W. R. Berkley (WRB) 10-Q 4 Nov 24 2024 Q3 Quarterly report Financial data

Cover Page

Cover Page - shares	9 Months Ended
	Sep. 30, 2024	Oct. 28, 2024
Entity Information [Line Items]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2024
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		381,069,120
Entity Central Index Key	0000011544
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2024
Document Fiscal Period Focus	Q3
Amendment Flag	false
5.700% Subordinated Debentures due 2058
Entity Information [Line Items]
Title of 12(b) Security	5.700% Subordinated Debentures due 2058
Trading Symbol	WRB-PE
Security Exchange Name	NYSE
5.100% Subordinated Debentures due 2059
Entity Information [Line Items]
Title of 12(b) Security	5.100% Subordinated Debentures due 2059
Trading Symbol	WRB-PF
Security Exchange Name	NYSE
4.250% Subordinated Debentures due 2060
Entity Information [Line Items]
Title of 12(b) Security	4.250% 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	Sep. 30, 2024	Dec. 31, 2023
Investments:
Debt Securities, Available-for-Sale and Held-to-Maturity, after Allowance for Credit Loss	$ 22,663,878	$ 20,178,308
Investment funds	1,607,381	1,621,655
Real estate	1,297,314	1,249,874
Equity securities	1,048,126	1,090,347
Arbitrage trading account	820,928	938,049
Loans receivable (net of allowance for expected credit losses of $1,425 and $3,004 at September 30, 2024 and December 31, 2023, respectively)	389,869	201,271
Total investments	27,827,496	25,279,504
Cash and cash equivalents	1,573,238	1,363,195
Premiums and fees receivable (net of allowance for expected credit losses of $38,071 and $35,110 at September 30, 2024 and December 31, 2023, respectively)	3,414,385	3,109,334
Due from reinsurers (net of allowance for expected credit losses of $8,332 and $8,404 at September 30, 2024 and December 31, 2023, respectively)	3,478,354	3,534,527
Deferred policy acquisition costs	957,997	861,609
Prepaid reinsurance premiums	830,797	758,927
Trading account receivables from brokers and clearing organizations	410,756	303,614
Property, furniture and equipment	478,361	426,803
Goodwill	184,089	174,597
Accrued investment income	234,084	213,408
Current and deferred federal and foreign income taxes	131,209	220,756
Other assets	838,532	865,556
Total assets	40,359,298	37,111,830
Liabilities:
Reserves for losses and loss expenses	20,155,310	18,739,652
Unearned premiums	6,489,597	5,922,326
Due to reinsurers	727,074	631,164
Trading account securities sold but not yet purchased	36,093	9,357
Other liabilities	1,674,405	1,503,053
Senior notes and other debt	1,827,788	1,827,951
Subordinated debentures	1,009,629	1,009,090
Total liabilities	31,919,896	29,642,593
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	158,705	158,705
Additional paid-in capital	973,032	964,789
Retained earnings	11,909,408	11,040,908
Accumulated other comprehensive loss	(603,144)	(925,838)
Treasury stock, at cost, 412,331,903 and 408,704,807 shares, respectively	(4,011,737)	(3,783,133)
Total stockholders’ equity	8,426,264	7,455,431
Noncontrolling interests	13,138	13,806
Total equity	8,439,402	7,469,237
Total liabilities and equity	$ 40,359,298	$ 37,111,830

Consolidated Balance Sheets C_2

Consolidated Balance Sheets Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Statement of Financial Position [Abstract]
Fixed maturity securities, amortized cost	$ 23,003,148	$ 20,915,245
Fixed maturity securities, allowance for credit loss	6,983	36,751
Cumulative effect adjustment resulting from changes in accounting principles	1,425	3,004
Cumulative effect adjustment resulting from changes in accounting principles	38,071	35,110
Reinsurance recoverable, allowance for credit loss	$ 8,332	$ 8,404
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)		1,250,000,000
Common shares issued (in shares)	381,189,906	384,817,136
Common shares outstanding (in shares)	381,189,906	384,817,136
Treasury stock issued at cost (in shares)	412,331,903	408,704,807

Consolidated Statements Income

Consolidated Statements Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
REVENUES:
Net premiums written	$ 3,057,276	$ 2,848,459	$ 9,035,346	$ 8,234,799
Change in net unearned premiums	(130,453)	(206,545)	(497,761)	(548,726)
Net premiums earned	2,926,823	2,641,914	8,537,585	7,686,073
Net investment income	323,756	270,944	1,015,723	739,494
Net realized and unrealized (losses) gains on investments	(23,362)	(40,855)	(72,165)	50,403
Change in allowance for expected credit losses on investments	15,276	(1,571)	31,347	(11,164)
Net investment (losses) gains	(8,086)	(42,426)	(40,818)	39,239
Revenues from non-insurance businesses	128,610	137,116	375,307	375,225
Insurance service fees	28,666	22,962	81,583	81,290
Other income	610	128	1,804	235
Total revenues	3,400,379	3,030,638	9,971,184	8,921,556
OPERATING COSTS AND EXPENSES:
Losses and loss expenses	1,825,960	1,636,193	5,270,334	4,744,602
Other operating costs and expenses	943,365	808,669	2,704,890	2,457,925
Expenses from non-insurance businesses	124,885	133,939	364,612	370,244
Interest expense	31,720	31,888	95,156	95,580
Total operating costs and expenses	2,925,930	2,610,689	8,434,992	7,668,351
Income before income taxes	474,449	419,949	1,536,192	1,253,205
Income tax expense	(109,135)	(86,519)	(356,958)	(268,322)
Net income before noncontrolling interests	365,314	333,430	1,179,234	984,883
Noncontrolling interests	320	156	780	(863)
Net income to common stockholders	$ 365,634	$ 333,586	$ 1,180,014	$ 984,020
NET INCOME PER SHARE:
Basic (in dollar per share)	$ 0.92	$ 0.83	$ 2.95	$ 2.41
Diluted (in dollar per share)	$ 0.91	$ 0.82	$ 2.92	$ 2.39

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Statement of Comprehensive Income [Abstract]
Net income before noncontrolling interests	$ 365,314	$ 333,430	$ 1,179,234	$ 984,883
Other comprehensive income (loss):
Change in unrealized currency translation adjustments	49,503	(22,781)	25,160	(7,387)
Change in unrealized investment gains (losses), net of taxes	380,993	(118,365)	297,533	(50,850)
Other comprehensive income (loss)	430,496	(141,146)	322,693	(58,237)
Comprehensive income	795,810	192,284	1,501,927	926,646
Noncontrolling interests	320	156	779	(862)
Comprehensive income to common stockholders	$ 796,130	$ 192,440	$ 1,502,706	$ 925,784

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 (Losses) Gains	Currency Translation Adjustments	Treasury stock	Noncontrolling interest
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect adjustment resulting from changes in accounting principles		$ 158,705	$ 944,632	$ 10,161,005	$ (1,264,581)	$ (892,905)	$ (371,676)	$ (3,251,429)	$ 19,829
Beginning of period at Dec. 31, 2022		158,705	944,632	10,161,005	(1,264,581)	(892,905)	(371,676)	(3,251,429)	19,829
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Restricted stock units issued			(25,228)
Restricted stock units expensed			35,995
Net income before noncontrolling interests	$ 984,883			984,020					863
Dividends ($0.33, $0.41, $0.81 and $0.88 per share, respectively)				(344,328)
Change in unrealized gains (losses) on securities without an allowance for expected credit losses	(50,850)					(47,757)
Change in unrealized gains (losses) on securities with an allowance for expected credit losses						(3,094)
Net change in period	(7,387)						(7,387)
Stock exercised/vested								9,461
Stock repurchased								(430,536)
Other	(3,899)
Contributions (distribution)									(6,361)
Other comprehensive income (loss), net of tax	$ (58,237)				(58,237)	(50,850)	(7,387)		(1)
End of period at Sep. 30, 2023			955,399	10,800,697	(1,322,819)	(943,756)	(379,063)	(3,676,403)	14,330
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock dividends, per share, cash paid (in dollars per share)	$ 0.88
Cumulative effect adjustment resulting from changes in accounting principles		158,705	967,916	10,624,518	(1,181,673)	(825,391)	(356,282)	(3,682,281)	21,167
Beginning of period at Jun. 30, 2023		158,705	967,916	10,624,518	(1,181,673)	(825,391)	(356,282)	(3,682,281)	21,167
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Restricted stock units issued			(25,226)
Restricted stock units expensed			12,709
Net income before noncontrolling interests	$ 333,430			333,586					(156)
Dividends ($0.33, $0.41, $0.81 and $0.88 per share, respectively)				(157,407)
Change in unrealized gains (losses) on securities without an allowance for expected credit losses	(118,365)					(108,121)
Change in unrealized gains (losses) on securities with an allowance for expected credit losses						(10,244)
Net change in period	(22,781)						(22,781)
Stock exercised/vested								8,469
Stock repurchased								(2,917)
Other	326
Contributions (distribution)									(6,681)
Other comprehensive income (loss), net of tax	$ (141,146)				(141,146)	(118,365)	(22,781)		0
End of period at Sep. 30, 2023			955,399	10,800,697	(1,322,819)	(943,756)	(379,063)	(3,676,403)	14,330
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock dividends, per share, cash paid (in dollars per share)	$ 0.41
Cumulative effect adjustment resulting from changes in accounting principles			955,399	10,800,697	(1,322,819)	(943,756)	(379,063)	(3,676,403)	14,330
Cumulative effect adjustment resulting from changes in accounting principles	$ 7,469,237	158,705	964,789	11,040,908	(925,838)	(586,354)	(339,484)	(3,783,133)	13,806
Beginning of period at Dec. 31, 2023	7,469,237	158,705	964,789	11,040,908	(925,838)	(586,354)	(339,484)	(3,783,133)	13,806
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Restricted stock units issued			(30,075)
Restricted stock units expensed			38,318
Net income before noncontrolling interests	1,179,234			1,180,014					(780)
Dividends ($0.33, $0.41, $0.81 and $0.88 per share, respectively)				(311,514)
Change in unrealized gains (losses) on securities without an allowance for expected credit losses	297,533					293,064
Change in unrealized gains (losses) on securities with an allowance for expected credit losses						4,470
Net change in period	25,160						25,160
Stock exercised/vested								9,488
Stock repurchased								(236,243)
Other	(1,849)
Contributions (distribution)									111
Other comprehensive income (loss), net of tax	322,693				322,693	297,533	25,160		1
End of period at Sep. 30, 2024	$ 8,439,402		973,032	11,909,408	(603,144)	(288,820)	(314,324)	(4,011,737)	13,138
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock dividends, per share, cash paid (in dollars per share)	$ 0.81
Cumulative effect adjustment resulting from changes in accounting principles		158,705	986,892	11,669,567	(1,033,640)	(669,813)	(363,827)	(4,007,742)	13,269
Beginning of period at Jun. 30, 2024		$ 158,705	986,892	11,669,567	(1,033,640)	(669,813)	(363,827)	(4,007,742)	13,269
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Restricted stock units issued			(26,930)
Restricted stock units expensed			13,070
Net income before noncontrolling interests	$ 365,314			365,634					(320)
Dividends ($0.33, $0.41, $0.81 and $0.88 per share, respectively)				(125,793)
Change in unrealized gains (losses) on securities without an allowance for expected credit losses	380,993					369,827
Change in unrealized gains (losses) on securities with an allowance for expected credit losses						11,166
Net change in period	49,503						49,503
Stock exercised/vested								8,164
Stock repurchased								(12,480)
Other	321
Contributions (distribution)									189
Other comprehensive income (loss), net of tax	430,496				430,496	380,993	49,503		0
End of period at Sep. 30, 2024	$ 8,439,402		973,032	11,909,408	(603,144)	(288,820)	(314,324)	(4,011,737)	13,138
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock dividends, per share, cash paid (in dollars per share)	$ 0.33
Cumulative effect adjustment resulting from changes in accounting principles	$ 8,439,402		$ 973,032	$ 11,909,408	$ (603,144)	$ (288,820)	$ (314,324)	$ (4,011,737)	$ 13,138

Consolidated Statements of Cash

Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023
CASH FROM OPERATING ACTIVITIES:
Net income to common stockholders	$ 1,180,014	$ 984,020
Adjustments to reconcile net income to net cash from operating activities:
Net investment losses (gains)	40,818	(39,239)
Depreciation and (accretion) amortization	(156,993)	3,294
Noncontrolling interests	(780)	863
Investment funds	(868)	(5,444)
Stock incentive plans	40,319	37,796
Change in:
Arbitrage trading account	36,714	(41,399)
Premiums and fees receivable	(311,827)	(340,056)
Reinsurance accounts	85,226	(194,610)
Deferred policy acquisition costs	(94,393)	(93,270)
Income taxes	16,825	49,722
Reserves for losses and loss expenses	1,402,623	1,288,975
Unearned premiums	569,416	608,300
Other	61,241	(27,790)
Net cash from operating activities	2,868,335	2,231,162
CASH USED IN INVESTING ACTIVITIES:
Proceeds from sale of fixed maturity securities	1,688,623	877,019
Proceeds from sale of equity securities	288,366	161,470
Distributions from investment funds	15,533	8,385
Proceeds from maturities and prepayments of fixed maturity securities	3,483,326	2,654,140
Purchase of fixed maturity securities	(7,177,379)	(5,091,866)
Purchase of equity securities	(186,382)	(63,815)
Real estate purchased	(66,813)	(15,158)
Change in loans receivable	(173,548)	12,796
Net purchases of property, furniture and equipment	(91,670)	(42,127)
Change in balances due to security brokers	122,519	8,224
Cash received in connection with business disposition	0	94,076
Other	0	320
Net cash used in investing activities	(2,097,425)	(1,396,536)
CASH USED IN FINANCING ACTIVITIES:
Repayment of senior notes and other debt	(240)	(1,954)
Net proceeds from issuance of debt	0	1,100
Cash dividends to common stockholders	(311,514)	(186,921)
Purchase of common treasury shares	(236,243)	(430,536)
Other, net	(13,944)	(20,545)
Net cash used in financing activities	(561,941)	(638,856)
Net impact on cash due to change in foreign exchange rates	1,074	959
Net change in cash and cash equivalents	210,043	196,728
Cash and cash equivalents at beginning of period	1,363,195	1,449,346
Cash and cash equivalents at end of period	$ 1,573,238	$ 1,646,074

General

General	9 Months Ended
	Sep. 30, 2024
Organization, Consolidation and Presentation of Financial Statements [Abstract]
General	General The unaudited consolidated financial statements, which include the accounts of W. R. Berkley Corporation and its subsidiaries (the “Company”), have been prepared on the basis of U.S. generally accepted accounting principles (“GAAP”) for interim financial information. Accordingly, they do not include all the information and notes required by GAAP for annual financial statements. The unaudited consolidated financial statements reflect all adjustments, consisting only of normal recurring items, which are necessary to present fairly the Company’s financial position and results of operations on a basis consistent with the prior audited consolidated financial statements. Operating results for interim periods are not necessarily indicative of the results that may be expected for the year. All significant intercompany accounts and transactions have been eliminated. The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosures of contingent assets and liabilities at the date of the financial statements and the revenues and expenses reflected during the reporting period. For further information related to areas of judgment and estimates and other information necessary to understand the Company’s financial position and results of operations, refer to the audited consolidated financial statements and notes included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2023. Reclassifications have been made in the 2023 financial statements as originally reported to conform to the presentation of the 2024 financial statements. The Company reclassified a program management business from the Insurance segment to the Reinsurance & Monoline Excess segment. The reclassified business is a program management business offering support on a nationwide basis for commercial casualty and property program administrators. In addition, share and per share amounts have been adjusted to reflect the 3-for-2 common stock split effected on July 10, 2024.

Per Share Data

Per Share Data	9 Months Ended
	Sep. 30, 2024
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 17,495,175 and 17,125,284 common shares held in a grantor trust as of September 30, 2024 and 2023, 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 Nine Months (In thousands) 2024 2023 2024 2023 Basic 398,338 403,787 400,302 407,484 Diluted 401,817 407,158 404,053 411,219

Recent Accounting Pronouncement

Recent Accounting Pronouncements and Accounting Policies	9 Months Ended
	Sep. 30, 2024
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 became effective in 2024 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 (Loss) Income	9 Months Ended
	Sep. 30, 2024
Equity [Abstract]
Consolidated Statements of Comprehensive (Loss) Income	Consolidated Statements of Comprehensive Income (Loss) The following table presents the components of the changes in accumulated other comprehensive income (loss) ("AOCI"): (In thousands) Unrealized Investment (Losses) Gains Currency Translation Adjustments Accumulated Other Comprehensive As of and for the nine months ended September 30, 2024 Changes in AOCI Beginning of period $ (586,354) $ (339,484) $ (925,838) Other comprehensive income before reclassifications 218,087 25,160 243,247 Amounts reclassified from AOCI 79,446 — 79,446 Other comprehensive income 297,533 25,160 322,693 Unrealized investment gain related to noncontrolling interest 1 — 1 End of period $ (288,820) $ (314,324) $ (603,144) Amounts reclassified from AOCI Pre-tax $ 100,565 (1) $ — $ 100,565 Tax effect (21,119) (2) — (21,119) After-tax amounts reclassified $ 79,446 $ — $ 79,446 Other comprehensive income Pre-tax $ 370,831 $ 25,160 $ 395,991 Tax effect (73,298) — (73,298) Other comprehensive income $ 297,533 $ 25,160 $ 322,693 As of and for the three months ended September 30, 2024 Changes in AOCI Beginning of period $ (669,813) $ (363,827) $ (1,033,640) Other comprehensive income before reclassifications 374,110 49,503 423,613 Amounts reclassified from AOCI 6,883 — 6,883 Other comprehensive income 380,993 49,503 430,496 Unrealized investment gain to noncontrolling interest — — — Ending balance $ (288,820) $ (314,324) $ (603,144) Amounts reclassified from AOCI Pre-tax $ 8,713 (1) $ — $ 8,713 Tax effect (1,830) (2) — (1,830) After-tax amounts reclassified $ 6,883 $ — $ 6,883 Other comprehensive income Pre-tax $ 480,768 $ 49,503 $ 530,271 Tax effect (99,775) — (99,775) Other comprehensive income $ 380,993 $ 49,503 $ 430,496 (In thousands) Unrealized Investment (Losses) Gains Currency Translation Adjustments Accumulated Other Comprehensive As of and for the nine months ended September 30, 2023 Changes in AOCI Beginning of period $ (892,905) $ (371,676) $ (1,264,581) Other comprehensive loss before reclassifications (103,087) (7,387) (110,474) Amounts reclassified from AOCI 52,237 — 52,237 Other comprehensive loss (50,850) (7,387) (58,237) Unrealized investment loss related to noncontrolling interest (1) — (1) End of period $ (943,756) $ (379,063) $ (1,322,819) Amounts reclassified from AOCI Pre-tax $ 66,123 (1) $ — $ 66,123 Tax effect (13,886) (2) — (13,886) After-tax amounts reclassified $ 52,237 $ — $ 52,237 Other comprehensive loss Pre-tax $ (62,476) $ (7,387) $ (69,863) Tax effect 11,626 — 11,626 Other comprehensive income $ (50,850) $ (7,387) $ (58,237) As of and for the three months ended September 30, 2023 Changes in AOCI Beginning of period $ (825,391) $ (356,282) $ (1,181,673) Other comprehensive loss before reclassifications (133,018) (22,781) (155,799) Amounts reclassified from AOCI 14,653 — 14,653 Other comprehensive loss (118,365) (22,781) (141,146) Unrealized investment loss related to noncontrolling interest — — — Ending balance $ (943,756) $ (379,063) $ (1,322,819) Amounts reclassified from AOCI Pre-tax $ 18,548 (1) $ — $ 18,548 Tax effect (3,895) (2) — (3,895) After-tax amounts reclassified $ 14,653 $ — $ 14,653 Other comprehensive loss Pre-tax $ (150,455) $ (22,781) $ (173,236) Tax effect 32,090 — 32,090 Other comprehensive loss $ (118,365) $ (22,781) $ (141,146) ____________ (1) Net investment (losses) gains in the consolidated statements of income. (2) Income tax expense in the consolidated statements of income.

Statements of Cash Flows

Statements of Cash Flows	9 Months Ended
	Sep. 30, 2024
Supplemental Cash Flow Elements [Abstract]
Statements of Cash Flows	Statements of Cash Flows    Interest payments were $116,462,000 and $79,336,000 for the nine months ended September 30, 2024 and 2023, respectively. Income taxes paid were $271,739,000 and $180,000,000 for the nine months ended September 30, 2024 and 2023, respectively.

Investments In Fixed Maturity S

Investments In Fixed Maturity Securities	9 Months Ended
	Sep. 30, 2024
Investments, Debt and Equity Securities [Abstract]
Investments In Fixed Maturity Securities	Investments in Fixed Maturity Securities At September 30, 2024 and December 31, 2023, investments in fixed maturity securities were as follows: (In thousands) Amortized Allowance for Expected Credit Losses (1) Gross Unrealized Fair Carrying Gains Losses September 30, 2024 Held to maturity: State and municipal $ 41,561 $ (30) $ 1,944 $ — $ 43,475 $ 41,531 Residential mortgage-backed 2,398 — 109 — 2,507 2,398 Total held to maturity 43,959 (30) 2,053 — 45,982 43,929 Available for sale: U.S. government and government agency 2,083,085 — 23,974 (36,074) 2,070,985 2,070,985 State and municipal: Special revenue 1,732,996 — 8,414 (51,652) 1,689,758 1,689,758 State general obligation 273,232 — 4,565 (7,375) 270,422 270,422 Pre-refunded 85,683 — 1,260 (90) 86,853 86,853 Corporate backed 168,276 — 1,847 (4,968) 165,155 165,155 Local general obligation 307,754 — 2,483 (6,123) 304,114 304,114 Total state and municipal 2,567,941 — 18,569 (70,208) 2,516,302 2,516,302 Mortgage-backed: Residential 2,736,493 — 31,527 (130,929) 2,637,091 2,637,091 Commercial 600,597 (52) 3,254 (2,918) 600,881 600,881 Total mortgage-backed 3,337,090 (52) 34,781 (133,847) 3,237,972 3,237,972 Asset-backed 4,118,052 (546) 26,592 (36,777) 4,107,321 4,107,321 Corporate: Industrial 3,980,058 — 55,042 (80,692) 3,954,408 3,954,408 Financial 3,326,838 — 54,929 (33,205) 3,348,562 3,348,562 Utilities 774,956 — 13,319 (13,877) 774,398 774,398 Other 774,274 — 4,715 (3,593) 775,396 775,396 Total corporate 8,856,126 — 128,005 (131,367) 8,852,764 8,852,764 Foreign government 1,996,895 (6,355) 23,701 (179,636) 1,834,605 1,834,605 Total available for sale 22,959,189 (6,953) 255,622 (587,909) 22,619,949 22,619,949 Total investments in fixed maturity securities $ 23,003,148 $ (6,983) $ 257,675 $ (587,909) $ 22,665,931 $ 22,663,878 ____________ (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, 2023 Held to maturity: State and municipal $ 50,547 $ (43) $ 3,132 $ — $ 53,636 $ 50,504 Residential mortgage-backed 2,868 — 107 — 2,975 2,868 Total held to maturity 53,415 (43) 3,239 — 56,611 53,372 Available for sale: U.S. government and government agency 1,762,997 — 11,403 (57,669) 1,716,731 1,716,731 State and municipal: Special revenue 1,682,550 — 5,651 (82,006) 1,606,195 1,606,195 State general obligation 394,429 — 3,550 (16,405) 381,574 381,574 Pre-refunded 103,029 — 1,634 (185) 104,478 104,478 Corporate backed 166,873 (757) 696 (11,973) 154,839 154,839 Local general obligation 396,041 — 3,188 (11,893) 387,336 387,336 Total state and municipal 2,742,922 (757) 14,719 (122,462) 2,634,422 2,634,422 Mortgage-backed: Residential 1,773,206 — 12,780 (163,844) 1,622,142 1,622,142 Commercial 657,157 (158) 626 (13,312) 644,313 644,313 Total mortgage-backed 2,430,363 (158) 13,406 (177,156) 2,266,455 2,266,455 Asset-backed 4,252,883 (1,164) 8,527 (73,206) 4,187,040 4,187,040 Corporate: Industrial 3,679,219 (40) 24,312 (143,936) 3,559,555 3,559,555 Financial 2,838,220 (4,986) 14,681 (68,681) 2,779,234 2,779,234 Utilities 701,865 — 6,471 (23,412) 684,924 684,924 Other 635,975 — 1,605 (7,234) 630,346 630,346 Total corporate 7,855,279 (5,026) 47,069 (243,263) 7,654,059 7,654,059 Foreign government 1,817,386 (29,603) 15,865 (137,419) 1,666,229 1,666,229 Total available for sale 20,861,830 (36,708) 110,989 (811,175) 20,124,936 20,124,936 Total investments in fixed maturity securities $ 20,915,245 $ (36,751) $ 114,228 $ (811,175) $ 20,181,547 $ 20,178,308 ____________ (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. The following table presents the rollforward of the allowance for expected credit losses for held to maturity securities for the nine months ended September 30, 2024 and 2023: (In thousands) 2024 2023 Allowance for expected credit losses, beginning of period $ 43 $ 114 Change in expected credit losses (13) (66) Allowance for expected credit losses, end of period $ 30 $ 48 The following table presents the rollforward of the allowance for expected credit losses for held to maturity securities for the three months ended September 30, 2024 and 2023: (In thousands) 2024 2023 Allowance for expected credit losses, beginning of period $ 34 $ 53 Change in expected credit losses (4) (5) Allowance for expected credit losses, end of period $ 30 $ 48 The following table presents the rollforward of the allowance for expected credit losses for available for sale securities for the nine months ended September 30, 2024 and 2023: 2024 2023 (In thousands) Foreign Government Corporate Mortgage-backed Asset-backed State and Municipal Total Foreign Government Corporate Mortgage-backed Asset-backed State and Municipal Total Balance, beginning of period $ 29,603 $ 5,026 $ 158 $ 1,164 $ 757 $ 36,708 $ 32,633 $ 4,701 $ 18 $ — $ — $ 37,352 Change on securities for which credit losses were not previously recorded 347 — 1,701 — — 2,048 — 942 1,766 1,444 821 4,973 Change on securities for which credit losses were previously recorded (23,216) (5,026) (1,246) (618) (757) (30,863) 3,538 134 316 58 — 4,046 Reduction due to disposals (379) — (561) — — (940) — (7) — — — (7) Balance, end of period $ 6,355 $ — $ 52 $ 546 $ — $ 6,953 $ 36,171 $ 5,770 $ 2,100 $ 1,502 $ 821 $ 46,364 During the nine months ended September 30, 2024, the Company decreased 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 improved pricing associated with foreign government securities and corporate securities. During the nine months ended September 30, 2023, the Company increased the allowance for expected credit losses for available for sale securities in part due to changes in economic assumptions utilized in its credit loss model, primarily affecting the financial services and real estate sectors, and an increase in unrealized loss related to the foreign government portfolio. The following table presents the rollforward of the allowance for expected credit losses for available for sale securities for the three months ended September 30, 2024 and 2023: 2024 2023 (In thousands) Foreign Government Corporate Mortgage-backed Asset-backed State and Municipal Total Foreign Government Corporate Mortgage-backed Asset-backed State and Municipal Total Balance, beginning of period $ 19,469 $ — $ 1,140 $ 889 $ 339 $ 21,837 $ 33,052 $ 8,867 $ 885 $ 1,444 $ — $ 44,248 Change on securities for which credit losses were not previously recorded 47 — — — — 47 — 756 905 — 821 2,482 Change on securities for which credit losses were previously recorded (12,782) — (1,088) (343) (339) (14,552) 3,119 (3,853) 310 58 — (366) Reduction due to disposals (379) — — — — (379) — — — — — — Balance, end of period $ 6,355 $ — $ 52 $ 546 $ — $ 6,953 $ 36,171 $ 5,770 $ 2,100 $ 1,502 $ 821 $ 46,364 During the three months ended September 30, 2024, the Company decreased 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 improved pricing associated with foreign government securities. The amortized cost and fair value of fixed maturity securities at September 30, 2024, 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 $ 1,910,941 $ 1,886,626 Due after one year through five years 9,907,127 9,724,883 Due after five years through ten years 4,282,838 4,283,690 Due after ten years 3,562,724 3,530,253 Mortgage-backed securities 3,339,488 3,240,479 Total $ 23,003,118 $ 22,665,931 _______________ (1) Amortized cost is reduced by the allowance for expected credit losses of $30 thousand related to held to maturity securities.

Investments in Equity Securitie

Investments in Equity Securities	9 Months Ended
	Sep. 30, 2024
Debt Securities, Available-for-sale [Line Items]
Investments in Equity Securities	Investments in Fixed Maturity Securities At September 30, 2024 and December 31, 2023, investments in fixed maturity securities were as follows: (In thousands) Amortized Allowance for Expected Credit Losses (1) Gross Unrealized Fair Carrying Gains Losses September 30, 2024 Held to maturity: State and municipal $ 41,561 $ (30) $ 1,944 $ — $ 43,475 $ 41,531 Residential mortgage-backed 2,398 — 109 — 2,507 2,398 Total held to maturity 43,959 (30) 2,053 — 45,982 43,929 Available for sale: U.S. government and government agency 2,083,085 — 23,974 (36,074) 2,070,985 2,070,985 State and municipal: Special revenue 1,732,996 — 8,414 (51,652) 1,689,758 1,689,758 State general obligation 273,232 — 4,565 (7,375) 270,422 270,422 Pre-refunded 85,683 — 1,260 (90) 86,853 86,853 Corporate backed 168,276 — 1,847 (4,968) 165,155 165,155 Local general obligation 307,754 — 2,483 (6,123) 304,114 304,114 Total state and municipal 2,567,941 — 18,569 (70,208) 2,516,302 2,516,302 Mortgage-backed: Residential 2,736,493 — 31,527 (130,929) 2,637,091 2,637,091 Commercial 600,597 (52) 3,254 (2,918) 600,881 600,881 Total mortgage-backed 3,337,090 (52) 34,781 (133,847) 3,237,972 3,237,972 Asset-backed 4,118,052 (546) 26,592 (36,777) 4,107,321 4,107,321 Corporate: Industrial 3,980,058 — 55,042 (80,692) 3,954,408 3,954,408 Financial 3,326,838 — 54,929 (33,205) 3,348,562 3,348,562 Utilities 774,956 — 13,319 (13,877) 774,398 774,398 Other 774,274 — 4,715 (3,593) 775,396 775,396 Total corporate 8,856,126 — 128,005 (131,367) 8,852,764 8,852,764 Foreign government 1,996,895 (6,355) 23,701 (179,636) 1,834,605 1,834,605 Total available for sale 22,959,189 (6,953) 255,622 (587,909) 22,619,949 22,619,949 Total investments in fixed maturity securities $ 23,003,148 $ (6,983) $ 257,675 $ (587,909) $ 22,665,931 $ 22,663,878 ____________ (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, 2023 Held to maturity: State and municipal $ 50,547 $ (43) $ 3,132 $ — $ 53,636 $ 50,504 Residential mortgage-backed 2,868 — 107 — 2,975 2,868 Total held to maturity 53,415 (43) 3,239 — 56,611 53,372 Available for sale: U.S. government and government agency 1,762,997 — 11,403 (57,669) 1,716,731 1,716,731 State and municipal: Special revenue 1,682,550 — 5,651 (82,006) 1,606,195 1,606,195 State general obligation 394,429 — 3,550 (16,405) 381,574 381,574 Pre-refunded 103,029 — 1,634 (185) 104,478 104,478 Corporate backed 166,873 (757) 696 (11,973) 154,839 154,839 Local general obligation 396,041 — 3,188 (11,893) 387,336 387,336 Total state and municipal 2,742,922 (757) 14,719 (122,462) 2,634,422 2,634,422 Mortgage-backed: Residential 1,773,206 — 12,780 (163,844) 1,622,142 1,622,142 Commercial 657,157 (158) 626 (13,312) 644,313 644,313 Total mortgage-backed 2,430,363 (158) 13,406 (177,156) 2,266,455 2,266,455 Asset-backed 4,252,883 (1,164) 8,527 (73,206) 4,187,040 4,187,040 Corporate: Industrial 3,679,219 (40) 24,312 (143,936) 3,559,555 3,559,555 Financial 2,838,220 (4,986) 14,681 (68,681) 2,779,234 2,779,234 Utilities 701,865 — 6,471 (23,412) 684,924 684,924 Other 635,975 — 1,605 (7,234) 630,346 630,346 Total corporate 7,855,279 (5,026) 47,069 (243,263) 7,654,059 7,654,059 Foreign government 1,817,386 (29,603) 15,865 (137,419) 1,666,229 1,666,229 Total available for sale 20,861,830 (36,708) 110,989 (811,175) 20,124,936 20,124,936 Total investments in fixed maturity securities $ 20,915,245 $ (36,751) $ 114,228 $ (811,175) $ 20,181,547 $ 20,178,308 ____________ (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. The following table presents the rollforward of the allowance for expected credit losses for held to maturity securities for the nine months ended September 30, 2024 and 2023: (In thousands) 2024 2023 Allowance for expected credit losses, beginning of period $ 43 $ 114 Change in expected credit losses (13) (66) Allowance for expected credit losses, end of period $ 30 $ 48 The following table presents the rollforward of the allowance for expected credit losses for held to maturity securities for the three months ended September 30, 2024 and 2023: (In thousands) 2024 2023 Allowance for expected credit losses, beginning of period $ 34 $ 53 Change in expected credit losses (4) (5) Allowance for expected credit losses, end of period $ 30 $ 48 The following table presents the rollforward of the allowance for expected credit losses for available for sale securities for the nine months ended September 30, 2024 and 2023: 2024 2023 (In thousands) Foreign Government Corporate Mortgage-backed Asset-backed State and Municipal Total Foreign Government Corporate Mortgage-backed Asset-backed State and Municipal Total Balance, beginning of period $ 29,603 $ 5,026 $ 158 $ 1,164 $ 757 $ 36,708 $ 32,633 $ 4,701 $ 18 $ — $ — $ 37,352 Change on securities for which credit losses were not previously recorded 347 — 1,701 — — 2,048 — 942 1,766 1,444 821 4,973 Change on securities for which credit losses were previously recorded (23,216) (5,026) (1,246) (618) (757) (30,863) 3,538 134 316 58 — 4,046 Reduction due to disposals (379) — (561) — — (940) — (7) — — — (7) Balance, end of period $ 6,355 $ — $ 52 $ 546 $ — $ 6,953 $ 36,171 $ 5,770 $ 2,100 $ 1,502 $ 821 $ 46,364 During the nine months ended September 30, 2024, the Company decreased 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 improved pricing associated with foreign government securities and corporate securities. During the nine months ended September 30, 2023, the Company increased the allowance for expected credit losses for available for sale securities in part due to changes in economic assumptions utilized in its credit loss model, primarily affecting the financial services and real estate sectors, and an increase in unrealized loss related to the foreign government portfolio. The following table presents the rollforward of the allowance for expected credit losses for available for sale securities for the three months ended September 30, 2024 and 2023: 2024 2023 (In thousands) Foreign Government Corporate Mortgage-backed Asset-backed State and Municipal Total Foreign Government Corporate Mortgage-backed Asset-backed State and Municipal Total Balance, beginning of period $ 19,469 $ — $ 1,140 $ 889 $ 339 $ 21,837 $ 33,052 $ 8,867 $ 885 $ 1,444 $ — $ 44,248 Change on securities for which credit losses were not previously recorded 47 — — — — 47 — 756 905 — 821 2,482 Change on securities for which credit losses were previously recorded (12,782) — (1,088) (343) (339) (14,552) 3,119 (3,853) 310 58 — (366) Reduction due to disposals (379) — — — — (379) — — — — — — Balance, end of period $ 6,355 $ — $ 52 $ 546 $ — $ 6,953 $ 36,171 $ 5,770 $ 2,100 $ 1,502 $ 821 $ 46,364 During the three months ended September 30, 2024, the Company decreased 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 improved pricing associated with foreign government securities. The amortized cost and fair value of fixed maturity securities at September 30, 2024, 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 $ 1,910,941 $ 1,886,626 Due after one year through five years 9,907,127 9,724,883 Due after five years through ten years 4,282,838 4,283,690 Due after ten years 3,562,724 3,530,253 Mortgage-backed securities 3,339,488 3,240,479 Total $ 23,003,118 $ 22,665,931 _______________ (1) Amortized cost is reduced by the allowance for expected credit losses of $30 thousand related to held to maturity securities.
Equity securities
Debt Securities, Available-for-sale [Line Items]
Investments in Equity Securities	Investments in Equity Securities At September 30, 2024 and December 31, 2023, investments in equity securities were as follows: (In thousands) Cost Gross Unrealized Fair Carrying Gains Losses September 30, 2024 Common stocks $ 604,288 $ 157,761 $ (60,382) $ 701,667 $ 701,667 Preferred stocks 345,265 10,921 (9,727) 346,459 346,459 Total $ 949,553 $ 168,682 $ (70,109) $ 1,048,126 $ 1,048,126 December 31, 2023 Common stocks $ 664,997 $ 191,806 $ (18,749) $ 838,054 $ 838,054 Preferred stocks 284,335 3,075 (35,117) 252,293 252,293 Total $ 949,332 $ 194,881 $ (53,866) $ 1,090,347 $ 1,090,347

Arbitrage Trading Account

Arbitrage Trading Account	9 Months Ended
	Sep. 30, 2024
Debt Securities, Trading, and Equity Securities, FV-NI [Abstract]
Arbitrage Trading Account	Arbitrage Trading Account At September 30, 2024 and December 31, 2023, the fair and carrying values of the arbitrage trading account were $821 million and $938 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 September 30, 2024, the fair value of long option contracts outstanding was $6 million (notional amount of $340 million) and the fair value of short option contracts was $36 million (notional amount of $340 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	9 Months Ended
	Sep. 30, 2024
Net Investment Income [Abstract]
Net Investment Income	Net Investment Income Net investment income consisted of the following: For the Three Months For the Nine Months (In thousands) 2024 2023 2024 2023 Investment income (loss) earned on: Fixed maturity securities, including cash and cash equivalents and loans receivable $ 295,272 $ 239,727 $ 954,655 $ 653,200 Arbitrage trading account (1) 17,869 17,876 52,562 53,168 Equity securities 12,203 12,714 35,924 41,714 Investment funds 4,741 4,450 868 5,444 Real estate (3,711) (1,986) (20,579) (7,821) Gross investment income 326,374 272,781 1,023,430 745,705 Investment expense (2,618) (1,837) (7,707) (6,211) Net investment income $ 323,756 $ 270,944 $ 1,015,723 $ 739,494

Investment Funds

Investment Funds	9 Months Ended
	Sep. 30, 2024
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 $248 million as of September 30, 2024. Investment funds consisted of the following: Carrying Value as of Income (Loss) from September 30, December 31, For the Nine Months (In thousands) 2024 2023 2024 2023 Financial services $ 460,264 $ 433,407 $ (16,908) $ (15,606) Transportation 300,937 344,278 962 37,894 Real Estate 190,318 201,625 11,471 (5,062) Infrastructure 146,936 130,589 12,730 7,813 Energy 131,113 114,794 9,473 3,921 Other funds 377,813 396,962 (16,860) (23,516) Total $ 1,607,381 $ 1,621,655 $ 868 $ 5,444 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 minority investment in Lifson Re, a Bermuda reinsurance company. Effective January 1, 2021, Lifson Re participated on a fully collateralized basis in a majority of the Company’s reinsurance placements for a 22.5% share of placed amounts. The percentage increased from 22.5% to 30.0% effective July 1, 2022. This pertains to all traditional reinsurance/retrocessional placements for both property and casualty business where there is more than one open market reinsurer participating. For the nine months ended September 30, 2024 and 2023, the Company ceded approximately $315 million and $348 million, respectively, of written premiums to Lifson Re. Other funds include deferred compensation trust assets of $38 million and $36 million as of September 30, 2024 and December 31, 2023, respectively. These assets support other liabilities reflected in the balance sheet of an equal amount for employees who have elected to defer a portion of their compensation. The change in the net asset value of the trust is recorded in other funds within net investment income with an offsetting equal amount within corporate expenses.

Real Estate

Real Estate	9 Months Ended
	Sep. 30, 2024
Real Estate [Abstract]
Real Estate	Real Estate Investment in real estate represents directly owned property held for investment, as follows: Carrying Value September 30, December 31, (In thousands) 2024 2023 Properties in operation $ 1,069,589 $ 1,022,654 Properties under development 227,725 227,220 Total $ 1,297,314 $ 1,249,874 As of September 30, 2024, properties in operation included a long-term ground lease in Washington, D.C., an office complex in New York City and the completed portion of a mixed-use project in Washington D.C. Properties in operation are net of accumulated depreciation and amortization of $36,999,000 and $32,745,000 as of September 30, 2024 and December 31, 2023, respectively. Related depreciation expense was $6,401,000 and $6,667,000 for the nine months ended September 30, 2024 and 2023, respectively. Future minimum rental income expected on operating leases relating to properties in operation is $8,884,653 in 2024, $34,771,667 in 2025, $33,308,460 in 2026, $32,567,952 in 2027, $33,133,057 in 2028, $28,606,364 in 2029 and $415,176,586 thereafter.

Loans Receivable

Loans Receivable	9 Months Ended
	Sep. 30, 2024
Receivables [Abstract]
Loans Receivable	Loans Receivable At September 30, 2024 and December 31, 2023, loans receivable were as follows: (In thousands) September 30, December 31, Amortized cost (net of allowance for expected credit losses): Real estate loans $ 387,642 $ 200,381 Commercial loans 2,227 890 Total $ 389,869 $ 201,271 Fair value: Real estate loans $ 387,634 $ 197,354 Commercial loans 2,227 890 Total $ 389,861 $ 198,244 The real estate loans are secured by commercial and residential real estate primarily located in the UK and New York. These loans generally earn interest at fixed or stepped interest rates and have maturities through 2028. 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 5 years. The following table presents the rollforward of the allowance for expected credit losses for loans receivable for the nine months ended September 30, 2024 and 2023: 2024 2023 (In thousands) Real Estate Loans Commercial Loans Total Real Estate Loans Commercial Loans Total Allowance for expected credit losses, beginning of period $ 2,983 $ 21 $ 3,004 $ 1,100 $ 691 $ 1,791 Change in expected credit losses (1,581) 2 (1,579) 2,302 (84) 2,218 Allowance for expected credit losses, end of period $ 1,402 $ 23 $ 1,425 $ 3,402 $ 607 $ 4,009 During the nine months ended September 30, 2024, the Company decreased the allowance for expected credit losses due to a decrease in the weighted average life of the loan portfolio. During the nine months ended September 30, 2023, the Company increased the allowance for expected credit losses due to changes in economic assumptions utilized in its credit loss model. The following table presents the rollforward of the allowance for expected credit losses for loans receivable for the three months ended September 30, 2024 and 2023: 2024 2023 (In thousands) Real Estate Loans Commercial Loans Total Real Estate Loans Commercial Loans Total Allowance for expected credit losses, beginning of period $ 1,793 $ 20 $ 1,813 $ 3,658 $ 892 $ 4,550 Change in expected credit losses (391) 3 (388) (256) (285) (541) Allowance for expected credit losses, end of period $ 1,402 $ 23 $ 1,425 $ 3,402 $ 607 $ 4,009 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 (Losses) Gains

Net Investment (Losses) Gains	9 Months Ended
	Sep. 30, 2024
Realized and Unrealized Investment Gains (Losses) [Abstract]
Net Investment (Losses) Gains	Net Investment (Losses) Gains Net investment (losses) gains were as follows: For the Three Months For the Nine Months (In thousands) 2024 2023 2024 2023 Net investment (losses) gains: Fixed maturity securities: Gains $ 4,799 $ 299 $ 11,448 $ 1,357 Losses (3,884) (2,700) (11,569) (24,470) Equity securities (1): Net realized gains on investment sales (2) 407 23,631 102,205 135,763 Change in unrealized (losses) gains (1,537) (19,059) (42,442) 45,605 Investment funds (101) (3,329) 1,109 (3,417) Real estate (3) 1,470 (24,234) (2,704) (68,944) Loans receivable — (1,428) — (1,428) Other (4) (24,516) (14,035) (130,212) (34,063) Net realized and unrealized (losses) gains on investments in earnings before allowance for expected credit losses (23,362) (40,855) (72,165) 50,403 Change in allowance for expected credit losses on investments: Fixed maturity securities 14,888 (2,112) 29,768 (8,946) Loans receivable 388 541 1,579 (2,218) Change in allowance for expected credit losses on investments 15,276 (1,571) 31,347 (11,164) Net investment (losses) gains (8,086) (42,426) (40,818) 39,239 Income tax benefit (expense) 43 9,405 5,810 (8,033) After-tax net investment (losses) gains $ (8,043) $ (33,021) $ (35,008) $ 31,206 Change in unrealized investment gains (losses) on available for sale securities: Fixed maturity securities without allowance for expected credit losses $ 463,418 $ (136,388) $ 363,430 $ (57,293) Fixed maturity securities with allowance for expected credit losses 11,166 (10,244) 4,470 (3,094) Investment funds 6,152 (3,217) 3,112 (818) Other 32 (606) (181) (1,271) Total change in unrealized investment gains (losses) 480,768 (150,455) 370,831 (62,476) Income tax (expense) benefit (99,775) 32,090 (73,298) 11,626 Noncontrolling interests — — 1 (1) After-tax change in unrealized investment gains (losses) of available for sale securities $ 380,993 $ (118,365) $ 297,534 $ (50,851) ______________________ (1) The net realized gains or losses on investment sales represent the total gains or losses from the purchase dates of the equity securities. The change in unrealized gains (losses) consists of two components: (i) the reversal of the gain or loss recognized in previous periods on equity securities sold and (ii) the change in unrealized gain or loss resulting from mark-to-market adjustments on equity securities still held. (2) In June 2023, the Company completed a sale of the property and casualty insurance services division of Breckenridge IS, Inc. and recognized a pre-tax net realized gain on investment of $88 million on the sale (proceeds from the sale is presented on the business disposition line within the Consolidated Statements of Cash Flows). (3) The Company recognized impairments on real estate of $21 million and $72 million in the three months and nine months ended September 30, 2023, respectively.

Fixed Maturity Securities In An

Fixed Maturity Securities In An Unrealized Loss Position	9 Months Ended
	Sep. 30, 2024
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 September 30, 2024 and December 31, 2023 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 September 30, 2024 U.S. government and government agency $ 142,850 $ 3,128 $ 586,823 $ 32,946 $ 729,673 $ 36,074 State and municipal 119,658 2,875 1,636,735 67,333 1,756,393 70,208 Mortgage-backed 237,206 925 1,162,601 132,922 1,399,807 133,847 Asset-backed 471,907 1,236 787,420 35,541 1,259,327 36,777 Corporate 308,606 4,573 3,325,568 126,794 3,634,174 131,367 Foreign government 141,247 17,405 617,409 162,231 758,656 179,636 Fixed maturity securities $ 1,421,474 $ 30,142 $ 8,116,556 $ 557,767 $ 9,538,030 $ 587,909 December 31, 2023 U.S. government and government agency $ 384,392 $ 6,655 $ 614,623 $ 51,014 $ 999,015 $ 57,669 State and municipal 264,273 3,013 1,680,034 119,449 1,944,307 122,462 Mortgage-backed 278,819 2,025 1,360,748 175,131 1,639,567 177,156 Asset-backed 413,511 2,070 2,176,035 71,136 2,589,546 73,206 Corporate 874,754 11,975 4,418,309 231,288 5,293,063 243,263 Foreign government 204,908 1,758 794,174 135,661 999,082 137,419 Fixed maturity securities $ 2,420,657 $ 27,496 $ 11,043,923 $ 783,679 $ 13,464,580 $ 811,175 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 September 30, 2024 is presented in the table below: ($ in thousands) Number of Aggregate Gross Foreign government 62 $ 146,049 $ 163,081 State and municipal 5 28,143 1,894 Corporate 9 20,185 568 Mortgage-backed 15 2,930 143 Total 91 $ 197,307 $ 165,686 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 (loss).

Fair Value Measurements

Fair Value Measurements	9 Months Ended
	Sep. 30, 2024
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 September 30, 2024 and December 31, 2023 by level: (In thousands) Total Level 1 Level 2 Level 3 September 30, 2024 Assets: Fixed maturity securities available for sale: U.S. government and government agency $ 2,070,985 $ — $ 2,070,985 $ — State and municipal 2,516,302 — 2,516,302 — Mortgage-backed 3,237,972 — 3,237,972 — Asset-backed 4,107,321 — 4,107,321 — Corporate 8,852,764 — 8,852,764 — Foreign government 1,834,605 — 1,834,605 — Total fixed maturity securities available for sale 22,619,949 — 22,619,949 — Equity securities: Common stocks 701,667 698,364 1,130 2,173 Preferred stocks 346,459 — 342,823 3,636 Total equity securities 1,048,126 698,364 343,953 5,809 Arbitrage trading account 820,928 728,783 88,397 3,748 Total $ 24,489,003 $ 1,427,147 $ 23,052,299 $ 9,557 Liabilities: Trading account securities sold but not yet purchased $ 36,093 $ 36,093 $ — $ — December 31, 2023 Assets: Fixed maturity securities available for sale: U.S. government and government agency $ 1,716,731 $ — $ 1,716,731 $ — State and municipal 2,634,422 — 2,634,422 — Mortgage-backed 2,266,455 — 2,266,455 — Asset-backed 4,187,040 — 4,187,040 — Corporate 7,654,059 — 7,654,059 — Foreign government 1,666,229 — 1,666,229 — Total fixed maturity securities available for sale 20,124,936 — 20,124,936 — Equity securities: Common stocks 838,054 835,338 1,158 1,558 Preferred stocks 252,293 — 248,598 3,695 Total equity securities 1,090,347 835,338 249,756 5,253 Arbitrage trading account 938,049 546,110 388,167 3,772 Total $ 22,153,332 $ 1,381,448 $ 20,762,859 $ 9,025 Liabilities: Trading account securities sold but not yet purchased $ 9,357 $ 9,357 $ — $ — The following tables summarize changes in Level 3 assets and liabilities for the nine months ended September 30, 2024 and for the year ended December 31, 2023: Gains (Losses) Included In: (In thousands) Beginning Earnings (Losses) Other Impairments Purchases Sales Paydowns / Maturities Transfers In / (Out) Ending Nine Months Ended September 30, 2024 Assets: Equity securities: Common stocks $ 1,558 $ 743 $ — $ — $ — $ (128) $ — $ — $ 2,173 Preferred stocks 3,695 (2) — — — (57) — — 3,636 Total 5,253 741 — — — (185) — — 5,809 Arbitrage trading account 3,772 (23) — — — (38) — 37 3,748 Total $ 9,025 $ 718 $ — $ — $ — $ (223) $ — $ 37 $ 9,557 Year Ended Assets: Equity securities: Common stocks $ 2,599 $ (1,041) $ — $ — $ — $ — $ — $ — $ 1,558 Preferred stocks 11,299 (3) — (7,601) — — — — 3,695 Total 13,898 (1,044) — (7,601) — — — — 5,253 Arbitrage trading account 3,590 117 — — — — — 65 3,772 Total $ 17,488 $ (927) $ — $ (7,601) $ — $ — $ — $ 65 $ 9,025 For both the nine months ended September 30, 2024 and the year ended December 31, 2023, one security within the arbitrage trading account portfolio that no longer had a publicly traded price was transferred into Level 3. The following table presents the carrying amounts and estimated fair values of the Company’s financial instruments: September 30, 2024 December 31, 2023 (In thousands) Carrying Value Fair Value Carrying Value Fair Value Assets: Fixed maturity securities $ 22,663,878 $ 22,665,931 $ 20,178,308 $ 20,181,547 Equity securities 1,048,126 1,048,126 1,090,347 1,090,347 Arbitrage trading account 820,928 820,928 938,049 938,049 Loans receivable 389,869 389,861 201,271 198,244 Cash and cash equivalents 1,573,238 1,573,238 1,363,195 1,363,195 Trading account receivables from brokers and clearing organizations 410,756 410,756 303,614 303,614 Due from broker — — 36,747 36,747 Liabilities: Due to broker 85,920 85,920 — — Trading account securities sold but not yet purchased 36,093 36,093 9,357 9,357 Senior notes and other debt 1,827,788 1,522,430 1,827,951 1,480,076 Subordinated debentures 1,009,629 922,564 1,009,090 929,598

Reserves for Loss and Loss Expe

Reserves for Loss and Loss Expenses	9 Months Ended
	Sep. 30, 2024
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 auto, 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 business 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: September 30, (In thousands) 2024 2023 Net reserves at beginning of period $ 15,661,820 $ 14,248,879 Net provision for losses and loss expenses: Claims occurring during the current year (1) 5,229,468 4,694,554 Increase in estimates for claims occurring in prior years (2) (3) 15,279 27,186 Loss reserve discount accretion 25,587 22,862 Total 5,270,334 4,744,602 Net payments for claims: Current year 795,792 743,416 Prior years 3,164,720 2,915,979 Total 3,960,512 3,659,395 Foreign currency translation 19,659 (48,162) Net reserves at end of period 16,991,301 15,285,924 Ceded reserves at end of period 3,164,009 2,987,386 Gross reserves at end of period $ 20,155,310 $ 18,273,310 _______________________________________ (1) Claims occurring during the current year are net of loss reserve discounts of $37 million and $35 million for the nine months ended September 30, 2024 and 2023, 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 increased by $12 million and decreased by $12 million for the nine months ended September 30, 2024 and 2023, 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 $3 million and adverse development was $20 million for the nine months ended September 30, 2024 and 2023, respectively. The ultimate net impact of COVID-19 on the Company’s reserves remains uncertain. As of September 30, 2024, the Company had recognized losses for COVID-19-related claims activity, net of reinsurance, of approximately $382 million, of which $325 million relates to the Insurance segment and $57 million relates to the Reinsurance & Monoline Excess segment. Such $382 million of COVID-19-related losses included $379 million of reported losses and $3 million of IBNR. During the nine months ended September 30, 2024, favorable prior year development (net of additional and return premiums) of $3 million included $5 million for the Reinsurance & Monoline Excess segment partially offset by $2 million of adverse development for the Insurance segment. For the Insurance segment, the adverse development during the first nine months of 2024 was driven by commercial auto liability and other liability (mainly umbrella and excess liability), which was largely offset by favorable development for workers’ compensation and professional liability. The adverse commercial auto liability development was concentrated in accident years 2020 through 2023. The other liability development was mainly driven by umbrella and excess liability claims, and was focused in accident years 2017 through 2021. A significant portion of the umbrella and excess liability development related to underlying commercial auto exposures. The Company believes that commercial auto-related claims are being particularly impacted by social inflation, which is contributing to an increase in the frequency of large losses beyond expectations. Social inflation can include higher settlement demands from plaintiffs, use of aggressive actions by the plaintiffs’ bar such as litigation funding, negative public sentiment towards large businesses and corporations, and erosion of tort reforms, among other factors. The favorable workers’ compensation development for the Insurance segment was mainly related to accident years 2017 through 2023, while the favorable professional liability development was mainly in accident years 2020 through 2022. For workers' compensation, favorable reported claim frequency, below expectations, continued to be the main driver of the favorable reserve development. For professional liability, reported loss experience for accident years 2020 through 2022 was better than expected, which drove the favorable reserve development. These accident years also feature business written at peak pricing levels, which the Company now believes will result in higher profitability than initially anticipated. For the Reinsurance & Monoline Excess segment, the favorable development during the first nine months of 2024 was driven mainly by favorable development in excess workers’ compensation, partially offset by adverse development in the non-proportional reinsurance assumed liability line of business. The favorable excess workers’ compensation development was driven by continued lower claim frequency and reported losses relative to expectations, and to favorable claim settlements spread across many prior accident years. The unfavorable development for non-proportional reinsurance was concentrated mainly in accident years 2015 through 2019 and was associated primarily with our U.S. and U.K. excess general liability reinsurance businesses, including coverage for cedants insuring construction projects. During the nine months ended September 30, 2023, adverse prior year development (net of additional and return premiums) of $20 million included $21 million of adverse development for the Insurance segment, partially offset by $1 million of favorable development for the Reinsurance & Monoline Excess segment. Such adverse development during the nine months ended September 30, 2023 was concentrated in the first quarter, with $24 million of adverse development (net of additional and return premiums) recorded in the first quarter, partially offset by favorable development totaling $4 million recorded during the second and third quarters. The recorded adverse development during the first quarter in both business segments was due to property catastrophe losses related to 2022 events which were still being adjusted and settled. In particular, losses related to U.S. winter storms which occurred during the month of December 2022 were a significant driver of the development, as information gathering and evaluation of many of these losses were still ongoing into the new year. For the Insurance segment, in addition to the property prior year adverse development discussed above, the adverse development during the nine months ended September 30, 2023 included adverse prior year development on casualty lines for the 2016 through 2019 accident years, which was largely offset by favorable prior year development on casualty lines for the 2020 through 2022 accident years. The adverse development on the 2016 through 2019 accident years was concentrated in the general liability line of business, and to a lesser degree professional liability, including medical professional, and commercial auto liability. The development, which particularly impacted business attaching excess of primary policy limits, was driven by a larger than expected number of large losses reported. The Company believes social inflation is contributing to an increase in the frequency of large losses for these accident years. Social inflation can include higher settlement demands from plaintiffs, use of tactics such as litigation funding by the plaintiffs’ bar, negative public sentiment towards large businesses and corporations, and erosion of tort reforms, among others. The favorable prior year development on casualty lines for the 2020 through 2022 accident years in the Insurance segment was concentrated in the professional liability, workers’ compensation, and general liability lines of business. Due to uncertainty regarding incurred loss frequency and severity in light of ongoing social inflation and the impacts of the COVID-19 pandemic, the Company set its initial loss ratios for the 2020 through 2022 accident years prudently, and largely maintained these estimates through the end of each respective accident year. The reported loss experience to date for these lines of business for the 2020 through 2022 accident years has been significantly better than was expected, and the Company began to react to this favorable emergence as the accident years matured beyond the age of 12 months. However, commercial auto liability experienced adverse prior year development for the 2020 through 2022 accident years, partially offsetting the favorable development discussed above, which was driven by a larger than expected number of large losses reported. For the Reinsurance & Monoline Excess segment, the favorable development during the nine months ended September 30, 2023 was driven mainly by favorable development in excess workers’ compensation, largely offset by adverse development in property (discussed above), non-proportional reinsurance assumed liability, and commercial auto liability lines of business. The favorable excess workers’ compensation development was driven by continued lower claim frequency and reported losses relative to our expectations, and to favorable claim settlements. The favorable development was spread across many prior accident years. The adverse development on reinsurance assumed liability was associated primarily with our U.S. assumed reinsurance business, and related to accounts reinsuring excess and umbrella business and construction projects. The adverse development was concentrated mainly in accident years 2017 through 2020. The adverse development on commercial auto liability was concentrated in the 2022 accident year and related to commercial auto program business.

Fair Value Of Financial Instrum

Fair Value Of Financial Instruments	9 Months Ended
	Sep. 30, 2024
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 September 30, 2024 and December 31, 2023 by level: (In thousands) Total Level 1 Level 2 Level 3 September 30, 2024 Assets: Fixed maturity securities available for sale: U.S. government and government agency $ 2,070,985 $ — $ 2,070,985 $ — State and municipal 2,516,302 — 2,516,302 — Mortgage-backed 3,237,972 — 3,237,972 — Asset-backed 4,107,321 — 4,107,321 — Corporate 8,852,764 — 8,852,764 — Foreign government 1,834,605 — 1,834,605 — Total fixed maturity securities available for sale 22,619,949 — 22,619,949 — Equity securities: Common stocks 701,667 698,364 1,130 2,173 Preferred stocks 346,459 — 342,823 3,636 Total equity securities 1,048,126 698,364 343,953 5,809 Arbitrage trading account 820,928 728,783 88,397 3,748 Total $ 24,489,003 $ 1,427,147 $ 23,052,299 $ 9,557 Liabilities: Trading account securities sold but not yet purchased $ 36,093 $ 36,093 $ — $ — December 31, 2023 Assets: Fixed maturity securities available for sale: U.S. government and government agency $ 1,716,731 $ — $ 1,716,731 $ — State and municipal 2,634,422 — 2,634,422 — Mortgage-backed 2,266,455 — 2,266,455 — Asset-backed 4,187,040 — 4,187,040 — Corporate 7,654,059 — 7,654,059 — Foreign government 1,666,229 — 1,666,229 — Total fixed maturity securities available for sale 20,124,936 — 20,124,936 — Equity securities: Common stocks 838,054 835,338 1,158 1,558 Preferred stocks 252,293 — 248,598 3,695 Total equity securities 1,090,347 835,338 249,756 5,253 Arbitrage trading account 938,049 546,110 388,167 3,772 Total $ 22,153,332 $ 1,381,448 $ 20,762,859 $ 9,025 Liabilities: Trading account securities sold but not yet purchased $ 9,357 $ 9,357 $ — $ — The following tables summarize changes in Level 3 assets and liabilities for the nine months ended September 30, 2024 and for the year ended December 31, 2023: Gains (Losses) Included In: (In thousands) Beginning Earnings (Losses) Other Impairments Purchases Sales Paydowns / Maturities Transfers In / (Out) Ending Nine Months Ended September 30, 2024 Assets: Equity securities: Common stocks $ 1,558 $ 743 $ — $ — $ — $ (128) $ — $ — $ 2,173 Preferred stocks 3,695 (2) — — — (57) — — 3,636 Total 5,253 741 — — — (185) — — 5,809 Arbitrage trading account 3,772 (23) — — — (38) — 37 3,748 Total $ 9,025 $ 718 $ — $ — $ — $ (223) $ — $ 37 $ 9,557 Year Ended Assets: Equity securities: Common stocks $ 2,599 $ (1,041) $ — $ — $ — $ — $ — $ — $ 1,558 Preferred stocks 11,299 (3) — (7,601) — — — — 3,695 Total 13,898 (1,044) — (7,601) — — — — 5,253 Arbitrage trading account 3,590 117 — — — — — 65 3,772 Total $ 17,488 $ (927) $ — $ (7,601) $ — $ — $ — $ 65 $ 9,025 For both the nine months ended September 30, 2024 and the year ended December 31, 2023, one security within the arbitrage trading account portfolio that no longer had a publicly traded price was transferred into Level 3. The following table presents the carrying amounts and estimated fair values of the Company’s financial instruments: September 30, 2024 December 31, 2023 (In thousands) Carrying Value Fair Value Carrying Value Fair Value Assets: Fixed maturity securities $ 22,663,878 $ 22,665,931 $ 20,178,308 $ 20,181,547 Equity securities 1,048,126 1,048,126 1,090,347 1,090,347 Arbitrage trading account 820,928 820,928 938,049 938,049 Loans receivable 389,869 389,861 201,271 198,244 Cash and cash equivalents 1,573,238 1,573,238 1,363,195 1,363,195 Trading account receivables from brokers and clearing organizations 410,756 410,756 303,614 303,614 Due from broker — — 36,747 36,747 Liabilities: Due to broker 85,920 85,920 — — Trading account securities sold but not yet purchased 36,093 36,093 9,357 9,357 Senior notes and other debt 1,827,788 1,522,430 1,827,951 1,480,076 Subordinated debentures 1,009,629 922,564 1,009,090 929,598

Premiums and Reinsurance Relate

Premiums and Reinsurance Related Information	9 Months Ended
	Sep. 30, 2024
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 Nine Months (In thousands) 2024 2023 2024 2023 Written premiums: Direct $ 3,303,682 $ 3,037,932 $ 9,723,219 $ 8,762,249 Assumed 329,596 315,273 990,587 977,047 Ceded (576,002) (504,746) (1,678,460) (1,504,497) Total net premiums written $ 3,057,276 $ 2,848,459 $ 9,035,346 $ 8,234,799 Earned premiums: Direct $ 3,141,883 $ 2,825,176 $ 9,127,399 $ 8,217,888 Assumed 346,780 316,134 1,012,804 913,795 Ceded (561,840) (499,396) (1,602,618) (1,445,610) Total net premiums earned $ 2,926,823 $ 2,641,914 $ 8,537,585 $ 7,686,073 Ceded losses and loss expenses incurred $ 319,472 $ 320,995 $ 952,666 $ 970,267 Ceded commissions earned $ 129,916 $ 118,207 $ 374,618 $ 354,148 The following table presents the rollforward of the allowance for expected credit losses for premiums and fees receivable for the nine months ended September 30, 2024 and 2023: (In thousands) 2024 2023 Allowance for expected credit losses, beginning of period $ 35,110 $ 30,660 Change in expected credit losses 2,961 2,942 Allowance for expected credit losses, end of period $ 38,071 $ 33,602 The following table presents the rollforward of the allowance for expected credit losses for premiums and fees receivable for the three months ended September 30, 2024 and 2023: (In thousands) 2024 2023 Allowance for expected credit losses, beginning of period $ 37,279 $ 32,770 Change in expected credit losses 792 832 Allowance for expected credit losses, end of period $ 38,071 $ 33,602 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 nine months ended September 30, 2024 and 2023: (In thousands) 2024 2023 Allowance for expected credit losses, beginning of period $ 8,404 $ 8,064 Change in expected credit losses (72) 1,379 Allowance for expected credit losses, end of period $ 8,332 $ 9,443 The following table presents the rollforward of the allowance for expected credit losses associated with due from reinsurers for the three months ended September 30, 2024 and 2023: (In thousands) 2024 2023 Allowance for expected credit losses, beginning of period $ 10,255 $ 9,365 Change in expected credit losses (1,923) 78 Allowance for expected credit losses, end of period $ 8,332 $ 9,443

Restricted Stock Units

Restricted Stock Units	9 Months Ended
	Sep. 30, 2024
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 2024 1,215,623 $ 70,195 2023 1,638,195 $ 68,936

Litigation and Contingent Liabi

Litigation and Contingent Liabilities	9 Months Ended
	Sep. 30, 2024
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. On December 22, 2023, one of the Company’s subsidiaries filed a lawsuit against certain reinsurers to recover in excess of $90 million in respect of certain losses paid to its policyholders under certain event cancellation and related insurance policies. The Company believes its claims against the reinsurers are meritorious and expects a positive resolution to its lawsuit. While an adverse outcome is possible, the Company believes that the outcome, in any case, will not be material to the Company’s financial condition.

Leases

Leases	9 Months Ended
	Sep. 30, 2024
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 Nine Months Ended September 30, (In thousands) 2024 2023 2024 2023 Leases: Lease cost $ 11,230 $ 10,122 $ 33,633 $ 30,448 Cash paid for amounts included in the measurement of lease liabilities reported in operating cash flows $ 12,222 $ 11,403 $ 36,818 $ 33,247 Right-of-use assets obtained in exchange for new lease liabilities $ 3,458 $ 6,543 $ 37,007 $ 14,489 As of September 30, ($ in thousands) 2024 2023 Right-of-use assets $ 184,166 $ 155,662 Lease liabilities $ 224,776 $ 188,141 Weighted-average remaining lease term 7.4 years 6.9 years Weighted-average discount rate 5.53 % 4.55 % Contractual maturities of the Company’s future minimum lease payments are as follows: (In thousands) September 30, 2024 Contractual Maturities: 2024 $ 13,277 2025 46,867 2026 40,116 2027 31,122 2028 29,436 Thereafter 109,555 Total undiscounted future minimum lease payments 270,373 Less: Discount impact 45,597 Total lease liability $ 224,776

Business Segments

Business Segments	9 Months Ended
	Sep. 30, 2024
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 Asia, Australia, Canada, Continental Europe, Mexico, Scandinavia, South America and the United Kingdom. • 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 and certain program management business. 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 September 30, 2024 Insurance $ 2,564,490 $ 253,234 $ 9,189 $ 2,826,913 $ 469,421 $ 363,026 Reinsurance & Monoline Excess 362,333 57,037 — 419,370 105,225 82,659 Corporate, other and eliminations (3) — 13,485 148,697 162,182 (92,111) (72,008) Net investment losses — — (8,086) (8,086) (8,086) (8,043) Total $ 2,926,823 $ 323,756 $ 149,800 $ 3,400,379 $ 474,449 $ 365,634 Three months ended September 30, 2023 Insurance $ 2,291,917 $ 204,030 $ 9,143 $ 2,505,090 $ 410,909 $ 326,086 Reinsurance & Monoline Excess 349,997 59,021 — 409,018 110,442 86,747 Corporate, other and eliminations (3) — 7,893 151,063 158,956 (58,976) (46,226) Net investment losses — — (42,426) (42,426) (42,426) (33,021) Total $ 2,641,914 $ 270,944 $ 117,780 $ 3,030,638 $ 419,949 $ 333,586 Nine months ended September 30, 2024 Insurance $ 7,447,828 $ 801,573 $ 28,202 $ 8,277,603 $ 1,437,623 $ 1,102,363 Reinsurance & Monoline Excess 1,089,757 168,721 — 1,258,478 357,299 282,423 Corporate, other and eliminations (3) — 45,429 430,492 475,921 (217,912) (169,764) Net investment losses — — (40,818) (40,818) (40,818) (35,008) Total $ 8,537,585 $ 1,015,723 $ 417,876 $ 9,971,184 $ 1,536,192 $ 1,180,014 Nine months ended September 30, 2023 Insurance $ 6,650,027 $ 552,917 $ 27,570 $ 7,230,514 $ 1,149,886 $ 900,434 Reinsurance & Monoline Excess 1,036,046 155,790 — 1,191,836 317,146 251,420 Corporate, other and eliminations (3) — 30,787 429,180 459,967 (253,066) (199,040) Net investment gains — — 39,239 39,239 39,239 31,206 Total $ 7,686,073 $ 739,494 $ 495,989 $ 8,921,556 $ 1,253,205 $ 984,020 _________________ (1) Certain amounts included in earned premiums of each segment are related to inter-segment transactions. (2) Revenues for Insurance from foreign operations for the three months ended September 30, 2024 and 2023 were $350 million and $298 million, respectively, and for the nine months ended September 30, 2024 and 2023 were $1,112 million and $852 million, respectively. Revenues for Reinsurance & Monoline Excess from foreign operations for the three months ended September 30, 2024 and 2023 were $125 million and $124 million, respectively, and for the nine months ended September 30, 2024 and 2023 were $353 million and $333 million, respectively. (3) Corporate, other and eliminations represent corporate revenues and expenses that are not allocated to business segments. Identifiable Assets (In thousands) September 30, December 31, Insurance $ 32,687,852 $ 29,923,282 Reinsurance & Monoline Excess 5,842,643 5,545,249 Corporate, other and eliminations 1,828,803 1,643,299 Consolidated $ 40,359,298 $ 37,111,830 Net premiums earned by major line of business are as follows: For the Three Months For the Nine Months (In thousands) 2024 2023 2024 2023 Insurance: Other liability $ 1,031,087 $ 916,394 $ 3,000,335 $ 2,660,850 Short-tail lines (1) 563,736 472,805 1,613,342 1,330,173 Auto 376,762 327,507 1,092,354 929,201 Workers' compensation 313,154 300,694 925,214 905,405 Professional liability 279,751 274,517 816,583 824,398 Total Insurance 2,564,490 2,291,917 7,447,828 6,650,027 Reinsurance & Monoline Excess: Casualty (2) 188,284 201,795 585,208 618,855 Property (2) 108,386 87,838 308,024 239,338 Monoline excess (3) 65,663 60,364 196,525 177,853 Total Reinsurance & Monoline Excess 362,333 349,997 1,089,757 1,036,046 Total $ 2,926,823 $ 2,641,914 $ 8,537,585 $ 7,686,073 ______________ (1) Short-tail lines include commercial multi-peril (non-liability), inland marine, accident and health, fidelity and surety, boiler and machinery, high net worth homeowners and other lines. (2) Includes reinsurance casualty and property and certain program management business.

Pay vs Performance Disclosure

Pay vs Performance Disclosure - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Pay vs Performance Disclosure
Net Income (Loss) to Common Stockholders	$ 365,634	$ 333,586	$ 1,180,014	$ 984,020

Insider Trading Arrangements

Insider Trading Arrangements	3 Months Ended
	Sep. 30, 2024
Trading Arrangements, by Individual
Rule 10b5-1 Arrangement Adopted	false
Non-Rule 10b5-1 Arrangement Adopted	false
Rule 10b5-1 Arrangement Terminated	false
Non-Rule 10b5-1 Arrangement Terminated	false

Recent Accounting Pronounceme_2

Recent Accounting Pronouncements and Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2024
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 17,495,175 and 17,125,284 common shares held in a grantor trust as of September 30, 2024 and 2023, 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 Nine Months (In thousands) 2024 2023 2024 2023 Basic 398,338 403,787 400,302 407,484 Diluted 401,817 407,158 404,053 411,219
Recent Accounting Pronouncements	Recent Accounting Pronouncements and Accounting Policies Recently adopted accounting pronouncements: All accounting and reporting standards that became effective in 2024 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)	9 Months Ended
	Sep. 30, 2024
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 Nine Months (In thousands) 2024 2023 2024 2023 Basic 398,338 403,787 400,302 407,484 Diluted 401,817 407,158 404,053 411,219

Consolidated Statements of Co_3

Consolidated Statements of Comprehensive (Loss) Income (Tables)	9 Months Ended
	Sep. 30, 2024
Equity [Abstract]
Components of changes in accumulated other comprehensive income (loss)	The following table presents the components of the changes in accumulated other comprehensive income (loss) ("AOCI"): (In thousands) Unrealized Investment (Losses) Gains Currency Translation Adjustments Accumulated Other Comprehensive As of and for the nine months ended September 30, 2024 Changes in AOCI Beginning of period $ (586,354) $ (339,484) $ (925,838) Other comprehensive income before reclassifications 218,087 25,160 243,247 Amounts reclassified from AOCI 79,446 — 79,446 Other comprehensive income 297,533 25,160 322,693 Unrealized investment gain related to noncontrolling interest 1 — 1 End of period $ (288,820) $ (314,324) $ (603,144) Amounts reclassified from AOCI Pre-tax $ 100,565 (1) $ — $ 100,565 Tax effect (21,119) (2) — (21,119) After-tax amounts reclassified $ 79,446 $ — $ 79,446 Other comprehensive income Pre-tax $ 370,831 $ 25,160 $ 395,991 Tax effect (73,298) — (73,298) Other comprehensive income $ 297,533 $ 25,160 $ 322,693 As of and for the three months ended September 30, 2024 Changes in AOCI Beginning of period $ (669,813) $ (363,827) $ (1,033,640) Other comprehensive income before reclassifications 374,110 49,503 423,613 Amounts reclassified from AOCI 6,883 — 6,883 Other comprehensive income 380,993 49,503 430,496 Unrealized investment gain to noncontrolling interest — — — Ending balance $ (288,820) $ (314,324) $ (603,144) Amounts reclassified from AOCI Pre-tax $ 8,713 (1) $ — $ 8,713 Tax effect (1,830) (2) — (1,830) After-tax amounts reclassified $ 6,883 $ — $ 6,883 Other comprehensive income Pre-tax $ 480,768 $ 49,503 $ 530,271 Tax effect (99,775) — (99,775) Other comprehensive income $ 380,993 $ 49,503 $ 430,496 (In thousands) Unrealized Investment (Losses) Gains Currency Translation Adjustments Accumulated Other Comprehensive As of and for the nine months ended September 30, 2023 Changes in AOCI Beginning of period $ (892,905) $ (371,676) $ (1,264,581) Other comprehensive loss before reclassifications (103,087) (7,387) (110,474) Amounts reclassified from AOCI 52,237 — 52,237 Other comprehensive loss (50,850) (7,387) (58,237) Unrealized investment loss related to noncontrolling interest (1) — (1) End of period $ (943,756) $ (379,063) $ (1,322,819) Amounts reclassified from AOCI Pre-tax $ 66,123 (1) $ — $ 66,123 Tax effect (13,886) (2) — (13,886) After-tax amounts reclassified $ 52,237 $ — $ 52,237 Other comprehensive loss Pre-tax $ (62,476) $ (7,387) $ (69,863) Tax effect 11,626 — 11,626 Other comprehensive income $ (50,850) $ (7,387) $ (58,237) As of and for the three months ended September 30, 2023 Changes in AOCI Beginning of period $ (825,391) $ (356,282) $ (1,181,673) Other comprehensive loss before reclassifications (133,018) (22,781) (155,799) Amounts reclassified from AOCI 14,653 — 14,653 Other comprehensive loss (118,365) (22,781) (141,146) Unrealized investment loss related to noncontrolling interest — — — Ending balance $ (943,756) $ (379,063) $ (1,322,819) Amounts reclassified from AOCI Pre-tax $ 18,548 (1) $ — $ 18,548 Tax effect (3,895) (2) — (3,895) After-tax amounts reclassified $ 14,653 $ — $ 14,653 Other comprehensive loss Pre-tax $ (150,455) $ (22,781) $ (173,236) Tax effect 32,090 — 32,090 Other comprehensive loss $ (118,365) $ (22,781) $ (141,146) ____________ (1) Net investment (losses) gains in the consolidated statements of income. (2) Income tax expense in the consolidated statements of income.

Investments in Fixed Maturity_2

Investments in Fixed Maturity Securities (Tables)	9 Months Ended
	Sep. 30, 2024
Investments, Debt and Equity Securities [Abstract]
Schedule of investments in fixed maturity securities	At September 30, 2024 and December 31, 2023, investments in fixed maturity securities were as follows: (In thousands) Amortized Allowance for Expected Credit Losses (1) Gross Unrealized Fair Carrying Gains Losses September 30, 2024 Held to maturity: State and municipal $ 41,561 $ (30) $ 1,944 $ — $ 43,475 $ 41,531 Residential mortgage-backed 2,398 — 109 — 2,507 2,398 Total held to maturity 43,959 (30) 2,053 — 45,982 43,929 Available for sale: U.S. government and government agency 2,083,085 — 23,974 (36,074) 2,070,985 2,070,985 State and municipal: Special revenue 1,732,996 — 8,414 (51,652) 1,689,758 1,689,758 State general obligation 273,232 — 4,565 (7,375) 270,422 270,422 Pre-refunded 85,683 — 1,260 (90) 86,853 86,853 Corporate backed 168,276 — 1,847 (4,968) 165,155 165,155 Local general obligation 307,754 — 2,483 (6,123) 304,114 304,114 Total state and municipal 2,567,941 — 18,569 (70,208) 2,516,302 2,516,302 Mortgage-backed: Residential 2,736,493 — 31,527 (130,929) 2,637,091 2,637,091 Commercial 600,597 (52) 3,254 (2,918) 600,881 600,881 Total mortgage-backed 3,337,090 (52) 34,781 (133,847) 3,237,972 3,237,972 Asset-backed 4,118,052 (546) 26,592 (36,777) 4,107,321 4,107,321 Corporate: Industrial 3,980,058 — 55,042 (80,692) 3,954,408 3,954,408 Financial 3,326,838 — 54,929 (33,205) 3,348,562 3,348,562 Utilities 774,956 — 13,319 (13,877) 774,398 774,398 Other 774,274 — 4,715 (3,593) 775,396 775,396 Total corporate 8,856,126 — 128,005 (131,367) 8,852,764 8,852,764 Foreign government 1,996,895 (6,355) 23,701 (179,636) 1,834,605 1,834,605 Total available for sale 22,959,189 (6,953) 255,622 (587,909) 22,619,949 22,619,949 Total investments in fixed maturity securities $ 23,003,148 $ (6,983) $ 257,675 $ (587,909) $ 22,665,931 $ 22,663,878 ____________ (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, 2023 Held to maturity: State and municipal $ 50,547 $ (43) $ 3,132 $ — $ 53,636 $ 50,504 Residential mortgage-backed 2,868 — 107 — 2,975 2,868 Total held to maturity 53,415 (43) 3,239 — 56,611 53,372 Available for sale: U.S. government and government agency 1,762,997 — 11,403 (57,669) 1,716,731 1,716,731 State and municipal: Special revenue 1,682,550 — 5,651 (82,006) 1,606,195 1,606,195 State general obligation 394,429 — 3,550 (16,405) 381,574 381,574 Pre-refunded 103,029 — 1,634 (185) 104,478 104,478 Corporate backed 166,873 (757) 696 (11,973) 154,839 154,839 Local general obligation 396,041 — 3,188 (11,893) 387,336 387,336 Total state and municipal 2,742,922 (757) 14,719 (122,462) 2,634,422 2,634,422 Mortgage-backed: Residential 1,773,206 — 12,780 (163,844) 1,622,142 1,622,142 Commercial 657,157 (158) 626 (13,312) 644,313 644,313 Total mortgage-backed 2,430,363 (158) 13,406 (177,156) 2,266,455 2,266,455 Asset-backed 4,252,883 (1,164) 8,527 (73,206) 4,187,040 4,187,040 Corporate: Industrial 3,679,219 (40) 24,312 (143,936) 3,559,555 3,559,555 Financial 2,838,220 (4,986) 14,681 (68,681) 2,779,234 2,779,234 Utilities 701,865 — 6,471 (23,412) 684,924 684,924 Other 635,975 — 1,605 (7,234) 630,346 630,346 Total corporate 7,855,279 (5,026) 47,069 (243,263) 7,654,059 7,654,059 Foreign government 1,817,386 (29,603) 15,865 (137,419) 1,666,229 1,666,229 Total available for sale 20,861,830 (36,708) 110,989 (811,175) 20,124,936 20,124,936 Total investments in fixed maturity securities $ 20,915,245 $ (36,751) $ 114,228 $ (811,175) $ 20,181,547 $ 20,178,308
Debt Securities, Held-to-maturity, Allowance for Credit Loss	The following table presents the rollforward of the allowance for expected credit losses for held to maturity securities for the nine months ended September 30, 2024 and 2023: (In thousands) 2024 2023 Allowance for expected credit losses, beginning of period $ 43 $ 114 Change in expected credit losses (13) (66) Allowance for expected credit losses, end of period $ 30 $ 48
Debt Securities, Available-for-sale, Allowance for Credit Loss	The following table presents the rollforward of the allowance for expected credit losses for held to maturity securities for the three months ended September 30, 2024 and 2023: (In thousands) 2024 2023 Allowance for expected credit losses, beginning of period $ 34 $ 53 Change in expected credit losses (4) (5) Allowance for expected credit losses, end of period $ 30 $ 48 The following table presents the rollforward of the allowance for expected credit losses for available for sale securities for the nine months ended September 30, 2024 and 2023: 2024 2023 (In thousands) Foreign Government Corporate Mortgage-backed Asset-backed State and Municipal Total Foreign Government Corporate Mortgage-backed Asset-backed State and Municipal Total Balance, beginning of period $ 29,603 $ 5,026 $ 158 $ 1,164 $ 757 $ 36,708 $ 32,633 $ 4,701 $ 18 $ — $ — $ 37,352 Change on securities for which credit losses were not previously recorded 347 — 1,701 — — 2,048 — 942 1,766 1,444 821 4,973 Change on securities for which credit losses were previously recorded (23,216) (5,026) (1,246) (618) (757) (30,863) 3,538 134 316 58 — 4,046 Reduction due to disposals (379) — (561) — — (940) — (7) — — — (7) Balance, end of period $ 6,355 $ — $ 52 $ 546 $ — $ 6,953 $ 36,171 $ 5,770 $ 2,100 $ 1,502 $ 821 $ 46,364
Amortized cost and fair value of fixed maturity securities by contractual maturity	The amortized cost and fair value of fixed maturity securities at September 30, 2024, 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 $ 1,910,941 $ 1,886,626 Due after one year through five years 9,907,127 9,724,883 Due after five years through ten years 4,282,838 4,283,690 Due after ten years 3,562,724 3,530,253 Mortgage-backed securities 3,339,488 3,240,479 Total $ 23,003,118 $ 22,665,931 _______________

Investments in Equity Securit_2

Investments in Equity Securities (Tables)	9 Months Ended
	Sep. 30, 2024
Equity securities
Debt Securities, Available-for-sale [Line Items]
Schedule of Investments in Equity Securities	At September 30, 2024 and December 31, 2023, investments in equity securities were as follows: (In thousands) Cost Gross Unrealized Fair Carrying Gains Losses September 30, 2024 Common stocks $ 604,288 $ 157,761 $ (60,382) $ 701,667 $ 701,667 Preferred stocks 345,265 10,921 (9,727) 346,459 346,459 Total $ 949,553 $ 168,682 $ (70,109) $ 1,048,126 $ 1,048,126 December 31, 2023 Common stocks $ 664,997 $ 191,806 $ (18,749) $ 838,054 $ 838,054 Preferred stocks 284,335 3,075 (35,117) 252,293 252,293 Total $ 949,332 $ 194,881 $ (53,866) $ 1,090,347 $ 1,090,347

Net Investment Income (Tables)

Net Investment Income (Tables)	9 Months Ended
	Sep. 30, 2024
Net Investment Income [Abstract]
Schedule of Net Investment Income	Net investment income consisted of the following: For the Three Months For the Nine Months (In thousands) 2024 2023 2024 2023 Investment income (loss) earned on: Fixed maturity securities, including cash and cash equivalents and loans receivable $ 295,272 $ 239,727 $ 954,655 $ 653,200 Arbitrage trading account (1) 17,869 17,876 52,562 53,168 Equity securities 12,203 12,714 35,924 41,714 Investment funds 4,741 4,450 868 5,444 Real estate (3,711) (1,986) (20,579) (7,821) Gross investment income 326,374 272,781 1,023,430 745,705 Investment expense (2,618) (1,837) (7,707) (6,211) Net investment income $ 323,756 $ 270,944 $ 1,015,723 $ 739,494

Investment Funds (Tables)

Investment Funds (Tables)	9 Months Ended
	Sep. 30, 2024
Equity Method Investments and Joint Ventures [Abstract]
Schedule of Investment Funds	Investment funds consisted of the following: Carrying Value as of Income (Loss) from September 30, December 31, For the Nine Months (In thousands) 2024 2023 2024 2023 Financial services $ 460,264 $ 433,407 $ (16,908) $ (15,606) Transportation 300,937 344,278 962 37,894 Real Estate 190,318 201,625 11,471 (5,062) Infrastructure 146,936 130,589 12,730 7,813 Energy 131,113 114,794 9,473 3,921 Other funds 377,813 396,962 (16,860) (23,516) Total $ 1,607,381 $ 1,621,655 $ 868 $ 5,444

Real Estate (Tables)

Real Estate (Tables)	9 Months Ended
	Sep. 30, 2024
Real Estate [Abstract]
Schedule of Real Estate Investments	Investment in real estate represents directly owned property held for investment, as follows: Carrying Value September 30, December 31, (In thousands) 2024 2023 Properties in operation $ 1,069,589 $ 1,022,654 Properties under development 227,725 227,220 Total $ 1,297,314 $ 1,249,874

Loans Receivable Loans Receivab

Loans Receivable Loans Receivable (Tables)	9 Months Ended
	Sep. 30, 2024
Receivables [Abstract]
Schedule of Loans Receivable	At September 30, 2024 and December 31, 2023, loans receivable were as follows: (In thousands) September 30, December 31, Amortized cost (net of allowance for expected credit losses): Real estate loans $ 387,642 $ 200,381 Commercial loans 2,227 890 Total $ 389,869 $ 201,271 Fair value: Real estate loans $ 387,634 $ 197,354 Commercial loans 2,227 890 Total $ 389,861 $ 198,244
Financing Receivable, Allowance for Credit Loss	The following table presents the rollforward of the allowance for expected credit losses for loans receivable for the nine months ended September 30, 2024 and 2023: 2024 2023 (In thousands) Real Estate Loans Commercial Loans Total Real Estate Loans Commercial Loans Total Allowance for expected credit losses, beginning of period $ 2,983 $ 21 $ 3,004 $ 1,100 $ 691 $ 1,791 Change in expected credit losses (1,581) 2 (1,579) 2,302 (84) 2,218 Allowance for expected credit losses, end of period $ 1,402 $ 23 $ 1,425 $ 3,402 $ 607 $ 4,009 During the nine months ended September 30, 2024, the Company decreased the allowance for expected credit losses due to a decrease in the weighted average life of the loan portfolio. During the nine months ended September 30, 2023, the Company increased the allowance for expected credit losses due to changes in economic assumptions utilized in its credit loss model. The following table presents the rollforward of the allowance for expected credit losses for loans receivable for the three months ended September 30, 2024 and 2023: 2024 2023 (In thousands) Real Estate Loans Commercial Loans Total Real Estate Loans Commercial Loans Total Allowance for expected credit losses, beginning of period $ 1,793 $ 20 $ 1,813 $ 3,658 $ 892 $ 4,550 Change in expected credit losses (391) 3 (388) (256) (285) (541) Allowance for expected credit losses, end of period $ 1,402 $ 23 $ 1,425 $ 3,402 $ 607 $ 4,009

Net Investment (Losses) Gains (

Net Investment (Losses) Gains (Tables)	9 Months Ended
	Sep. 30, 2024
Realized and Unrealized Investment Gains (Losses) [Abstract]
Realized And Unrealized Investment Gains (Losses)	Net investment (losses) gains were as follows: For the Three Months For the Nine Months (In thousands) 2024 2023 2024 2023 Net investment (losses) gains: Fixed maturity securities: Gains $ 4,799 $ 299 $ 11,448 $ 1,357 Losses (3,884) (2,700) (11,569) (24,470) Equity securities (1): Net realized gains on investment sales (2) 407 23,631 102,205 135,763 Change in unrealized (losses) gains (1,537) (19,059) (42,442) 45,605 Investment funds (101) (3,329) 1,109 (3,417) Real estate (3) 1,470 (24,234) (2,704) (68,944) Loans receivable — (1,428) — (1,428) Other (4) (24,516) (14,035) (130,212) (34,063) Net realized and unrealized (losses) gains on investments in earnings before allowance for expected credit losses (23,362) (40,855) (72,165) 50,403 Change in allowance for expected credit losses on investments: Fixed maturity securities 14,888 (2,112) 29,768 (8,946) Loans receivable 388 541 1,579 (2,218) Change in allowance for expected credit losses on investments 15,276 (1,571) 31,347 (11,164) Net investment (losses) gains (8,086) (42,426) (40,818) 39,239 Income tax benefit (expense) 43 9,405 5,810 (8,033) After-tax net investment (losses) gains $ (8,043) $ (33,021) $ (35,008) $ 31,206 Change in unrealized investment gains (losses) on available for sale securities: Fixed maturity securities without allowance for expected credit losses $ 463,418 $ (136,388) $ 363,430 $ (57,293) Fixed maturity securities with allowance for expected credit losses 11,166 (10,244) 4,470 (3,094) Investment funds 6,152 (3,217) 3,112 (818) Other 32 (606) (181) (1,271) Total change in unrealized investment gains (losses) 480,768 (150,455) 370,831 (62,476) Income tax (expense) benefit (99,775) 32,090 (73,298) 11,626 Noncontrolling interests — — 1 (1) After-tax change in unrealized investment gains (losses) of available for sale securities $ 380,993 $ (118,365) $ 297,534 $ (50,851) ______________________ (1) The net realized gains or losses on investment sales represent the total gains or losses from the purchase dates of the equity securities. The change in unrealized gains (losses) consists of two components: (i) the reversal of the gain or loss recognized in previous periods on equity securities sold and (ii) the change in unrealized gain or loss resulting from mark-to-market adjustments on equity securities still held. (2) In June 2023, the Company completed a sale of the property and casualty insurance services division of Breckenridge IS, Inc. and recognized a pre-tax net realized gain on investment of $88 million on the sale (proceeds from the sale is presented on the business disposition line within the Consolidated Statements of Cash Flows). (3) The Company recognized impairments on real estate of $21 million and $72 million in the three months and nine months ended September 30, 2023, respectively.

Fixed Maturity Securities In _2

Fixed Maturity Securities In An Unrealized Loss Position (Tables)	9 Months Ended
	Sep. 30, 2024
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 September 30, 2024 and December 31, 2023 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 September 30, 2024 U.S. government and government agency $ 142,850 $ 3,128 $ 586,823 $ 32,946 $ 729,673 $ 36,074 State and municipal 119,658 2,875 1,636,735 67,333 1,756,393 70,208 Mortgage-backed 237,206 925 1,162,601 132,922 1,399,807 133,847 Asset-backed 471,907 1,236 787,420 35,541 1,259,327 36,777 Corporate 308,606 4,573 3,325,568 126,794 3,634,174 131,367 Foreign government 141,247 17,405 617,409 162,231 758,656 179,636 Fixed maturity securities $ 1,421,474 $ 30,142 $ 8,116,556 $ 557,767 $ 9,538,030 $ 587,909 December 31, 2023 U.S. government and government agency $ 384,392 $ 6,655 $ 614,623 $ 51,014 $ 999,015 $ 57,669 State and municipal 264,273 3,013 1,680,034 119,449 1,944,307 122,462 Mortgage-backed 278,819 2,025 1,360,748 175,131 1,639,567 177,156 Asset-backed 413,511 2,070 2,176,035 71,136 2,589,546 73,206 Corporate 874,754 11,975 4,418,309 231,288 5,293,063 243,263 Foreign government 204,908 1,758 794,174 135,661 999,082 137,419 Fixed maturity securities $ 2,420,657 $ 27,496 $ 11,043,923 $ 783,679 $ 13,464,580 $ 811,175
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 September 30, 2024 is presented in the table below: ($ in thousands) Number of Aggregate Gross Foreign government 62 $ 146,049 $ 163,081 State and municipal 5 28,143 1,894 Corporate 9 20,185 568 Mortgage-backed 15 2,930 143 Total 91 $ 197,307 $ 165,686

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	9 Months Ended
	Sep. 30, 2024
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 September 30, 2024 and December 31, 2023 by level: (In thousands) Total Level 1 Level 2 Level 3 September 30, 2024 Assets: Fixed maturity securities available for sale: U.S. government and government agency $ 2,070,985 $ — $ 2,070,985 $ — State and municipal 2,516,302 — 2,516,302 — Mortgage-backed 3,237,972 — 3,237,972 — Asset-backed 4,107,321 — 4,107,321 — Corporate 8,852,764 — 8,852,764 — Foreign government 1,834,605 — 1,834,605 — Total fixed maturity securities available for sale 22,619,949 — 22,619,949 — Equity securities: Common stocks 701,667 698,364 1,130 2,173 Preferred stocks 346,459 — 342,823 3,636 Total equity securities 1,048,126 698,364 343,953 5,809 Arbitrage trading account 820,928 728,783 88,397 3,748 Total $ 24,489,003 $ 1,427,147 $ 23,052,299 $ 9,557 Liabilities: Trading account securities sold but not yet purchased $ 36,093 $ 36,093 $ — $ — December 31, 2023 Assets: Fixed maturity securities available for sale: U.S. government and government agency $ 1,716,731 $ — $ 1,716,731 $ — State and municipal 2,634,422 — 2,634,422 — Mortgage-backed 2,266,455 — 2,266,455 — Asset-backed 4,187,040 — 4,187,040 — Corporate 7,654,059 — 7,654,059 — Foreign government 1,666,229 — 1,666,229 — Total fixed maturity securities available for sale 20,124,936 — 20,124,936 — Equity securities: Common stocks 838,054 835,338 1,158 1,558 Preferred stocks 252,293 — 248,598 3,695 Total equity securities 1,090,347 835,338 249,756 5,253 Arbitrage trading account 938,049 546,110 388,167 3,772 Total $ 22,153,332 $ 1,381,448 $ 20,762,859 $ 9,025 Liabilities: Trading account securities sold but not yet purchased $ 9,357 $ 9,357 $ — $ —
Summarize Changes In Level 3 Assets	The following tables summarize changes in Level 3 assets and liabilities for the nine months ended September 30, 2024 and for the year ended December 31, 2023: Gains (Losses) Included In: (In thousands) Beginning Earnings (Losses) Other Impairments Purchases Sales Paydowns / Maturities Transfers In / (Out) Ending Nine Months Ended September 30, 2024 Assets: Equity securities: Common stocks $ 1,558 $ 743 $ — $ — $ — $ (128) $ — $ — $ 2,173 Preferred stocks 3,695 (2) — — — (57) — — 3,636 Total 5,253 741 — — — (185) — — 5,809 Arbitrage trading account 3,772 (23) — — — (38) — 37 3,748 Total $ 9,025 $ 718 $ — $ — $ — $ (223) $ — $ 37 $ 9,557 Year Ended Assets: Equity securities: Common stocks $ 2,599 $ (1,041) $ — $ — $ — $ — $ — $ — $ 1,558 Preferred stocks 11,299 (3) — (7,601) — — — — 3,695 Total 13,898 (1,044) — (7,601) — — — — 5,253 Arbitrage trading account 3,590 117 — — — — — 65 3,772 Total $ 17,488 $ (927) $ — $ (7,601) $ — $ — $ — $ 65 $ 9,025

Reserves for Loss and Loss Ex_2

Reserves for Loss and Loss Expenses (Tables)	9 Months Ended
	Sep. 30, 2024
Insurance [Abstract]
Reserve Balances	The table below provides a reconciliation of the beginning and ending reserve balances: September 30, (In thousands) 2024 2023 Net reserves at beginning of period $ 15,661,820 $ 14,248,879 Net provision for losses and loss expenses: Claims occurring during the current year (1) 5,229,468 4,694,554 Increase in estimates for claims occurring in prior years (2) (3) 15,279 27,186 Loss reserve discount accretion 25,587 22,862 Total 5,270,334 4,744,602 Net payments for claims: Current year 795,792 743,416 Prior years 3,164,720 2,915,979 Total 3,960,512 3,659,395 Foreign currency translation 19,659 (48,162) Net reserves at end of period 16,991,301 15,285,924 Ceded reserves at end of period 3,164,009 2,987,386 Gross reserves at end of period $ 20,155,310 $ 18,273,310 _______________________________________ (1) Claims occurring during the current year are net of loss reserve discounts of $37 million and $35 million for the nine months ended September 30, 2024 and 2023, 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 increased by $12 million and decreased by $12 million for the nine months ended September 30, 2024 and 2023, 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 $3 million and adverse development was $20 million for the nine months ended September 30, 2024 and 2023, respectively.

Fair Value of Financial Instr_2

Fair Value of Financial Instruments (Tables)	9 Months Ended
	Sep. 30, 2024
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: September 30, 2024 December 31, 2023 (In thousands) Carrying Value Fair Value Carrying Value Fair Value Assets: Fixed maturity securities $ 22,663,878 $ 22,665,931 $ 20,178,308 $ 20,181,547 Equity securities 1,048,126 1,048,126 1,090,347 1,090,347 Arbitrage trading account 820,928 820,928 938,049 938,049 Loans receivable 389,869 389,861 201,271 198,244 Cash and cash equivalents 1,573,238 1,573,238 1,363,195 1,363,195 Trading account receivables from brokers and clearing organizations 410,756 410,756 303,614 303,614 Due from broker — — 36,747 36,747 Liabilities: Due to broker 85,920 85,920 — — Trading account securities sold but not yet purchased 36,093 36,093 9,357 9,357 Senior notes and other debt 1,827,788 1,522,430 1,827,951 1,480,076 Subordinated debentures 1,009,629 922,564 1,009,090 929,598

Premiums and Reinsurance Rela_2

Premiums and Reinsurance Related Information (Tables)	9 Months Ended
	Sep. 30, 2024
Insurance [Abstract]
Reinsurance Financial Information	The following is a summary of insurance and reinsurance financial information: For the Three Months For the Nine Months (In thousands) 2024 2023 2024 2023 Written premiums: Direct $ 3,303,682 $ 3,037,932 $ 9,723,219 $ 8,762,249 Assumed 329,596 315,273 990,587 977,047 Ceded (576,002) (504,746) (1,678,460) (1,504,497) Total net premiums written $ 3,057,276 $ 2,848,459 $ 9,035,346 $ 8,234,799 Earned premiums: Direct $ 3,141,883 $ 2,825,176 $ 9,127,399 $ 8,217,888 Assumed 346,780 316,134 1,012,804 913,795 Ceded (561,840) (499,396) (1,602,618) (1,445,610) Total net premiums earned $ 2,926,823 $ 2,641,914 $ 8,537,585 $ 7,686,073 Ceded losses and loss expenses incurred $ 319,472 $ 320,995 $ 952,666 $ 970,267 Ceded commissions earned $ 129,916 $ 118,207 $ 374,618 $ 354,148
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 nine months ended September 30, 2024 and 2023: (In thousands) 2024 2023 Allowance for expected credit losses, beginning of period $ 35,110 $ 30,660 Change in expected credit losses 2,961 2,942 Allowance for expected credit losses, end of period $ 38,071 $ 33,602 The following table presents the rollforward of the allowance for expected credit losses for premiums and fees receivable for the three months ended September 30, 2024 and 2023: (In thousands) 2024 2023 Allowance for expected credit losses, beginning of period $ 37,279 $ 32,770 Change in expected credit losses 792 832 Allowance for expected credit losses, end of period $ 38,071 $ 33,602
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 nine months ended September 30, 2024 and 2023: (In thousands) 2024 2023 Allowance for expected credit losses, beginning of period $ 8,404 $ 8,064 Change in expected credit losses (72) 1,379 Allowance for expected credit losses, end of period $ 8,332 $ 9,443 The following table presents the rollforward of the allowance for expected credit losses associated with due from reinsurers for the three months ended September 30, 2024 and 2023: (In thousands) 2024 2023 Allowance for expected credit losses, beginning of period $ 10,255 $ 9,365 Change in expected credit losses (1,923) 78 Allowance for expected credit losses, end of period $ 8,332 $ 9,443

Restricted Stock Units (Tables)

Restricted Stock Units (Tables)	9 Months Ended
	Sep. 30, 2024
Share-Based Payment Arrangement [Abstract]
Summary Of Restricted Stock Units Issued	A summary of RSUs issued in the nine months ended September 30, 2024 and 2023 follows: ($ in thousands) Units Fair Value 2024 1,215,623 $ 70,195 2023 1,638,195 $ 68,936

Leases (Tables)

Leases (Tables)	9 Months Ended
	Sep. 30, 2024
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 Nine Months Ended September 30, (In thousands) 2024 2023 2024 2023 Leases: Lease cost $ 11,230 $ 10,122 $ 33,633 $ 30,448 Cash paid for amounts included in the measurement of lease liabilities reported in operating cash flows $ 12,222 $ 11,403 $ 36,818 $ 33,247 Right-of-use assets obtained in exchange for new lease liabilities $ 3,458 $ 6,543 $ 37,007 $ 14,489
Supplemental Balance Sheet Information	As of September 30, ($ in thousands) 2024 2023 Right-of-use assets $ 184,166 $ 155,662 Lease liabilities $ 224,776 $ 188,141 Weighted-average remaining lease term 7.4 years 6.9 years Weighted-average discount rate 5.53 % 4.55 %
Maturities of Operating Lease Liabilities	Contractual maturities of the Company’s future minimum lease payments are as follows: (In thousands) September 30, 2024 Contractual Maturities: 2024 $ 13,277 2025 46,867 2026 40,116 2027 31,122 2028 29,436 Thereafter 109,555 Total undiscounted future minimum lease payments 270,373 Less: Discount impact 45,597 Total lease liability $ 224,776

Business Segments (Tables)

Business Segments (Tables)	9 Months Ended
	Sep. 30, 2024
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 September 30, 2024 Insurance $ 2,564,490 $ 253,234 $ 9,189 $ 2,826,913 $ 469,421 $ 363,026 Reinsurance & Monoline Excess 362,333 57,037 — 419,370 105,225 82,659 Corporate, other and eliminations (3) — 13,485 148,697 162,182 (92,111) (72,008) Net investment losses — — (8,086) (8,086) (8,086) (8,043) Total $ 2,926,823 $ 323,756 $ 149,800 $ 3,400,379 $ 474,449 $ 365,634 Three months ended September 30, 2023 Insurance $ 2,291,917 $ 204,030 $ 9,143 $ 2,505,090 $ 410,909 $ 326,086 Reinsurance & Monoline Excess 349,997 59,021 — 409,018 110,442 86,747 Corporate, other and eliminations (3) — 7,893 151,063 158,956 (58,976) (46,226) Net investment losses — — (42,426) (42,426) (42,426) (33,021) Total $ 2,641,914 $ 270,944 $ 117,780 $ 3,030,638 $ 419,949 $ 333,586 Nine months ended September 30, 2024 Insurance $ 7,447,828 $ 801,573 $ 28,202 $ 8,277,603 $ 1,437,623 $ 1,102,363 Reinsurance & Monoline Excess 1,089,757 168,721 — 1,258,478 357,299 282,423 Corporate, other and eliminations (3) — 45,429 430,492 475,921 (217,912) (169,764) Net investment losses — — (40,818) (40,818) (40,818) (35,008) Total $ 8,537,585 $ 1,015,723 $ 417,876 $ 9,971,184 $ 1,536,192 $ 1,180,014 Nine months ended September 30, 2023 Insurance $ 6,650,027 $ 552,917 $ 27,570 $ 7,230,514 $ 1,149,886 $ 900,434 Reinsurance & Monoline Excess 1,036,046 155,790 — 1,191,836 317,146 251,420 Corporate, other and eliminations (3) — 30,787 429,180 459,967 (253,066) (199,040) Net investment gains — — 39,239 39,239 39,239 31,206 Total $ 7,686,073 $ 739,494 $ 495,989 $ 8,921,556 $ 1,253,205 $ 984,020 _________________ (1) Certain amounts included in earned premiums of each segment are related to inter-segment transactions. (2) Revenues for Insurance from foreign operations for the three months ended September 30, 2024 and 2023 were $350 million and $298 million, respectively, and for the nine months ended September 30, 2024 and 2023 were $1,112 million and $852 million, respectively. Revenues for Reinsurance & Monoline Excess from foreign operations for the three months ended September 30, 2024 and 2023 were $125 million and $124 million, respectively, and for the nine months ended September 30, 2024 and 2023 were $353 million and $333 million, respectively.
Identifiable Assets By Segment	(In thousands) September 30, December 31, Insurance $ 32,687,852 $ 29,923,282 Reinsurance & Monoline Excess 5,842,643 5,545,249 Corporate, other and eliminations 1,828,803 1,643,299 Consolidated $ 40,359,298 $ 37,111,830
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 Nine Months (In thousands) 2024 2023 2024 2023 Insurance: Other liability $ 1,031,087 $ 916,394 $ 3,000,335 $ 2,660,850 Short-tail lines (1) 563,736 472,805 1,613,342 1,330,173 Auto 376,762 327,507 1,092,354 929,201 Workers' compensation 313,154 300,694 925,214 905,405 Professional liability 279,751 274,517 816,583 824,398 Total Insurance 2,564,490 2,291,917 7,447,828 6,650,027 Reinsurance & Monoline Excess: Casualty (2) 188,284 201,795 585,208 618,855 Property (2) 108,386 87,838 308,024 239,338 Monoline excess (3) 65,663 60,364 196,525 177,853 Total Reinsurance & Monoline Excess 362,333 349,997 1,089,757 1,036,046 Total $ 2,926,823 $ 2,641,914 $ 8,537,585 $ 7,686,073 ______________ (1) Short-tail lines include commercial multi-peril (non-liability), inland marine, accident and health, fidelity and surety, boiler and machinery, high net worth homeowners and other lines. (2) Includes reinsurance casualty and property and certain program management business.

Per Share Data (Narrative) (Det

Per Share Data (Narrative) (Details) - shares	9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023
Earnings Per Share [Abstract]
Weighted average number of shares held in grantor trust (in shares)	17,495,175,000	17,125,284

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		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Earnings Per Share [Abstract]
Basic (shares)	398,338	403,787	400,302	407,484
Diluted (shares)	401,817	407,158	404,053	411,219

Consolidated Statements of Co_4

Consolidated Statements of Comprehensive (Loss) Income (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning of period			$ 7,469,237
Other comprehensive income (loss)	$ 430,496	$ (141,146)	322,693	$ (58,237)
End of period	8,439,402		8,439,402
Net realized and unrealized (losses) gains on investments	(23,362)	(40,855)	(72,165)	50,403
Income before income taxes	474,449	419,949	1,536,192	1,253,205
Tax effect	(109,135)	(86,519)	(356,958)	(268,322)
Net income before noncontrolling interests	365,314	333,430	1,179,234	984,883
Total change in unrealized investment gains (losses)	480,768	(150,455)	370,831	(62,476)
Net change in period	49,503	(22,781)	25,160	(7,387)
Other comprehensive income (loss), pre-tax	530,271	(173,236)	395,991	(69,863)
Other comprehensive income (loss), tax effect	(99,775)	32,090	(73,298)	11,626
Other comprehensive income (loss), net of tax	430,496	(141,146)	322,693	(58,237)
Accumulated Other Comprehensive Income (Loss)
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning of period	(1,033,640)	(1,181,673)	(925,838)	(1,264,581)
Other comprehensive income before reclassifications	423,613	(155,799)	243,247	(110,474)
Amounts reclassified from AOCI	6,883	14,653	79,446	52,237
Other comprehensive income (loss)	430,496	(141,146)	322,693	(58,237)
Unrealized investment gain related to noncontrolling interest	0	0	1	(1)
End of period	(603,144)	(1,322,819)	(603,144)	(1,322,819)
Other comprehensive income (loss), net of tax	430,496	(141,146)	322,693	(58,237)
Accumulated Other Comprehensive Income (Loss) | Amounts reclassified from AOCI
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Income before income taxes	8,713	18,548	100,565	66,123
Tax effect	(1,830)	(3,895)	(21,119)	(13,886)
Net income before noncontrolling interests	6,883	14,653	79,446	52,237
Unrealized Investment (Losses) Gains
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning of period	(669,813)	(825,391)	(586,354)	(892,905)
Other comprehensive income before reclassifications	374,110	(133,018)	218,087	(103,087)
Amounts reclassified from AOCI	6,883	14,653	79,446	52,237
Other comprehensive income (loss)	380,993	(118,365)	297,533	(50,850)
Unrealized investment gain related to noncontrolling interest	0	0	1	(1)
End of period	(288,820)	(943,756)	(288,820)	(943,756)
Total change in unrealized investment gains (losses)	480,768	(150,455)	370,831	(62,476)
Unrealized investment gains, tax effect	(99,775)	32,090	(73,298)	11,626
Unrealized investment gains (losses), after-tax amounts	380,993	(118,365)	297,533	(50,850)
Other comprehensive income (loss), net of tax	380,993	(118,365)	297,533	(50,850)
Unrealized Investment (Losses) Gains | Amounts reclassified from AOCI
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Net realized and unrealized (losses) gains on investments	8,713	18,548	100,565	66,123
Tax effect	(1,830)	(3,895)	(21,119)	(13,886)
Net income before noncontrolling interests	6,883	14,653	79,446	52,237
Currency Translation Adjustments
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning of period	(363,827)	(356,282)	(339,484)	(371,676)
Other comprehensive income before reclassifications	49,503	(22,781)	25,160	(7,387)
Amounts reclassified from AOCI	0	0		0
Other comprehensive income (loss)	49,503	(22,781)	25,160	(7,387)
Unrealized investment gain related to noncontrolling interest		0	0	0
End of period	(314,324)	(379,063)	(314,324)	(379,063)
Currency translation adjustment, pre-tax	49,503	(22,781)	25,160	(7,387)
Currency translation adjustment, tax effect	0	0	0	0
Net change in period	49,503	(22,781)	25,160	(7,387)
Other comprehensive income (loss), net of tax	49,503	(22,781)	25,160	(7,387)
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

Statements of Cash Flows (Detai

Statements of Cash Flows (Details) - USD ($)	9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023
Supplemental Cash Flow Elements [Abstract]
Interest payments	$ 116,462,000	$ 79,336,000
Income taxes paid	$ 271,739,000	$ 180,000,000

Investments in Fixed Maturity_3

Investments in Fixed Maturity Securities (Investments in fixed maturity securities) (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Jun. 30, 2024	Dec. 31, 2023	Sep. 30, 2023	Jun. 30, 2023	Dec. 31, 2022
Debt Securities, Available-for-sale [Line Items]
Held to maturity, Amortized cost	$ 43,959		$ 53,415
Held-to-maturity, Allowance for Credit Loss	(30)	$ (34)	(43)	$ (48)	$ (53)	$ (114)
Held to maturity, Gross Unrealized Gains	2,053		3,239
Held to maturity, Gross Unrealized Losses	0		0
Total held to maturity, Fair Value	45,982		56,611
Held to maturity, Carrying Value	43,929		53,372
Total available for sale, Amortized Cost	22,959,189		20,861,830
Available-for-sale, Allowance for Credit Loss	(6,953)	(21,837)	(36,708)	(46,364)	(44,248)	(37,352)
Total available for sale, Gross Unrealized Gains	255,622		110,989
Total available for sale, Gross Unrealized Losses	(587,909)		(811,175)
Total available for sale, Fair Value	22,619,949		20,124,936
Total fixed maturity securities available for sale	22,619,949		20,124,936
Fixed maturity securities, amortized cost	23,003,148		20,915,245
Fixed maturity securities, allowance for credit loss	(6,983)		(36,751)
Total investments in fixed maturity securities, Gross Unrealized Gains	257,675		114,228
Total investments in fixed maturity securities, Gross Unrealized Losses	(587,909)		(811,175)
Total investments in fixed maturity securities, Fair Value	22,665,931		20,181,547
Total investments in fixed maturity securities, Carrying Value	22,663,878		20,178,308
State and municipal
Debt Securities, Available-for-sale [Line Items]
Held to maturity, Amortized cost	41,561		50,547
Held-to-maturity, Allowance for Credit Loss	(30)		(43)
Held to maturity, Gross Unrealized Gains	1,944		3,132
Held to maturity, Gross Unrealized Losses	0		0
Total held to maturity, Fair Value	43,475		53,636
Held to maturity, Carrying Value	41,531		50,504
Total available for sale, Amortized Cost	2,567,941		2,742,922
Available-for-sale, Allowance for Credit Loss	0	(339)	(757)	(821)	0	0
Total available for sale, Gross Unrealized Gains	18,569		14,719
Total available for sale, Gross Unrealized Losses	(70,208)		(122,462)
Total available for sale, Fair Value	2,516,302		2,634,422
Total fixed maturity securities available for sale	2,516,302		2,634,422
Residential mortgage-backed
Debt Securities, Available-for-sale [Line Items]
Held to maturity, Amortized cost	2,398		2,868
Held-to-maturity, Allowance for Credit Loss	0		0
Held to maturity, Gross Unrealized Gains	109		107
Held to maturity, Gross Unrealized Losses	0		0
Total held to maturity, Fair Value	2,507		2,975
Held to maturity, Carrying Value	2,398		2,868
Total available for sale, Amortized Cost	2,736,493		1,773,206
Available-for-sale, Allowance for Credit Loss	0		0
Total available for sale, Gross Unrealized Gains	31,527		12,780
Total available for sale, Gross Unrealized Losses	(130,929)		(163,844)
Total available for sale, Fair Value	2,637,091		1,622,142
Total fixed maturity securities available for sale	2,637,091		1,622,142
U.S. government and government agency
Debt Securities, Available-for-sale [Line Items]
Total available for sale, Amortized Cost	2,083,085		1,762,997
Available-for-sale, Allowance for Credit Loss	0		0
Total available for sale, Gross Unrealized Gains	23,974		11,403
Total available for sale, Gross Unrealized Losses	(36,074)		(57,669)
Total available for sale, Fair Value	2,070,985		1,716,731
Total fixed maturity securities available for sale	2,070,985		1,716,731
Special revenue
Debt Securities, Available-for-sale [Line Items]
Total available for sale, Amortized Cost	1,732,996		1,682,550
Available-for-sale, Allowance for Credit Loss	0		0
Total available for sale, Gross Unrealized Gains	8,414		5,651
Total available for sale, Gross Unrealized Losses	(51,652)		(82,006)
Total available for sale, Fair Value	1,689,758		1,606,195
Total fixed maturity securities available for sale	1,689,758		1,606,195
State general obligation
Debt Securities, Available-for-sale [Line Items]
Total available for sale, Amortized Cost	273,232		394,429
Available-for-sale, Allowance for Credit Loss	0		0
Total available for sale, Gross Unrealized Gains	4,565		3,550
Total available for sale, Gross Unrealized Losses	(7,375)		(16,405)
Total available for sale, Fair Value	270,422		381,574
Total fixed maturity securities available for sale	270,422		381,574
Pre-refunded
Debt Securities, Available-for-sale [Line Items]
Total available for sale, Amortized Cost	85,683		103,029
Available-for-sale, Allowance for Credit Loss	0		0
Total available for sale, Gross Unrealized Gains	1,260		1,634
Total available for sale, Gross Unrealized Losses	(90)		(185)
Total available for sale, Fair Value	86,853		104,478
Total fixed maturity securities available for sale	86,853		104,478
Corporate backed
Debt Securities, Available-for-sale [Line Items]
Total available for sale, Amortized Cost	168,276		166,873
Available-for-sale, Allowance for Credit Loss	0		(757)
Total available for sale, Gross Unrealized Gains	1,847		696
Total available for sale, Gross Unrealized Losses	(4,968)		(11,973)
Total available for sale, Fair Value	165,155		154,839
Total fixed maturity securities available for sale	165,155		154,839
Local general obligation
Debt Securities, Available-for-sale [Line Items]
Total available for sale, Amortized Cost	307,754		396,041
Available-for-sale, Allowance for Credit Loss	0		0
Total available for sale, Gross Unrealized Gains	2,483		3,188
Total available for sale, Gross Unrealized Losses	(6,123)		(11,893)
Total available for sale, Fair Value	304,114		387,336
Total fixed maturity securities available for sale	304,114		387,336
Commercial
Debt Securities, Available-for-sale [Line Items]
Total available for sale, Amortized Cost	600,597		657,157
Available-for-sale, Allowance for Credit Loss	(52)		(158)
Total available for sale, Gross Unrealized Gains	3,254		626
Total available for sale, Gross Unrealized Losses	(2,918)		(13,312)
Total available for sale, Fair Value	600,881		644,313
Total fixed maturity securities available for sale	600,881		644,313
Mortgage-backed
Debt Securities, Available-for-sale [Line Items]
Total available for sale, Amortized Cost	3,337,090		2,430,363
Available-for-sale, Allowance for Credit Loss	(52)	(1,140)	(158)	(2,100)	(885)	(18)
Total available for sale, Gross Unrealized Gains	34,781		13,406
Total available for sale, Gross Unrealized Losses	(133,847)		(177,156)
Total available for sale, Fair Value	3,237,972		2,266,455
Total fixed maturity securities available for sale	3,237,972		2,266,455
Asset-backed
Debt Securities, Available-for-sale [Line Items]
Total available for sale, Amortized Cost	4,118,052		4,252,883
Available-for-sale, Allowance for Credit Loss	(546)	(889)	(1,164)	(1,502)	(1,444)	0
Total available for sale, Gross Unrealized Gains	26,592		8,527
Total available for sale, Gross Unrealized Losses	(36,777)		(73,206)
Total available for sale, Fair Value	4,107,321		4,187,040
Total fixed maturity securities available for sale	4,107,321		4,187,040
Industrial
Debt Securities, Available-for-sale [Line Items]
Total available for sale, Amortized Cost	3,980,058		3,679,219
Available-for-sale, Allowance for Credit Loss	0		(40)
Total available for sale, Gross Unrealized Gains	55,042		24,312
Total available for sale, Gross Unrealized Losses	(80,692)		(143,936)
Total available for sale, Fair Value	3,954,408		3,559,555
Total fixed maturity securities available for sale	3,954,408		3,559,555
Financial
Debt Securities, Available-for-sale [Line Items]
Total available for sale, Amortized Cost	3,326,838		2,838,220
Available-for-sale, Allowance for Credit Loss	0		(4,986)
Total available for sale, Gross Unrealized Gains	54,929		14,681
Total available for sale, Gross Unrealized Losses	(33,205)		(68,681)
Total available for sale, Fair Value	3,348,562		2,779,234
Total fixed maturity securities available for sale	3,348,562		2,779,234
Utilities
Debt Securities, Available-for-sale [Line Items]
Total available for sale, Amortized Cost	774,956		701,865
Available-for-sale, Allowance for Credit Loss	0		0
Total available for sale, Gross Unrealized Gains	13,319		6,471
Total available for sale, Gross Unrealized Losses	(13,877)		(23,412)
Total available for sale, Fair Value	774,398		684,924
Total fixed maturity securities available for sale	774,398		684,924
Other
Debt Securities, Available-for-sale [Line Items]
Total available for sale, Amortized Cost	774,274		635,975
Available-for-sale, Allowance for Credit Loss	0		0
Total available for sale, Gross Unrealized Gains	4,715		1,605
Total available for sale, Gross Unrealized Losses	(3,593)		(7,234)
Total available for sale, Fair Value	775,396		630,346
Total fixed maturity securities available for sale	775,396		630,346
Corporate
Debt Securities, Available-for-sale [Line Items]
Total available for sale, Amortized Cost	8,856,126		7,855,279
Available-for-sale, Allowance for Credit Loss	0	0	(5,026)	(5,770)	(8,867)	(4,701)
Total available for sale, Gross Unrealized Gains	128,005		47,069
Total available for sale, Gross Unrealized Losses	(131,367)		(243,263)
Total available for sale, Fair Value	8,852,764		7,654,059
Total fixed maturity securities available for sale	8,852,764		7,654,059
Foreign government
Debt Securities, Available-for-sale [Line Items]
Total available for sale, Amortized Cost	1,996,895		1,817,386
Available-for-sale, Allowance for Credit Loss	(6,355)	$ (19,469)	(29,603)	$ (36,171)	$ (33,052)	$ (32,633)
Total available for sale, Gross Unrealized Gains	23,701		15,865
Total available for sale, Gross Unrealized Losses	(179,636)		(137,419)
Total available for sale, Fair Value	1,834,605		1,666,229
Total fixed maturity securities available for sale	$ 1,834,605		$ 1,666,229

Investments in Fixed Maturity_4

Investments in Fixed Maturity Securities (HTM Allowance for Credit Loss) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Debt Securities, Held-to-maturity, Allowance for Credit Loss [Roll Forward]
Allowance for expected credit losses, beginning of period	$ 34	$ 53	$ 43	$ 114
Change in expected credit losses	(4)	(5)	(13)	(66)
Allowance for expected credit losses, end of period	$ 30	$ 48	$ 30	$ 48

Investments in Fixed Maturity_5

Investments in Fixed Maturity Securities (AFS Allowance for Credit Loss) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Debt Securities, Available-for-sale, Allowance for Credit Loss [Roll Forward]
Balance, beginning of period	$ 21,837	$ 44,248	$ 36,708	$ 37,352
Change on securities for which credit losses were not previously recorded	47	2,482	2,048	4,973
Change on securities for which credit losses were previously recorded	(14,552)	(366)	(30,863)	4,046
Reduction due to disposals	(379)	0	(940)	(7)
Balance, end of period	6,953	46,364	6,953	46,364
Foreign government
Debt Securities, Available-for-sale, Allowance for Credit Loss [Roll Forward]
Balance, beginning of period	19,469	33,052	29,603	32,633
Change on securities for which credit losses were not previously recorded	47	0	347	0
Change on securities for which credit losses were previously recorded	(12,782)	3,119	(23,216)	3,538
Reduction due to disposals	(379)	0	(379)	0
Balance, end of period	6,355	36,171	6,355	36,171
Corporate
Debt Securities, Available-for-sale, Allowance for Credit Loss [Roll Forward]
Balance, beginning of period	0	8,867	5,026	4,701
Change on securities for which credit losses were not previously recorded	0	756	0	942
Change on securities for which credit losses were previously recorded	0	(3,853)	(5,026)	134
Reduction due to disposals	0	0	0	(7)
Balance, end of period	0	5,770	0	5,770
Mortgage-backed
Debt Securities, Available-for-sale, Allowance for Credit Loss [Roll Forward]
Balance, beginning of period	1,140	885	158	18
Change on securities for which credit losses were not previously recorded	0	905	1,701	1,766
Change on securities for which credit losses were previously recorded	(1,088)	310	(1,246)	316
Reduction due to disposals	0	0	(561)	0
Balance, end of period	52	2,100	52	2,100
Asset-backed
Debt Securities, Available-for-sale, Allowance for Credit Loss [Roll Forward]
Balance, beginning of period	889	1,444	1,164	0
Change on securities for which credit losses were not previously recorded	0	0	0	1,444
Change on securities for which credit losses were previously recorded	(343)	58	(618)	58
Reduction due to disposals	0	0	0	0
Balance, end of period	546	1,502	546	1,502
State and municipal
Debt Securities, Available-for-sale, Allowance for Credit Loss [Roll Forward]
Balance, beginning of period	339	0	757	0
Change on securities for which credit losses were not previously recorded	0	821	0	821
Change on securities for which credit losses were previously recorded	(339)	0	(757)	0
Reduction due to disposals	0	0	0	0
Balance, end of period	$ 0	$ 821	$ 0	$ 821

Investments in Fixed Maturity_6

Investments in Fixed Maturity Securities (Amortized cost and fair value of fixed maturity securities) (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Jun. 30, 2024	Dec. 31, 2023	Sep. 30, 2023	Jun. 30, 2023	Dec. 31, 2022
Investments, Debt and Equity Securities [Abstract]
Amortized Cost, Due in one year or less	$ 1,910,941
Amortized Cost, Due after one year through five years	9,907,127
Amortized Cost, Due after five years through ten years	4,282,838
Amortized Cost, Due after ten years	3,562,724
Amortized Cost, Mortgaged-backed securities	3,339,488
Total investments in fixed maturity securities, Amortized Value	23,003,118
Fair Value, Due in one year or less	1,886,626
Fair Value, Due after one year through five years	9,724,883
Fair Value, Due after five years through ten years	4,283,690
Fair Value, Due after ten years	3,530,253
Fair Value, Mortgage-backed securities	3,240,479
Total investments in fixed maturity securities, Fair Value	22,665,931		$ 20,181,547
Cumulative effect adjustment resulting from changes in accounting principles	$ 30	$ 34	$ 43	$ 48	$ 53	$ 114

Investments in Equity Securit_3

Investments in Equity Securities (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2024	Dec. 31, 2023
Debt Securities, Available-for-sale [Line Items]
Equity securities	$ 1,048,126	$ 1,090,347
Fair Value
Debt Securities, Available-for-sale [Line Items]
Cost	949,553	949,332
Gross Unrealized, Gains	168,682	194,881
Gross Unrealized, Losses	(70,109)	(53,866)
Equity securities	1,048,126	1,090,347
Fair Value | Common stock
Debt Securities, Available-for-sale [Line Items]
Cost	604,288	664,997
Gross Unrealized, Gains	157,761	191,806
Gross Unrealized, Losses	(60,382)	(18,749)
Equity securities	701,667	838,054
Fair Value | Preferred stocks
Debt Securities, Available-for-sale [Line Items]
Cost	345,265	284,335
Gross Unrealized, Gains	10,921	3,075
Gross Unrealized, Losses	(9,727)	(35,117)
Equity securities	346,459	252,293
Carrying Value
Debt Securities, Available-for-sale [Line Items]
Equity securities	1,048,126	1,090,347
Carrying Value | Common stock
Debt Securities, Available-for-sale [Line Items]
Equity securities	701,667	838,054
Carrying Value | Preferred stocks
Debt Securities, Available-for-sale [Line Items]
Equity securities	$ 346,459	$ 252,293

Arbitrage Trading Account (Deta

Arbitrage Trading Account (Details) - USD ($)	Sep. 30, 2024	Dec. 31, 2023
Derivative [Line Items]
Arbitrage trading account	$ 821,000,000	$ 938,000,000
Long | Options held
Derivative [Line Items]
Fair value of derivative	6,000,000
Notional amount of derivative	340,000,000
Short | Options held
Derivative [Line Items]
Fair value of derivative	36,000,000
Notional amount of derivative	$ 340,000,000

Net Investment Income (Details)

Net Investment Income (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Net Investment Income [Line Items]
Gross investment income	$ 326,374	$ 272,781	$ 1,023,430	$ 745,705
Investment expense	(2,618)	(1,837)	(7,707)	(6,211)
Net investment income	323,756	270,944	1,015,723	739,494
Fixed maturity securities, including cash and cash equivalents and loans receivable
Net Investment Income [Line Items]
Gross investment income	295,272	239,727	954,655	653,200
Arbitrage trading account (1)
Net Investment Income [Line Items]
Gross investment income	4,741	4,450	868	5,444
Equity securities
Net Investment Income [Line Items]
Gross investment income	12,203	12,714	35,924	41,714
Investment funds
Net Investment Income [Line Items]
Gross investment income	17,869	17,876	52,562	53,168
Real estate
Net Investment Income [Line Items]
Gross investment income	$ (3,711)	$ (1,986)	$ (20,579)	$ (7,821)

Investment Funds (Details)

Investment Funds (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended		18 Months Ended
	Jul. 01, 2022	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023	Jun. 30, 2022	Dec. 31, 2023
Schedule of Equity Method Investments [Line Items]
Unfunded commitments		$ 248,000		$ 248,000
Investment funds		1,607,381		1,607,381			$ 1,621,655
Income (Loss) from Investment Funds				868	$ 5,444
Written premiums ceded		576,002	$ 504,746	1,678,460	1,504,497
Fair Value
Schedule of Equity Method Investments [Line Items]
Trading account receivables from brokers and clearing organizations		410,756		410,756			303,614
Lifson Re
Schedule of Equity Method Investments [Line Items]
Percentage of reinsurance placements of share placed amounts	30%					22.50%
Written premiums ceded				315,000	348,000
Financial services
Schedule of Equity Method Investments [Line Items]
Investment funds		190,318		190,318			201,625
Income (Loss) from Investment Funds				11,471	(5,062)
Transportation
Schedule of Equity Method Investments [Line Items]
Investment funds		460,264		460,264			433,407
Income (Loss) from Investment Funds				(16,908)	(15,606)
Real Estate
Schedule of Equity Method Investments [Line Items]
Investment funds		300,937		300,937			344,278
Income (Loss) from Investment Funds				962	37,894
Energy
Schedule of Equity Method Investments [Line Items]
Investment funds		131,113		131,113			114,794
Income (Loss) from Investment Funds				9,473	3,921
Infrastructure
Schedule of Equity Method Investments [Line Items]
Investment funds		146,936		146,936			130,589
Income (Loss) from Investment Funds				12,730	7,813
Other funds
Schedule of Equity Method Investments [Line Items]
Investment funds		377,813		377,813			396,962
Income (Loss) from Investment Funds				(16,860)	$ (23,516)
Deferred compensation trust assets		$ 38,000		$ 38,000			$ 36,000

Real Estate (Details)

Real Estate (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Real Estate [Abstract]
Properties in operation	$ 1,069,589	$ 1,022,654
Properties under development	227,725	227,220
Total	$ 1,297,314	$ 1,249,874

Real Estate (Narrative) (Detail

Real Estate (Narrative) (Details) - USD ($)	9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Dec. 31, 2023
Real Estate [Abstract]
Accumulated depreciation and amortization on properties	$ 36,999,000		$ 32,745,000
Real estate depreciation expense	6,401,000	$ 6,667,000
Lease future minimum payments 2021	8,884,653
Lease future minimum payments 2022	34,771,667
Lease future minimum payments 2023	33,308,460
Lease future minimum payments 2024	32,567,952
Lease future minimum payments 2025	33,133,057
Lease future minimum payments 2026	28,606,364
Lease future minimum payments there after	$ 415,176,586

Loans Receivable (Details)

Loans Receivable (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans receivable, Amortized cost	$ 389,869	$ 201,271
Loans receivable, Fair value	389,861	198,244
Real estate loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans receivable, Amortized cost	387,642	200,381
Loans receivable, Fair value	387,634	197,354
Commercial loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans receivable, Amortized cost	2,227	890
Loans receivable, Fair value	$ 2,227	$ 890
Loans receivable maturity term	5 years

Loans Receivable - Allowance Fo

Loans Receivable - Allowance For Credit Loss (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for expected credit losses, beginning of period	$ 1,813	$ 4,550	$ 3,004	$ 1,791
Change in expected credit losses	(388)	(541)	(1,579)	2,218
Allowance for expected credit losses, end of period	1,425	4,009	1,425	4,009
Real estate loans
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for expected credit losses, beginning of period	1,793	3,658	2,983	1,100
Change in expected credit losses	(391)	(256)	(1,581)	2,302
Allowance for expected credit losses, end of period	1,402	3,402	1,402	3,402
Commercial loans
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for expected credit losses, beginning of period	20	892	21	691
Change in expected credit losses	3	(285)	2	(84)
Allowance for expected credit losses, end of period	$ 23	$ 607	$ 23	$ 607

Net Investment (Losses) Gains_2

Net Investment (Losses) Gains (Net Investment Gains (Losses)) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Investments, Debt and Equity Securities [Abstract]
Fixed maturity securities, gains	$ 4,799	$ 299	$ 11,448	$ 1,357
Fixed maturity securities, losses	(3,884)	(2,700)	(11,569)	(24,470)
Net realized gains on investment sales (2)	407	23,631	102,205	135,763
Change in unrealized (losses) gains	(1,537)	(19,059)	(42,442)	45,605
Investment funds	(101)	(3,329)	1,109	(3,417)
Real estate (3)	1,470	(24,234)	(2,704)	(68,944)
Loans receivable	0	(1,428)	0	(1,428)
Other (4)	(24,516)	(14,035)	(130,212)	(34,063)
Net realized and unrealized (losses) gains on investments in earnings before allowance for expected credit losses	(23,362)	(40,855)	(72,165)	50,403
Fixed maturity securities	14,888	(2,112)	29,768	(8,946)
Loans receivable	388	541	1,579	(2,218)
Change in allowance for expected credit losses on investments	15,276	(1,571)	31,347	(11,164)
Net investment (losses) gains	(8,086)	(42,426)	(40,818)	39,239
Income tax benefit (expense)	$ 43	9,405	$ 5,810	(8,033)
After-tax net investment (losses) gains		$ (33,021)		$ 31,206

Net Investment (Losses) Gains_3

Net Investment (Losses) Gains (Change in Unrealized Gains (Losses) of Available For Sales Securities) (Details) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended		9 Months Ended
	Jun. 30, 2023	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Realized and Unrealized Investment Gains Losses [Line Items]
Total change in unrealized investment gains (losses)		$ 480,768	$ (150,455)	$ 370,831	$ (62,476)
Income tax (expense) benefit		(99,775)	32,090	(73,298)	11,626
Noncontrolling interests		0	0	1	(1)
Total change in unrealized gains		380,993	(118,365)	297,534	(50,851)
Gain on sale of investment	$ 88,000
Real estate impairment			21,000		72,000
Debt securities
Realized and Unrealized Investment Gains Losses [Line Items]
Total change in unrealized investment gains (losses)		463,418	(136,388)	363,430	(57,293)
Fixed maturity securities with allowance for expected credit losses
Realized and Unrealized Investment Gains Losses [Line Items]
Total change in unrealized investment gains (losses)		11,166	(10,244)	4,470	(3,094)
Investment funds
Realized and Unrealized Investment Gains Losses [Line Items]
Total change in unrealized investment gains (losses)		6,152	(3,217)	3,112	(818)
Other
Realized and Unrealized Investment Gains Losses [Line Items]
Total change in unrealized investment gains (losses)		$ 32	$ (606)	$ (181)	$ (1,271)

Fixed Maturity Securities In _3

Fixed Maturity Securities In An Unrealized Loss Position (Securities in an Unrealized Loss Position) (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Debt securities
Debt Securities, Available-for-sale [Line Items]
Fair value, Less than 12 months	$ 1,421,474	$ 2,420,657
Gross Unrealized Losses, Less than 12 Months	30,142	27,496
Fair Value, 12 Months or Greater	8,116,556	11,043,923
Gross Unrealized Losses, 12 Months or Greater	557,767	783,679
Fair Value, Total	9,538,030	13,464,580
Gross Unrealized Losses, Total	587,909	811,175
U.S. government and government agency
Debt Securities, Available-for-sale [Line Items]
Fair value, Less than 12 months	142,850	384,392
Gross Unrealized Losses, Less than 12 Months	3,128	6,655
Fair Value, 12 Months or Greater	586,823	614,623
Gross Unrealized Losses, 12 Months or Greater	32,946	51,014
Fair Value, Total	729,673	999,015
Gross Unrealized Losses, Total	36,074	57,669
State and municipal
Debt Securities, Available-for-sale [Line Items]
Fair value, Less than 12 months	119,658	264,273
Gross Unrealized Losses, Less than 12 Months	2,875	3,013
Fair Value, 12 Months or Greater	1,636,735	1,680,034
Gross Unrealized Losses, 12 Months or Greater	67,333	119,449
Fair Value, Total	1,756,393	1,944,307
Gross Unrealized Losses, Total	70,208	122,462
Mortgage-backed
Debt Securities, Available-for-sale [Line Items]
Fair value, Less than 12 months	237,206	278,819
Gross Unrealized Losses, Less than 12 Months	925	2,025
Fair Value, 12 Months or Greater	1,162,601	1,360,748
Gross Unrealized Losses, 12 Months or Greater	132,922	175,131
Fair Value, Total	1,399,807	1,639,567
Gross Unrealized Losses, Total	133,847	177,156
Asset-backed
Debt Securities, Available-for-sale [Line Items]
Fair value, Less than 12 months	471,907	413,511
Gross Unrealized Losses, Less than 12 Months	1,236	2,070
Fair Value, 12 Months or Greater	787,420	2,176,035
Gross Unrealized Losses, 12 Months or Greater	35,541	71,136
Fair Value, Total	1,259,327	2,589,546
Gross Unrealized Losses, Total	36,777	73,206
Corporate
Debt Securities, Available-for-sale [Line Items]
Fair value, Less than 12 months	308,606	874,754
Gross Unrealized Losses, Less than 12 Months	4,573	11,975
Fair Value, 12 Months or Greater	3,325,568	4,418,309
Gross Unrealized Losses, 12 Months or Greater	126,794	231,288
Fair Value, Total	3,634,174	5,293,063
Gross Unrealized Losses, Total	131,367	243,263
Foreign government
Debt Securities, Available-for-sale [Line Items]
Fair value, Less than 12 months	141,247	204,908
Gross Unrealized Losses, Less than 12 Months	17,405	1,758
Fair Value, 12 Months or Greater	617,409	794,174
Gross Unrealized Losses, 12 Months or Greater	162,231	135,661
Fair Value, Total	758,656	999,082
Gross Unrealized Losses, Total	$ 179,636	$ 137,419

Fixed Maturity Securities In _4

Fixed Maturity Securities In An Unrealized Loss Position (Non-Investment Grade Fixed Maturity Securities) (Details) - External Credit Rating, Non Investment Grade $ in Thousands	Sep. 30, 2024 USD ($)
Foreign government
Debt Securities, Available-for-sale [Line Items]
Number of Securities	62
Aggregate Fair Value	$ 146,049
Gross Unrealized Loss	$ 163,081
State and municipal
Debt Securities, Available-for-sale [Line Items]
Number of Securities	5
Aggregate Fair Value	$ 28,143
Gross Unrealized Loss	$ 1,894
Corporate
Debt Securities, Available-for-sale [Line Items]
Number of Securities	9
Aggregate Fair Value	$ 20,185
Gross Unrealized Loss	$ 568
Mortgage-backed
Debt Securities, Available-for-sale [Line Items]
Number of Securities	15
Aggregate Fair Value	$ 2,930
Gross Unrealized Loss	$ 143
Special revenue
Debt Securities, Available-for-sale [Line Items]
Number of Securities	91
Aggregate Fair Value	$ 197,307
Gross Unrealized Loss	$ 165,686

Fair Value Measurements (Assets

Fair Value Measurements (Assets and Liabilities Measured At Fair Value, On a Recurring Basis) (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Assets:
Total fixed maturity securities available for sale	$ 22,619,949	$ 20,124,936
Equity securities	1,048,126	1,090,347
Arbitrage trading account	821,000	938,000
Fair Value, Measurements, Recurring
Assets:
Total fixed maturity securities available for sale	22,619,949	20,124,936
Equity securities	1,048,126	1,090,347
Arbitrage trading account	820,928	938,049
Total	24,489,003	22,153,332
Liabilities:
Trading account securities sold but not yet purchased	36,093	9,357
Fair Value, Measurements, Recurring | U.S. government and government agency
Assets:
Total fixed maturity securities available for sale	2,070,985	1,716,731
Fair Value, Measurements, Recurring | State and municipal
Assets:
Total fixed maturity securities available for sale	2,516,302	2,634,422
Fair Value, Measurements, Recurring | Mortgage-backed
Assets:
Total fixed maturity securities available for sale	3,237,972	2,266,455
Fair Value, Measurements, Recurring | Asset-backed
Assets:
Total fixed maturity securities available for sale	4,107,321	4,187,040
Fair Value, Measurements, Recurring | Corporate
Assets:
Total fixed maturity securities available for sale	8,852,764	7,654,059
Fair Value, Measurements, Recurring | Foreign government
Assets:
Total fixed maturity securities available for sale	1,834,605	1,666,229
Fair Value, Measurements, Recurring | Common stocks
Assets:
Equity securities	701,667	838,054
Fair Value, Measurements, Recurring | Preferred stocks
Assets:
Equity securities	346,459	252,293
Level 1 | Fair Value, Measurements, Recurring
Assets:
Total fixed maturity securities available for sale	0	0
Equity securities	698,364	835,338
Arbitrage trading account	728,783	546,110
Total	1,427,147	1,381,448
Liabilities:
Trading account securities sold but not yet purchased	36,093	9,357
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	698,364	835,338
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	22,619,949	20,124,936
Equity securities	343,953	249,756
Arbitrage trading account	88,397	388,167
Total	23,052,299	20,762,859
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	2,070,985	1,716,731
Level 2 | Fair Value, Measurements, Recurring | State and municipal
Assets:
Total fixed maturity securities available for sale	2,516,302	2,634,422
Level 2 | Fair Value, Measurements, Recurring | Mortgage-backed
Assets:
Total fixed maturity securities available for sale	3,237,972	2,266,455
Level 2 | Fair Value, Measurements, Recurring | Asset-backed
Assets:
Total fixed maturity securities available for sale	4,107,321	4,187,040
Level 2 | Fair Value, Measurements, Recurring | Corporate
Assets:
Total fixed maturity securities available for sale	8,852,764	7,654,059
Level 2 | Fair Value, Measurements, Recurring | Foreign government
Assets:
Total fixed maturity securities available for sale	1,834,605	1,666,229
Level 2 | Fair Value, Measurements, Recurring | Common stocks
Assets:
Equity securities	1,130	1,158
Level 2 | Fair Value, Measurements, Recurring | Preferred stocks
Assets:
Equity securities	342,823	248,598
Level 3 | Fair Value, Measurements, Recurring
Assets:
Total fixed maturity securities available for sale	0	0
Equity securities	5,809	5,253
Arbitrage trading account	3,748	3,772
Total	9,557	9,025
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	0
Level 3 | Fair Value, Measurements, Recurring | Foreign government
Assets:
Total fixed maturity securities available for sale	0	0
Level 3 | Fair Value, Measurements, Recurring | Common stocks
Assets:
Equity securities	2,173	1,558
Level 3 | Fair Value, Measurements, Recurring | Preferred stocks
Assets:
Equity securities	$ 3,636	$ 3,695

Fair Value Measurements (Summar

Fair Value Measurements (Summarize Changes in Level 3 Assets) (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2024	Dec. 31, 2023
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Assets, beginning balance	$ 9,025	$ 17,488
Assets, earnings	718	(927)
Assets, other comprehensive income	0	0
Assets, Impairments	0	(7,601)
Assets, purchases	0	0
Assets, (sales)	(223)	0
Assets, maturities	0	0
Assets. transfers out	37	65
Assets, ending balance	9,557	9,025
Equity securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Assets, beginning balance	5,253	13,898
Assets, earnings	741	(1,044)
Assets, other comprehensive income	0	0
Assets, Impairments	0	(7,601)
Assets, purchases	0	0
Assets, (sales)	(185)	0
Assets, maturities	0	0
Assets. transfers out	0	0
Assets, ending balance	5,809	5,253
Common stock
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Assets, beginning balance	1,558	2,599
Assets, earnings	743	(1,041)
Assets, other comprehensive income	0	0
Assets, Impairments	0	0
Assets, purchases	0	0
Assets, (sales)	(128)	0
Assets, maturities	0	0
Assets. transfers out	0	0
Assets, ending balance	2,173	1,558
Preferred stocks
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Assets, beginning balance	3,695	11,299
Assets, earnings	(2)	(3)
Assets, other comprehensive income	0	0
Assets, Impairments	0	(7,601)
Assets, purchases	0	0
Assets, (sales)	(57)	0
Assets, maturities	0	0
Assets. transfers out	0	0
Assets, ending balance	3,636	3,695
Arbitrage trading account
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Assets, beginning balance	3,772	3,590
Assets, earnings	(23)	117
Assets, other comprehensive income	0	0
Assets, Impairments	0	0
Assets, purchases	0	0
Assets, (sales)	(38)	0
Assets, maturities	0	0
Assets. transfers out	37	65
Assets, ending balance	$ 3,748	$ 3,772

Reserves for Loss and Loss Ex_3

Reserves for Loss and Loss Expenses (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Dec. 31, 2023
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Net reserves at beginning of period	$ 15,661,820	$ 14,248,879
Net provision for losses and loss expenses:
Claims occurring during the current year	5,229,468	4,694,554
Decrease in estimates for claims occurring in prior years	15,279	27,186
Loss reserve discount accretion	25,587	22,862
Liability for Unpaid Claims and Claims Adjustment Expense, Incurred Claims	5,270,334	4,744,602
Net payments for claims:
Current year	795,792	743,416
Prior years	3,164,720	2,915,979
Total	3,960,512	3,659,395
Foreign currency translation	19,659	(48,162)
Net reserves at end of period	16,991,301	15,285,924	$ 15,661,820
Ceded reserves at end of period	3,164,009	2,987,386
Gross reserves at end of period	$ 20,155,310	$ 18,273,310	$ 18,739,652

Reserves for Loss and Loss Ex_4

Reserves for Loss and Loss Expenses (Narrative) (Details) - USD ($)	9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023
Liability for Claims and Claims Adjustment Expense [Line Items]
Net of loss reserves discount	$ 37,000,000	$ 35,000,000
Increase (decrease) in estimates for claims	12,000,000	(12,000,000)
Adjustment expense	(3,000,000)	20,000,000
Liability recognized for best estimate net of reinsurance	382,000,000
Liability recognized for best estimate net of reinsurance, reported losses	379,000,000
Liability recognized for best estimate net of reinsurance, incurred but not reported (IBNR)	3,000,000
Insurance
Liability for Claims and Claims Adjustment Expense [Line Items]
Liability recognized for best estimate net of reinsurance	325,000,000
Unfavorable reserve development net of premium offsets	2,000,000	21,000,000
Reinsurance & Monoline Excess
Liability for Claims and Claims Adjustment Expense [Line Items]
Liability recognized for best estimate net of reinsurance	57,000,000
Favorable reserve development net of premium offsets	$ 5,000,000	$ 1,000,000

Fair Value of Financial Instr_3

Fair Value of Financial Instruments (Carrying Amounts and Estimated Fair Values of Financial Instruments) (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Assets:
Equity securities	$ 1,048,126	$ 1,090,347
Arbitrage trading account	821,000	938,000
Carrying Value
Assets:
Fixed maturity securities	22,663,878	20,178,308
Equity securities	1,048,126	1,090,347
Arbitrage trading account	820,928	938,049
Loans receivable	389,869	201,271
Cash and cash equivalents	1,573,238	1,363,195
Trading account receivables from brokers and clearing organizations	410,756	303,614
Due from broker	0	36,747
Liabilities:
Due to broker	85,920	0
Trading account securities sold but not yet purchased	36,093	9,357
Senior notes and other debt	1,827,788	1,827,951
Subordinated debentures	1,009,629	1,009,090
Fair Value
Assets:
Fixed maturity securities	22,665,931	20,181,547
Equity securities	1,048,126	1,090,347
Arbitrage trading account	820,928	938,049
Loans receivable	389,861	198,244
Cash and cash equivalents	1,573,238	1,363,195
Trading account receivables from brokers and clearing organizations	410,756	303,614
Due from broker	0	36,747
Liabilities:
Due to broker	85,920	0
Trading account securities sold but not yet purchased	36,093	9,357
Senior notes and other debt	1,522,430	1,480,076
Subordinated debentures	$ 922,564	$ 929,598

Premiums and Reinsurance Rela_3

Premiums and Reinsurance Related Information (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Written premiums:
Written premiums, direct	$ 3,303,682	$ 3,037,932	$ 9,723,219	$ 8,762,249
Written premiums, assumed	329,596	315,273	990,587	977,047
Written premiums, ceded	(576,002)	(504,746)	(1,678,460)	(1,504,497)
Total net premiums written	3,057,276	2,848,459	9,035,346	8,234,799
Earned premiums:
Earned premiums, direct	3,141,883	2,825,176	9,127,399	8,217,888
Earned premiums, assumed	346,780	316,134	1,012,804	913,795
Earned premiums, ceded	(561,840)	(499,396)	(1,602,618)	(1,445,610)
Net premiums earned	2,926,823	2,641,914	8,537,585	7,686,073
Ceded losses and loss expenses incurred	319,472	320,995	952,666	970,267
Ceded commissions earned	$ 129,916	$ 118,207	$ 374,618	$ 354,148

Premiums and Reinsurance Rela_4

Premiums and Reinsurance Related Information - Premiums and Reinsurance, Allowance For Credit Loss (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Premium Receivable, Allowance for Credit Loss [Roll Forward]
Allowance for expected credit losses, beginning of period	$ 37,279	$ 32,770	$ 35,110	$ 30,660
Cumulative effect adjustment resulting from changes in accounting principles	38,071	33,602	38,071	33,602
Change in expected credit losses	792	832	2,961	2,942
Allowance for expected credit losses, end of period	38,071	33,602	38,071	33,602
Reinsurance Recoverable, Allowance for Credit Loss [Roll Forward]
Allowance for expected credit losses, beginning of period	10,255	9,365	8,404	8,064
Cumulative effect adjustment resulting from changes in accounting principles	8,332	9,443	8,332	9,443
Reinsurance Recoverable, Credit Loss Expense (Reversal)	(1,923)	78	(72)	1,379
Allowance for expected credit losses, end of period	$ 8,332	$ 9,443	$ 8,332	$ 9,443

Restricted Stock Units (Summary

Restricted Stock Units (Summary of Restricted Stock Units Issued) (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023
Share-Based Compensation Arrangement by Share-based Payment Award [Line Item]
Share based compensation expense	$ 38,000	$ 36,000
Restricted stock
Share-Based Compensation Arrangement by Share-based Payment Award [Line Item]
Restricted stock units (in units)	1,215,623	1,638,195
Fair Value	$ 70,195	$ 68,936
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

Litigation and Contingent Lia_2

Litigation and Contingent Liabilities (Details) $ in Millions	Dec. 22, 2023 USD ($)
Subsidiary of Common Parent | Reinsurance Recovery Lawsuit | Pending Litigation
Gain Contingencies [Line Items]
Gain Contingency, Unrecorded Amount	$ 90

Leases (Lease Cost) (Details)

Leases (Lease Cost) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Leases [Abstract]
Lease cost	$ 11,230	$ 10,122	$ 33,633	$ 30,448
Cash paid for amounts included in the measurement of lease liabilities reported in operating cash flows	12,222	11,403	36,818	33,247
Right-of-use assets obtained in exchange for new lease liabilities	$ 3,458	$ 6,543	$ 37,007	$ 14,489

Leases (Supplemental Balance Sh

Leases (Supplemental Balance Sheet Information) (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Sep. 30, 2023
Leases [Abstract]
Operating lease, right-of-use asset	$ 184,166	$ 155,662
Operating lease, liability	$ 224,776	$ 188,141
Weighted-average remaining lease term	7 years 4 months 24 days	6 years 10 months 24 days
Weighted-average discount rate	5.53%	4.55%

Leases (Maturities of Operating

Leases (Maturities of Operating Lease Liabilities) (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Sep. 30, 2023
Leases [Abstract]
2024	$ 13,277
2025	46,867
2026	40,116
2027	31,122
2028	29,436
Thereafter	109,555
Total undiscounted future minimum lease payments	270,373
Less: Discount impact	45,597
Total lease liability	$ 224,776	$ 188,141

Business Segments (Financial In

Business Segments (Financial Information of Company Operating Segments) (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024 USD ($)	Sep. 30, 2023 USD ($)	Sep. 30, 2024 USD ($) segment	Sep. 30, 2023 USD ($)
Segment Reporting [Abstract]
Number of reportable segments | segment			2
Segment Reporting Information [Line Items]
Earned Premiums (1)	$ 2,926,823	$ 2,641,914	$ 8,537,585	$ 7,686,073
Investment Income	323,756	270,944	1,015,723	739,494
Other	149,800	117,780	417,876	495,989
Total revenues	3,400,379	3,030,638	9,971,184	8,921,556
Pre-Tax Income (Loss)	474,449	419,949	1,536,192	1,253,205
Net Income (Loss) to Common Stockholders	365,634	333,586	1,180,014	984,020
Net investment gains	(8,086)	(42,426)	(40,818)	39,239
Net investment gains, net of tax	(8,043)	(33,021)	(35,008)	31,206
Corporate, other and eliminations
Segment Reporting Information [Line Items]
Earned Premiums (1)	0	0	0	0
Investment Income	13,485	7,893	45,429	30,787
Other	148,697	151,063	430,492	429,180
Total revenues	162,182	158,956	475,921	459,967
Pre-Tax Income (Loss)	(92,111)	(58,976)	(217,912)	(253,066)
Net Income (Loss) to Common Stockholders	(72,008)	(46,226)	(169,764)	(199,040)
Insurance
Segment Reporting Information [Line Items]
Earned Premiums (1)		2,291,917		6,650,027
Insurance | Operating Segments
Segment Reporting Information [Line Items]
Earned Premiums (1)	2,564,490	2,291,917	7,447,828	6,650,027
Investment Income	253,234	204,030	801,573	552,917
Other	9,189	9,143	28,202	27,570
Total revenues	2,826,913	2,505,090	8,277,603	7,230,514
Pre-Tax Income (Loss)	469,421	410,909	1,437,623	1,149,886
Net Income (Loss) to Common Stockholders	363,026	326,086	1,102,363	900,434
Insurance | Operating Segments | Non-US
Segment Reporting Information [Line Items]
Total revenues	350,000	298,000	1,112,000	852,000
Reinsurance & Monoline Excess
Segment Reporting Information [Line Items]
Earned Premiums (1)		349,997		1,036,046
Reinsurance & Monoline Excess | Operating Segments
Segment Reporting Information [Line Items]
Earned Premiums (1)	362,333	349,997	1,089,757	1,036,046
Investment Income	57,037	59,021	168,721	155,790
Other	0	0	0	0
Total revenues	419,370	409,018	1,258,478	1,191,836
Pre-Tax Income (Loss)	105,225	110,442	357,299	317,146
Net Income (Loss) to Common Stockholders	82,659	86,747	282,423	251,420
Reinsurance & Monoline Excess | Operating Segments | Non-US
Segment Reporting Information [Line Items]
Total revenues	125,000	124,000	353,000	333,000
Net investment gains
Segment Reporting Information [Line Items]
Earned Premiums (1)	0	0	0	0
Investment Income	$ 0	$ 0	$ 0	$ 0

Business Segments (Identifiable

Business Segments (Identifiable Assets by Segment) (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Segment Reporting, Asset Reconciling Item [Line Items]
Consolidated Assets	$ 40,359,298	$ 37,111,830
Operating Segments | Insurance
Segment Reporting, Asset Reconciling Item [Line Items]
Consolidated Assets	32,687,852	29,923,282
Operating Segments | Reinsurance & Monoline Excess
Segment Reporting, Asset Reconciling Item [Line Items]
Consolidated Assets	5,842,643	5,545,249
Corporate Reconciling Items And Eliminations
Segment Reporting, Asset Reconciling Item [Line Items]
Consolidated Assets	$ 1,828,803	$ 1,643,299

Business Segments (Net Premiums

Business Segments (Net Premiums Earned By Major Line of Business) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Revenue from External Customer [Line Items]
Net premiums earned	$ 2,926,823	$ 2,641,914	$ 8,537,585	$ 7,686,073
Insurance
Revenue from External Customer [Line Items]
Net premiums earned		2,291,917		6,650,027
Insurance | Operating Segments
Revenue from External Customer [Line Items]
Net premiums earned	2,564,490	2,291,917	7,447,828	6,650,027
Insurance | Other liability
Revenue from External Customer [Line Items]
Net premiums earned	1,031,087	916,394	3,000,335	2,660,850
Insurance | Short-tail lines
Revenue from External Customer [Line Items]
Net premiums earned	563,736	472,805	1,613,342	1,330,173
Insurance | Auto
Revenue from External Customer [Line Items]
Net premiums earned	376,762	327,507	1,092,354	929,201
Insurance | Workers' compensation
Revenue from External Customer [Line Items]
Net premiums earned	313,154	300,694	925,214	905,405
Insurance | Professional liability
Revenue from External Customer [Line Items]
Net premiums earned	279,751	274,517	816,583	824,398
Reinsurance & Monoline Excess
Revenue from External Customer [Line Items]
Net premiums earned		349,997		1,036,046
Reinsurance & Monoline Excess | Operating Segments
Revenue from External Customer [Line Items]
Net premiums earned	362,333	349,997	1,089,757	1,036,046
Reinsurance & Monoline Excess | Casualty
Revenue from External Customer [Line Items]
Net premiums earned	188,284	201,795	585,208	618,855
Reinsurance & Monoline Excess | Property
Revenue from External Customer [Line Items]
Net premiums earned	108,386	87,838	308,024	239,338
Reinsurance & Monoline Excess | Monoline excess
Revenue from External Customer [Line Items]
Net premiums earned	$ 65,663	$ 60,364	$ 196,525	$ 177,853