 1 Total 42 $ 145,781 $ 32,249 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 income.

Fair Value Measurements

Fair Value Measurements	6 Months Ended
	Jun. 30, 2021
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 June 30, 2021 and December 31, 2020 by level: (In thousands) Total Level 1 Level 2 Level 3 June 30, 2021 Assets: Fixed maturity securities available for sale: U.S. government and government agency $ 502,625 $ — $ 502,625 $ — State and municipal 3,426,156 — 3,426,156 — Mortgage-backed 923,702 — 923,702 — Asset-backed 4,317,863 — 4,317,863 — Corporate 5,340,663 — 5,340,663 — Foreign government 1,068,918 — 1,068,918 — Total fixed maturity securities available for sale 15,579,927 — 15,579,927 — Equity securities: Common stocks 449,500 437,758 2,261 9,481 Preferred stocks 193,493 — 184,160 9,333 Total equity securities 642,993 437,758 186,421 18,814 Arbitrage trading account 634,276 621,883 12,393 — Total $ 16,857,196 $ 1,059,641 $ 15,778,741 $ 18,814 Liabilities: Trading account securities sold but not yet purchased $ 190 $ 190 $ — $ — December 31, 2020 Assets: Fixed maturity securities available for sale: U.S. government and government agency $ 603,871 $ — $ 603,871 $ — State and municipal 3,620,664 — 3,620,664 — Mortgage-backed 1,020,330 — 1,020,330 — Asset-backed 3,194,586 — 3,194,586 — Corporate 4,671,581 — 4,670,581 1,000 Foreign government 975,563 — 975,563 — Total fixed maturity securities available for sale 14,086,595 — 14,085,595 1,000 Equity securities: Common stocks 350,181 340,966 — 9,215 Preferred stocks 275,486 — 266,155 9,331 Total equity securities 625,667 340,966 266,155 18,546 Arbitrage trading account 341,473 298,359 43,114 — Total $ 15,053,735 $ 639,325 $ 14,394,864 $ 19,546 Liabilities: Trading account securities sold but not yet purchased $ 10,048 $ 10,048 $ — $ — The following tables summarize changes in Level 3 assets and liabilities for the six months ended June 30, 2021 and for the year ended December 31, 2020: Gains (Losses) Included in: (In thousands) Beginning Earnings (Losses) Other Impairments Purchases (Sales) Paydowns / Maturities Transfers In / (Out) Ending Six Months Ended June 30, 2021 Assets: Fixed maturities securities available for sale: Corporate $ 1,000 $ — $ — $ — $ — $ (1,000) $ — $ — $ — Total 1,000 — — — — (1,000) — — — Equity securities: Common stocks $ 9,215 $ 827 $ — $ — $ — $ (561) $ — $ — $ 9,481 Preferred stocks 9,331 2 — — — — — — 9,333 Total 18,546 829 — — — (561) — — 18,814 Arbitrage trading account — 1 — — — (1) — — — Total $ 19,546 $ 830 $ — $ — $ — $ (1,562) $ — $ — $ 18,814 Year Ended Assets: Fixed maturities securities available for sale: Corporate $ — $ — $ — $ — $ — $ — $ — $ 1,000 $ 1,000 Total — — — — — — — 1,000 1,000 Equity securities: Common stocks 9,053 1,228 — — — (1,066) — — 9,215 Preferred stocks 6,505 (174) — — 3,000 — — — 9,331 Total 15,558 1,054 — — 3,000 (1,066) — — 18,546 Arbitrage trading account — 19 — — — (19) — — — Total $ 15,558 $ 1,073 $ — $ — $ 3,000 $ (1,085) $ — $ 1,000 $ 19,546 For the six months ended June 30, 2021, there were no securities transferred into or out of Level 3. For the year ended December 31, 2020, a fixed maturity security was transferred from Level 2 into Level 3 as a result of observable valuation inputs no longer being available. The following table presents the carrying amounts and estimated fair values of the Company’s financial instruments: June 30, 2021 December 31, 2020 (In thousands) Carrying Value Fair Value Carrying Value Fair Value Assets: Fixed maturity securities $ 15,653,508 $ 15,666,436 $ 14,159,369 $ 14,173,629 Equity securities 642,993 642,993 625,667 625,667 Arbitrage trading account 634,276 634,276 341,473 341,473 Loans receivable 116,009 117,510 84,913 86,596 Cash and cash equivalents 1,790,199 1,790,199 2,372,366 2,372,366 Trading account receivables from brokers and clearing organizations 361,586 361,586 524,727 524,727 Due from broker — — 2,585 2,585 Liabilities: Due to broker 63,276 63,276 — — Trading account securities sold but not yet purchased 190 190 10,048 10,048 Senior notes and other debt 1,911,753 2,176,756 1,623,025 1,892,444 Subordinated debentures 1,007,293 1,112,812 1,102,309 1,202,842

Reserves for Loss and Loss Expe

Reserves for Loss and Loss Expenses	6 Months Ended
	Jun. 30, 2021
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: June 30, (In thousands) 2021 2020 Net reserves at beginning of period $ 11,620,393 $ 10,697,998 Cumulative effect adjustment resulting from changes in accounting principles — 5,927 Restated net reserves at beginning of period 11,620,393 10,703,925 Net provision for losses and loss expenses: Claims occurring during the current year (1) 2,308,309 2,222,671 Increase in estimates for claims occurring in prior years (2) (3) 1,530 2,050 Loss reserve discount accretion 15,399 17,658 Total 2,325,238 2,242,379 Net payments for claims: Current year 279,703 289,154 Prior years 1,485,116 1,545,471 Total 1,764,819 1,834,625 Foreign currency translation (16,153) (45,572) Net reserves at end of period 12,164,659 11,066,107 Ceded reserves at end of period 2,316,288 2,022,797 Gross reserves at end of period $ 14,480,947 $ 13,088,904 _______________________________________ (1) Claims occurring during the current year are net of loss reserve discounts of $10 million and $5 million for the six months ended June 30, 2021 and 2020, 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 $16 million and $8 million for the six months ended June 30, 2021 and 2020, 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 six months ended June 30, 2021 and 2020, respectively. The COVID-19 global pandemic has impacted, and may further impact, the Company’s results through its effect on claim frequency and severity. Loss cost trends have been impacted and may be further impacted by COVID-19-related claims in certain lines of business. Losses incurred from COVID-19-related claims have been offset, to a certain extent, by lower claim frequency in certain lines of our businesses; however, as the economy and legal systems have reopened, the benefit of lower claim frequency has begun to abate. Although as populations have continued to be vaccinated against the virus and the effects of the pandemic have receded in many jurisdictions, most particularly the United States, it remains too early to determine the ultimate net impact of COVID-19 on the Company. New variants of the COVID-19 virus, including the “Delta” variant, and the slowing of vaccination rates among certain populations continue to create risks with respect to loss costs and the potential for renewed impact of the other effects of COVID-19 associated with economic conditions, inflation, and social distancing and work from home rules. Most of the COVID-19-related claims reported to the Company to date involve certain short-tailed lines of business, including contingency and event cancellation, business interruption, and film production delay. The Company has also received COVID-19-related claims for longer-tailed casualty lines of business such as workers’ compensation and other liability; however, the estimated incurred loss impact for these reported claims are not material at this time. Given the continuing uncertainty regarding the pandemic's pervasiveness, the future impact that the pandemic may have on claim frequency and severity remains uncertain at this time. The Company has estimated the potential COVID-19 impact to its contingency and event cancellation, workers’ compensation, and other lines of business under a number of possible scenarios; however, due to COVID-19’s continued evolving impact, there remains a high degree of uncertainty around the Company’s COVID-19 reserves. In addition, should the pandemic continue or worsen as a result of new COVID-19 variants or otherwise, governments in the jurisdictions where we operate may renew their efforts to expand policy coverage terms beyond the policy’s intended coverage. Accordingly, losses arising from these actions, and the other factors described above, could exceed the Company’s reserves established for those related policies. As of June 30, 2021, the Company had recognized losses for COVID-19-related claims activity, net of reinsurance, of approximately $241 million, of which $208 million relates to the Insurance segment and $33 million relates to the Reinsurance & Monoline Excess segment. Such $241 million of COVID-19-related losses included $164 million of reported losses and $77 million of IBNR. For the six months ended June 30, 2021, the Company recognized current accident year losses for COVID-19-related claims activity, net of reinsurance, of approximately $40 million, of which $38 million relates to the Insurance segment and $2 million relates to the Reinsurance & Monoline Excess segment. During the six months ended June 30, 2021, favorable prior year development (net of additional and return premiums) of $4 million included $12 million of favorable development for the Insurance segment, partially offset by $8 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 the 2020 accident year, partially offset by adverse development on the 2016 through 2019 accident years. The favorable development on the 2020 accident year was largely concentrated in the commercial auto liability and other liability lines of business. During 2020 the Company achieved larger rate increases in these lines of business than were contemplated in our budget and in our initial loss ratio selections. The Company also experienced significantly lower reported claim frequency in these lines in 2020 relative to historical averages, and lower reported incurred losses relative to our expectations. We believe that the lower claim frequency and lower reported incurred losses were caused by the impacts of the COVID-19 pandemic, for example, lockdowns, reduced driving and traffic, work from home, court closures, etc.; however, due to the ongoing uncertainty regarding the ultimate impacts of the pandemic on accident year 2020 incurred losses, the Company did not adjust its reserves due to these lower trends during 2020. However, as the accident year has begun to mature, the Company has recognized some of the favorable accident year 2020 experience in its ultimate loss picks made as of June 30, 2021. The adverse development on the 2016 through 2019 accident years is concentrated in the other liability line of business, and is driven by a larger number than expected of large losses reported. The large losses particularly impacted directors and officers liability and excess and surplus lines casualty classes of business. The overall adverse development for the Reinsurance & Monoline Excess segment was mainly concentrated in the non-proportional reinsurance assumed liability and non-proportional reinsurance assumed property lines of business, related to accident years 2018 through 2020. The development was driven by higher than expected reported losses on excess of loss treaties written in the U.S. and U.K. During the six months ended June 30, 2020, favorable prior year development (net of additional and return premiums) of $7 million included $12 million of favorable development for the Insurance segment, partially offset by $5 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, but was especially significant in accident year 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). The Company's 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 also added to the favorable workers’ compensation prior year development. The adverse professional liability development was concentrated in accident years 2016 through 2018 and predominately resulted from a greater than expected number of large losses being reported in the period in two niches of our professional liability business. 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 2014 through 2018. The development was driven by a greater than expected number of reported large losses during the period.

Fair Value Of Financial Instrum

Fair Value Of Financial Instruments	6 Months Ended
	Jun. 30, 2021
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 June 30, 2021 and December 31, 2020 by level: (In thousands) Total Level 1 Level 2 Level 3 June 30, 2021 Assets: Fixed maturity securities available for sale: U.S. government and government agency $ 502,625 $ — $ 502,625 $ — State and municipal 3,426,156 — 3,426,156 — Mortgage-backed 923,702 — 923,702 — Asset-backed 4,317,863 — 4,317,863 — Corporate 5,340,663 — 5,340,663 — Foreign government 1,068,918 — 1,068,918 — Total fixed maturity securities available for sale 15,579,927 — 15,579,927 — Equity securities: Common stocks 449,500 437,758 2,261 9,481 Preferred stocks 193,493 — 184,160 9,333 Total equity securities 642,993 437,758 186,421 18,814 Arbitrage trading account 634,276 621,883 12,393 — Total $ 16,857,196 $ 1,059,641 $ 15,778,741 $ 18,814 Liabilities: Trading account securities sold but not yet purchased $ 190 $ 190 $ — $ — December 31, 2020 Assets: Fixed maturity securities available for sale: U.S. government and government agency $ 603,871 $ — $ 603,871 $ — State and municipal 3,620,664 — 3,620,664 — Mortgage-backed 1,020,330 — 1,020,330 — Asset-backed 3,194,586 — 3,194,586 — Corporate 4,671,581 — 4,670,581 1,000 Foreign government 975,563 — 975,563 — Total fixed maturity securities available for sale 14,086,595 — 14,085,595 1,000 Equity securities: Common stocks 350,181 340,966 — 9,215 Preferred stocks 275,486 — 266,155 9,331 Total equity securities 625,667 340,966 266,155 18,546 Arbitrage trading account 341,473 298,359 43,114 — Total $ 15,053,735 $ 639,325 $ 14,394,864 $ 19,546 Liabilities: Trading account securities sold but not yet purchased $ 10,048 $ 10,048 $ — $ — The following tables summarize changes in Level 3 assets and liabilities for the six months ended June 30, 2021 and for the year ended December 31, 2020: Gains (Losses) Included in: (In thousands) Beginning Earnings (Losses) Other Impairments Purchases (Sales) Paydowns / Maturities Transfers In / (Out) Ending Six Months Ended June 30, 2021 Assets: Fixed maturities securities available for sale: Corporate $ 1,000 $ — $ — $ — $ — $ (1,000) $ — $ — $ — Total 1,000 — — — — (1,000) — — — Equity securities: Common stocks $ 9,215 $ 827 $ — $ — $ — $ (561) $ — $ — $ 9,481 Preferred stocks 9,331 2 — — — — — — 9,333 Total 18,546 829 — — — (561) — — 18,814 Arbitrage trading account — 1 — — — (1) — — — Total $ 19,546 $ 830 $ — $ — $ — $ (1,562) $ — $ — $ 18,814 Year Ended Assets: Fixed maturities securities available for sale: Corporate $ — $ — $ — $ — $ — $ — $ — $ 1,000 $ 1,000 Total — — — — — — — 1,000 1,000 Equity securities: Common stocks 9,053 1,228 — — — (1,066) — — 9,215 Preferred stocks 6,505 (174) — — 3,000 — — — 9,331 Total 15,558 1,054 — — 3,000 (1,066) — — 18,546 Arbitrage trading account — 19 — — — (19) — — — Total $ 15,558 $ 1,073 $ — $ — $ 3,000 $ (1,085) $ — $ 1,000 $ 19,546 For the six months ended June 30, 2021, there were no securities transferred into or out of Level 3. For the year ended December 31, 2020, a fixed maturity security was transferred from Level 2 into Level 3 as a result of observable valuation inputs no longer being available. The following table presents the carrying amounts and estimated fair values of the Company’s financial instruments: June 30, 2021 December 31, 2020 (In thousands) Carrying Value Fair Value Carrying Value Fair Value Assets: Fixed maturity securities $ 15,653,508 $ 15,666,436 $ 14,159,369 $ 14,173,629 Equity securities 642,993 642,993 625,667 625,667 Arbitrage trading account 634,276 634,276 341,473 341,473 Loans receivable 116,009 117,510 84,913 86,596 Cash and cash equivalents 1,790,199 1,790,199 2,372,366 2,372,366 Trading account receivables from brokers and clearing organizations 361,586 361,586 524,727 524,727 Due from broker — — 2,585 2,585 Liabilities: Due to broker 63,276 63,276 — — Trading account securities sold but not yet purchased 190 190 10,048 10,048 Senior notes and other debt 1,911,753 2,176,756 1,623,025 1,892,444 Subordinated debentures 1,007,293 1,112,812 1,102,309 1,202,842

Premiums and Reinsurance Relate

Premiums and Reinsurance Related Information	6 Months Ended
	Jun. 30, 2021
Insurance [Abstract]
Premiums and Reinsurance Related Information	Premiums and Reinsurance Related Information The following is a summary of insurance and reinsurance financial information: For the Three Months For the Six Months (In thousands) 2021 2020 2021 2020 Written premiums: Direct $ 2,395,114 $ 1,892,359 $ 4,572,276 $ 3,856,848 Assumed 266,122 239,887 573,672 506,769 Ceded (449,055) (392,428) (883,729) (777,953) Total net premiums written $ 2,212,181 $ 1,739,818 $ 4,262,219 $ 3,585,664 Earned premiums: Direct $ 2,151,739 $ 1,804,844 $ 4,154,784 $ 3,634,558 Assumed 259,166 232,996 518,707 461,210 Ceded (439,281) (360,925) (851,911) (727,435) Total net premiums earned $ 1,971,624 $ 1,676,915 $ 3,821,580 $ 3,368,333 Ceded losses and loss expenses incurred $ 255,163 $ 232,873 $ 553,903 $ 468,055 Ceded commissions earned $ 106,834 $ 85,593 $ 208,515 $ 166,638 The following table presents the rollforward of the allowance for expected credit losses for premiums and fees receivable for the six months ended June 30, 2021 and 2020: (In thousands) 2021 2020 Allowance for expected credit losses, beginning of period $ 22,883 $ 19,823 Cumulative effect adjustment resulting from changes in accounting principles — 1,270 Provision for expected credit losses 1,925 1,013 Allowance for expected credit losses, end of period $ 24,808 $ 22,106 The following table presents the rollforward of the allowance for expected credit losses for premiums and fees receivable for the three months ended June 30, 2021 and 2020: (In thousands) 2021 2020 Allowance for expected credit losses, beginning of period $ 24,264 $ 21,524 Provision for expected credit losses 544 582 Allowance for expected credit losses, end of period $ 24,808 $ 22,106 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 six months ended June 30, 2021 and 2020: (In thousands) 2021 2020 Allowance for expected credit losses, beginning of period $ 7,801 $ 690 Cumulative effect adjustment resulting from changes in accounting principles — 5,927 Provision for expected credit losses (518) 558 Allowance for expected credit losses, end of period $ 7,283 $ 7,175 The following table presents the rollforward of the allowance for expected credit losses associated with due from reinsurers for the three months ended June 30, 2021 and 2020: (In thousands) 2021 2020 Allowance for expected credit losses, beginning of period $ 7,373 $ 6,800 Provision for expected credit losses (90) 375 Allowance for expected credit losses, end of period $ 7,283 $ 7,175

Restricted Stock Units

Restricted Stock Units	6 Months Ended
	Jun. 30, 2021
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 ($ in thousands) Units Fair Value 2021 1,531 $ 75 2020 724 $ 57

Litigation and Contingent Liabi

Litigation and Contingent Liabilities	6 Months Ended
	Jun. 30, 2021
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	6 Months Ended
	Jun. 30, 2021
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 For the Six Months Ended June 30, (In thousands) 2021 2020 2021 2020 Leases: Lease cost $ 11,429 $ 10,878 $ 22,693 $ 22,114 Cash paid for amounts included in the measurement of lease liabilities reported in operating cash flows $ 11,920 $ 11,479 $ 23,297 $ 22,309 Right-of-use assets (reduced) obtained in exchange for new lease liabilities $ (181) $ 2,682 $ (151) $ 4,294 As of June 30, ($ in thousands) 2021 2020 Right-of-use assets $ 148,455 $ 180,011 Lease liabilities $ 185,738 $ 219,444 Weighted-average remaining lease term 6.7 years 6.8 years Weighted-average discount rate 5.95 % 5.94 % Contractual maturities of the Company’s future minimum lease payments are as follows: (In thousands) June 30, 2021 Contractual Maturities: 2021 $ 22,960 2022 42,677 2023 39,081 2024 32,467 2025 23,227 Thereafter 59,736 Total undiscounted future minimum lease payments 220,148 Less: Discount impact (34,410) Total lease liability $ 185,738

Business Segments

Business Segments	6 Months Ended
	Jun. 30, 2021
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 Investment Other Total (2) Pre-Tax Income (Loss) Net Income (Loss) to Common Stockholders Three months ended June 30, 2021 Insurance $ 1,727,202 $ 116,703 $ 8,212 $ 1,852,117 $ 291,290 $ 230,313 Reinsurance & Monoline Excess 244,422 46,879 — 291,301 74,794 59,334 Corporate, other and eliminations (3) — 4,605 124,000 128,604 (90,208) (71,209) Net investment gains — — 24,064 24,064 24,064 18,800 Total $ 1,971,624 $ 168,187 $ 156,276 $ 2,296,086 $ 299,940 $ 237,238 Three months ended June 30, 2020 Insurance $ 1,465,044 $ 44,105 $ 8,018 $ 1,517,167 $ 76,546 $ 48,607 Reinsurance & Monoline Excess 211,871 23,461 — 235,332 12,566 10,689 Corporate, other and eliminations (3) — 17,865 87,777 105,642 (61,548) (47,823) Net investment gains — — 77,885 77,885 77,885 59,787 Total $ 1,676,915 $ 85,431 $ 173,680 $ 1,936,026 $ 105,449 $ 71,260 Six months ended June 30, 2021 Insurance $ 3,332,181 $ 221,941 $ 16,490 $ 3,570,612 $ 548,399 $ 429,022 Reinsurance & Monoline Excess 489,399 84,587 — 573,986 143,443 113,806 Corporate, other and eliminations (3) — 20,236 229,218 249,454 (154,737) (123,817) Net investment gains — — 58,903 58,903 58,903 47,752 Total $ 3,821,580 $ 326,764 $ 304,611 $ 4,452,955 $ 596,008 $ 466,763 Six Months Ended June 30, 2020 Insurance $ 2,949,999 $ 167,564 $ 16,490 $ 3,134,053 $ 252,493 $ 185,467 Reinsurance & Monoline Excess 418,334 61,171 — 479,505 49,080 39,877 Corporate, other and eliminations (3) — 31,459 200,907 232,366 (103,302) (81,689) Net investment losses — — (99,289) (99,289) (99,289) (76,813) Total $ 3,368,333 $ 260,194 $ 118,108 $ 3,746,635 $ 98,982 $ 66,842 _________________ (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 June 30, 2021 and 2020 were $221 million and $149 million, respectively, and for the six months ended June 30, 2021 and 2020 were $418 million and $317 million, respectively. Revenues for Reinsurance & Monoline Excess from foreign countries for the three months ended June 30, 2021 and 2020 were $90 million and $65 million, respectively, and for the six months ended June 30, 2021 and 2020 were $178 million and $134 million, respectively. (3) Corporate, other and eliminations represent corporate revenues and expenses that are not allocated to business segments. Identifiable Assets (In thousands) June 30, December 31, Insurance $ 22,771,988 $ 21,702,328 Reinsurance & Monoline Excess 4,670,226 4,654,158 Corporate, other and eliminations 2,855,703 2,215,479 Consolidated $ 30,297,917 $ 28,571,965 Net premiums earned by major line of business are as follows: For the Three Months For the Six Months (In thousands) 2021 2020 2021 2020 Insurance: Other liability $ 638,404 $ 544,465 $ 1,240,306 $ 1,091,594 Short-tail lines (1) 339,890 295,968 664,630 591,446 Workers' compensation 291,471 278,699 558,920 580,299 Commercial automobile 237,444 190,335 458,205 379,978 Professional liability 219,993 155,577 410,120 306,682 Total Insurance 1,727,202 1,465,044 3,332,181 2,949,999 Reinsurance & Monoline Excess: Casualty reinsurance 152,531 130,459 302,169 253,190 Monoline excess (2) 48,247 41,062 94,120 83,224 Property reinsurance 43,644 40,350 93,110 81,920 Total Reinsurance & Monoline Excess 244,422 211,871 489,399 418,334 Total $ 1,971,624 $ 1,676,915 $ 3,821,580 $ 3,368,333 ______________ (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 and Accounting Policies (Policies)	6 Months Ended
	Jun. 30, 2021
Accounting Policies [Abstract]
Per Share Data	Per Share Data The Company presents both basic and diluted net income per share (“EPS”) amounts. Basic EPS is calculated by dividing net income by the weighted average number of common shares outstanding during the period (including 7,767,874 and 7,575,168 common shares held in a grantor trust as of June 30, 2021 and 2020, respectively). The common shares held in the grantor trust are for delivery upon settlement of vested but mandatorily deferred restricted stock units ("RSUs"). Shares held by the grantor trust do not affect diluted shares outstanding since the shares deliverable under vested RSUs were already included in diluted shares outstanding. Diluted EPS is based upon the weighted average number of basic and common equivalent shares outstanding during the period and is calculated using the treasury stock method for stock incentive plans. Common equivalent shares are excluded from the computation in periods in which they have an anti-dilutive effect. The weighted average number of common shares used in the computation of basic and diluted earnings per share was as follows: For the Three Months For the Six Months (In thousands) 2021 2020 2021 2020 Basic 185,155 185,979 185,175 188,133 Diluted 187,106 187,862 186,985 190,078
Recent Accounting Pronouncements	Recent Accounting Pronouncements and Accounting Policies Recently adopted accounting pronouncements: All accounting and reporting standards that have become effective in 2021 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)	6 Months Ended
	Jun. 30, 2021
Earnings Per Share [Abstract]
Weighted average number of common shares	The weighted average number of common shares used in the computation of basic and diluted earnings per share was as follows: For the Three Months For the Six Months (In thousands) 2021 2020 2021 2020 Basic 185,155 185,979 185,175 188,133 Diluted 187,106 187,862 186,985 190,078

Consolidated Statements of Co_3

Consolidated Statements of Comprehensive Income (Tables)	6 Months Ended
	Jun. 30, 2021
Equity [Abstract]
Components of changes in accumulated other comprehensive income (loss)	The following table presents the components of the changes in accumulated other comprehensive (loss) income ("AOCI"): (In thousands) Unrealized Investment Gains (Losses) Currency Translation Adjustments Accumulated Other Comprehensive As of and for the six months ended June 30, 2021 Changes in AOCI Beginning of period $ 289,714 $ (351,886) $ (62,172) Other comprehensive (loss) income before reclassifications (87,168) 6,587 (80,581) Amounts reclassified from AOCI 20,310 — 20,310 Other comprehensive (loss) income (66,858) 6,587 (60,271) Unrealized investment gain related to noncontrolling interest (1) — (1) End of period $ 222,855 $ (345,299) $ (122,444) Amounts reclassified from AOCI Pre-tax $ 25,709 (1) $ — $ 25,709 Tax effect (5,399) (2) — (5,399) After-tax amounts reclassified $ 20,310 $ — $ 20,310 Other comprehensive (loss) income Pre-tax $ (84,931) $ 6,587 $ (78,344) Tax effect 18,073 — 18,073 Other comprehensive (loss) income $ (66,858) $ 6,587 $ (60,271) As of and for the three months ended June 30, 2021 Changes in AOCI Beginning of period $ 199,584 $ (347,836) $ (148,252) Other comprehensive income before reclassifications 11,823 2,537 14,360 Amounts reclassified from AOCI 11,449 — 11,449 Other comprehensive income 23,272 2,537 25,809 Unrealized investment gain related to noncontrolling interest (1) — (1) Ending balance $ 222,855 $ (345,299) $ (122,444) Amounts reclassified from AOCI Pre-tax $ 14,493 (1) $ — $ 14,493 Tax effect (3,044) (2) — (3,044) After-tax amounts reclassified $ 11,449 $ — $ 11,449 Other comprehensive income Pre-tax $ 28,804 $ 2,537 $ 31,341 Tax effect (5,532) — (5,532) Other comprehensive income $ 23,272 $ 2,537 $ 25,809 As of and for the six months ended June 30, 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 income (loss) before reclassifications 36,986 (76,747) (39,761) Amounts reclassified from AOCI 22,757 — 22,757 Other comprehensive income (loss) 59,743 (76,747) (17,004) Unrealized investment loss related to noncontrolling interest 1 — 1 End of period $ 209,210 $ (458,560) $ (249,350) Amounts reclassified from AOCI Pre-tax $ 28,806 (1) $ — $ 28,806 Tax effect (6,049) (2) — (6,049) After-tax amounts reclassified $ 22,757 $ — $ 22,757 Other comprehensive income (loss) Pre-tax $ 62,777 $ (76,747) $ (13,970) Tax effect (3,034) — (3,034) Other comprehensive income (loss) $ 59,743 $ (76,747) $ (17,004) As of and for the three months ended June 30, 2020 Changes in AOCI Beginning of period $ (109,514) $ (480,007) $ (589,521) Other comprehensive income before reclassifications 335,518 21,447 356,965 Amounts reclassified from AOCI (16,793) — (16,793) Other comprehensive income 318,725 21,447 340,172 Unrealized investment gain related to noncontrolling interest (1) — (1) Ending balance $ 209,210 $ (458,560) $ (249,350) Amounts reclassified from AOCI Pre-tax $ (21,257) (1) $ — $ (21,257) Tax effect 4,464 (2) — 4,464 After-tax amounts reclassified $ (16,793) $ — $ (16,793) Other comprehensive income Pre-tax $ 395,624 $ 21,447 $ 417,071 Tax effect (76,899) — (76,899) Other comprehensive income $ 318,725 $ 21,447 $ 340,172 ____________ (1) Net investment gains (losses) in the consolidated statements of income. (2) Income tax (expense) benefit in the consolidated statements of income.

Investments in Fixed Maturity_2

Investments in Fixed Maturity Securities (Tables)	6 Months Ended
	Jun. 30, 2021
Investments, Debt and Equity Securities [Abstract]
Schedule of investments in fixed maturity securities	At June 30, 2021 and December 31, 2020, investments in fixed maturity securities were as follows: (In thousands) Amortized Allowance for Expected Credit Losses (1) Gross Unrealized Fair Carrying Gains Losses June 30, 2021 Held to maturity: State and municipal $ 68,310 $ (453) $ 12,069 $ — $ 79,926 $ 67,857 Residential mortgage-backed 5,724 — 859 — 6,583 5,724 Total held to maturity 74,034 (453) 12,928 — 86,509 73,581 Available for sale: U.S. government and government agency 488,196 — 14,890 (461) 502,625 502,625 State and municipal: Special revenue 2,074,036 — 85,037 (1,433) 2,157,640 2,157,640 State general obligation 378,596 — 29,413 (250) 407,759 407,759 Pre-refunded 225,787 — 17,677 (607) 242,857 242,857 Corporate backed 156,970 — 9,082 (862) 165,190 165,190 Local general obligation 419,506 — 33,630 (426) 452,710 452,710 Total state and municipal 3,254,895 — 174,839 (3,578) 3,426,156 3,426,156 Mortgage-backed: Residential 771,507 — 16,798 (8,189) 780,116 780,116 Commercial 137,996 — 5,740 (150) 143,586 143,586 Total mortgage-backed 909,503 — 22,538 (8,339) 923,702 923,702 Asset-backed 4,333,543 — 8,449 (24,129) 4,317,863 4,317,863 Corporate: Industrial 3,019,720 (12) 94,056 (7,761) 3,106,003 3,106,003 Financial 1,583,291 — 51,103 (1,076) 1,633,318 1,633,318 Utilities 406,423 — 18,531 (1,106) 423,848 423,848 Other 177,445 — 416 (367) 177,494 177,494 Total corporate 5,186,879 (12) 164,106 (10,310) 5,340,663 5,340,663 Foreign government 1,103,503 (18,899) 17,176 (32,862) 1,068,918 1,068,918 Total available for sale 15,276,519 (18,911) 401,998 (79,679) 15,579,927 15,579,927 Total investments in fixed maturity securities $ 15,350,553 $ (19,364) $ 414,926 $ (79,679) $ 15,666,436 $ 15,653,508 ____________ (1) Represents the amount of impairment that has resulted from credit-related factors. The change in the allowance for expected credit losses is recognized in the consolidated statements of income. Amount excludes unrealized losses relating to non-credit factors. (In thousands) Amortized Allowance for Expected Credit Losses (1) Gross Unrealized Fair Carrying Gains Losses December 31, 2020 Held to maturity: State and municipal $ 67,117 $ (798) $ 13,217 $ — $ 79,536 $ 66,319 Residential mortgage-backed 6,455 — 1,043 — 7,498 6,455 Total held to maturity 73,572 (798) 14,260 — 87,034 72,774 Available for sale: U.S. government and government agency 586,020 — 18,198 (347) 603,871 603,871 State and municipal: Special revenue 2,137,162 — 96,924 (714) 2,233,372 2,233,372 State general obligation 417,397 — 33,407 — 450,804 450,804 Pre-refunded 250,081 — 21,472 (162) 271,391 271,391 Corporate backed 206,356 — 8,755 (638) 214,473 214,473 Local general obligation 410,583 — 40,596 (555) 450,624 450,624 Total state and municipal 3,421,579 — 201,154 (2,069) 3,620,664 3,620,664 Mortgage-backed: Residential 813,187 — 24,664 (5,238) 832,613 832,613 Commercial 181,105 — 6,725 (113) 187,717 187,717 Total mortgage-backed securities 994,292 — 31,389 (5,351) 1,020,330 1,020,330 Asset-backed 3,218,048 — 10,035 (33,497) 3,194,586 3,194,586 Corporate: Industrial 2,456,516 (518) 115,926 (7,449) 2,564,475 2,564,475 Financial 1,513,943 — 62,947 (987) 1,575,903 1,575,903 Utilities 389,267 — 31,931 (33) 421,165 421,165 Other 109,353 — 696 (11) 110,038 110,038 Total corporate 4,469,079 (518) 211,500 (8,480) 4,671,581 4,671,581 Foreign government 993,268 (1,264) 28,007 (44,448) 975,563 975,563 Total available for sale 13,682,286 (1,782) 500,283 (94,192) 14,086,595 14,086,595 Total investments in fixed maturity securities $ 13,755,858 $ (2,580) $ 514,543 $ (94,192) $ 14,173,629 $ 14,159,369
Debt Securities, Held-to-maturity, Allowance for Credit Loss	The following table presents the rollforward of the allowance for expected credit losses for state and municipal held to maturity securities for the six months ended June 30, 2021 and 2020: (In thousands) 2021 2020 Allowance for expected credit losses, beginning of period $ 798 $ — Cumulative effect adjustment resulting from changes in accounting principles — 69 Provision for expected credit losses (345) 879 Allowance for expected credit losses, end of period $ 453 $ 948 The following table presents the rollforward of the allowance for expected credit losses for state and municipal held to maturity securities for the three months ended June 30, 2021 and 2020: (In thousands) 2021 2020 Allowance for expected credit losses, beginning of period $ 730 $ 107 Provision for expected credit losses (277) 841 Allowance for expected credit losses, end of period $ 453 $ 948
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 six months ended June 30, 2021 and 2020: 2021 2020 (In thousands) Foreign Government Corporate Total Foreign Government Corporate Total Allowance for expected credit losses, beginning of period $ 1,264 $ 518 $ 1,782 $ — $ — $ — 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 18,990 16 19,006 12,494 6,797 19,291 Expected credit losses on securities for which credit losses were previously recorded (861) (517) (1,378) 547 (3,758) (3,211) Reduction due to disposals (494) (5) (499) (3,917) (2,315) (6,232) Allowance for expected credit losses, end of period $ 18,899 $ 12 $ 18,911 $ 44,769 $ 724 $ 45,493 The following table presents the rollforward of the allowance for expected credit losses for available for sale securities for the three months ended June 30, 2021 and 2020: 2021 2020 (In thousands) Foreign Government Corporate Total Foreign Government Corporate Total Allowance for expected credit losses, beginning of period $ 19,993 $ 16 $ 20,009 $ 60,920 $ 6,436 $ 67,356 Expected credit losses on securities for which credit losses were not previously recorded — — — — 361 361 Expected credit losses on securities for which credit losses were previously recorded (600) (4) (604) (15,822) (3,758) (19,580) Reduction due to disposals (494) — (494) (329) (2,315) (2,644) Allowance for expected credit losses, end of period $ 18,899 $ 12 $ 18,911 $ 44,769 $ 724 $ 45,493
Amortized cost and fair value of fixed maturity securities by contractual maturity	The amortized cost and fair value of fixed maturity securities at June 30, 2021, 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 $ 1,735,412 $ 1,739,369 Due after one year through five years 6,570,612 6,726,040 Due after five years through ten years 3,888,420 3,993,735 Due after ten years 2,240,429 2,277,007 Mortgage-backed securities 915,227 930,285 Total $ 15,350,100 $ 15,666,436 ________________

Investments in Equity Securit_2

Investments in Equity Securities (Tables)	6 Months Ended
	Jun. 30, 2021
Real estate
Debt Securities, Available-for-sale [Line Items]
Schedule of Investments in Equity Securities	At June 30, 2021 and December 31, 2020, investments in equity securities were as follows: (In thousands) Cost Gross Unrealized Fair Carrying Gains Losses June 30, 2021 Common stocks $ 367,228 $ 88,228 $ (5,956) $ 449,500 $ 449,500 Preferred stocks 208,685 8,398 (23,590) 193,493 193,493 Total $ 575,913 $ 96,626 $ (29,546) $ 642,993 $ 642,993 December 31, 2020 Common stocks $ 335,617 $ 28,742 $ (14,178) $ 350,181 $ 350,181 Preferred stocks 180,397 95,581 (492) 275,486 275,486 Total $ 516,014 $ 124,323 $ (14,670) $ 625,667 $ 625,667

Net Investment Income (Tables)

Net Investment Income (Tables)	6 Months Ended
	Jun. 30, 2021
Net Investment Income [Abstract]
Schedule of Net Investment Income	Net investment income consisted of the following: For the Three Months For the Six Months (In thousands) 2021 2020 2021 2020 Investment income (loss) earned on: Fixed maturity securities, including cash and cash equivalents and loans receivable $ 96,996 $ 105,843 $ 191,673 $ 233,861 Investment funds 61,311 (57,552) 100,246 (16,975) Arbitrage trading account 3,914 31,304 22,989 32,442 Equity securities 7,212 2,726 13,392 4,288 Real estate 872 5,045 2,032 11,141 Gross investment income 170,305 87,366 330,332 264,757 Investment expense (2,118) (1,935) (3,568) (4,563) Net investment income $ 168,187 $ 85,431 $ 326,764 $ 260,194

Investment Funds (Tables)

Investment Funds (Tables)	6 Months Ended
	Jun. 30, 2021
Equity Method Investments and Joint Ventures [Abstract]
Schedule of Investment Funds	Investment funds consisted of the following: Carrying Value as of Income (Loss) from June 30, December 31, For the Six Months (In thousands) 2021 2020 2021 2020 Financial services $ 452,233 $ 434,437 $ 48,990 $ (6,881) Real Estate 262,889 310,783 10,506 4,021 Transportation 271,536 190,125 17,177 (4,627) Energy 149,008 140,935 9,492 (20,968) Other funds 233,787 233,150 14,081 11,480 Total $ 1,369,453 $ 1,309,430 $ 100,246 $ (16,975)

Real Estate (Tables)

Real Estate (Tables)	6 Months Ended
	Jun. 30, 2021
Real Estate [Abstract]
Schedule of Real Estate Investments	Investment in real estate represents directly owned property held for investment, as follows: Carrying Value June 30, December 31, (In thousands) 2021 2020 Properties in operation $ 1,586,911 $ 1,738,144 Properties under development 224,352 222,770 Total $ 1,811,263 $ 1,960,914

Loans Receivable Loans Receivab

Loans Receivable Loans Receivable (Tables)	6 Months Ended
	Jun. 30, 2021
Receivables [Abstract]
Schedule of Loans Receivable	At June 30, 2021 and December 31, 2020, loans receivable were as follows: (In thousands) June 30, December 31, Amortized cost (net of allowance for expected credit losses): Real estate loans $ 89,821 $ 51,910 Commercial loans 26,188 33,003 Total $ 116,009 $ 84,913 Fair value: Real estate loans $ 91,322 $ 53,593 Commercial loans 26,188 33,003 Total $ 117,510 $ 86,596
Financing Receivable, Allowance for Credit Loss	The following table presents the rollforward of the allowance for expected credit losses for loans receivable for the six months ended June 30, 2021 and 2020: 2021 2020 (In thousands) Real Estate Loans Commercial Loans Total Real Estate Loans Commercial Loans Total Allowance for expected credit losses, beginning of period $ 1,683 $ 3,754 $ 5,437 $ 1,502 $ 644 $ 2,146 Cumulative effect adjustment resulting from changes in accounting principles — — — (905) 548 (357) Provision for expected credit losses (182) (3,285) (3,467) 3,721 3,209 6,930 Allowance for expected credit losses, end of period $ 1,501 $ 469 $ 1,970 $ 4,318 $ 4,401 $ 8,719 The following table presents the rollforward of the allowance for expected credit losses for loans receivable for the three months ended June 30, 2021 and 2020: 2021 2020 (In thousands) Real Estate Loans Commercial Loans Total Real Estate Loans Commercial Loans Total Allowance for expected credit losses, beginning of period $ 1,608 $ 2,590 $ 4,198 $ 1,435 $ 2,493 $ 3,928 Provision for expected credit losses (107) (2,121) (2,228) 2,883 1,908 4,791 Allowance for expected credit losses, end of period $ 1,501 $ 469 $ 1,970 $ 4,318 $ 4,401 $ 8,719

Net Investment Gains (Losses) (

Net Investment Gains (Losses) (Tables)	6 Months Ended
	Jun. 30, 2021
Realized and Unrealized Investment Gains (Losses) [Abstract]
Realized And Unrealized Investment Gains (Losses)	Net investment gains (losses) were as follows: For the Three Months For the Six Months (In thousands) 2021 2020 2021 2020 Net investment gains (losses): Fixed maturity securities: Gains $ 5,440 $ 14,844 $ 13,680 $ 19,775 Losses (2,236) (9,234) (4,307) (14,081) Equity securities (1): Net realized gains on investment sales 6,256 5,727 14,828 5,727 Change in unrealized (losses) gains (18,239) 61,914 (42,574) (92,552) Investment funds (300) 913 47,371 31,096 Real estate 49,492 (7,137) 62,401 (7,824) Loans receivable (881) — (881) — Other (19,071) (5,374) (18,299) (23,773) Net realized and unrealized gains (losses) on investments in earnings before allowance for expected credit losses 20,461 61,653 72,219 (81,632) Change in allowance for expected credit losses on investments: Fixed maturity securities 1,375 21,023 (16,783) (10,727) Loans receivable 2,228 (4,791) 3,467 (6,930) Change in allowance for expected credit losses on investments 3,603 16,232 (13,316) (17,657) Net investment gains (losses) 24,064 77,885 58,903 (99,289) Income tax (expense) benefit (5,264) (18,098) (11,151) 22,476 After-tax net investment gains (losses) $ 18,800 $ 59,787 $ 47,752 $ (76,813) Change in unrealized investment gains (losses) on available for sale securities: Fixed maturity securities without allowance for expected credit losses $ 28,511 $ 369,615 $ (94,058) $ 43,199 Fixed maturity securities with allowance for expected credit losses (69) 23,450 10,286 24,991 Investment funds 762 4,212 (257) (3,434) Other (400) (1,653) (902) (1,979) Total change in unrealized investment gains (losses) 28,804 395,624 (84,931) 62,777 Income tax (expense) benefit (5,532) (76,899) 18,073 (3,034) Noncontrolling interests (1) (1) (1) 1 After-tax change in unrealized investment gains (losses) of available for sale securities $ 23,271 $ 318,724 $ (66,859) $ 59,744 ______________________ (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 (losses) 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.

Fixed Maturity Securities In _2

Fixed Maturity Securities In An Unrealized Loss Position (Tables)	6 Months Ended
	Jun. 30, 2021
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 June 30, 2021 and December 31, 2020 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 Gross Fair Gross Fair Gross June 30, 2021 U.S. government and government agency $ 38,752 $ 458 $ 524 $ 3 $ 39,276 $ 461 State and municipal 205,730 2,222 22,655 1,356 228,385 3,578 Mortgage-backed 266,963 7,799 29,570 540 296,533 8,339 Asset-backed 2,581,697 6,817 606,663 17,312 3,188,360 24,129 Corporate 972,383 8,212 44,055 2,098 1,016,438 10,310 Foreign government 376,746 11,433 11,921 21,429 388,667 32,862 Fixed maturity securities $ 4,442,271 $ 36,941 $ 715,388 $ 42,738 $ 5,157,659 $ 79,679 December 31, 2020 U.S. government and government agency $ 47,649 $ 347 $ 17 $ — $ 47,666 $ 347 State and municipal 147,754 1,165 20,528 904 168,282 2,069 Mortgage-backed 212,388 5,121 23,943 230 236,331 5,351 Asset-backed 1,389,133 6,563 656,877 26,934 2,046,010 33,497 Corporate 612,177 6,721 39,985 1,759 652,162 8,480 Foreign government 143,729 22,871 6,218 21,577 149,947 44,448 Fixed maturity securities $ 2,552,830 $ 42,788 $ 747,568 $ 51,404 $ 3,300,398 $ 94,192
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 June 30, 2021 is presented in the table below: ($ in thousands) Number of Aggregate Gross Foreign government 27 $ 108,910 $ 30,171 Corporate 10 36,482 2,058 Mortgage-backed 4 276 19 Asset-backed 1 113 1 Total 42 $ 145,781 $ 32,249

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	6 Months Ended
	Jun. 30, 2021
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 June 30, 2021 and December 31, 2020 by level: (In thousands) Total Level 1 Level 2 Level 3 June 30, 2021 Assets: Fixed maturity securities available for sale: U.S. government and government agency $ 502,625 $ — $ 502,625 $ — State and municipal 3,426,156 — 3,426,156 — Mortgage-backed 923,702 — 923,702 — Asset-backed 4,317,863 — 4,317,863 — Corporate 5,340,663 — 5,340,663 — Foreign government 1,068,918 — 1,068,918 — Total fixed maturity securities available for sale 15,579,927 — 15,579,927 — Equity securities: Common stocks 449,500 437,758 2,261 9,481 Preferred stocks 193,493 — 184,160 9,333 Total equity securities 642,993 437,758 186,421 18,814 Arbitrage trading account 634,276 621,883 12,393 — Total $ 16,857,196 $ 1,059,641 $ 15,778,741 $ 18,814 Liabilities: Trading account securities sold but not yet purchased $ 190 $ 190 $ — $ — December 31, 2020 Assets: Fixed maturity securities available for sale: U.S. government and government agency $ 603,871 $ — $ 603,871 $ — State and municipal 3,620,664 — 3,620,664 — Mortgage-backed 1,020,330 — 1,020,330 — Asset-backed 3,194,586 — 3,194,586 — Corporate 4,671,581 — 4,670,581 1,000 Foreign government 975,563 — 975,563 — Total fixed maturity securities available for sale 14,086,595 — 14,085,595 1,000 Equity securities: Common stocks 350,181 340,966 — 9,215 Preferred stocks 275,486 — 266,155 9,331 Total equity securities 625,667 340,966 266,155 18,546 Arbitrage trading account 341,473 298,359 43,114 — Total $ 15,053,735 $ 639,325 $ 14,394,864 $ 19,546 Liabilities: Trading account securities sold but not yet purchased $ 10,048 $ 10,048 $ — $ —
Summarize Changes In Level 3 Assets	The following tables summarize changes in Level 3 assets and liabilities for the six months ended June 30, 2021 and for the year ended December 31, 2020: Gains (Losses) Included in: (In thousands) Beginning Earnings (Losses) Other Impairments Purchases (Sales) Paydowns / Maturities Transfers In / (Out) Ending Six Months Ended June 30, 2021 Assets: Fixed maturities securities available for sale: Corporate $ 1,000 $ — $ — $ — $ — $ (1,000) $ — $ — $ — Total 1,000 — — — — (1,000) — — — Equity securities: Common stocks $ 9,215 $ 827 $ — $ — $ — $ (561) $ — $ — $ 9,481 Preferred stocks 9,331 2 — — — — — — 9,333 Total 18,546 829 — — — (561) — — 18,814 Arbitrage trading account — 1 — — — (1) — — — Total $ 19,546 $ 830 $ — $ — $ — $ (1,562) $ — $ — $ 18,814 Year Ended Assets: Fixed maturities securities available for sale: Corporate $ — $ — $ — $ — $ — $ — $ — $ 1,000 $ 1,000 Total — — — — — — — 1,000 1,000 Equity securities: Common stocks 9,053 1,228 — — — (1,066) — — 9,215 Preferred stocks 6,505 (174) — — 3,000 — — — 9,331 Total 15,558 1,054 — — 3,000 (1,066) — — 18,546 Arbitrage trading account — 19 — — — (19) — — — Total $ 15,558 $ 1,073 $ — $ — $ 3,000 $ (1,085) $ — $ 1,000 $ 19,546

Reserves for Loss and Loss Ex_2

Reserves for Loss and Loss Expenses (Tables)	6 Months Ended
	Jun. 30, 2021
Insurance [Abstract]
Reserve Balances	The table below provides a reconciliation of the beginning and ending reserve balances: June 30, (In thousands) 2021 2020 Net reserves at beginning of period $ 11,620,393 $ 10,697,998 Cumulative effect adjustment resulting from changes in accounting principles — 5,927 Restated net reserves at beginning of period 11,620,393 10,703,925 Net provision for losses and loss expenses: Claims occurring during the current year (1) 2,308,309 2,222,671 Increase in estimates for claims occurring in prior years (2) (3) 1,530 2,050 Loss reserve discount accretion 15,399 17,658 Total 2,325,238 2,242,379 Net payments for claims: Current year 279,703 289,154 Prior years 1,485,116 1,545,471 Total 1,764,819 1,834,625 Foreign currency translation (16,153) (45,572) Net reserves at end of period 12,164,659 11,066,107 Ceded reserves at end of period 2,316,288 2,022,797 Gross reserves at end of period $ 14,480,947 $ 13,088,904 _______________________________________ (1) Claims occurring during the current year are net of loss reserve discounts of $10 million and $5 million for the six months ended June 30, 2021 and 2020, 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 $16 million and $8 million for the six months ended June 30, 2021 and 2020, 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 six months ended June 30, 2021 and 2020, respectively.

Fair Value of Financial Instr_2

Fair Value of Financial Instruments (Tables)	6 Months Ended
	Jun. 30, 2021
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: June 30, 2021 December 31, 2020 (In thousands) Carrying Value Fair Value Carrying Value Fair Value Assets: Fixed maturity securities $ 15,653,508 $ 15,666,436 $ 14,159,369 $ 14,173,629 Equity securities 642,993 642,993 625,667 625,667 Arbitrage trading account 634,276 634,276 341,473 341,473 Loans receivable 116,009 117,510 84,913 86,596 Cash and cash equivalents 1,790,199 1,790,199 2,372,366 2,372,366 Trading account receivables from brokers and clearing organizations 361,586 361,586 524,727 524,727 Due from broker — — 2,585 2,585 Liabilities: Due to broker 63,276 63,276 — — Trading account securities sold but not yet purchased 190 190 10,048 10,048 Senior notes and other debt 1,911,753 2,176,756 1,623,025 1,892,444 Subordinated debentures 1,007,293 1,112,812 1,102,309 1,202,842

Premiums and Reinsurance Rela_2

Premiums and Reinsurance Related Information (Tables)	6 Months Ended
	Jun. 30, 2021
Insurance [Abstract]
Reinsurance Financial Information	The following is a summary of insurance and reinsurance financial information: For the Three Months For the Six Months (In thousands) 2021 2020 2021 2020 Written premiums: Direct $ 2,395,114 $ 1,892,359 $ 4,572,276 $ 3,856,848 Assumed 266,122 239,887 573,672 506,769 Ceded (449,055) (392,428) (883,729) (777,953) Total net premiums written $ 2,212,181 $ 1,739,818 $ 4,262,219 $ 3,585,664 Earned premiums: Direct $ 2,151,739 $ 1,804,844 $ 4,154,784 $ 3,634,558 Assumed 259,166 232,996 518,707 461,210 Ceded (439,281) (360,925) (851,911) (727,435) Total net premiums earned $ 1,971,624 $ 1,676,915 $ 3,821,580 $ 3,368,333 Ceded losses and loss expenses incurred $ 255,163 $ 232,873 $ 553,903 $ 468,055 Ceded commissions earned $ 106,834 $ 85,593 $ 208,515 $ 166,638
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 six months ended June 30, 2021 and 2020: (In thousands) 2021 2020 Allowance for expected credit losses, beginning of period $ 22,883 $ 19,823 Cumulative effect adjustment resulting from changes in accounting principles — 1,270 Provision for expected credit losses 1,925 1,013 Allowance for expected credit losses, end of period $ 24,808 $ 22,106 The following table presents the rollforward of the allowance for expected credit losses for premiums and fees receivable for the three months ended June 30, 2021 and 2020: (In thousands) 2021 2020 Allowance for expected credit losses, beginning of period $ 24,264 $ 21,524 Provision for expected credit losses 544 582 Allowance for expected credit losses, end of period $ 24,808 $ 22,106
Reinsurance Recoverable, Allowance for Credit Loss	The following table presents the rollforward of the allowance for expected credit losses associated with due from reinsurers for the six months ended June 30, 2021 and 2020: (In thousands) 2021 2020 Allowance for expected credit losses, beginning of period $ 7,801 $ 690 Cumulative effect adjustment resulting from changes in accounting principles — 5,927 Provision for expected credit losses (518) 558 Allowance for expected credit losses, end of period $ 7,283 $ 7,175 The following table presents the rollforward of the allowance for expected credit losses associated with due from reinsurers for the three months ended June 30, 2021 and 2020: (In thousands) 2021 2020 Allowance for expected credit losses, beginning of period $ 7,373 $ 6,800 Provision for expected credit losses (90) 375 Allowance for expected credit losses, end of period $ 7,283 $ 7,175

Restricted Stock Units (Tables)

Restricted Stock Units (Tables)	6 Months Ended
	Jun. 30, 2021
Share-based Payment Arrangement [Abstract]
Summary Of Restricted Stock Units Issued	A summary of RSUs issued in the six months ended June 30, 2021 and 2020 follows: ($ in thousands) Units Fair Value 2021 1,531 $ 75 2020 724 $ 57

Leases (Tables)

Leases (Tables)	6 Months Ended
	Jun. 30, 2021
Leases [Abstract]
Lease, Cost	Further information relating to operating lease expense and other operating lease information are as follows: For the Three Months Ended For the Six Months Ended June 30, (In thousands) 2021 2020 2021 2020 Leases: Lease cost $ 11,429 $ 10,878 $ 22,693 $ 22,114 Cash paid for amounts included in the measurement of lease liabilities reported in operating cash flows $ 11,920 $ 11,479 $ 23,297 $ 22,309 Right-of-use assets (reduced) obtained in exchange for new lease liabilities $ (181) $ 2,682 $ (151) $ 4,294
Supplemental Balance Sheet Information	As of June 30, ($ in thousands) 2021 2020 Right-of-use assets $ 148,455 $ 180,011 Lease liabilities $ 185,738 $ 219,444 Weighted-average remaining lease term 6.7 years 6.8 years Weighted-average discount rate 5.95 % 5.94 %
Maturities of Operating Lease Liabilities	Contractual maturities of the Company’s future minimum lease payments are as follows: (In thousands) June 30, 2021 Contractual Maturities: 2021 $ 22,960 2022 42,677 2023 39,081 2024 32,467 2025 23,227 Thereafter 59,736 Total undiscounted future minimum lease payments 220,148 Less: Discount impact (34,410) Total lease liability $ 185,738

Business Segments (Tables)

Business Segments (Tables)	6 Months Ended
	Jun. 30, 2021
Segment Reporting [Abstract]
Financial Information Of Company Operating Segments	Revenues (In thousands) Earned Investment Other Total (2) Pre-Tax Income (Loss) Net Income (Loss) to Common Stockholders Three months ended June 30, 2021 Insurance $ 1,727,202 $ 116,703 $ 8,212 $ 1,852,117 $ 291,290 $ 230,313 Reinsurance & Monoline Excess 244,422 46,879 — 291,301 74,794 59,334 Corporate, other and eliminations (3) — 4,605 124,000 128,604 (90,208) (71,209) Net investment gains — — 24,064 24,064 24,064 18,800 Total $ 1,971,624 $ 168,187 $ 156,276 $ 2,296,086 $ 299,940 $ 237,238 Three months ended June 30, 2020 Insurance $ 1,465,044 $ 44,105 $ 8,018 $ 1,517,167 $ 76,546 $ 48,607 Reinsurance & Monoline Excess 211,871 23,461 — 235,332 12,566 10,689 Corporate, other and eliminations (3) — 17,865 87,777 105,642 (61,548) (47,823) Net investment gains — — 77,885 77,885 77,885 59,787 Total $ 1,676,915 $ 85,431 $ 173,680 $ 1,936,026 $ 105,449 $ 71,260 Six months ended June 30, 2021 Insurance $ 3,332,181 $ 221,941 $ 16,490 $ 3,570,612 $ 548,399 $ 429,022 Reinsurance & Monoline Excess 489,399 84,587 — 573,986 143,443 113,806 Corporate, other and eliminations (3) — 20,236 229,218 249,454 (154,737) (123,817) Net investment gains — — 58,903 58,903 58,903 47,752 Total $ 3,821,580 $ 326,764 $ 304,611 $ 4,452,955 $ 596,008 $ 466,763 Six Months Ended June 30, 2020 Insurance $ 2,949,999 $ 167,564 $ 16,490 $ 3,134,053 $ 252,493 $ 185,467 Reinsurance & Monoline Excess 418,334 61,171 — 479,505 49,080 39,877 Corporate, other and eliminations (3) — 31,459 200,907 232,366 (103,302) (81,689) Net investment losses — — (99,289) (99,289) (99,289) (76,813) Total $ 3,368,333 $ 260,194 $ 118,108 $ 3,746,635 $ 98,982 $ 66,842 _________________ (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 June 30, 2021 and 2020 were $221 million and $149 million, respectively, and for the six months ended June 30, 2021 and 2020 were $418 million and $317 million, respectively. Revenues for Reinsurance & Monoline Excess from foreign countries for the three months ended June 30, 2021 and 2020 were $90 million and $65 million, respectively, and for the six months ended June 30, 2021 and 2020 were $178 million and $134 million, respectively.
Identifiable Assets By Segment	(In thousands) June 30, December 31, Insurance $ 22,771,988 $ 21,702,328 Reinsurance & Monoline Excess 4,670,226 4,654,158 Corporate, other and eliminations 2,855,703 2,215,479 Consolidated $ 30,297,917 $ 28,571,965
Net Premiums Earned By Major Line Of Business	Net premiums earned by major line of business are as follows: For the Three Months For the Six Months (In thousands) 2021 2020 2021 2020 Insurance: Other liability $ 638,404 $ 544,465 $ 1,240,306 $ 1,091,594 Short-tail lines (1) 339,890 295,968 664,630 591,446 Workers' compensation 291,471 278,699 558,920 580,299 Commercial automobile 237,444 190,335 458,205 379,978 Professional liability 219,993 155,577 410,120 306,682 Total Insurance 1,727,202 1,465,044 3,332,181 2,949,999 Reinsurance & Monoline Excess: Casualty reinsurance 152,531 130,459 302,169 253,190 Monoline excess (2) 48,247 41,062 94,120 83,224 Property reinsurance 43,644 40,350 93,110 81,920 Total Reinsurance & Monoline Excess 244,422 211,871 489,399 418,334 Total $ 1,971,624 $ 1,676,915 $ 3,821,580 $ 3,368,333 ______________ (1) Short-tail lines include commercial multi-peril (non-liability), inland marine, accident and health, fidelity and surety, boiler and machinery and other lines.

General (Details)

General (Details)	6 Months Ended
	Jun. 30, 2021
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	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
Earnings Per Share [Abstract]
Weighted average number of shares held in grantor trust (in shares)	7,767,874,000	7,575,168

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		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Earnings Per Share [Abstract]
Basic (shares)	185,155	185,979	185,175	188,133
Diluted (shares)	187,106	187,862	186,985	190,078

Consolidated Statements of Co_4

Consolidated Statements of Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning of period			$ 6,325,797
Other comprehensive income (loss)	$ 25,809	$ 340,172	(60,271)	$ (17,004)
End of period	6,587,954		6,587,954
Net realized and unrealized gains (losses) on investments	20,461	61,653	72,219	(81,632)
Income before income taxes	299,940	105,449	596,008	98,982
Tax effect	(62,262)	(33,793)	(126,614)	(30,852)
Net income before noncontrolling interests	237,678	71,656	469,394	68,130
Total change in unrealized investment gains (losses)	28,804	395,624	(84,931)	62,777
Net change in period	2,537	21,447	6,587	(76,747)
Other comprehensive income (loss), pre-tax	31,341	417,071	(78,344)	(13,970)
Other comprehensive income (loss), tax effect	(5,532)	(76,899)	18,073	(3,034)
Accumulated Other Comprehensive Income (Loss)
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning of period	(148,252)	(589,521)	(62,172)	(257,299)
Other comprehensive income (loss) before reclassifications	14,360	356,965	(80,581)	(39,761)
Amounts reclassified from AOCI	11,449	(16,793)	20,310	22,757
Other comprehensive income (loss)	25,809	340,172	(60,271)	(17,004)
Unrealized investment loss related to noncontrolling interest	(1)	(1)	(1)	1
End of period	(122,444)	(249,350)	(122,444)	(249,350)
Accumulated Other Comprehensive Income (Loss) | Amounts reclassified from AOCI
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Income before income taxes	14,493	(21,257)	25,709	28,806
Tax effect	(3,044)	4,464	(5,399)	(6,049)
Net income before noncontrolling interests	11,449	(16,793)	20,310	22,757
Unrealized Investment Gains (Losses)
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning of period	199,584	(109,514)	289,714	124,514
Other comprehensive income (loss) before reclassifications	11,823	335,518	(87,168)	36,986
Amounts reclassified from AOCI	11,449	(16,793)	20,310	22,757
Other comprehensive income (loss)	23,272	318,725	(66,858)	59,743
Unrealized investment loss related to noncontrolling interest	(1)	(1)	(1)	1
End of period	222,855	209,210	222,855	209,210
Total change in unrealized investment gains (losses)	28,804	395,624	(84,931)	62,777
Unrealized investment gains, tax effect	(5,532)	(76,899)	18,073	(3,034)
Unrealized investment gains (losses), after-tax amounts	23,272	318,725	(66,858)	59,743
Unrealized Investment Gains (Losses) | Amounts reclassified from AOCI
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Net realized and unrealized gains (losses) on investments	14,493	(21,257)	25,709	28,806
Tax effect	(3,044)	4,464	(5,399)	(6,049)
Net income before noncontrolling interests	11,449	(16,793)	20,310	22,757
Currency Translation Adjustments
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning of period	(347,836)	(480,007)	(351,886)	(381,813)
Other comprehensive income (loss) before reclassifications	2,537	21,447	6,587	(76,747)
Amounts reclassified from AOCI	0	0	0	0
Other comprehensive income (loss)	2,537	21,447	6,587	(76,747)
Unrealized investment loss related to noncontrolling interest	0	0	0	0
End of period	(345,299)	(458,560)	(345,299)	(458,560)
Currency translation adjustment, pre-tax	2,537	21,447	6,587	(76,747)
Currency translation adjustment, tax effect	0	0	0	0
Net change in period	2,537	21,447	6,587	(76,747)
Currency Translation Adjustments | Amounts reclassified from AOCI
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Income before income taxes	0	0	0	0
Tax effect	0	0	0	0
Net income before noncontrolling interests	$ 0	$ 0	$ 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 Flows (Detai

Statements of Cash Flows (Details) - USD ($)	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
Supplemental Cash Flow Elements [Abstract]
Interest payments	$ 71,781,000	$ 73,056,000
Income taxes paid	$ 177,000,000	$ 0

Investments in Fixed Maturity_3

Investments in Fixed Maturity Securities (Investments in fixed maturity securities) (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019
Debt Securities, Available-for-sale [Line Items]
Total held to maturity, Amortized Cost	$ 74,034		$ 73,572
Held-to-maturity, Allowance for Credit Loss	(453)	$ (730)	(798)	$ (948)	$ (107)	$ 0
Held to maturity, Gross Unrealized Gains	12,928		14,260
Held to maturity, Gross Unrealized Losses	0		0
Total held to maturity, Fair Value	86,509		87,034
Total held to maturity, Carrying Value	73,581		72,774
Total available for sale, Amortized Cost	15,276,519		13,682,286
Available-for-sale, Allowance for Credit Loss	(18,911)	(20,009)	(1,782)	(45,493)	(67,356)	0
Total available for sale, Gross Unrealized Gains	401,998		500,283
Total available for sale, Gross Unrealized Losses	(79,679)		(94,192)
Total available for sale, Fair Value	15,579,927		14,086,595
Total available for sale, Carrying Value	15,579,927		14,086,595
Total investments in fixed maturity securities, Amortized Value	15,350,553		13,755,858
Fixed maturity securities, allowance for credit loss	(19,364)		(2,580)
Total investments in fixed maturity securities, Gross Unrealized Gains	414,926		514,543
Total investments in fixed maturity securities, Gross Unrealized Losses	(79,679)		(94,192)
Total investments in fixed maturity securities, Fair Value	15,666,436		14,173,629
Total investments in fixed maturity securities, Carrying Value	15,653,508		14,159,369
State and municipal
Debt Securities, Available-for-sale [Line Items]
Total held to maturity, Amortized Cost	68,310		67,117
Held-to-maturity, Allowance for Credit Loss	(453)		(798)
Held to maturity, Gross Unrealized Gains	12,069		13,217
Held to maturity, Gross Unrealized Losses	0		0
Total held to maturity, Fair Value	79,926		79,536
Total held to maturity, Carrying Value	67,857		66,319
Total available for sale, Amortized Cost	3,254,895		3,421,579
Available-for-sale, Allowance for Credit Loss	0		0
Total available for sale, Gross Unrealized Gains	174,839		201,154
Total available for sale, Gross Unrealized Losses	(3,578)		(2,069)
Total available for sale, Fair Value	3,426,156		3,620,664
Total available for sale, Carrying Value	3,426,156		3,620,664
Residential mortgage-backed
Debt Securities, Available-for-sale [Line Items]
Total held to maturity, Amortized Cost	5,724		6,455
Held-to-maturity, Allowance for Credit Loss	0		0
Held to maturity, Gross Unrealized Gains	859		1,043
Held to maturity, Gross Unrealized Losses	0		0
Total held to maturity, Fair Value	6,583		7,498
Total held to maturity, Carrying Value	5,724		6,455
Total available for sale, Amortized Cost	771,507		813,187
Available-for-sale, Allowance for Credit Loss	0		0
Total available for sale, Gross Unrealized Gains	16,798		24,664
Total available for sale, Gross Unrealized Losses	(8,189)		(5,238)
Total available for sale, Fair Value	780,116		832,613
Total available for sale, Carrying Value	780,116		832,613
U.S. government and government agency
Debt Securities, Available-for-sale [Line Items]
Total available for sale, Amortized Cost	488,196		586,020
Available-for-sale, Allowance for Credit Loss	0		0
Total available for sale, Gross Unrealized Gains	14,890		18,198
Total available for sale, Gross Unrealized Losses	(461)		(347)
Total available for sale, Fair Value	502,625		603,871
Total available for sale, Carrying Value	502,625		603,871
Special revenue
Debt Securities, Available-for-sale [Line Items]
Total available for sale, Amortized Cost	2,074,036		2,137,162
Available-for-sale, Allowance for Credit Loss	0		0
Total available for sale, Gross Unrealized Gains	85,037		96,924
Total available for sale, Gross Unrealized Losses	(1,433)		(714)
Total available for sale, Fair Value	2,157,640		2,233,372
Total available for sale, Carrying Value	2,157,640		2,233,372
State general obligation
Debt Securities, Available-for-sale [Line Items]
Total available for sale, Amortized Cost	378,596		417,397
Available-for-sale, Allowance for Credit Loss	0		0
Total available for sale, Gross Unrealized Gains	29,413		33,407
Total available for sale, Gross Unrealized Losses	(250)		0
Total available for sale, Fair Value	407,759		450,804
Total available for sale, Carrying Value	407,759		450,804
Pre-refunded
Debt Securities, Available-for-sale [Line Items]
Total available for sale, Amortized Cost	225,787		250,081
Available-for-sale, Allowance for Credit Loss	0		0
Total available for sale, Gross Unrealized Gains	17,677		21,472
Total available for sale, Gross Unrealized Losses	(607)		(162)
Total available for sale, Fair Value	242,857		271,391
Total available for sale, Carrying Value	242,857		271,391
Corporate backed
Debt Securities, Available-for-sale [Line Items]
Total available for sale, Amortized Cost	156,970		206,356
Available-for-sale, Allowance for Credit Loss	0		0
Total available for sale, Gross Unrealized Gains	9,082		8,755
Total available for sale, Gross Unrealized Losses	(862)		(638)
Total available for sale, Fair Value	165,190		214,473
Total available for sale, Carrying Value	165,190		214,473
Local general obligation
Debt Securities, Available-for-sale [Line Items]
Total available for sale, Amortized Cost	419,506		410,583
Available-for-sale, Allowance for Credit Loss	0		0
Total available for sale, Gross Unrealized Gains	33,630		40,596
Total available for sale, Gross Unrealized Losses	(426)		(555)
Total available for sale, Fair Value	452,710		450,624
Total available for sale, Carrying Value	452,710		450,624
Commercial
Debt Securities, Available-for-sale [Line Items]
Total available for sale, Amortized Cost	137,996		181,105
Available-for-sale, Allowance for Credit Loss	0		0
Total available for sale, Gross Unrealized Gains	5,740		6,725
Total available for sale, Gross Unrealized Losses	(150)		(113)
Total available for sale, Fair Value	143,586		187,717
Total available for sale, Carrying Value	143,586		187,717
Mortgage-backed
Debt Securities, Available-for-sale [Line Items]
Total available for sale, Amortized Cost	909,503		994,292
Available-for-sale, Allowance for Credit Loss	0		0
Total available for sale, Gross Unrealized Gains	22,538		31,389
Total available for sale, Gross Unrealized Losses	(8,339)		(5,351)
Total available for sale, Fair Value	923,702		1,020,330
Total available for sale, Carrying Value	923,702		1,020,330
Asset-backed
Debt Securities, Available-for-sale [Line Items]
Total available for sale, Amortized Cost	4,333,543		3,218,048
Available-for-sale, Allowance for Credit Loss	0		0
Total available for sale, Gross Unrealized Gains	8,449		10,035
Total available for sale, Gross Unrealized Losses	(24,129)		(33,497)
Total available for sale, Fair Value	4,317,863		3,194,586
Total available for sale, Carrying Value	4,317,863		3,194,586
Industrial
Debt Securities, Available-for-sale [Line Items]
Total available for sale, Amortized Cost	3,019,720		2,456,516
Available-for-sale, Allowance for Credit Loss	(12)		(518)
Total available for sale, Gross Unrealized Gains	94,056		115,926
Total available for sale, Gross Unrealized Losses	(7,761)		(7,449)
Total available for sale, Fair Value	3,106,003		2,564,475
Total available for sale, Carrying Value	3,106,003		2,564,475
Financial
Debt Securities, Available-for-sale [Line Items]
Total available for sale, Amortized Cost	1,583,291		1,513,943
Available-for-sale, Allowance for Credit Loss	0		0
Total available for sale, Gross Unrealized Gains	51,103		62,947
Total available for sale, Gross Unrealized Losses	(1,076)		(987)
Total available for sale, Fair Value	1,633,318		1,575,903
Total available for sale, Carrying Value	1,633,318		1,575,903
Utilities
Debt Securities, Available-for-sale [Line Items]
Total available for sale, Amortized Cost	406,423		389,267
Available-for-sale, Allowance for Credit Loss	0		0
Total available for sale, Gross Unrealized Gains	18,531		31,931
Total available for sale, Gross Unrealized Losses	(1,106)		(33)
Total available for sale, Fair Value	423,848		421,165
Total available for sale, Carrying Value	423,848		421,165
Other
Debt Securities, Available-for-sale [Line Items]
Total available for sale, Amortized Cost	177,445		109,353
Available-for-sale, Allowance for Credit Loss	0		0
Total available for sale, Gross Unrealized Gains	416		696
Total available for sale, Gross Unrealized Losses	(367)		(11)
Total available for sale, Fair Value	177,494		110,038
Total available for sale, Carrying Value	177,494		110,038
Corporate
Debt Securities, Available-for-sale [Line Items]
Total available for sale, Amortized Cost	5,186,879		4,469,079
Available-for-sale, Allowance for Credit Loss	(12)	(16)	(518)	(724)	(6,436)	0
Total available for sale, Gross Unrealized Gains	164,106		211,500
Total available for sale, Gross Unrealized Losses	(10,310)		(8,480)
Total available for sale, Fair Value	5,340,663		4,671,581
Total available for sale, Carrying Value	5,340,663		4,671,581
Foreign government
Debt Securities, Available-for-sale [Line Items]
Total available for sale, Amortized Cost	1,103,503		993,268
Available-for-sale, Allowance for Credit Loss	(18,899)	$ (19,993)	(1,264)	$ (44,769)	$ (60,920)	$ 0
Total available for sale, Gross Unrealized Gains	17,176		28,007
Total available for sale, Gross Unrealized Losses	(32,862)		(44,448)
Total available for sale, Fair Value	1,068,918		975,563
Total available for sale, Carrying Value	$ 1,068,918		$ 975,563

Investments in Fixed Maturity_4

Investments in Fixed Maturity Securities (HTM Allowance for Credit Loss) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Debt Securities, Held-to-maturity, Allowance for Credit Loss [Roll Forward]
Allowance for expected credit losses, beginning of period	$ 730	$ 107	$ 798	$ 0
Cumulative effect adjustment resulting from changes in accounting principles	453	948	453	948
Provision for expected credit losses	(277)	841	(345)	879
Allowance for expected credit losses, end of period	$ 453	$ 948	453	948
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, beginning of period			$ 0	$ 69
Cumulative effect adjustment resulting from changes in accounting principles

Investments in Fixed Maturity_5

Investments in Fixed Maturity Securities (AFS Allowance for Credit Loss) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Debt Securities, Available-for-sale, Allowance for Credit Loss [Roll Forward]
Allowance for expected credit losses, beginning of period	$ 20,009	$ 67,356	$ 1,782	$ 0
Cumulative effect adjustment resulting from changes in accounting principles	18,911	45,493	18,911	45,493
Expected credit losses on securities for which credit losses were not previously recorded	0	361	19,006	19,291
Expected credit losses on securities for which credit losses were previously recorded	(604)	(19,580)	(1,378)	(3,211)
Reduction due to disposals	(494)	(2,644)	(499)	(6,232)
Allowance for expected credit losses, end of period	18,911	45,493	18,911	45,493
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, beginning of period			0	35,645
Cumulative effect adjustment resulting from changes in accounting principles
Foreign government
Debt Securities, Available-for-sale, Allowance for Credit Loss [Roll Forward]
Allowance for expected credit losses, beginning of period	19,993	60,920	1,264	0
Cumulative effect adjustment resulting from changes in accounting principles	18,899	44,769	18,899	44,769
Expected credit losses on securities for which credit losses were not previously recorded	0	0	18,990	12,494
Expected credit losses on securities for which credit losses were previously recorded	(600)	(15,822)	(861)	547
Reduction due to disposals	(494)	(329)	(494)	(3,917)
Allowance for expected credit losses, end of period	18,899	44,769	18,899	44,769
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, beginning of period			0	35,645
Cumulative effect adjustment resulting from changes in accounting principles
Corporate
Debt Securities, Available-for-sale, Allowance for Credit Loss [Roll Forward]
Allowance for expected credit losses, beginning of period	16	6,436	518	0
Cumulative effect adjustment resulting from changes in accounting principles	12	724	12	724
Expected credit losses on securities for which credit losses were not previously recorded	0	361	16	6,797
Expected credit losses on securities for which credit losses were previously recorded	(4)	(3,758)	(517)	(3,758)
Reduction due to disposals	0	(2,315)	(5)	(2,315)
Allowance for expected credit losses, end of period	$ 12	$ 724	12	724
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, beginning of period			$ 0	$ 0
Cumulative effect adjustment resulting from changes in accounting principles

Investments in Fixed Maturity_6

Investments in Fixed Maturity Securities (Amortized cost and fair value of fixed maturity securities) (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019
Investments, Debt and Equity Securities [Abstract]
Amortized Cost, Due in one year or less	$ 1,735,412
Amortized Cost, Due after one year through five years	6,570,612
Amortized Cost, Due after five years through ten years	3,888,420
Amortized Cost, Due after ten years	2,240,429
Amortized Cost, Mortgaged-backed securities	915,227
Total investments in fixed maturity securities, Amortized Value	15,350,100
Fair Value, Due in one year or less	1,739,369
Fair Value, Due after one year through five years	6,726,040
Fair Value, Due after five years through ten years	3,993,735
Fair Value, Due after ten years	2,277,007
Fair Value, Mortgage-backed securities	930,285
Total investments in fixed maturity securities, Fair Value	15,666,436		$ 14,173,629
Cumulative effect adjustment resulting from changes in accounting principles	$ 453	$ 730	$ 798	$ 948	$ 107	$ 0

Investments in Equity Securit_3

Investments in Equity Securities (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Debt Securities, Available-for-sale [Line Items]
Equity securities	$ 642,993	$ 625,667
Fair Value
Debt Securities, Available-for-sale [Line Items]
Cost	575,913	516,014
Gross Unrealized, Gains	96,626	124,323
Gross Unrealized, Losses	(29,546)	(14,670)
Equity securities	642,993	625,667
Fair Value | Common stock
Debt Securities, Available-for-sale [Line Items]
Cost	367,228	335,617
Gross Unrealized, Gains	88,228	28,742
Gross Unrealized, Losses	(5,956)	(14,178)
Equity securities	449,500	350,181
Fair Value | Preferred stocks
Debt Securities, Available-for-sale [Line Items]
Cost	208,685	180,397
Gross Unrealized, Gains	8,398	95,581
Gross Unrealized, Losses	(23,590)	(492)
Equity securities	193,493	275,486
Carrying Value
Debt Securities, Available-for-sale [Line Items]
Equity securities	642,993	625,667
Carrying Value | Common stock
Debt Securities, Available-for-sale [Line Items]
Equity securities	449,500	350,181
Carrying Value | Preferred stocks
Debt Securities, Available-for-sale [Line Items]
Equity securities	$ 193,493	$ 275,486

Arbitrage Trading Account (Deta

Arbitrage Trading Account (Details) - USD ($)	Jun. 30, 2021	Dec. 31, 2020
Derivative [Line Items]
Arbitrage trading account	$ 634,276,000	$ 341,473,000
Short | Options held
Derivative [Line Items]
Fair value of derivative	183,000
Notional amount of derivative	9,800,000
Long | Options held
Derivative [Line Items]
Fair value of derivative	3,000
Notional amount of derivative	$ 741,000,000

Net Investment Income (Details)

Net Investment Income (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Net Investment Income [Line Items]
Gross investment income	$ 170,305	$ 87,366	$ 330,332	$ 264,757
Investment expense	(2,118)	(1,935)	(3,568)	(4,563)
Net investment income	168,187	85,431	326,764	260,194
Fixed maturity securities, including cash and cash equivalents and loans receivable
Net Investment Income [Line Items]
Gross investment income	96,996	105,843	191,673	233,861
Investment funds
Net Investment Income [Line Items]
Investment funds	61,311	(57,552)	100,246	(16,975)
Arbitrage trading account
Net Investment Income [Line Items]
Gross investment income	3,914	31,304	22,989	32,442
Equity securities
Net Investment Income [Line Items]
Gross investment income	872	5,045	2,032	11,141
Real estate
Net Investment Income [Line Items]
Gross investment income	$ 7,212	$ 2,726	$ 13,392	$ 4,288

Investment Funds (Details)

Investment Funds (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020
Schedule of Equity Method Investments [Line Items]
Unfunded commitments	$ 166,000		$ 166,000
Investment funds	1,369,453		1,369,453		$ 1,309,430
Income (Loss) from Investment Funds			100,246	$ (16,975)
Written premiums ceded	449,055	$ 392,428	$ 883,729	777,953
Lifson Re
Schedule of Equity Method Investments [Line Items]
Percentage of reinsurance placements of share placed amounts			22.50%
Written premiums ceded			$ 139,000
Financial services
Schedule of Equity Method Investments [Line Items]
Investment funds	262,889		262,889		310,783
Income (Loss) from Investment Funds			10,506	4,021
Real Estate
Schedule of Equity Method Investments [Line Items]
Investment funds	452,233		452,233		434,437
Income (Loss) from Investment Funds			48,990	(6,881)
Transportation
Schedule of Equity Method Investments [Line Items]
Investment funds	271,536		271,536		190,125
Income (Loss) from Investment Funds			17,177	(4,627)
Energy
Schedule of Equity Method Investments [Line Items]
Investment funds	149,008		149,008		140,935
Income (Loss) from Investment Funds			9,492	(20,968)
Other funds
Schedule of Equity Method Investments [Line Items]
Investment funds	$ 233,787		233,787		$ 233,150
Income (Loss) from Investment Funds			$ 14,081	$ 11,480

Real Estate (Details)

Real Estate (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Real Estate [Abstract]
Properties in operation	$ 1,586,911	$ 1,738,144
Properties under development	224,352	222,770
Total	$ 1,811,263	$ 1,960,914

Real Estate (Narrative) (Detail

Real Estate (Narrative) (Details)	3 Months Ended	6 Months Ended
	Jun. 30, 2021USD ($)officeBuilding	Jun. 30, 2021USD ($)	Jun. 30, 2020USD ($)	Dec. 31, 2020USD ($)
Debt Instrument [Line Items]
Accumulated depreciation and amortization on properties	$ 64,226,000	$ 64,226,000		$ 86,970,000
Real estate depreciation expense		9,622,000	$ 13,776,000
Lease future minimum payments 2021	29,265,862	29,265,862
Lease future minimum payments 2022	59,450,838	59,450,838
Lease future minimum payments 2023	53,607,393	53,607,393
Lease future minimum payments 2024	52,500,378	52,500,378
Lease future minimum payments 2025	50,115,697	50,115,697
Lease future minimum payments 2026	47,602,823	47,602,823
Lease future minimum payments there after	$ 597,389,153	597,389,153
Number of real estate properties sold | officeBuilding	2
Secured Debt
Debt Instrument [Line Items]
Fae value of debt	$ 102	$ 102

Loans Receivable (Details)

Loans Receivable (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2021	Dec. 31, 2020
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans receivable, gross	$ 116,009	$ 84,913
Loans receivable	117,510	86,596
Loans in nonaccrual status	200	200
Real estate loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans receivable, gross	89,821	51,910
Loans receivable	91,322	53,593
Commercial loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans receivable, gross	26,188	33,003
Loans receivable	$ 26,188	$ 33,003
Loans receivable maturity term	10 years

Loans Receivable - Allowance Fo

Loans Receivable - Allowance For Credit Loss (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for expected credit losses, beginning of period	$ 4,198	$ 3,928	$ 5,437	$ 2,146
Cumulative effect adjustment resulting from changes in accounting principles	1,970	8,719	1,970	8,719
Provision for expected credit losses	(2,228)	4,791	(3,467)	6,930
Allowance for expected credit losses, end of period	1,970	8,719	1,970	8,719
Cumulative effect adjustment resulting from changes in accounting principles
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for expected credit losses, beginning of period			0	(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, beginning of period	1,608	1,435	1,683	1,502
Cumulative effect adjustment resulting from changes in accounting principles	1,501	4,318	1,501	4,318
Provision for expected credit losses	(107)	2,883	(182)	3,721
Allowance for expected credit losses, end of period	1,501	4,318	1,501	4,318
Real estate loans | Cumulative effect adjustment resulting from changes in accounting principles
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for expected credit losses, beginning of period			0	(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, beginning of period	2,590	2,493	3,754	644
Cumulative effect adjustment resulting from changes in accounting principles	469	4,401	469	4,401
Provision for expected credit losses	(2,121)	1,908	(3,285)	3,209
Allowance for expected credit losses, end of period	$ 469	$ 4,401	469	4,401
Commercial loans | Cumulative effect adjustment resulting from changes in accounting principles
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for expected credit losses, beginning of period			$ 0	$ 548
Cumulative effect adjustment resulting from changes in accounting principles

Net Investment Gains (Losses)_2

Net Investment Gains (Losses) (Net Investment Gains (Losses)) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Investments, Debt and Equity Securities [Abstract]
Fixed maturity securities, gains	$ 5,440	$ 14,844	$ 13,680	$ 19,775
Fixed maturity securities, losses	(2,236)	(9,234)	(4,307)	(14,081)
Net realized gains on investment sales	6,256	5,727	14,828	5,727
Change in unrealized (losses) gains	(18,239)	61,914	(42,574)	(92,552)
Investment funds	(300)	913	47,371	31,096
Real estate	49,492	(7,137)	62,401	(7,824)
Loans receivable	(881)	0	(881)	0
Other	(19,071)	(5,374)	(18,299)	(23,773)
Net realized and unrealized gains (losses) on investments in earnings before allowance for expected credit losses	20,461	61,653	72,219	(81,632)
Fixed maturity securities	1,375	21,023	(16,783)	(10,727)
Loans receivable	2,228	(4,791)	3,467	(6,930)
Change in allowance for expected credit losses on investments	3,603	16,232	(13,316)	(17,657)
Net investment gains (losses)	24,064	77,885	58,903	(99,289)
Income tax (expense) benefit	(5,264)	(18,098)	(11,151)	22,476
After-tax net investment gains (losses)	$ 18,800	$ 59,787	$ 47,752	$ (76,813)

Net Investment Gains (Losses)_3

Net Investment Gains (Losses) (Change in Unrealized Gains (Losses) of Available For Sales Securities) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Realized and Unrealized Investment Gains Losses [Line Items]
Total change in unrealized investment gains (losses)	$ 28,804	$ 395,624	$ (84,931)	$ 62,777
Income tax (expense) benefit	(5,532)	(76,899)	18,073	(3,034)
Noncontrolling interests	(1)	(1)	(1)	1
Total change in unrealized gains	23,271	318,724	(66,859)	59,744
Debt securities
Realized and Unrealized Investment Gains Losses [Line Items]
Total change in unrealized investment gains (losses)	28,511	369,615	(94,058)	43,199
Fixed maturity securities with allowance for expected credit losses
Realized and Unrealized Investment Gains Losses [Line Items]
Total change in unrealized investment gains (losses)	(69)	23,450	10,286	24,991
Investment funds
Realized and Unrealized Investment Gains Losses [Line Items]
Total change in unrealized investment gains (losses)	762	4,212	(257)	(3,434)
Other
Realized and Unrealized Investment Gains Losses [Line Items]
Total change in unrealized investment gains (losses)	$ (400)	$ (1,653)	$ (902)	$ (1,979)

Fixed Maturity Securities In _3

Fixed Maturity Securities In An Unrealized Loss Position (Securities in an Unrealized Loss Position) (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Debt securities
Debt Securities, Available-for-sale [Line Items]
Fair Value, Less than 12 Months	$ 4,442,271	$ 2,552,830
Gross Unrealized Losses, Less than 12 Months	36,941	42,788
Fair Value, 12 Months or Greater	715,388	747,568
Gross Unrealized Losses, 12 Months or Greater	42,738	51,404
Fair Value, Total	5,157,659	3,300,398
Gross Unrealized Losses, Total	79,679	94,192
U.S. government and government agency
Debt Securities, Available-for-sale [Line Items]
Fair Value, Less than 12 Months	38,752	47,649
Gross Unrealized Losses, Less than 12 Months	458	347
Fair Value, 12 Months or Greater	524	17
Gross Unrealized Losses, 12 Months or Greater	3	0
Fair Value, Total	39,276	47,666
Gross Unrealized Losses, Total	461	347
State and municipal
Debt Securities, Available-for-sale [Line Items]
Fair Value, Less than 12 Months	205,730	147,754
Gross Unrealized Losses, Less than 12 Months	2,222	1,165
Fair Value, 12 Months or Greater	22,655	20,528
Gross Unrealized Losses, 12 Months or Greater	1,356	904
Fair Value, Total	228,385	168,282
Gross Unrealized Losses, Total	3,578	2,069
Mortgage-backed
Debt Securities, Available-for-sale [Line Items]
Fair Value, Less than 12 Months	266,963	212,388
Gross Unrealized Losses, Less than 12 Months	7,799	5,121
Fair Value, 12 Months or Greater	29,570	23,943
Gross Unrealized Losses, 12 Months or Greater	540	230
Fair Value, Total	296,533	236,331
Gross Unrealized Losses, Total	8,339	5,351
Asset-backed
Debt Securities, Available-for-sale [Line Items]
Fair Value, Less than 12 Months	2,581,697	1,389,133
Gross Unrealized Losses, Less than 12 Months	6,817	6,563
Fair Value, 12 Months or Greater	606,663	656,877
Gross Unrealized Losses, 12 Months or Greater	17,312	26,934
Fair Value, Total	3,188,360	2,046,010
Gross Unrealized Losses, Total	24,129	33,497
Corporate
Debt Securities, Available-for-sale [Line Items]
Fair Value, Less than 12 Months	972,383	612,177
Gross Unrealized Losses, Less than 12 Months	8,212	6,721
Fair Value, 12 Months or Greater	44,055	39,985
Gross Unrealized Losses, 12 Months or Greater	2,098	1,759
Fair Value, Total	1,016,438	652,162
Gross Unrealized Losses, Total	10,310	8,480
Foreign government
Debt Securities, Available-for-sale [Line Items]
Fair Value, Less than 12 Months	376,746	143,729
Gross Unrealized Losses, Less than 12 Months	11,433	22,871
Fair Value, 12 Months or Greater	11,921	6,218
Gross Unrealized Losses, 12 Months or Greater	21,429	21,577
Fair Value, Total	388,667	149,947
Gross Unrealized Losses, Total	$ 32,862	$ 44,448

Fixed Maturity Securities In _4

Fixed Maturity Securities In An Unrealized Loss Position (Non-Investment Grade Fixed Maturity Securities) (Details) $ in Thousands	Jun. 30, 2021USD ($)position	Dec. 31, 2020USD ($)
Corporate
Debt Securities, Available-for-sale [Line Items]
Aggregate Fair Value	$ 1,016,438	$ 652,162
Mortgage-backed
Debt Securities, Available-for-sale [Line Items]
Aggregate Fair Value	296,533	236,331
Asset-backed
Debt Securities, Available-for-sale [Line Items]
Aggregate Fair Value	$ 3,188,360	$ 2,046,010
Noninvestment Grade Investments at Loss Position
Debt Securities, Available-for-sale [Line Items]
Number of Securities | position	42
Aggregate Fair Value	$ 145,781
Gross Unrealized Loss	$ 32,249
Noninvestment Grade Investments at Loss Position | Foreign government
Debt Securities, Available-for-sale [Line Items]
Number of Securities | position	27
Aggregate Fair Value	$ 108,910
Gross Unrealized Loss	$ 30,171
Noninvestment Grade Investments at Loss Position | Corporate
Debt Securities, Available-for-sale [Line Items]
Number of Securities | position	10
Aggregate Fair Value	$ 36,482
Gross Unrealized Loss	$ 2,058
Noninvestment Grade Investments at Loss Position | Mortgage-backed
Debt Securities, Available-for-sale [Line Items]
Number of Securities | position	4
Aggregate Fair Value	$ 276
Gross Unrealized Loss	$ 19
Noninvestment Grade Investments at Loss Position | Asset-backed
Debt Securities, Available-for-sale [Line Items]
Number of Securities | position	1
Aggregate Fair Value	$ 113
Gross Unrealized Loss	$ 1

Fair Value Measurements (Assets

Fair Value Measurements (Assets and Liabilities Measured At Fair Value, On a Recurring Basis) (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Assets:
Total fixed maturity securities available for sale	$ 15,579,927	$ 14,086,595
Equity securities	642,993	625,667
Arbitrage trading account	634,276	341,473
Fair Value, Measurements, Recurring
Assets:
Total fixed maturity securities available for sale	15,579,927	14,086,595
Equity securities	642,993	625,667
Arbitrage trading account	634,276	341,473
Assets, fair value disclosure	16,857,196	15,053,735
Liabilities:
Trading account securities sold but not yet purchased	190	10,048
Fair Value, Measurements, Recurring | U.S. government and government agency
Assets:
Total fixed maturity securities available for sale	502,625	603,871
Fair Value, Measurements, Recurring | State and municipal
Assets:
Total fixed maturity securities available for sale	3,426,156	3,620,664
Fair Value, Measurements, Recurring | Mortgage-backed
Assets:
Total fixed maturity securities available for sale	923,702	1,020,330
Fair Value, Measurements, Recurring | Asset-backed
Assets:
Total fixed maturity securities available for sale	4,317,863	3,194,586
Fair Value, Measurements, Recurring | Corporate
Assets:
Total fixed maturity securities available for sale	5,340,663	4,671,581
Fair Value, Measurements, Recurring | Foreign government
Assets:
Total fixed maturity securities available for sale	1,068,918	975,563
Fair Value, Measurements, Recurring | Common stocks
Assets:
Equity securities	449,500	350,181
Fair Value, Measurements, Recurring | Preferred stocks
Assets:
Equity securities	193,493	275,486
Level 1 | Fair Value, Measurements, Recurring
Assets:
Total fixed maturity securities available for sale	0	0
Equity securities	437,758	340,966
Arbitrage trading account	621,883	298,359
Assets, fair value disclosure	1,059,641	639,325
Liabilities:
Trading account securities sold but not yet purchased	190	10,048
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
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	437,758	340,966
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	15,579,927	14,085,595
Equity securities	186,421	266,155
Arbitrage trading account	12,393	43,114
Assets, fair value disclosure	15,778,741	14,394,864
Liabilities:
Trading account 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	502,625	603,871
Level 2 | Fair Value, Measurements, Recurring | State and municipal
Assets:
Total fixed maturity securities available for sale	3,426,156	3,620,664
Level 2 | Fair Value, Measurements, Recurring | Mortgage-backed
Assets:
Total fixed maturity securities available for sale	923,702	1,020,330
Level 2 | Fair Value, Measurements, Recurring | Asset-backed
Assets:
Total fixed maturity securities available for sale	4,317,863	3,194,586
Level 2 | Fair Value, Measurements, Recurring | Corporate
Assets:
Total fixed maturity securities available for sale	5,340,663	4,670,581
Level 2 | Fair Value, Measurements, Recurring | Foreign government
Assets:
Total fixed maturity securities available for sale	1,068,918	975,563
Level 2 | Fair Value, Measurements, Recurring | Common stocks
Assets:
Equity securities	2,261	0
Level 2 | Fair Value, Measurements, Recurring | Preferred stocks
Assets:
Equity securities	184,160	266,155
Level 3 | Fair Value, Measurements, Recurring
Assets:
Total fixed maturity securities available for sale	0	1,000
Equity securities	18,814	18,546
Arbitrage trading account	0	0
Assets, fair value disclosure	18,814	19,546
Liabilities:
Trading account 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
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	1,000
Level 3 | Fair Value, Measurements, Recurring | Foreign government
Assets:
Total fixed maturity securities available for sale	0	0
Level 3 | Fair Value, Measurements, Recurring | Common stocks
Assets:
Equity securities	9,481	9,215
Level 3 | Fair Value, Measurements, Recurring | Preferred stocks
Assets:
Equity securities	$ 9,333	$ 9,331

Fair Value Measurements (Summar

Fair Value Measurements (Summarize Changes in Level 3 Assets) (Details) - USD ($)	6 Months Ended	12 Months Ended
	Jun. 30, 2021	Dec. 31, 2020
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Assets, impairments		$ 0
Securities transferred into or out of level 3, net	$ 0
Level 3
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Assets, beginning balance	19,546,000	15,558,000
Assets, earnings	830,000	1,073,000
Assets, other comprehensive income	0	0
Impairment of Intangible Assets (Excluding Goodwill)	0
Assets, purchases	0	3,000,000
Assets, (sales)	(1,562,000)	(1,085,000)
Assets, maturities	0
Assets. transfers out		1,000,000
Securities transferred into or out of level 3, net	0
Assets, ending balance	18,814,000	19,546,000
Level 3 | Debt securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Assets, beginning balance	1,000,000	0
Assets, earnings	0	0
Assets, other comprehensive income	0	0
Impairment of Intangible Assets (Excluding Goodwill)	0
Assets, impairments		0
Assets, purchases	0	0
Assets, (sales)	(1,000,000)	0
Assets, maturities	0
Assets. transfers out		1,000,000
Securities transferred into or out of level 3, net	0
Assets, ending balance	0	1,000,000
Level 3 | Real estate
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Assets, beginning balance	18,546,000	15,558,000
Assets, earnings	829,000	1,054,000
Assets, other comprehensive income	0	0
Assets, impairments	0	0
Assets, purchases	0	3,000,000
Assets, (sales)	(561,000)	(1,066,000)
Assets, maturities		0
Assets. transfers out	0	0
Assets, ending balance	18,814,000	18,546,000
Level 3 | Common stock
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Assets, beginning balance	9,215,000	9,053,000
Assets, earnings	827,000	1,228,000
Assets, other comprehensive income	0	0
Assets, impairments	0	0
Assets, purchases	0	0
Assets, (sales)	(561,000)	(1,066,000)
Assets. transfers out	0	0
Assets, ending balance	9,481,000	9,215,000
Level 3 | Preferred stocks
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Assets, beginning balance	9,331,000	6,505,000
Assets, earnings	2,000	(174,000)
Assets, other comprehensive income	0	0
Assets, impairments	0	0
Assets, purchases	0	3,000,000
Assets, (sales)	0	0
Assets. transfers out	0	0
Assets, ending balance	9,333,000	9,331,000
Level 3 | Arbitrage trading account
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Assets, beginning balance	0	0
Assets, earnings	1,000	19,000
Assets, other comprehensive income	0	0
Impairment of Intangible Assets (Excluding Goodwill)	0
Assets, impairments		0
Assets, purchases	0	0
Assets, (sales)	(1,000)	(19,000)
Assets, maturities	0
Securities transferred into or out of level 3, net	0
Assets, ending balance	0	0
Level 3 | Corporate
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Assets, beginning balance	1,000,000	0
Assets, earnings	0	0
Assets, other comprehensive income	0	0
Impairment of Intangible Assets (Excluding Goodwill)	0	0
Assets, purchases	0	0
Assets, (sales)	(1,000,000)	0
Assets, maturities	0	0
Securities transferred into or out of level 3, net	0	1,000,000
Assets, ending balance	$ 0	$ 1,000,000

Fair Value Measurements (Narrat

Fair Value Measurements (Narrative) (Details)	6 Months Ended
	Jun. 30, 2021USD ($)
Fair Value Disclosures [Abstract]
Securities transferred into or out of level 3, net	$ 0

Reserves for Loss and Loss Ex_3

Reserves for Loss and Loss Expenses (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Net reserves at beginning of period	$ 11,620,393	$ 10,697,998
Net provision for losses and loss expenses:
Claims occurring during the current year	2,308,309	2,222,671
Decrease in estimates for claims occurring in prior years	1,530	2,050
Loss reserve discount accretion	15,399	17,658
Liability for Unpaid Claims and Claims Adjustment Expense, Incurred Claims	2,325,238	2,242,379
Net payments for claims:
Current year	279,703	289,154
Prior years	1,485,116	1,545,471
Total	1,764,819	1,834,625
Foreign currency translation	(16,153)	(45,572)
Net reserves at end of period	12,164,659	11,066,107	$ 11,620,393
Ceded reserves at end of period	2,316,288	2,022,797
Gross reserves at end of period	14,480,947	13,088,904	13,784,430
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	0	5,927
Net payments for claims:
Net reserves at end of period			0
Cumulative Effect, Period Of Adoption, Adjusted Balance
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Net reserves at beginning of period	$ 11,620,393	$ 10,703,925
Net payments for claims:
Net reserves at end of period			$ 11,620,393

Reserves for Loss and Loss Ex_4

Reserves for Loss and Loss Expenses (Narrative) (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
Liability for Claims and Claims Adjustment Expense [Line Items]
Net of loss reserve discounts	$ 10	$ 5
Increase (decrease) in estimates for claims	16	(8)
Adjustment expense	4	7
Liability recognized for best estimate net of reinsurance	241
Liability recognized for best estimate net of reinsurance, reported losses	164
Liability recognized for best estimate net of reinsurance, incurred but not reported (IBNR)	77
Liability recognized for best estimate net of reinsurance, current accident year losses	40
Insurance
Liability for Claims and Claims Adjustment Expense [Line Items]
Liability recognized for best estimate net of reinsurance	208
Liability recognized for best estimate net of reinsurance, current accident year losses	38
Favorable reserve development net of premium offsets	12	12
Reinsurance & Monoline Excess
Liability for Claims and Claims Adjustment Expense [Line Items]
Liability recognized for best estimate net of reinsurance	33
Liability recognized for best estimate net of reinsurance, current accident year losses	2
Unfavorable reserve development net of premium offsets	$ 8	$ 5

Fair Value of Financial Instr_3

Fair Value of Financial Instruments (Carrying Amounts and Estimated Fair Values of Financial Instruments) (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Assets:
Arbitrage trading account	$ 634,276	$ 341,473
Loans receivable	117,510	86,596
Carrying Value
Assets:
Fixed maturity securities	15,653,508	14,159,369
Equity securities	642,993	625,667
Arbitrage trading account	634,276	341,473
Loans receivable	116,009	84,913
Cash and cash equivalents	1,790,199	2,372,366
Trading account receivables from brokers and clearing organizations	361,586	524,727
Due from broker	0	2,585
Liabilities:
Due to broker	63,276	0
Trading account securities sold but not yet purchased	190	10,048
Senior notes and other debt	1,911,753	1,623,025
Subordinated debentures	1,007,293	1,102,309
Fair Value
Assets:
Fixed maturity securities	15,666,436	14,173,629
Equity securities	642,993	625,667
Arbitrage trading account	634,276	341,473
Loans receivable	117,510	86,596
Cash and cash equivalents	1,790,199	2,372,366
Trading account receivables from brokers and clearing organizations	361,586	524,727
Due from broker	0	2,585
Liabilities:
Due to broker	63,276	0
Trading account securities sold but not yet purchased	190	10,048
Senior notes and other debt	2,176,756	1,892,444
Subordinated debentures	$ 1,112,812	$ 1,202,842

Premiums and Reinsurance Rela_3

Premiums and Reinsurance Related Information (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Mar. 31, 2021	Dec. 31, 2020	Mar. 31, 2020	Dec. 31, 2019
Written premiums:
Written premiums, direct	$ 2,395,114	$ 1,892,359	$ 4,572,276	$ 3,856,848
Written premiums, assumed	266,122	239,887	573,672	506,769
Written premiums, ceded	(449,055)	(392,428)	(883,729)	(777,953)
Total net premiums written	2,212,181	1,739,818	4,262,219	3,585,664
Earned premiums:
Earned premiums, direct	2,151,739	1,804,844	4,154,784	3,634,558
Earned premiums, assumed	259,166	232,996	518,707	461,210
Earned premiums, ceded	(439,281)	(360,925)	(851,911)	(727,435)
Net premiums earned	1,971,624	1,676,915	3,821,580	3,368,333
Ceded losses and loss expenses incurred	255,163	232,873	553,903	468,055
Ceded commissions earned	106,834	85,593	208,515	166,638
Cumulative effect adjustment resulting from changes in accounting principles	$ 7,283	$ 7,175	$ 7,283	$ 7,175	$ 7,373	$ 7,801	$ 6,800	$ 690

Premiums and Reinsurance Rela_4

Premiums and Reinsurance Related Information - Premiums and Reinsurance, Allowance For Credit Loss (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Premium Receivable, Allowance for Credit Loss [Roll Forward]
Allowance for expected credit losses, beginning of period	$ 24,264	$ 21,524	$ 22,883	$ 19,823
Cumulative effect adjustment resulting from changes in accounting principles	24,808	22,106	24,808	22,106
Provision for expected credit losses	544	582	1,925	1,013
Allowance for expected credit losses, end of period	24,808	22,106	24,808	22,106
Reinsurance Recoverable, Allowance for Credit Loss [Roll Forward]
Allowance for expected credit losses, beginning of period	7,373	6,800	7,801	690
Cumulative effect adjustment resulting from changes in accounting principles	7,283	7,175	7,283	7,175
Reinsurance Recoverable, Credit Loss Expense (Reversal)	(90)	375	(518)	558
Allowance for expected credit losses, end of period	$ 7,283	$ 7,175	7,283	7,175
Cumulative effect adjustment resulting from changes in accounting principles
Premium Receivable, Allowance for Credit Loss [Roll Forward]
Allowance for expected credit losses, beginning of period			0	1,270
Cumulative effect adjustment resulting from changes in accounting principles
Reinsurance Recoverable, Allowance for Credit Loss [Roll Forward]
Allowance for expected credit losses, beginning of period			$ 0	$ 5,927
Cumulative effect adjustment resulting from changes in accounting principles

Restricted Stock Units (Summary

Restricted Stock Units (Summary of Restricted Stock Units Issued) (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
Share-Based Compensation Arrangement by Share-based Payment Award [Line Item]
Share based compensation expense	$ 23,000	$ 23,000
Restricted stock
Share-Based Compensation Arrangement by Share-based Payment Award [Line Item]
Restricted stock units (in units)	1,531	724
Fair Value	$ 75	$ 57
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		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Leases [Abstract]
Lease cost	$ 11,429	$ 10,878	$ 22,693	$ 22,114
Cash paid for amounts included in the measurement of lease liabilities reported in operating cash flows	11,920	11,479	23,297	22,309
Right-of-use assets (reduced) obtained in exchange for new lease liabilities	$ (181)	$ 2,682	$ (151)	$ 4,294

Leases (Supplemental Balance Sh

Leases (Supplemental Balance Sheet Information) (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Jun. 30, 2020
Leases [Abstract]
Operating lease, right-of-use asset	$ 148,455	$ 180,011
Operating lease, liability	$ 185,738	$ 219,444
Weighted-average remaining lease term	6 years 8 months 12 days	6 years 9 months 18 days
Weighted-average discount rate	5.95%	5.94%

Leases (Maturities of Operating

Leases (Maturities of Operating Lease Liabilities) (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Jun. 30, 2020
Leases [Abstract]
2021	$ 22,960
2022	42,677
2023	39,081
2024	32,467
2025	23,227
Thereafter	59,736
Total undiscounted future minimum lease payments	220,148
Less: Discount impact	(34,410)
Total lease liability	$ 185,738	$ 219,444

Business Segments (Financial In

Business Segments (Financial Information of Company Operating Segments) (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021USD ($)	Jun. 30, 2020USD ($)	Jun. 30, 2021USD ($)segment	Jun. 30, 2020USD ($)
Segment Reporting [Abstract]
Number of reportable segments | segment			2
Segment Reporting Information [Line Items]
Earned Premiums (1)	$ 1,971,624	$ 1,676,915	$ 3,821,580	$ 3,368,333
Investment Income	168,187	85,431	326,764	260,194
Other	156,276	173,680	304,611	118,108
Total revenues	2,296,086	1,936,026	4,452,955	3,746,635
Pre-Tax Income (Loss)	299,940	105,449	596,008	98,982
Net Income (Loss) to Common Stockholders	237,238	71,260	466,763	66,842
Net investment gains	24,064	77,885	58,903	(99,289)
Net investment gains, net of tax	18,800	59,787	47,752	(76,813)
Corporate, other and eliminations
Segment Reporting Information [Line Items]
Earned Premiums (1)	0	0	0	0
Investment Income	4,605	17,865	20,236	31,459
Other	124,000	87,777	229,218	200,907
Total revenues	128,604	105,642	249,454	232,366
Pre-Tax Income (Loss)	(90,208)	(61,548)	(154,737)	(103,302)
Net Income (Loss) to Common Stockholders	(71,209)	(47,823)	(123,817)	(81,689)
Insurance
Segment Reporting Information [Line Items]
Earned Premiums (1)		1,465,044		2,949,999
Insurance | Operating Segments
Segment Reporting Information [Line Items]
Earned Premiums (1)	1,727,202	1,465,044	3,332,181	2,949,999
Investment Income	116,703	44,105	221,941	167,564
Other	8,212	8,018	16,490	16,490
Total revenues	1,852,117	1,517,167	3,570,612	3,134,053
Pre-Tax Income (Loss)	291,290	76,546	548,399	252,493
Net Income (Loss) to Common Stockholders	230,313	48,607	429,022	185,467
Reinsurance & Monoline Excess
Segment Reporting Information [Line Items]
Earned Premiums (1)		211,871		418,334
Reinsurance & Monoline Excess | Operating Segments
Segment Reporting Information [Line Items]
Earned Premiums (1)	244,422	211,871	489,399	418,334
Investment Income	46,879	23,461	84,587	61,171
Other	0	0	0	0
Total revenues	291,301	235,332	573,986	479,505
Pre-Tax Income (Loss)	74,794	12,566	143,443	49,080
Net Income (Loss) to Common Stockholders	59,334	10,689	113,806	39,877
Re-insurance - International | Operating Segments
Segment Reporting Information [Line Items]
Total revenues	90,000	65,000	178,000	134,000
Net investment gains
Segment Reporting Information [Line Items]
Earned Premiums (1)	0	0	0	0
Investment Income	0	0	0	0
Insurance-International Segment | Operating Segments
Segment Reporting Information [Line Items]
Total revenues	$ 221,000	$ 149,000	$ 418,000	$ 317,000

Business Segments (Identifiable

Business Segments (Identifiable Assets by Segment) (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Segment Reporting, Asset Reconciling Item [Line Items]
Consolidated Assets	$ 30,297,917	$ 28,571,965
Operating Segments | Insurance
Segment Reporting, Asset Reconciling Item [Line Items]
Consolidated Assets	22,771,988	21,702,328
Operating Segments | Reinsurance & Monoline Excess
Segment Reporting, Asset Reconciling Item [Line Items]
Consolidated Assets	4,670,226	4,654,158
Corporate, other and eliminations
Segment Reporting, Asset Reconciling Item [Line Items]
Consolidated Assets	$ 2,855,703	$ 2,215,479

Business Segments (Net Premiums

Business Segments (Net Premiums Earned By Major Line of Business) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Revenue from External Customer [Line Items]
Net premiums earned	$ 1,971,624	$ 1,676,915	$ 3,821,580	$ 3,368,333
Insurance
Revenue from External Customer [Line Items]
Net premiums earned		1,465,044		2,949,999
Insurance | Operating Segments
Revenue from External Customer [Line Items]
Net premiums earned	1,727,202	1,465,044	3,332,181	2,949,999
Insurance | Other liability
Revenue from External Customer [Line Items]
Net premiums earned	638,404	544,465	1,240,306	1,091,594
Insurance | Short-tail lines
Revenue from External Customer [Line Items]
Net premiums earned	339,890	295,968	664,630	591,446
Insurance | Workers' compensation
Revenue from External Customer [Line Items]
Net premiums earned	291,471	278,699	558,920	580,299
Insurance | Commercial automobile
Revenue from External Customer [Line Items]
Net premiums earned	237,444	190,335	458,205	379,978
Insurance | Professional liability
Revenue from External Customer [Line Items]
Net premiums earned	219,993	155,577	410,120	306,682
Reinsurance & Monoline Excess
Revenue from External Customer [Line Items]
Net premiums earned		211,871		418,334
Reinsurance & Monoline Excess | Operating Segments
Revenue from External Customer [Line Items]
Net premiums earned	244,422	211,871	489,399	418,334
Reinsurance & Monoline Excess | Casualty reinsurance
Revenue from External Customer [Line Items]
Net premiums earned	152,531	130,459	302,169	253,190
Reinsurance & Monoline Excess | Monoline excess
Revenue from External Customer [Line Items]
Net premiums earned	48,247	41,062	94,120	83,224
Reinsurance & Monoline Excess | Monoline excess (2)
Revenue from External Customer [Line Items]
Net premiums earned	$ 43,644	$ 40,350	$ 93,110	$ 81,920