BERKLEY W R CORP, 10-Q filed on 8/4/2025
Quarterly Report
v3.25.2
Cover Page - shares
 6 Months Ended
Jun. 30, 2025
Jul. 29, 2025
Entity Information [Line Items]    
Document Type 10-Q  
Document Quarterly Report true  
Document Period End Date Jun. 30, 2025  
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 $.20 per share  
Trading Symbol WRB  
Security Exchange Name NYSE  
Entity Current Reporting Status Yes  
Entity Interactive Data Current Yes  
Entity Filer Category Large Accelerated Filer  
Entity Small Business false  
Entity Emerging Growth Company false  
Entity Shell Company false  
Entity Common Stock, Shares Outstanding   379,292,773
Entity Central Index Key 0000011544  
Current Fiscal Year End Date --12-31  
Document Fiscal Year Focus 2025  
Document Fiscal Period Focus Q2  
Amendment Flag false  
5.700% Subordinated Debentures due 2058    
Entity Information [Line Items]    
Title of 12(b) Security 5.700% Subordinated Debentures due 2058  
Trading Symbol WRB-PE  
Security Exchange Name NYSE  
5.100% Subordinated Debentures due 2059    
Entity Information [Line Items]    
Title of 12(b) Security 5.100% Subordinated Debentures due 2059  
Trading Symbol WRB-PF  
Security Exchange Name NYSE  
4.250% Subordinated Debentures due 2060    
Entity Information [Line Items]    
Title of 12(b) Security 4.250% Subordinated Debentures due 2060  
Trading Symbol WRB-PG  
Security Exchange Name NYSE  
4.125% Subordinated Debentures due 2061    
Entity Information [Line Items]    
Title of 12(b) Security 4.125% Subordinated Debentures due 2061  
Trading Symbol WRB-PH  
Security Exchange Name NYSE  
v3.25.2
Consolidated Balance Sheets Consolidated Balance Sheets - USD ($)
$ in Thousands
Jun. 30, 2025
Dec. 31, 2024
Investments:    
Fixed maturity securities (amortized cost of $24,369,703 and $23,010,899; allowance for expected credit losses of $332 and $671 at June 30, 2025 and December 31, 2024, respectively) $ 24,093,156 $ 22,397,865
Investment funds 1,492,258 1,468,246
Real estate 1,294,505 1,291,455
Equity securities 1,262,192 1,203,788
Arbitrage trading account 1,034,557 1,122,599
Loans receivable (net of allowance for expected credit losses of $369 and $1,114 at June 30, 2025 and December 31, 2024, respectively) 324,365 405,453
Total investments 29,501,033 27,889,406
Cash and cash equivalents 1,984,529 1,974,747
Premiums and fees receivable (net of allowance for expected credit losses of $38,960 and $39,884 at June 30, 2025 and December 31, 2024, respectively) 3,647,860 3,266,845
Due from reinsurers (net of allowance for expected credit losses of $6,954 and $8,350 at June 30, 2025 and December 31, 2024, respectively) 3,601,233 3,557,695
Deferred policy acquisition costs 1,017,073 951,728
Prepaid reinsurance premiums 872,539 823,207
Trading account receivables from brokers and clearing organizations 138,891 60,327
Property, furniture and equipment 490,121 478,511
Goodwill 184,332 184,332
Accrued investment income 259,308 243,772
Current and deferred federal and foreign income taxes 36,255 140,966
Other assets 924,883 877,099
Total assets 42,658,057 40,448,635
Liabilities:    
Reserves for losses and loss expenses 21,496,123 20,368,030
Unearned premiums 6,818,407 6,375,112
Due to reinsurers 644,608 668,652
Trading account securities sold but not yet purchased 30,909 73,358
Other liabilities 1,521,396 1,715,078
Subordinated debentures 1,010,168 1,009,808
Senior notes and other debt 1,831,638 1,831,158
Total liabilities 33,353,249 32,041,196
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 1,005,428 984,825
Retained earnings 12,829,755 12,265,070
Accumulated other comprehensive loss (572,384) (934,269)
Treasury stock, at cost, 414,136,477 and 413,455,739 shares, respectively (4,126,967) (4,079,220)
Total stockholders’ equity 9,294,537 8,395,111
Noncontrolling interests 10,271 12,328
Total equity 9,304,808 8,407,439
Total liabilities and equity $ 42,658,057 $ 40,448,635
v3.25.2
Consolidated Balance Sheets Consolidated Balance Sheets (Parenthetical) - USD ($)
$ in Thousands
Jun. 30, 2025
Dec. 31, 2024
Statement of Financial Position [Abstract]    
Fixed maturity securities, amortized cost $ 24,369,703 $ 23,010,899
Fixed maturity securities, allowance for credit loss 332 671
Cumulative effect adjustment resulting from changes in accounting principles 369 1,114
Cumulative effect adjustment resulting from changes in accounting principles 38,960 39,884
Reinsurance recoverable, allowance for credit loss $ 6,954 $ 8,350
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)   1,875,000,000
Common shares issued (in shares) 379,385,332 380,066,070
Common shares outstanding (in shares) 379,385,332 380,066,070
Treasury stock issued at cost (in shares) 414,136,477 413,455,739
v3.25.2
Consolidated Statements Income (Unaudited) - USD ($)
$ in Thousands
 3 Months Ended 6 Months Ended
Jun. 30, 2025
Jun. 30, 2024
Jun. 30, 2025
Jun. 30, 2024
REVENUES:        
Net premiums written $ 3,351,439 $ 3,126,779 $ 6,484,742 $ 5,978,070
Change in net unearned premiums (253,254) (280,364) (374,176) (367,308)
Net premiums earned 3,098,185 2,846,415 6,110,566 5,610,762
Net investment income 379,303 372,129 739,595 691,967
Net realized and unrealized gains (losses) on investments 30,533 (60,306) 46,244 (48,803)
Change in allowance for expected credit losses on investments 440 1,794 1,084 16,070
Net investment gains (losses) 30,973 (58,512) 47,328 (32,733)
Revenues from non-insurance businesses 128,839 125,705 257,748 246,696
Insurance service fees 32,757 27,597 61,686 52,917
Other income 751 698 1,284 1,196
Total revenues 3,670,808 3,314,032 7,218,207 6,570,805
OPERATING COSTS AND EXPENSES:        
Losses and loss expenses 1,955,424 1,780,596 3,856,216 3,444,374
Other operating costs and expenses 1,039,307 892,935 1,989,217 1,761,524
Expenses from non-insurance businesses 122,437 121,120 248,801 239,727
Interest expense 31,777 31,708 63,504 63,436
Total 3,148,945 2,826,359 6,157,738 5,509,061
Income before income taxes 521,863 487,673 1,060,469 1,061,744
Income tax expense (121,155) (115,788) (242,411) (247,824)
Net income before noncontrolling interests 400,708 371,885 818,058 813,920
Noncontrolling interests 580 24 802 460
Net Income (Loss) to Common Stockholders $ 401,288 $ 371,909 $ 818,860 $ 814,380
NET INCOME PER SHARE:        
Basic (in dollar per share) $ 1.01 $ 0.93 $ 2.06 $ 2.03
Diluted (in dollar per share) $ 1.00 $ 0.92 $ 2.05 $ 2.01
v3.25.2
Consolidated Statements of Comprehensive Income (Unaudited) - USD ($)
$ in Thousands
 3 Months Ended 6 Months Ended
Jun. 30, 2025
Jun. 30, 2024
Jun. 30, 2025
Jun. 30, 2024
Statement of Comprehensive Income [Abstract]        
Net income before noncontrolling interests $ 400,708 $ 371,885 $ 818,058 $ 813,920
Other comprehensive income (loss):        
Change in unrealized currency translation adjustments 69,418 3,227 93,348 (24,343)
Change in unrealized investment gains (losses), net of taxes 120,265 (13,338) 268,538 (83,460)
Other comprehensive income (loss) 189,683 (10,111) 361,886 (107,803)
Comprehensive income 590,391 361,774 1,179,944 706,117
Noncontrolling interests 580 23 803 459
Comprehensive income to common stockholders $ 590,971 $ 361,797 $ 1,180,747 $ 706,576
v3.25.2
Consolidated Statements of Stockholders' Equity (Unaudited) - USD ($)
$ in Thousands
Total
Common stock
Additional paid-in capital
Retained earnings
Unrealized investment losses:
Change in unrealized gains (losses) on securities without an allowance for expected credit losses
Change in unrealized gains (losses) on securities with an allowance for expected credit losses
Currency translation adjustments:
Accumulated Other Comprehensive Income (Loss)
Treasury stock
Noncontrolling interest
Increase (Decrease) in Stockholders' Equity [Roll Forward]                      
Cumulative effect adjustment resulting from changes in accounting principles   $ 158,705 $ 964,789 $ 11,040,908 $ (586,354)     $ (339,484) $ (925,838) $ (3,783,133) $ 13,806
Beginning of period at Dec. 31, 2023   158,705 964,789 11,040,908 (586,354)     (339,484) (925,838) (3,783,133) 13,806
Increase (Decrease) in Stockholders' Equity [Roll Forward]                      
Restricted stock units issued     (3,145)                
Restricted stock units expensed     25,248                
Net income before noncontrolling interests $ 813,920     814,380             (460)
Dividends ($0.59, $0.41, $0.67 and $0.49 per share, respectively)       (185,721)              
Change in unrealized gains (losses) on securities without an allowance for expected credit losses (83,460)         $ (76,763)          
Change in unrealized gains (losses) on securities with an allowance for expected credit losses             $ (6,696)        
Net change in period (24,343)             (24,343)      
Stock exercised/vested                   1,324  
Stock repurchased                   (223,763)  
Other (2,170)                    
Distributions                     (78)
Other comprehensive income (loss), net of tax $ (107,803)       (83,460)     (24,343) (107,803)   1
End of period at Jun. 30, 2024     986,892 11,669,567 (669,813)     (363,827) (1,033,640) (4,007,742) 13,269
Increase (Decrease) in Stockholders' Equity [Roll Forward]                      
Common stock dividends, per share, cash paid (in dollars per share) $ 0.49                    
Cumulative effect adjustment resulting from changes in accounting principles   158,705 977,573 11,455,158 (656,476)     (367,054) (1,023,530) (3,783,074) 13,680
Beginning of period at Mar. 31, 2024   158,705 977,573 11,455,158 (656,476)     (367,054) (1,023,530) (3,783,074) 13,680
Increase (Decrease) in Stockholders' Equity [Roll Forward]                      
Restricted stock units issued     (2,950)                
Restricted stock units expensed     12,269                
Net income before noncontrolling interests $ 371,885     371,909             (24)
Dividends ($0.59, $0.41, $0.67 and $0.49 per share, respectively)       (157,500)              
Change in unrealized gains (losses) on securities without an allowance for expected credit losses (13,338)         (5,654)          
Change in unrealized gains (losses) on securities with an allowance for expected credit losses             (7,683)        
Net change in period 3,227             3,227      
Stock exercised/vested                   1,265  
Stock repurchased                   (223,763)  
Other (2,170)                    
Distributions                     (388)
Other comprehensive income (loss), net of tax (10,111)       (13,338)     3,227 (10,111)   1
End of period at Jun. 30, 2024     986,892 11,669,567 (669,813)     (363,827) (1,033,640) (4,007,742) 13,269
Increase (Decrease) in Stockholders' Equity [Roll Forward]                      
Cumulative effect adjustment resulting from changes in accounting principles     986,892 11,669,567 (669,813)     (363,827) (1,033,640) (4,007,742) 13,269
Cumulative effect adjustment resulting from changes in accounting principles 8,407,439 158,705 984,825 12,265,070 (517,170)     (417,099) (934,269) (4,079,220) 12,328
Beginning of period at Dec. 31, 2024 8,407,439 158,705 984,825 12,265,070 (517,170)     (417,099) (934,269) (4,079,220) 12,328
Increase (Decrease) in Stockholders' Equity [Roll Forward]                      
Restricted stock units issued     (4,885)                
Restricted stock units expensed     25,488                
Net income before noncontrolling interests 818,058     818,860             (802)
Dividends ($0.59, $0.41, $0.67 and $0.49 per share, respectively)       (254,175)              
Change in unrealized gains (losses) on securities without an allowance for expected credit losses 268,538         268,610          
Change in unrealized gains (losses) on securities with an allowance for expected credit losses             (73)        
Net change in period 93,348             93,348      
Stock exercised/vested                   1,836  
Stock repurchased                   (49,202)  
Other (381)                    
Distributions                     (1,254)
Other comprehensive income (loss), net of tax 361,886       268,538     93,348 361,886   (1)
End of period at Jun. 30, 2025 $ 9,304,808   1,005,428 12,829,755 (248,633)     (323,751) (572,384) (4,126,967) 10,271
Increase (Decrease) in Stockholders' Equity [Roll Forward]                      
Common stock dividends, per share, cash paid (in dollars per share) $ 0.67                    
Cumulative effect adjustment resulting from changes in accounting principles   158,705 992,901 12,652,303 (368,898)     (393,169) (762,067) (4,127,803) 12,333
Beginning of period at Mar. 31, 2025   $ 158,705 992,901 12,652,303 (368,898)     (393,169) (762,067) (4,127,803) 12,333
Increase (Decrease) in Stockholders' Equity [Roll Forward]                      
Restricted stock units issued     (538)                
Restricted stock units expensed     13,065                
Net income before noncontrolling interests $ 400,708     401,288             (580)
Dividends ($0.59, $0.41, $0.67 and $0.49 per share, respectively)       (223,836)              
Change in unrealized gains (losses) on securities without an allowance for expected credit losses 120,265         $ 119,787          
Change in unrealized gains (losses) on securities with an allowance for expected credit losses             $ 478        
Net change in period 69,418             69,418      
Stock exercised/vested                   786  
Stock repurchased                   0  
Other 50                    
Distributions                     (1,482)
Other comprehensive income (loss), net of tax 189,683       120,265     69,418 189,683   0
End of period at Jun. 30, 2025 9,304,808   1,005,428 12,829,755 (248,633)     (323,751) (572,384) (4,126,967) 10,271
Increase (Decrease) in Stockholders' Equity [Roll Forward]                      
Cumulative effect adjustment resulting from changes in accounting principles $ 9,304,808   $ 1,005,428 $ 12,829,755 $ (248,633)     $ (323,751) $ (572,384) $ (4,126,967) $ 10,271
v3.25.2
Consolidated Statements of Cash Flows (Unaudited) - USD ($)
$ in Thousands
 6 Months Ended
Jun. 30, 2025
Jun. 30, 2024
CASH FROM OPERATING ACTIVITIES:    
Net income to common stockholders $ 818,860 $ 814,380
Adjustments to reconcile net income to net cash from operating activities:    
Net investment (gains) losses (47,328) 32,733
Depreciation and (accretion) amortization (23,755) (145,062)
Noncontrolling interests (802) (460)
Investment funds (54,291) 3,873
Stock incentive plans 27,487 26,856
Change in:    
Arbitrage trading account (32,970) 51,013
Premiums and fees receivable (362,327) (332,640)
Reinsurance accounts (133,771) 81,755
Deferred policy acquisition costs (65,570) (77,772)
Income taxes 28,500 27,699
Reserves for losses and loss expenses 1,067,618 852,523
Unearned premiums 422,524 422,409
Other (196,551) (129,742)
Net cash from operating activities 1,447,624 1,627,565
CASH USED IN INVESTING ACTIVITIES:    
Proceeds from sale of fixed maturity securities 529,223 1,089,183
Proceeds from sale of equity securities 142,927 253,498
Distributions from investment funds 39,421 21,011
Proceeds from maturities and prepayments of fixed maturity securities 2,477,846 2,133,775
Purchase of fixed maturity securities (4,228,781) (4,203,540)
Purchase of equity securities (121,451) (180,350)
Real estate purchased (15,950) (44,603)
Change in loans receivable 109,279 (148,241)
Net purchases of property, furniture and equipment (36,794) (78,468)
Change in balances due to security brokers (54,351) 165,430
Net cash used in investing activities (1,158,631) (992,305)
CASH USED IN FINANCING ACTIVITIES:    
Net proceeds from issuance of debt 429 420
Cash dividends to common stockholders (254,175) (185,721)
Purchase of common treasury shares (49,202) (223,763)
Other, net (10,176) 943
Net cash used in financing activities (313,124) (408,121)
Net impact on cash due to change in foreign exchange rates 33,913 (10,064)
Net change in cash and cash equivalents 9,782 217,075
Cash and cash equivalents at beginning of period 1,974,747 1,363,195
Cash and cash equivalents at end of period $ 1,984,529 $ 1,580,270
v3.25.2
Statement of Cash Flows
 6 Months Ended
Jun. 30, 2025
Supplemental Cash Flow Elements [Abstract]  
Statements of Cash Flows Statements of Cash Flows    Interest payments were $63,228,000 and $63,051,000 for the six months ended June 30, 2025 and 2024, respectively. Income tax payments were $164,260,000 and $165,739,000 for the six months ended June 30, 2025 and 2024, respectively.
v3.25.2
General
 6 Months Ended
Jun. 30, 2025
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, 2024.
The income tax provision has been computed based on the Company’s estimated annual effective tax rate. The effective income tax rate is greater than the federal income tax rate of 21%, primarily due to the geographical mix of earnings and amounts being subject to tax at a rate greater than the U.S. statutory rate and state taxes, which are partially offset by tax benefits related to tax-exempt investment income.
v3.25.2
Per Share Data
 6 Months Ended
Jun. 30, 2025
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 17,659,297 and 17,495,175 common shares held in a grantor trust as of June 30, 2025 and 2024, respectively). The common shares held in the grantor trust are designated for delivery upon the settlement of vested but mandatorily deferred restricted stock units ("RSUs"). Accordingly, such shares deliverable under vested RSUs do not affect diluted shares outstanding since the shares are already included in basic shares outstanding (which includes the shares in the grantor trust referenced above). Diluted EPS is based upon the weighted average number of basic and common equivalent shares outstanding during the period and is calculated using the treasury stock method for stock incentive plans. Common equivalent shares are excluded from the computation in periods in which they have an anti-dilutive effect.
    The weighted average number of common shares used in the computation of basic and diluted earnings per share was as follows:
For the Three Months
Ended June 30,		For the Six Months
Ended June 30,
(In thousands)2025202420252024
Basic397,016 400,273 396,972 401,295 
Diluted400,368 403,737 400,098 404,679 
v3.25.2
Recent Accounting Pronouncements and Accounting Policies
 6 Months Ended
Jun. 30, 2025
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 2025 were either not applicable to the Company or their adoption did not have a material impact on the Company.

Accounting and reporting standards that are not yet effective:
    In December 2023, the Financial Accounting Standards Board issued Accounting Standards Update 2023-09, Improvements to Income Tax Disclosures (Topic 740), to enhance the transparency and usefulness of income tax disclosures. The guidance requires improvements to income tax disclosures primarily related to the rate reconciliation and income taxes paid. This guidance is effective for annual periods beginning after December 15, 2024. The Company will provide these additional disclosures in its financial statements for the year ended December 31, 2025.
All other recently issued but not yet effective accounting and reporting standards are either not applicable to the Company or are not expected to have a material impact on the Company.
v3.25.2
Consolidated Statements of Comprehensive Income (Loss)
 6 Months Ended
Jun. 30, 2025
Equity [Abstract]  
Consolidated Statements of Comprehensive Income (Loss) 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 Gains (Losses)Currency Translation AdjustmentsAccumulated Other Comprehensive
Income (Loss)
As of and for the six months ended June 30, 2025
Changes in AOCI
Beginning of period$(517,170)$(417,099)$(934,269)
Other comprehensive income before reclassifications242,620 93,348 335,968 
Amounts reclassified from AOCI25,918 — 25,918 
Other comprehensive income268,538 93,348 361,886 
Unrealized investment loss related to noncontrolling interest(1)— (1)
End of period$(248,633)$(323,751)$(572,384)
Amounts reclassified from AOCI
Pre-tax$32,808 (1)$— $32,808 
Tax effect (6,890)(2)— (6,890)
After-tax amounts reclassified$25,918 $— $25,918 
Other comprehensive income
Pre-tax$343,713 $93,348 $437,061 
Tax effect(75,175)— (75,175)
Other comprehensive income$268,538 $93,348 $361,886 
As of and for the three months ended June 30, 2025
Changes in AOCI
Beginning of period$(368,898)$(393,169)$(762,067)
Other comprehensive income before reclassifications98,518 69,418 167,936 
Amounts reclassified from AOCI21,747 — 21,747 
Other comprehensive income120,265 69,418 189,683 
Unrealized investment loss related to noncontrolling interest— — — 
Ending balance$(248,633)$(323,751)$(572,384)
Amounts reclassified from AOCI
Pre-tax$27,528 (1)$— $27,528 
Tax effect (5,781)(2)— (5,781)
After-tax amounts reclassified$21,747 $— $21,747 
Other comprehensive income
Pre-tax$157,858 $69,418 $227,276 
Tax effect(37,593)— (37,593)
Other comprehensive income$120,265 $69,418 $189,683 
(In thousands)Unrealized Investment (Losses) GainsCurrency Translation AdjustmentsAccumulated Other Comprehensive
(Loss) Income
As of and for the six months ended June 30, 2024
Changes in AOCI
Beginning of period$(586,354)$(339,484)$(925,838)
Other comprehensive loss before reclassifications(156,023)(24,343)(180,366)
Amounts reclassified from AOCI72,563 — 72,563 
Other comprehensive loss(83,460)(24,343)(107,803)
Unrealized investment gain related to noncontrolling interest1 — 1 
End of period$(669,813)$(363,827)$(1,033,640)
Amounts reclassified from AOCI
Pre-tax$91,852 (1)$— $91,852 
Tax effect (19,289)(2)— (19,289)
After-tax amounts reclassified$72,563 $— $72,563 
Other comprehensive loss
Pre-tax$(109,937)$(24,343)$(134,280)
Tax effect26,477 — 26,477 
Other comprehensive loss$(83,460)$(24,343)$(107,803)
As of and for the three months ended June 30, 2024
Changes in AOCI
Beginning of period$(656,476)$(367,054)$(1,023,530)
Other comprehensive (loss) income before reclassifications(54,711)3,227 (51,484)
Amounts reclassified from AOCI41,373 — 41,373 
Other comprehensive (loss) income(13,338)3,227 (10,111)
Unrealized investment gain related to noncontrolling interest1 — 1 
Ending balance$(669,813)$(363,827)$(1,033,640)
Amounts reclassified from AOCI
Pre-tax$52,371 (1)$— $52,371 
Tax effect (10,998)(2)— (10,998)
After-tax amounts reclassified$41,373 $— $41,373 
Other comprehensive (loss) income
Pre-tax$(20,640)$3,227 $(17,413)
Tax effect7,302 — 7,302 
Other comprehensive (loss) income$(13,338)$3,227 $(10,111)
____________
(1) Net investment gains in the consolidated statements of income.
(2) Income tax expense in the consolidated statements of income.
v3.25.2
Investments In Fixed Maturity Securities
 6 Months Ended
Jun. 30, 2025
Investments, Debt and Equity Securities [Abstract]  
Investments In Fixed Maturity Securities Investments in Fixed Maturity Securities
    At June 30, 2025 and December 31, 2024, investments in fixed maturity securities were as follows:
 
(In thousands)Amortized
Cost		Allowance for Expected Credit Losses (1)Gross UnrealizedFair
Value		Carrying
Value
GainsLosses
June 30, 2025
Held to maturity:
State and municipal$27,983 $(14)$1,040 $— $29,009 $27,969 
Residential mortgage-backed2,082 — 74 — 2,156 2,082 
Total held to maturity30,065 (14)1,114 — 31,165 30,051 
Available for sale:
U.S. government and government agency3,108,090 — 23,421 (30,449)3,101,062 3,101,062 
State and municipal:
Special revenue1,387,506 — 6,306 (40,427)1,353,385 1,353,385 
State general obligation258,795 — 2,817 (5,451)256,161 256,161 
Pre-refunded77,145 — 555 (223)77,477 77,477 
Corporate backed187,565 — 1,688 (5,053)184,200 184,200 
Local general obligation277,592 — 1,852 (4,066)275,378 275,378 
Total state and municipal2,188,603 — 13,218 (55,220)2,146,601 2,146,601 
Mortgage-backed:
Residential4,090,672 — 34,670 (157,265)3,968,077 3,968,077 
Commercial355,922 — 3,911 (333)359,500 359,500 
Total mortgage-backed4,446,594 — 38,581 (157,598)4,327,577 4,327,577 
Asset-backed3,862,993 — 17,247 (26,805)3,853,435 3,853,435 
Corporate:
Industrial3,680,399 — 45,729 (53,582)3,672,546 3,672,546 
Financial3,417,541 — 54,356 (19,722)3,452,175 3,452,175 
Utilities1,146,714 — 15,476 (10,772)1,151,418 1,151,418 
Other481,868 — 2,775 (2,006)482,637 482,637 
Total corporate8,726,522 — 118,336 (86,082)8,758,776 8,758,776 
Foreign government2,006,836 (318)34,642 (165,506)1,875,654 1,875,654 
Total available for sale24,339,638 (318)245,445 (521,660)24,063,105 24,063,105 
Total investments in fixed maturity securities$24,369,703 $(332)$246,559 $(521,660)$24,094,270 $24,093,156 
____________
(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
Cost		Allowance for Expected Credit Losses (1)Gross UnrealizedFair
Value		Carrying
Value
GainsLosses
December 31, 2024
Held to maturity:
State and municipal$42,145 $(25)$1,492 $— $43,612 $42,120 
Residential mortgage-backed2,292 — 69 — 2,361 2,292 
Total held to maturity44,437 (25)1,561 — 45,973 44,412 
Available for sale:
U.S. government and government agency2,268,596 — 9,608 (42,863)2,235,341 2,235,341 
State and municipal:
Special revenue1,581,778 — 3,521 (67,591)1,517,708 1,517,708 
State general obligation272,936 — 1,439 (8,981)265,394 265,394 
Pre-refunded85,340 — 599 (347)85,592 85,592 
Corporate backed158,322 — 1,079 (5,827)153,574 153,574 
Local general obligation278,165 — 922 (6,711)272,376 272,376 
Total state and municipal2,376,541 — 7,560 (89,457)2,294,644 2,294,644 
Mortgage-backed:
Residential3,411,796 (5)11,047 (189,630)3,233,208 3,233,208 
Commercial534,936 (425)1,201 (3,430)532,282 532,282 
Total mortgage-backed3,946,732 (430)12,248 (193,060)3,765,490 3,765,490 
Asset-backed3,910,363 — 16,161 (41,512)3,885,012 3,885,012 
Corporate:
Industrial3,746,501 — 14,518 (93,820)3,667,199 3,667,199 
Financial3,339,718 — 18,871 (38,076)3,320,513 3,320,513 
Utilities795,839 — 2,970 (20,115)778,694 778,694 
Other653,194 — 2,493 (4,452)651,235 651,235 
Total corporate8,535,252 — 38,852 (156,463)8,417,641 8,417,641 
Foreign government1,928,978 (216)11,936 (185,373)1,755,325 1,755,325 
Total available for sale22,966,462 (646)96,365 (708,728)22,353,453 22,353,453 
Total investments in fixed maturity securities$23,010,899 $(671)$97,926 $(708,728)$22,399,426 $22,397,865 
____________
(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 six months ended June 30, 2025 and 2024:
(In thousands)20252024
Balance, beginning of period$25 $43 
Provision for expected credit losses(11)(9)
Balance, end of period$14 $34 
The following table presents the rollforward of the allowance for expected credit losses for held to maturity securities for the three months ended June 30, 2025 and 2024:
(In thousands)20252024
Balance, beginning of period$20 $38 
Provision for expected credit losses(6)(4)
Balance, end of period$14 $34 
The following table presents the rollforward of the allowance for expected credit losses for available for sale securities for the six months ended June 30, 2025 and 2024:
20252024
(In thousands)Foreign GovernmentMortgage-backedState and MunicipalTotalForeign GovernmentCorporateMortgage-backedAsset-backedState and MunicipalTotal
Balance, beginning of period$216 $430 $— $646 $29,603 $5,026 $158 $1,164 $757 $36,708 
Change on securities for which credit losses were not previously recorded— — 10 10 300 — 1,701 — — 2,001 
Change on securities for which credit losses were previously recorded102 (430)(10)(338)(10,434)(5,026)(158)(275)(418)(16,311)
Reduction due to disposals— — — — — — (561)— — (561)
Balance, end of period$318 $— $— $318 $19,469 $— $1,140 $889 $339 $21,837 
During the six months ended June 30, 2025, the Company decreased the allowance for expected credit losses for available for sale securities primarily due to improved pricing related to mortgage-backed securities. During the six months ended June 30, 2024, the Company decreased the allowance for expected credit losses for available for sale securities primarily due to improved pricing associated with foreign government securities and corporate securities.
The following table presents the rollforward of the allowance for expected credit losses for available for sale securities for the three months ended June 30, 2025 and 2024:

20252024
(In thousands)Foreign GovernmentState and MunicipalTotalForeign GovernmentMortgage-backedAsset-backedState and MunicipalTotal
Balance, beginning of period$323 $10 $333 $20,479 $562 $1,097 $693 $22,831 
Change on securities for which credit losses were not previously recorded— — — 300 1,139 — — 1,439 
Change on securities for which credit losses were previously recorded(5)(10)(15)(1,310)— (208)(354)(1,872)
Reduction due to disposals— — — — (561)— — (561)
Balance, end of period$318 $— $318 $19,469 $1,140 $889 $339 $21,837 
The amortized cost and fair value of fixed maturity securities at June 30, 2025, by contractual maturity, are shown below. Actual maturities may differ from contractual maturities because certain issuers may have the right to call or prepay obligations.  
(In thousands)Amortized
Cost (1)		Fair
Value
Due in one year or less$1,728,802 $1,720,156 
Due after one year through five years9,001,644 8,861,485 
Due after five years through ten years4,046,210 4,065,444 
Due after ten years5,144,357 5,117,452 
Mortgage-backed securities4,448,676 4,329,733 
Total$24,369,689 $24,094,270 
________________
(1) Amortized cost is reduced by the allowance for expected credit losses of $14 thousand related to held to maturity securities.    
At June 30, 2025 and December 31, 2024, there were no investments that exceeded 10% of common stockholders' equity, other than investments in United States government and government agency securities.
v3.25.2
Investments in Equity Securities
 6 Months Ended
Jun. 30, 2025
Debt Securities, Available-for-sale [Line Items]  
Investments in Equity Securities Investments in Fixed Maturity Securities
    At June 30, 2025 and December 31, 2024, investments in fixed maturity securities were as follows:
 
(In thousands)Amortized
Cost		Allowance for Expected Credit Losses (1)Gross UnrealizedFair
Value		Carrying
Value
GainsLosses
June 30, 2025
Held to maturity:
State and municipal$27,983 $(14)$1,040 $— $29,009 $27,969 
Residential mortgage-backed2,082 — 74 — 2,156 2,082 
Total held to maturity30,065 (14)1,114 — 31,165 30,051 
Available for sale:
U.S. government and government agency3,108,090 — 23,421 (30,449)3,101,062 3,101,062 
State and municipal:
Special revenue1,387,506 — 6,306 (40,427)1,353,385 1,353,385 
State general obligation258,795 — 2,817 (5,451)256,161 256,161 
Pre-refunded77,145 — 555 (223)77,477 77,477 
Corporate backed187,565 — 1,688 (5,053)184,200 184,200 
Local general obligation277,592 — 1,852 (4,066)275,378 275,378 
Total state and municipal2,188,603 — 13,218 (55,220)2,146,601 2,146,601 
Mortgage-backed:
Residential4,090,672 — 34,670 (157,265)3,968,077 3,968,077 
Commercial355,922 — 3,911 (333)359,500 359,500 
Total mortgage-backed4,446,594 — 38,581 (157,598)4,327,577 4,327,577 
Asset-backed3,862,993 — 17,247 (26,805)3,853,435 3,853,435 
Corporate:
Industrial3,680,399 — 45,729 (53,582)3,672,546 3,672,546 
Financial3,417,541 — 54,356 (19,722)3,452,175 3,452,175 
Utilities1,146,714 — 15,476 (10,772)1,151,418 1,151,418 
Other481,868 — 2,775 (2,006)482,637 482,637 
Total corporate8,726,522 — 118,336 (86,082)8,758,776 8,758,776 
Foreign government2,006,836 (318)34,642 (165,506)1,875,654 1,875,654 
Total available for sale24,339,638 (318)245,445 (521,660)24,063,105 24,063,105 
Total investments in fixed maturity securities$24,369,703 $(332)$246,559 $(521,660)$24,094,270 $24,093,156 
____________
(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
Cost		Allowance for Expected Credit Losses (1)Gross UnrealizedFair
Value		Carrying
Value
GainsLosses
December 31, 2024
Held to maturity:
State and municipal$42,145 $(25)$1,492 $— $43,612 $42,120 
Residential mortgage-backed2,292 — 69 — 2,361 2,292 
Total held to maturity44,437 (25)1,561 — 45,973 44,412 
Available for sale:
U.S. government and government agency2,268,596 — 9,608 (42,863)2,235,341 2,235,341 
State and municipal:
Special revenue1,581,778 — 3,521 (67,591)1,517,708 1,517,708 
State general obligation272,936 — 1,439 (8,981)265,394 265,394 
Pre-refunded85,340 — 599 (347)85,592 85,592 
Corporate backed158,322 — 1,079 (5,827)153,574 153,574 
Local general obligation278,165 — 922 (6,711)272,376 272,376 
Total state and municipal2,376,541 — 7,560 (89,457)2,294,644 2,294,644 
Mortgage-backed:
Residential3,411,796 (5)11,047 (189,630)3,233,208 3,233,208 
Commercial534,936 (425)1,201 (3,430)532,282 532,282 
Total mortgage-backed3,946,732 (430)12,248 (193,060)3,765,490 3,765,490 
Asset-backed3,910,363 — 16,161 (41,512)3,885,012 3,885,012 
Corporate:
Industrial3,746,501 — 14,518 (93,820)3,667,199 3,667,199 
Financial3,339,718 — 18,871 (38,076)3,320,513 3,320,513 
Utilities795,839 — 2,970 (20,115)778,694 778,694 
Other653,194 — 2,493 (4,452)651,235 651,235 
Total corporate8,535,252 — 38,852 (156,463)8,417,641 8,417,641 
Foreign government1,928,978 (216)11,936 (185,373)1,755,325 1,755,325 
Total available for sale22,966,462 (646)96,365 (708,728)22,353,453 22,353,453 
Total investments in fixed maturity securities$23,010,899 $(671)$97,926 $(708,728)$22,399,426 $22,397,865 
____________
(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 six months ended June 30, 2025 and 2024:
(In thousands)20252024
Balance, beginning of period$25 $43 
Provision for expected credit losses(11)(9)
Balance, end of period$14 $34 
The following table presents the rollforward of the allowance for expected credit losses for held to maturity securities for the three months ended June 30, 2025 and 2024:
(In thousands)20252024
Balance, beginning of period$20 $38 
Provision for expected credit losses(6)(4)
Balance, end of period$14 $34 
The following table presents the rollforward of the allowance for expected credit losses for available for sale securities for the six months ended June 30, 2025 and 2024:
20252024
(In thousands)Foreign GovernmentMortgage-backedState and MunicipalTotalForeign GovernmentCorporateMortgage-backedAsset-backedState and MunicipalTotal
Balance, beginning of period$216 $430 $— $646 $29,603 $5,026 $158 $1,164 $757 $36,708 
Change on securities for which credit losses were not previously recorded— — 10 10 300 — 1,701 — — 2,001 
Change on securities for which credit losses were previously recorded102 (430)(10)(338)(10,434)(5,026)(158)(275)(418)(16,311)
Reduction due to disposals— — — — — — (561)— — (561)
Balance, end of period$318 $— $— $318 $19,469 $— $1,140 $889 $339 $21,837 
During the six months ended June 30, 2025, the Company decreased the allowance for expected credit losses for available for sale securities primarily due to improved pricing related to mortgage-backed securities. During the six months ended June 30, 2024, the Company decreased the allowance for expected credit losses for available for sale securities primarily due to improved pricing associated with foreign government securities and corporate securities.
The following table presents the rollforward of the allowance for expected credit losses for available for sale securities for the three months ended June 30, 2025 and 2024:

20252024
(In thousands)Foreign GovernmentState and MunicipalTotalForeign GovernmentMortgage-backedAsset-backedState and MunicipalTotal
Balance, beginning of period$323 $10 $333 $20,479 $562 $1,097 $693 $22,831 
Change on securities for which credit losses were not previously recorded— — — 300 1,139 — — 1,439 
Change on securities for which credit losses were previously recorded(5)(10)(15)(1,310)— (208)(354)(1,872)
Reduction due to disposals— — — — (561)— — (561)
Balance, end of period$318 $— $318 $19,469 $1,140 $889 $339 $21,837 
The amortized cost and fair value of fixed maturity securities at June 30, 2025, by contractual maturity, are shown below. Actual maturities may differ from contractual maturities because certain issuers may have the right to call or prepay obligations.  
(In thousands)Amortized
Cost (1)		Fair
Value
Due in one year or less$1,728,802 $1,720,156 
Due after one year through five years9,001,644 8,861,485 
Due after five years through ten years4,046,210 4,065,444 
Due after ten years5,144,357 5,117,452 
Mortgage-backed securities4,448,676 4,329,733 
Total$24,369,689 $24,094,270 
________________
(1) Amortized cost is reduced by the allowance for expected credit losses of $14 thousand related to held to maturity securities.    
At June 30, 2025 and December 31, 2024, there were no investments that exceeded 10% of common stockholders' equity, other than investments in United States government and government agency securities.
Equity securities  
Debt Securities, Available-for-sale [Line Items]  
Investments in Equity Securities Investments in Equity Securities
    At June 30, 2025 and December 31, 2024, investments in equity securities were as follows:
 
(In thousands)CostGross UnrealizedFair
Value		Carrying
Value
GainsLosses
June 30, 2025
Common stocks$528,148 $211,335 $(19,913)$719,570 $719,570 
Preferred stocks388,653 158,950 (4,981)542,622 542,622 
Total$916,801 $370,285 $(24,894)$1,262,192 $1,262,192 
December 31, 2024
Common stocks$612,479 $223,981 $(76,293)$760,167 $760,167 
Preferred stocks329,495 122,716 (8,590)443,621 443,621 
Total$941,974 $346,697 $(84,883)$1,203,788 $1,203,788 
v3.25.2
Arbitrage Trading Account
 6 Months Ended
Jun. 30, 2025
Debt Securities, Trading, and Equity Securities, FV-NI [Abstract]  
Arbitrage Trading Account Arbitrage Trading Account
    At June 30, 2025 and December 31, 2024, the fair and carrying values of the arbitrage trading account were $1,035 million and $1,123 million, respectively. The primary focus of the trading account is merger arbitrage. Merger arbitrage is the business of investing in the securities of publicly held companies which are the targets in announced tender offers and mergers. Arbitrage investing differs from other types of investing in its focus on transactions and events believed likely to bring about a change in value over a relatively short time period (usually four months or less).
    The Company uses put options and call options in order to mitigate the impact of potential changes in market conditions on the merger arbitrage trading account. These options are reported at fair value. As of June 30, 2025, the fair value of long option contracts outstanding was $5 million (notional amount of $270 million) and the fair value of short option contracts was $31 million (notional amount of $271 million). Other than with respect to the use of these trading account securities, the Company does not make use of derivatives.
v3.25.2
Net Investment Income
 6 Months Ended
Jun. 30, 2025
Net Investment Income [Abstract]  
Net Investment Income Net Investment Income
    Net investment income consisted of the following: 
 For the Three Months
Ended June 30,		For the Six Months
Ended June 30,
(In thousands)2025202420252024
Investment income (loss) earned on:
Fixed maturity securities, including cash and cash equivalents and loans receivable$322,518 $324,136 $636,306 $659,384 
Investment funds27,268 25,476 54,291 (3,873)
Arbitrage trading account (1)23,672 16,682 40,001 34,693 
Equity securities12,485 12,386 23,126 23,721 
Real estate(4,092)(3,705)(8,109)(16,868)
Gross investment income381,851 374,975 745,615 697,057 
Investment expense(2,548)(2,846)(6,020)(5,090)
Net investment income$379,303 $372,129 $739,595 $691,967 
(1) Net investment income includes earnings from trading account receivables from brokers and clearing organizations.
v3.25.2
Investment Funds
 6 Months Ended
Jun. 30, 2025
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 $272 million as of June 30, 2025.
    Investment funds consisted of the following:
Carrying Value as of Income (Loss) from
Investment Funds
June 30,December 31,For the Six Months
Ended June 30,
(In thousands)2025202420252024
Financial services$434,518 $430,163 $12,277 $(18,231)
Transportation276,904 286,426 20,714 (3,732)
Real Estate181,509 178,685 5,614 12,880 
Infrastructure161,019 151,560 9,064 7,828 
Energy42,193 42,776 (1,234)8,505 
Other funds396,115 378,636 7,856 (11,123)
Total$1,492,258 $1,468,246 $54,291 $(3,873)
    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 Ltd. ("Lifson Re"), a Bermuda reinsurance company. Lifson Re participated on a fully collateralized basis in a majority of the Company’s reinsurance placements for a 30.0% share of placed amounts in 2024, which percentage was increased to 32.5% effective January 1, 2025. 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 six months ended June 30, 2025 and 2024, the Company ceded approximately $362 million and $206 million, respectively, of written premiums to Lifson Re.
Other funds include deferred compensation trust assets of $42 million and $38 million as of June 30, 2025 and December 31, 2024, 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.
v3.25.2
Real Estate
 6 Months Ended
Jun. 30, 2025
Real Estate [Abstract]  
Real Estate Real Estate
    Investment in real estate represents directly owned property held for investment, as follows:
Carrying Value
June 30,December 31,
(In thousands)20252024
Properties in operation$1,066,361 $1,063,687 
Properties under development228,144 227,768 
Total$1,294,505 $1,291,455 

    As of June 30, 2025, 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 $39,761,000 and $38,671,000 as of June 30, 2025 and December 31, 2024, respectively. Related depreciation expense was $4,547,000 and $4,164,000 for the six months ended June 30, 2025 and
2024, respectively. Future minimum rental income expected on operating leases relating to properties in operation is $17,986,813 in 2025, $37,365,898 in 2026, $37,887,121 in 2027, $38,646,570 in 2028, $33,546,284 in 2029, $27,798,317 in 2030 and $411,072,017 thereafter.
    A mixed-use project in Washington, D.C. had been under development in 2025 and 2024. The completed portion of the project is reported in properties in operation.
v3.25.2
Loans Receivable
 6 Months Ended
Jun. 30, 2025
Receivables [Abstract]  
Loans Receivable Loans Receivable
At June 30, 2025 and December 31, 2024, loans receivable were as follows:
(In thousands)June 30,
2025		December 31,
2024
Amortized cost (net of allowance for expected credit losses):
Real estate loans$320,309 $402,382 
Commercial loans4,056 3,071 
Total$324,365 $405,453 
Fair value:
Real estate loans$320,643 $402,177 
Commercial loans4,056 3,071 
Total$324,699 $405,248 
The real estate loans are secured by commercial and residential real estate primarily located in the U.K. 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 five years.
The following table presents the rollforward of the allowance for expected credit losses for loans receivable for the six months ended June 30, 2025 and 2024:
20252024
(In thousands)Real Estate LoansCommercial LoansTotalReal Estate LoansCommercial LoansTotal
Balance, beginning of period$1,088 $26 $1,114 $2,983 $21 $3,004 
Change in expected credit losses(754)9 (745)(1,190)(1)(1,191)
Balance, end of period$334 $35 $369 $1,793 $20 $1,813 
During six months ended June 30, 2025, the Company decreased the allowance for expected credit losses due to the redemption of one loan and a decrease in the weighted average life of the remaining loan portfolio. During the six months ended June 30, 2024, the Company decreased the allowance for expected credit losses due to a decrease in the weighted average life of the loan portfolio.
The following table presents the rollforward of the allowance for expected credit losses for loans receivable for the three months ended June 30, 2025 and 2024:
20252024
(In thousands)Real Estate LoansCommercial LoansTotalReal Estate LoansCommercial LoansTotal
Balance, beginning of period$776 $12 $788 $2,587 $22 $2,609 
Change in expected credit losses(442)23 (419)(794)(2)(796)
Balance, end of period$334 $35 $369 $1,793 $20 $1,813 
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.
    In evaluating the real estate loans, the Company considers their credit quality indicators, including loan to value ratios, which compare the outstanding loan amount to the estimated value of the property, the borrower’s financial condition and
performance with respect to loan terms, the position in the capital structure, the overall leverage in the capital structure and other market conditions.
v3.25.2
Net Investment (Losses) Gains
 6 Months Ended
Jun. 30, 2025
Realized and Unrealized Investment Gains (Losses) [Abstract]  
Net Investment (Losses) Gains Net Investment Gains
     Net investment gains (losses) were as follows:
For the Three Months
Ended June 30,		For the Six Months
Ended June 30,
(In thousands)2025202420252024
Net investment gains (losses):  
Fixed maturity securities:  
Gains$4,209 $3,092 $6,841 $6,649 
Losses(5,654)(5,362)(8,366)(7,685)
Equity securities (1):
Net realized (losses) gains on investment sales (1,100)61,521 (3,695)101,798 
Change in unrealized gains (losses)63,630 (66,717)83,577 (40,905)
Investment funds808 217 822 1,210 
Real estate (5,256)(1,958)(1,313)(4,174)
Other (2)(26,104)(51,099)(31,622)(105,696)
Net realized and unrealized gains (losses) on investments in earnings before allowance for expected credit losses30,533 (60,306)46,244 (48,803)
Change in allowance for expected credit losses on investments:
Fixed maturity securities21 998 339 14,879 
Loans receivable419 796 745 1,191 
Change in allowance for expected credit losses on investments440 1,794 1,084 16,070 
Net investment gains (losses)30,973 (58,512)47,328 (32,733)
Income tax (expense) benefit(6,685)12,401 (10,213)5,769 
After-tax net investment gains (losses)$24,288 $(46,111)$37,115 $(26,964)
Change in unrealized investment gains (losses) on available for sale securities:  
Fixed maturity securities without allowance for expected credit losses$152,235 $(11,394)$336,222 $(99,988)
Fixed maturity securities with allowance for expected credit losses478 (7,683)(73)(6,696)
Investment funds5,110 (1,338)7,606 (3,041)
Other35 (225)(42)(212)
Total change in unrealized investment gains (losses)157,858 (20,640)343,713 (109,937)
Income tax (expense) benefit(37,593)7,302 (75,175)26,477 
Noncontrolling interests— 1 (1)1 
After-tax change in unrealized investment gains (losses) of available for sale securities$120,265 $(13,337)$268,537 $(83,459)
______________________
(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) Primarily relates to realized foreign currency losses upon the disposition of fixed maturity securities.
v3.25.2
Fixed Maturity Securities In An Unrealized Loss Position
 6 Months Ended
Jun. 30, 2025
Investments, Debt and Equity Securities [Abstract]  
Fixed Maturity Securities In An Unrealized Loss Position Fixed Maturity Securities in an Unrealized Loss Position
    The following tables summarize all fixed maturity securities in an unrealized loss position at June 30, 2025 and December 31, 2024 by the length of time those securities have been continuously in an unrealized loss position:
  Less Than 12 Months12 Months or GreaterTotal
(In thousands)Fair
Value		Gross
Unrealized Losses		Fair
Value		Gross
Unrealized Losses		Fair
Value		Gross
Unrealized Losses
June 30, 2025
U.S. government and government agency$941,906 $11,134 $466,439 $19,315 $1,408,345 $30,449 
State and municipal200,033 3,908 1,262,830 51,312 1,462,863 55,220 
Mortgage-backed859,569 11,556 887,676 146,042 1,747,245 157,598 
Asset-backed610,864 2,675 532,828 24,130 1,143,692 26,805 
Corporate366,889 2,120 2,207,465 83,962 2,574,354 86,082 
Foreign government150,504 2,285 339,854 163,221 490,358 165,506 
Fixed maturity securities$3,129,765 $33,678 $5,697,092 $487,982 $8,826,857 $521,660 
December 31, 2024
U.S. government and government agency$767,515 $9,637 $560,260 $33,226 $1,327,775 $42,863 
State and municipal348,116 8,027 1,411,761 81,430 1,759,877 89,457 
Mortgage-backed1,541,464 21,326 1,060,823 171,734 2,602,287 193,060 
Asset-backed411,763 4,613 626,237 36,899 1,038,000 41,512 
Corporate1,791,970 21,346 2,951,377 135,117 4,743,347 156,463 
Foreign government600,103 17,933 476,479 167,440 1,076,582 185,373 
Fixed maturity securities$5,460,931 $82,882 $7,086,937 $625,846 $12,547,868 $708,728 
    Substantially all of the securities in an unrealized loss position are rated investment grade, except for the securities in the foreign government classification. A significant amount of the unrealized loss on foreign government securities is the result of changes in currency exchange rates. 
    A summary of the Company’s non-investment grade fixed maturity securities that were in an unrealized loss position at June 30, 2025 is presented in the table below:
($ in thousands)Number of
Securities		Aggregate
Fair Value		Gross
Unrealized Loss
Foreign government50 $144,584 $155,344 
State and municipal6 28,621 1,436 
Corporate8 29,131 622 
Mortgage-backed15 2,589 193 
Asset-backed1 9 1 
Total80 $204,934 $157,596 
    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).
     The Company has evaluated its fixed maturity securities in an unrealized loss position and believes the unrealized losses are due primarily to temporary market and sector-related factors rather than to issuer-specific factors. None of these securities are delinquent or in default under financial covenants. Based on its assessment of these issuers, the Company expects them to continue to meet their contractual payment obligations as they become due.
v3.25.2
Fair Value Measurements
 6 Months Ended
Jun. 30, 2025
Fair Value Disclosures [Abstract]  
Fair Value Measurements Fair Value Measurements
    The Company’s fixed maturity available for sale securities, equity securities and its arbitrage trading account securities are carried at fair value. Fair value is defined as “the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date.” The Company utilizes a fair value hierarchy that prioritizes the inputs to valuation techniques used to measure fair value into three broad levels, as follows:
Level 1 - Quoted prices (unadjusted) in active markets for identical assets or liabilities that the Company has the ability to access at the measurement date.
Level 2 - Quoted prices for similar assets or valuations based on inputs that are observable.
Level 3 - Estimates of fair value based on internal pricing methodologies using unobservable inputs. Unobservable inputs are only used to measure fair value to the extent that observable inputs are not available.
    Substantially all of the Company’s fixed maturity securities were priced by independent pricing services. The prices provided by the independent pricing services are estimated based on observable market data in active markets utilizing pricing models and processes, which may include benchmark yields, reported trades, broker/dealer quotes, issuer spreads, two-sided markets, benchmark securities, bids, offers, sector groupings, matrix pricing and reference data. The pricing services may prioritize inputs differently on any given day for any security based on market conditions, and not all inputs are available for each security evaluation on any given day. The pricing services used by the Company have indicated that they will only produce an estimate of fair value if objectively verifiable information is available. The determination of whether markets are active or inactive is based upon the volume and level of activity for a particular asset class. The Company reviews the prices provided by pricing services for reasonableness and periodically performs independent price tests of a sample of securities to ensure proper valuation.
    If prices from independent pricing services are not available for fixed maturity securities, the Company estimates the fair value. For Level 2 securities, the Company utilizes pricing models and processes which may include benchmark yields, sector groupings, matrix pricing, reported trades, broker/dealer quotes, issuer spreads, two-sided markets, bids, offers and reference data. Where broker quotes are used, the Company generally requests two or more quotes and sets a price within the range of quotes received based on its assessment of the credibility of the quote and its own evaluation of the security. The Company generally does not adjust quotes received from brokers. For securities traded only in private negotiations, the Company determines fair value based primarily on the cost of such securities, which is adjusted to reflect prices of recent placements of securities of the same issuer, financial projections, credit quality and business developments of the issuer and other relevant information.
    For Level 3 securities, the Company generally uses a discounted cash flow model to estimate the fair value of fixed maturity securities. The cash flow models are based upon assumptions as to prevailing credit spreads, interest rate and interest rate volatility, time to maturity and subordination levels. Projected cash flows are discounted at rates that are adjusted to reflect illiquidity, where appropriate.
    
    The following tables present the assets and liabilities measured at fair value on a recurring basis as of June 30, 2025 and December 31, 2024 by level:
(In thousands)TotalLevel 1Level 2Level 3
June 30, 2025
Assets:
Fixed maturity securities available for sale:
U.S. government and government agency$3,101,062 $— $3,101,062 $— 
State and municipal2,146,601 — 2,146,601 — 
Mortgage-backed4,327,577 — 4,327,577 — 
Asset-backed3,853,435 — 3,853,435 — 
Corporate8,758,776 — 8,738,800 19,976 
Foreign government1,875,654 — 1,875,654 — 
Total fixed maturity securities available for sale24,063,105 — 24,043,129 19,976 
Equity securities:
Common stocks719,570 716,561 858 2,151 
Preferred stocks542,622 — 533,948 8,674 
Total equity securities1,262,192 716,561 534,806 10,825 
Arbitrage trading account1,034,557 905,421 125,391 3,745 
Total$26,359,854 $1,621,982 $24,703,326 $34,546 
Liabilities:
Trading account securities sold but not yet purchased$30,909 $30,909 $— $— 
December 31, 2024
Assets:
Fixed maturity securities available for sale:
U.S. government and government agency$2,235,341 $— $2,235,341 $— 
State and municipal2,294,644 — 2,294,644 — 
Mortgage-backed3,765,490 — 3,765,490 — 
Asset-backed3,885,012 — 3,885,012 — 
Corporate8,417,641 — 8,397,974 19,667 
Foreign government1,755,325 — 1,755,325 — 
Total fixed maturity securities available for sale22,353,453 — 22,333,786 19,667 
Equity securities:
Common stocks760,167 757,115 1,011 2,041 
Preferred stocks443,621 — 439,947 3,674 
Total equity securities1,203,788 757,115 440,958 5,715 
Arbitrage trading account1,122,599 1,062,459 56,630 3,510 
Total$24,679,840 $1,819,574 $22,831,374 $28,892 
Liabilities:
Trading account securities sold but not yet purchased$73,358 $73,358 $— $— 
    The following tables summarize changes in Level 3 assets and liabilities for the six months ended June 30, 2025 and for the year ended December 31, 2024:
Gains (Losses) Included In:
(In thousands)Beginning
Balance		Earnings (Losses)Other
Comprehensive
Income (Losses)		ImpairmentsPurchasesSalesPaydowns / MaturitiesTransfers In / (Out)Ending
Balance
Six Months Ended June 30, 2025
Assets:
Fixed maturities securities available for sale:
Corporate$19,667 $— $309 $— $— $— $— $— $19,976 
Total19,667 — 309 — — — — — 19,976 
Equity securities:
Common stocks$2,041 $236 $— $— $— $(126)$— $— $2,151 
Preferred stocks3,674 — — — 6,160 (1,160)— — 8,674 
Total5,715 236 — — 6,160 (1,286)— — 10,825 
Arbitrage trading account3,510 235 — — — — — — 3,745 
Total$28,892 $471 $309 $— $6,160 $(1,286)$— $— $34,546 
Year Ended
December 31, 2024
Assets:
Fixed maturities securities available for sale:
Corporate$— $— $(333)$— $— $— $— $20,000 $19,667 
Total— — (333)— — — — 20,000 19,667 
Equity securities:
Common stocks$1,558 $611 $— $— $— $(128)$— $— $2,041 
Preferred stocks3,695 36 — — — (57)— — 3,674 
Total5,253 647 — — — (185)— — 5,715 
Arbitrage trading account3,772 (261)— — — (38)— 37 3,510 
Total$9,025 $386 $(333)$— $— $(223)$— $20,037 $28,892 
    For the six months ended June 30, 2025, there were no securities transferred into or out of Level 3. For the year ended December 31, 2024, there was one corporate security transferred into Level 3 from Level 2 given there were no quoted prices or
observable inputs available, and one security within the arbitrage trading account portfolio that no longer had a publicly traded price transferred into Level 3.
Fair Value of Financial Instruments
    The following table presents the carrying amounts and estimated fair values of the Company’s financial instruments:
  June 30, 2025December 31, 2024
(In thousands)Carrying ValueFair ValueCarrying ValueFair Value
Assets:
Fixed maturity securities$24,093,156 $24,094,270 $22,397,865 $22,399,426 
Equity securities1,262,192 1,262,192 1,203,788 1,203,788 
Arbitrage trading account1,034,557 1,034,557 1,122,599 1,122,599 
Loans receivable324,365 324,699 405,453 405,248 
Cash and cash equivalents1,984,529 1,984,529 1,974,747 1,974,747 
Trading account receivables from brokers and clearing organizations138,891 138,891 60,327 60,327 
Liabilities:
Due to broker16,160 16,160 70,483 70,483 
Trading account securities sold but not yet purchased30,909 30,909 73,358 73,358 
Senior notes and other debt1,831,638 1,438,943 1,831,158 1,425,852 
Subordinated debentures1,010,168 766,884 1,009,808 805,864 
    The estimated fair values of the Company’s fixed maturity securities, equity securities and arbitrage trading account securities are based on various valuation techniques that rely on fair value measurements as described in Note 15. The fair value of loans receivable are estimated by using current institutional purchaser yield requirements for loans with similar credit characteristics, which is considered a Level 2 input. The fair value of the senior notes and other debt and the subordinated debentures is based on spreads for similar securities, which is considered a Level 2 input.
v3.25.2
Reserves for Loss and Loss Expenses
 6 Months Ended
Jun. 30, 2025
Insurance [Abstract]  
Reserves for Loss and Loss Expenses Reserves for Loss and Loss Expenses
    The Company's reserves for losses and loss expenses are comprised of case reserves and incurred but not reported liabilities ("IBNR"). When a claim is reported, a case reserve is established for the estimated ultimate payment based upon known information about the claim. As more information about the claim becomes available over time, case reserves are adjusted up or down as appropriate. Reserves are also established on an aggregate basis to provide for IBNR liabilities and expected loss reserve development on reported claims.
    Loss reserves included in the Company’s financial statements represent management’s best estimates based upon an actuarially derived point estimate and other considerations. The Company uses a variety of actuarial techniques and methods to derive an actuarial point estimate for each operating unit. These methods include paid loss development, incurred loss development, paid and incurred Bornhuetter-Ferguson methods and frequency and severity methods. In circumstances where one actuarial method is considered more credible than the others, that method is used to set the point estimate. The actuarial point estimate may also be based on a judgmental weighting of estimates produced from each of the methods considered. Industry loss experience is used to supplement the Company’s own data in selecting “tail factors” in areas where the Company’s own data is limited. The actuarial data is analyzed by line of business, coverage and accident or policy year, as appropriate, for each operating unit.
    The establishment of the actuarially derived loss reserve point estimate also includes consideration of qualitative factors that may affect the ultimate losses. These qualitative considerations include, among others, the impact of re-underwriting initiatives, changes in the mix of business, changes in distribution sources and changes in policy terms and conditions.
    The key assumptions used to arrive at the best estimate of loss reserves are the expected loss ratios, rate of loss cost inflation, and reported and paid loss emergence patterns. Expected loss ratios represent management’s expectation of losses at the time the business is priced and written, before any actual claims experience has emerged. This expectation is a significant determinant of the estimate of loss reserves for recently written business where there is little paid or incurred loss data to consider. Expected loss ratios are generally derived from historical loss ratios adjusted for the impact of rate changes, loss cost trends and known changes in the type of risks underwritten. Expected loss ratios are estimated for each key line of business within each operating unit. Expected loss cost inflation is particularly important for the long-tail lines, such as excess casualty, and claims with a high medical component, such as workers’ compensation. Reported and paid loss emergence patterns are used to project current reported or paid loss amounts to their ultimate settlement value. Loss development factors are based on the historical emergence patterns of paid and incurred losses, and are derived from the Company’s own experience and industry data. The paid loss emergence pattern is also significant to excess and assumed workers’ compensation reserves because those reserves are discounted to their estimated present value based upon such estimated payout patterns.
    Loss frequency and severity are measures of loss activity that are considered in determining the key assumptions described in our discussion of loss and loss expense reserves, including expected loss ratios, rate of loss cost inflation and reported and paid loss emergence patterns. Loss frequency is a measure of the number of claims per unit of insured exposure, and loss severity is a measure of the average size of claims. Factors affecting loss frequency include the effectiveness of loss controls and safety programs and changes in economic activity or weather patterns. Factors affecting loss severity include changes in policy limits, retentions, rate of inflation and judicial interpretations.
    Another factor affecting estimates of loss frequency and severity is the loss reporting lag, which is the period of time between the occurrence of a loss and the date the loss is reported to the Company. The length of the loss reporting lag affects our ability to accurately predict loss frequency (loss frequencies are more predictable for lines with short reporting lags) as well as the amount of reserves needed for incurred but not reported losses (less IBNR is required for lines with short reporting lags). As a result, loss reserves for lines with short reporting lags are likely to have less variation from initial loss estimates. For lines with short reporting lags, which include commercial automobile, primary workers’ compensation, other liability (claims-made) and property business, the key assumption is the loss emergence pattern used to project ultimate loss estimates from known losses paid or reported to date. For lines of business with long reporting lags, which include other liability (occurrence), products liability, excess workers’ compensation and liability reinsurance, the key assumption is the expected loss ratio since there is often little paid or incurred loss data to consider. Historically, the Company has experienced less variation from its initial loss estimates for lines of 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:
June 30,
(In thousands)20252024
Net reserves at beginning of period$17,166,641 $15,661,820 
Net provision for losses and loss expenses:
Claims occurring during the current year (1)3,822,512 3,411,888 
Increase in estimates for claims occurring in prior years (2) (3)17,823 14,700 
Loss reserve discount accretion 15,881 17,786 
Total3,856,216 3,444,374 
Net payments for claims:  
Current year431,981 383,639 
Prior years2,537,599 2,205,566 
Total2,969,580 2,589,205 
Foreign currency translation164,747 (56,143)
Net reserves at end of period18,218,024 16,460,846 
Ceded reserves at end of period3,278,099 3,106,344 
Gross reserves at end of period$21,496,123 $19,567,190 
_______________________________________
(1) Claims occurring during the current year are net of loss reserve discounts of $28 million and $26 million for the six months ended June 30, 2025 and 2024, 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 $17 million and $7 million for the six months ended June 30, 2025 and 2024, 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 $1 million and $2 million for the six months ended June 30, 2025 and 2024, respectively.
During the six months ended June 30, 2025, favorable prior year development (net of additional and return premiums) of $1 million included $20 million of favorable prior year development for the Reinsurance & Monoline Excess segment largely offset by $19 million of adverse prior year development for the Insurance segment.
For the Insurance segment, the adverse development during the first half of 2025 was driven by other liability and commercial auto liability and was partially offset by favorable development for short tail lines of business, including commercial property and commercial auto physical damage. The adverse other liability development was driven primarily by umbrella and other claims attaching excess of primary policy limits and included a significant component stemming from underlying auto exposures. A secondary driver of the other liability development related to the Company’s excess and surplus lines casualty business. The other liability development was concentrated in accident years 2017 through 2022. The adverse commercial auto liability development was concentrated in accident years 2021 and 2022. The Company believes that 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 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 development for short tail property lines of business during the first half of 2025 related to the 2024 accident year, and resulted from favorable settlements of both catastrophe and non-catastrophe claims below our expectations.
For the Reinsurance & Monoline Excess segment, the favorable development during the first half of 2025 was driven mainly by favorable development in non-proportional reinsurance for assumed property. Similar to the Insurance segment, the favorable property reinsurance development was driven by favorable claim settlements, below our expectations, related mainly to the 2024 accident year.
During the six months ended June 30, 2024, favorable prior year development (net of additional and return premiums) of $2 million included $7 million for the Reinsurance & Monoline Excess segment partially offset by $5 million of adverse prior year development for the Insurance segment.
For the Insurance segment, the adverse development during the first half of 2024 was driven by commercial auto liability and other liability (mainly umbrella and excess liability), and was partially 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 were being particularly impacted by social inflation, which contributed 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 2016 through 2023, while the favorable professional liability development was mainly in accident years 2018 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 2018 through 2022 was better than expected, which drove the favorable reserve development. Accident years 2020 through 2022 also feature business written at peak pricing levels, which the Company believes will result in higher profitability than initially anticipated.
For the Reinsurance & Monoline Excess segment, the favorable development during the first half 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 by favorable claim settlements spread across many prior accident years. The unfavorable development for non-proportional reinsurance was concentrated mainly in accident years 2017 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.
v3.25.2
Fair Value Of Financial Instruments
 6 Months Ended
Jun. 30, 2025
Fair Value Disclosures [Abstract]  
Fair Value Of Financial Instruments Fair Value Measurements
    The Company’s fixed maturity available for sale securities, equity securities and its arbitrage trading account securities are carried at fair value. Fair value is defined as “the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date.” The Company utilizes a fair value hierarchy that prioritizes the inputs to valuation techniques used to measure fair value into three broad levels, as follows:
Level 1 - Quoted prices (unadjusted) in active markets for identical assets or liabilities that the Company has the ability to access at the measurement date.
Level 2 - Quoted prices for similar assets or valuations based on inputs that are observable.
Level 3 - Estimates of fair value based on internal pricing methodologies using unobservable inputs. Unobservable inputs are only used to measure fair value to the extent that observable inputs are not available.
    Substantially all of the Company’s fixed maturity securities were priced by independent pricing services. The prices provided by the independent pricing services are estimated based on observable market data in active markets utilizing pricing models and processes, which may include benchmark yields, reported trades, broker/dealer quotes, issuer spreads, two-sided markets, benchmark securities, bids, offers, sector groupings, matrix pricing and reference data. The pricing services may prioritize inputs differently on any given day for any security based on market conditions, and not all inputs are available for each security evaluation on any given day. The pricing services used by the Company have indicated that they will only produce an estimate of fair value if objectively verifiable information is available. The determination of whether markets are active or inactive is based upon the volume and level of activity for a particular asset class. The Company reviews the prices provided by pricing services for reasonableness and periodically performs independent price tests of a sample of securities to ensure proper valuation.
    If prices from independent pricing services are not available for fixed maturity securities, the Company estimates the fair value. For Level 2 securities, the Company utilizes pricing models and processes which may include benchmark yields, sector groupings, matrix pricing, reported trades, broker/dealer quotes, issuer spreads, two-sided markets, bids, offers and reference data. Where broker quotes are used, the Company generally requests two or more quotes and sets a price within the range of quotes received based on its assessment of the credibility of the quote and its own evaluation of the security. The Company generally does not adjust quotes received from brokers. For securities traded only in private negotiations, the Company determines fair value based primarily on the cost of such securities, which is adjusted to reflect prices of recent placements of securities of the same issuer, financial projections, credit quality and business developments of the issuer and other relevant information.
    For Level 3 securities, the Company generally uses a discounted cash flow model to estimate the fair value of fixed maturity securities. The cash flow models are based upon assumptions as to prevailing credit spreads, interest rate and interest rate volatility, time to maturity and subordination levels. Projected cash flows are discounted at rates that are adjusted to reflect illiquidity, where appropriate.
    
    The following tables present the assets and liabilities measured at fair value on a recurring basis as of June 30, 2025 and December 31, 2024 by level:
(In thousands)TotalLevel 1Level 2Level 3
June 30, 2025
Assets:
Fixed maturity securities available for sale:
U.S. government and government agency$3,101,062 $— $3,101,062 $— 
State and municipal2,146,601 — 2,146,601 — 
Mortgage-backed4,327,577 — 4,327,577 — 
Asset-backed3,853,435 — 3,853,435 — 
Corporate8,758,776 — 8,738,800 19,976 
Foreign government1,875,654 — 1,875,654 — 
Total fixed maturity securities available for sale24,063,105 — 24,043,129 19,976 
Equity securities:
Common stocks719,570 716,561 858 2,151 
Preferred stocks542,622 — 533,948 8,674 
Total equity securities1,262,192 716,561 534,806 10,825 
Arbitrage trading account1,034,557 905,421 125,391 3,745 
Total$26,359,854 $1,621,982 $24,703,326 $34,546 
Liabilities:
Trading account securities sold but not yet purchased$30,909 $30,909 $— $— 
December 31, 2024
Assets:
Fixed maturity securities available for sale:
U.S. government and government agency$2,235,341 $— $2,235,341 $— 
State and municipal2,294,644 — 2,294,644 — 
Mortgage-backed3,765,490 — 3,765,490 — 
Asset-backed3,885,012 — 3,885,012 — 
Corporate8,417,641 — 8,397,974 19,667 
Foreign government1,755,325 — 1,755,325 — 
Total fixed maturity securities available for sale22,353,453 — 22,333,786 19,667 
Equity securities:
Common stocks760,167 757,115 1,011 2,041 
Preferred stocks443,621 — 439,947 3,674 
Total equity securities1,203,788 757,115 440,958 5,715 
Arbitrage trading account1,122,599 1,062,459 56,630 3,510 
Total$24,679,840 $1,819,574 $22,831,374 $28,892 
Liabilities:
Trading account securities sold but not yet purchased$73,358 $73,358 $— $— 
    The following tables summarize changes in Level 3 assets and liabilities for the six months ended June 30, 2025 and for the year ended December 31, 2024:
Gains (Losses) Included In:
(In thousands)Beginning
Balance		Earnings (Losses)Other
Comprehensive
Income (Losses)		ImpairmentsPurchasesSalesPaydowns / MaturitiesTransfers In / (Out)Ending
Balance
Six Months Ended June 30, 2025
Assets:
Fixed maturities securities available for sale:
Corporate$19,667 $— $309 $— $— $— $— $— $19,976 
Total19,667 — 309 — — — — — 19,976 
Equity securities:
Common stocks$2,041 $236 $— $— $— $(126)$— $— $2,151 
Preferred stocks3,674 — — — 6,160 (1,160)— — 8,674 
Total5,715 236 — — 6,160 (1,286)— — 10,825 
Arbitrage trading account3,510 235 — — — — — — 3,745 
Total$28,892 $471 $309 $— $6,160 $(1,286)$— $— $34,546 
Year Ended
December 31, 2024
Assets:
Fixed maturities securities available for sale:
Corporate$— $— $(333)$— $— $— $— $20,000 $19,667 
Total— — (333)— — — — 20,000 19,667 
Equity securities:
Common stocks$1,558 $611 $— $— $— $(128)$— $— $2,041 
Preferred stocks3,695 36 — — — (57)— — 3,674 
Total5,253 647 — — — (185)— — 5,715 
Arbitrage trading account3,772 (261)— — — (38)— 37 3,510 
Total$9,025 $386 $(333)$— $— $(223)$— $20,037 $28,892 
    For the six months ended June 30, 2025, there were no securities transferred into or out of Level 3. For the year ended December 31, 2024, there was one corporate security transferred into Level 3 from Level 2 given there were no quoted prices or
observable inputs available, and one security within the arbitrage trading account portfolio that no longer had a publicly traded price transferred into Level 3.
Fair Value of Financial Instruments
    The following table presents the carrying amounts and estimated fair values of the Company’s financial instruments:
  June 30, 2025December 31, 2024
(In thousands)Carrying ValueFair ValueCarrying ValueFair Value
Assets:
Fixed maturity securities$24,093,156 $24,094,270 $22,397,865 $22,399,426 
Equity securities1,262,192 1,262,192 1,203,788 1,203,788 
Arbitrage trading account1,034,557 1,034,557 1,122,599 1,122,599 
Loans receivable324,365 324,699 405,453 405,248 
Cash and cash equivalents1,984,529 1,984,529 1,974,747 1,974,747 
Trading account receivables from brokers and clearing organizations138,891 138,891 60,327 60,327 
Liabilities:
Due to broker16,160 16,160 70,483 70,483 
Trading account securities sold but not yet purchased30,909 30,909 73,358 73,358 
Senior notes and other debt1,831,638 1,438,943 1,831,158 1,425,852 
Subordinated debentures1,010,168 766,884 1,009,808 805,864 
    The estimated fair values of the Company’s fixed maturity securities, equity securities and arbitrage trading account securities are based on various valuation techniques that rely on fair value measurements as described in Note 15. The fair value of loans receivable are estimated by using current institutional purchaser yield requirements for loans with similar credit characteristics, which is considered a Level 2 input. The fair value of the senior notes and other debt and the subordinated debentures is based on spreads for similar securities, which is considered a Level 2 input.
v3.25.2
Premiums and Reinsurance Related Information
 6 Months Ended
Jun. 30, 2025
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
Ended June 30,		For the Six Months
Ended June 30,
(In thousands)2025202420252024
Written premiums:
Direct$3,610,784 $3,380,470 $6,921,677 $6,419,537 
Assumed366,985 337,302 740,031 660,991 
Ceded(626,330)(590,993)(1,176,966)(1,102,458)
Total net premiums written$3,351,439 $3,126,779 $6,484,742 $5,978,070 
Earned premiums:
Direct$3,335,252 $3,048,872 $6,569,095 $5,985,516 
Assumed336,521 328,114 676,118 666,024 
Ceded(573,588)(530,571)(1,134,647)(1,040,778)
Total net premiums earned$3,098,185 $2,846,415 $6,110,566 $5,610,762 
Ceded losses and loss expenses incurred$354,923 $327,243 $669,175 $633,194 
Ceded commissions earned$135,919 $123,647 $275,523 $244,701 
    The following table presents the rollforward of the allowance for expected credit losses for premiums and fees receivable for the six months ended June 30, 2025 and 2024:
(In thousands)20252024
Allowance for expected credit losses, beginning of period$39,884 $35,110 
Change in expected credit losses(924)2,169 
Allowance for expected credit losses, end of period$38,960 $37,279 
The following table presents the rollforward of the allowance for expected credit losses for premiums and fees receivable for the three months ended June 30, 2025 and 2024:
(In thousands)20252024
Allowance for expected credit losses, beginning of period$38,861 $35,039 
Change in expected credit losses99 2,240 
Allowance for expected credit losses, end of period$38,960 $37,279 
The Company reinsures a portion of its insurance exposures in order to reduce its net liability on individual risks and catastrophe losses. The Company also cedes premiums to state assigned risk plans and captive insurance companies. Estimated amounts due from reinsurers are reported net of an allowance for expected credit losses.
The following table presents the rollforward of the allowance for expected credit losses associated with due from reinsurers for the six months ended June 30, 2025 and 2024:
(In thousands)20252024
Allowance for expected credit losses, beginning of period$8,350 $8,404 
Change in expected credit losses(1,396)1,851 
Allowance for expected credit losses, end of period$6,954 $10,255 
The following table presents the rollforward of the allowance for expected credit losses associated with due from reinsurers for the three months ended June 30, 2025 and 2024:
(In thousands)20252024
Allowance for expected credit losses, beginning of period$7,084 $9,185 
Change in expected credit losses(130)1,070 
Allowance for expected credit losses, end of period$6,954 $10,255 
v3.25.2
Restricted Stock Units
 6 Months Ended
Jun. 30, 2025
Share-Based Payment Arrangement [Abstract]  
Restricted Stock Units Restricted Stock Units
    Pursuant to its stock incentive plan, the Company may issue restricted stock units ("RSUs") to employees of the Company and its subsidiaries. The RSUs generally vest three to five years from the award date and are subject to other vesting and forfeiture provisions contained in the award agreement. RSUs are expensed pro-ratably over the vesting period. RSU expenses were $25 million for both the six months ended June 30, 2025 and 2024. A summary of RSUs issued in the six months ended June 30, 2025 and 2024 follows:
($ in thousands)
UnitsFair Value
202520,995 $1,235 
20242,277$125 
v3.25.2
Litigation and Contingent Liabilities
 6 Months Ended
Jun. 30, 2025
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.
v3.25.2
Leases
 6 Months Ended
Jun. 30, 2025
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
June 30,		For the Six Months Ended June 30,
(In thousands)2025202420252024
Leases:
Lease cost$13,220 $11,326 $25,998 $22,403 
Cash paid for amounts included in the measurement of lease liabilities reported in operating cash flows$11,832 $12,364 $25,314 $24,596 
Right-of-use assets obtained in exchange for new lease liabilities$31,224 $8,853 $44,434 $33,548 

As of June 30,
($ in thousands)20252024
Right-of-use assets$210,884$190,207
Lease liabilities$249,189$231,128
Weighted-average remaining lease term7.3 years7.5 years
Weighted-average discount rate5.82 %5.51 %

Contractual maturities of the Company’s future minimum lease payments are as follows:
(In thousands)June 30, 2025
Contractual Maturities:
2025$24,509 
202648,304 
202739,709 
202838,184 
202934,282 
Thereafter113,898 
Total undiscounted future minimum lease payments298,886 
Less: Discount impact49,697 
Total lease liability$249,189 
v3.25.2
Business Segments
 6 Months Ended
Jun. 30, 2025
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 Company's chief operating decision maker ("CODM") is the President and Chief Executive Officer. The CODM assesses performance, makes decisions and allocates resources for each of the three reportable segments based on their contribution towards the Company's profitability and balance sheet strength. Certain key metrics such as combined ratio and return on allocated capital for the Insurance and Reinsurance & Monoline Excess segments, as well as Corporate segment expenditures, are examples of key components of the assessment, decision-making and resource-allocation process.
    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.
  RevenuesExpenses  
(In thousands)Earned
Premiums (1)		Investment
Income
(Loss)		OtherTotal (2)Losses and Loss ExpensesPolicy Acquisition and Insurance Operating ExpensesOtherTotalPre-Tax Income (Loss)Net Income (Loss) to Common Stockholders
Three months ended June 30, 2025
Insurance$2,728,784 $299,476 $10,154 $3,038,414 $1,742,235 $772,328 $11,179 $2,525,742 $512,672 $393,450 
Reinsurance & Monoline Excess369,401 80,858 — 450,259 213,189 109,771 — 322,960 127,299 100,040 
Corporate, other and eliminations (3)— (1,031)152,193 151,162 — — 300,243 300,243 (149,081)(116,490)
Net investment gains— — 30,973 30,973 — — — — 30,973 24,288 
Total$3,098,185 $379,303 $193,320 $3,670,808 $1,955,424 $882,099 $311,422 $3,148,945 $521,863 $401,288 
Three months ended June 30, 2024
Insurance$2,484,569 $303,561 $9,591 $2,797,721 $1,589,569 $707,155 $10,944 $2,307,668 $490,053 $374,247 
Reinsurance & Monoline Excess361,846 58,472 — 420,318 191,027 104,842 — 295,869 124,449 97,638 
Corporate, other and eliminations (3)— 10,096 144,409 154,505 — — 222,822 222,822 (68,317)(53,865)
Net investment losses— — (58,512)(58,512)— — — — (58,512)(46,111)
Total$2,846,415 $372,129 $95,488 $3,314,032 $1,780,596 $811,997 $233,766 $2,826,359 $487,673 $371,909 
Six months ended June 30, 2025
Insurance$5,371,291 $590,724 $20,106 $5,982,121 $3,429,688 $1,507,989 $22,267 $4,959,944 $1,022,177 $786,572 
Reinsurance & Monoline Excess739,275 147,288 — 886,563 426,528 212,356 — 638,884 247,679 195,883 
Corporate, other and eliminations (3)— 1,583 300,612 302,195 — — 558,910 558,910 (256,715)(200,710)
Net investment gains— — 47,328 47,328 — — — — 47,328 37,115 
Total$6,110,566 $739,595 $368,046 $7,218,207 $3,856,216 $1,720,345 $581,177 $6,157,738 $1,060,469 $818,860 
Six months ended June 30, 2024
Insurance$4,883,338 $548,338 $19,014 $5,450,690 $3,071,121 $1,389,749 $21,618 $4,482,488 $968,202 $739,337 
Reinsurance & Monoline Excess727,424 111,683 — 839,107 373,253 213,780 — 587,033 252,074 199,764 
Corporate, other and eliminations (3)— 31,946 281,795 313,741 — — 439,540 439,540 (125,799)(97,757)
Net investment losses— — (32,733)(32,733)— — — — (32,733)(26,964)
Total$5,610,762 $691,967 $268,076 $6,570,805 $3,444,374 $1,603,529 $461,158 $5,509,061 $1,061,744 $814,380 
Identifiable Assets
(In thousands)June 30,
2025		December 31,
2024
Insurance$34,532,276 $32,911,507 
Reinsurance & Monoline Excess5,799,205 5,669,729 
Corporate, other and eliminations (3)2,326,576 1,867,399 
Consolidated$42,658,057 $40,448,635 
_________________
(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 June 30, 2025 and 2024 were $361 million and $368 million, respectively, and for the six months ended June 30, 2025 and 2024 were $694 million and $762 million, respectively. Revenues for Reinsurance & Monoline Excess from foreign operations for the three months ended June 30, 2025 and 2024 were $116 million and $117 million, respectively, and for the six months ended June 30, 2025 and 2024 were $246 million and $228 million, respectively.
(3) Corporate, other and eliminations represent corporate revenues and expenses and certain other items that are not allocated to business segments.
    Net premiums earned by major line of business are as follows:
 For the Three Months
Ended June 30,		For the Six Months
Ended June 30,
(In thousands)2025202420252024
Insurance:
Other liability$1,104,332 $1,001,987 $2,177,060 $1,969,247 
Short-tail lines (1)619,988 538,797 1,216,096 1,049,606 
Auto405,632 361,580 795,581 715,593 
Workers' compensation318,881 310,564 629,910 612,060 
Professional liability279,951 271,641 552,644 536,832 
Total Insurance2,728,784 2,484,569 5,371,291 4,883,338 
Reinsurance & Monoline Excess:
Casualty (2)184,903 199,080 366,670 396,924 
Property (2)113,136 97,255 233,979 199,638 
Monoline excess (3)71,362 65,511 138,626 130,862 
Total Reinsurance & Monoline Excess369,401 361,846 739,275 727,424 
Total$3,098,185 $2,846,415 $6,110,566 $5,610,762 
______________
(1) Short-tail lines include commercial multi-peril (non-liability), inland marine, accident and health, fidelity and surety, boiler and machinery, high net worth homeowners and other lines.
(2) Includes reinsurance casualty and property and certain program management business.
(3) Monoline excess includes operations that solely retain risk on an excess basis.
v3.25.2
Pay vs Performance Disclosure - USD ($)
$ in Thousands
 3 Months Ended 6 Months Ended
Jun. 30, 2025
Jun. 30, 2024
Jun. 30, 2025
Jun. 30, 2024
Pay vs Performance Disclosure        
Net Income (Loss) to Common Stockholders $ 401,288 $ 371,909 $ 818,860 $ 814,380
v3.25.2
Insider Trading Arrangements
 3 Months Ended
Jun. 30, 2025
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
v3.25.2
Recent Accounting Pronouncements and Accounting Policies (Policies)
 6 Months Ended
Jun. 30, 2025
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 17,659,297 and 17,495,175 common shares held in a grantor trust as of June 30, 2025 and 2024, respectively). The common shares held in the grantor trust are designated for delivery upon the settlement of vested but mandatorily deferred restricted stock units ("RSUs"). Accordingly, such shares deliverable under vested RSUs do not affect diluted shares outstanding since the shares are already included in basic shares outstanding (which includes the shares in the grantor trust referenced above). Diluted EPS is based upon the weighted average number of basic and common equivalent shares outstanding during the period and is calculated using the treasury stock method for stock incentive plans. Common equivalent shares are excluded from the computation in periods in which they have an anti-dilutive effect.
    The weighted average number of common shares used in the computation of basic and diluted earnings per share was as follows:
For the Three Months
Ended June 30,		For the Six Months
Ended June 30,
(In thousands)2025202420252024
Basic397,016 400,273 396,972 401,295 
Diluted400,368 403,737 400,098 404,679 
Recent Accounting Pronouncements Recent Accounting Pronouncements and Accounting Policies
Recently adopted accounting pronouncements:
    All accounting and reporting standards that became effective in 2025 were either not applicable to the Company or their adoption did not have a material impact on the Company.

Accounting and reporting standards that are not yet effective:
    In December 2023, the Financial Accounting Standards Board issued Accounting Standards Update 2023-09, Improvements to Income Tax Disclosures (Topic 740), to enhance the transparency and usefulness of income tax disclosures. The guidance requires improvements to income tax disclosures primarily related to the rate reconciliation and income taxes paid. This guidance is effective for annual periods beginning after December 15, 2024. The Company will provide these additional disclosures in its financial statements for the year ended December 31, 2025.
All other recently issued but not yet effective accounting and reporting standards are either not applicable to the Company or are not expected to have a material impact on the Company.
v3.25.2
Per Share Data (Tables)
 6 Months Ended
Jun. 30, 2025
Earnings Per Share [Abstract]  
Weighted average number of common shares The weighted average number of common shares used in the computation of basic and diluted earnings per share was as follows:
For the Three Months
Ended June 30,		For the Six Months
Ended June 30,
(In thousands)2025202420252024
Basic397,016 400,273 396,972 401,295 
Diluted400,368 403,737 400,098 404,679 
v3.25.2
Consolidated Statements of Comprehensive Income (Loss) (Tables)
 6 Months Ended
Jun. 30, 2025
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 Gains (Losses)Currency Translation AdjustmentsAccumulated Other Comprehensive
Income (Loss)
As of and for the six months ended June 30, 2025
Changes in AOCI
Beginning of period$(517,170)$(417,099)$(934,269)
Other comprehensive income before reclassifications242,620 93,348 335,968 
Amounts reclassified from AOCI25,918 — 25,918 
Other comprehensive income268,538 93,348 361,886 
Unrealized investment loss related to noncontrolling interest(1)— (1)
End of period$(248,633)$(323,751)$(572,384)
Amounts reclassified from AOCI
Pre-tax$32,808 (1)$— $32,808 
Tax effect (6,890)(2)— (6,890)
After-tax amounts reclassified$25,918 $— $25,918 
Other comprehensive income
Pre-tax$343,713 $93,348 $437,061 
Tax effect(75,175)— (75,175)
Other comprehensive income$268,538 $93,348 $361,886 
As of and for the three months ended June 30, 2025
Changes in AOCI
Beginning of period$(368,898)$(393,169)$(762,067)
Other comprehensive income before reclassifications98,518 69,418 167,936 
Amounts reclassified from AOCI21,747 — 21,747 
Other comprehensive income120,265 69,418 189,683 
Unrealized investment loss related to noncontrolling interest— — — 
Ending balance$(248,633)$(323,751)$(572,384)
Amounts reclassified from AOCI
Pre-tax$27,528 (1)$— $27,528 
Tax effect (5,781)(2)— (5,781)
After-tax amounts reclassified$21,747 $— $21,747 
Other comprehensive income
Pre-tax$157,858 $69,418 $227,276 
Tax effect(37,593)— (37,593)
Other comprehensive income$120,265 $69,418 $189,683 
(In thousands)Unrealized Investment (Losses) GainsCurrency Translation AdjustmentsAccumulated Other Comprehensive
(Loss) Income
As of and for the six months ended June 30, 2024
Changes in AOCI
Beginning of period$(586,354)$(339,484)$(925,838)
Other comprehensive loss before reclassifications(156,023)(24,343)(180,366)
Amounts reclassified from AOCI72,563 — 72,563 
Other comprehensive loss(83,460)(24,343)(107,803)
Unrealized investment gain related to noncontrolling interest1 — 1 
End of period$(669,813)$(363,827)$(1,033,640)
Amounts reclassified from AOCI
Pre-tax$91,852 (1)$— $91,852 
Tax effect (19,289)(2)— (19,289)
After-tax amounts reclassified$72,563 $— $72,563 
Other comprehensive loss
Pre-tax$(109,937)$(24,343)$(134,280)
Tax effect26,477 — 26,477 
Other comprehensive loss$(83,460)$(24,343)$(107,803)
As of and for the three months ended June 30, 2024
Changes in AOCI
Beginning of period$(656,476)$(367,054)$(1,023,530)
Other comprehensive (loss) income before reclassifications(54,711)3,227 (51,484)
Amounts reclassified from AOCI41,373 — 41,373 
Other comprehensive (loss) income(13,338)3,227 (10,111)
Unrealized investment gain related to noncontrolling interest1 — 1 
Ending balance$(669,813)$(363,827)$(1,033,640)
Amounts reclassified from AOCI
Pre-tax$52,371 (1)$— $52,371 
Tax effect (10,998)(2)— (10,998)
After-tax amounts reclassified$41,373 $— $41,373 
Other comprehensive (loss) income
Pre-tax$(20,640)$3,227 $(17,413)
Tax effect7,302 — 7,302 
Other comprehensive (loss) income$(13,338)$3,227 $(10,111)
____________
(1) Net investment gains in the consolidated statements of income.
(2) Income tax expense in the consolidated statements of income.
v3.25.2
Investments in Fixed Maturity Securities (Tables)
 6 Months Ended
Jun. 30, 2025
Investments, Debt and Equity Securities [Abstract]  
Schedule of investments in fixed maturity securities At June 30, 2025 and December 31, 2024, investments in fixed maturity securities were as follows:
 
(In thousands)Amortized
Cost		Allowance for Expected Credit Losses (1)Gross UnrealizedFair
Value		Carrying
Value
GainsLosses
June 30, 2025
Held to maturity:
State and municipal$27,983 $(14)$1,040 $— $29,009 $27,969 
Residential mortgage-backed2,082 — 74 — 2,156 2,082 
Total held to maturity30,065 (14)1,114 — 31,165 30,051 
Available for sale:
U.S. government and government agency3,108,090 — 23,421 (30,449)3,101,062 3,101,062 
State and municipal:
Special revenue1,387,506 — 6,306 (40,427)1,353,385 1,353,385 
State general obligation258,795 — 2,817 (5,451)256,161 256,161 
Pre-refunded77,145 — 555 (223)77,477 77,477 
Corporate backed187,565 — 1,688 (5,053)184,200 184,200 
Local general obligation277,592 — 1,852 (4,066)275,378 275,378 
Total state and municipal2,188,603 — 13,218 (55,220)2,146,601 2,146,601 
Mortgage-backed:
Residential4,090,672 — 34,670 (157,265)3,968,077 3,968,077 
Commercial355,922 — 3,911 (333)359,500 359,500 
Total mortgage-backed4,446,594 — 38,581 (157,598)4,327,577 4,327,577 
Asset-backed3,862,993 — 17,247 (26,805)3,853,435 3,853,435 
Corporate:
Industrial3,680,399 — 45,729 (53,582)3,672,546 3,672,546 
Financial3,417,541 — 54,356 (19,722)3,452,175 3,452,175 
Utilities1,146,714 — 15,476 (10,772)1,151,418 1,151,418 
Other481,868 — 2,775 (2,006)482,637 482,637 
Total corporate8,726,522 — 118,336 (86,082)8,758,776 8,758,776 
Foreign government2,006,836 (318)34,642 (165,506)1,875,654 1,875,654 
Total available for sale24,339,638 (318)245,445 (521,660)24,063,105 24,063,105 
Total investments in fixed maturity securities$24,369,703 $(332)$246,559 $(521,660)$24,094,270 $24,093,156 
____________
(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
Cost		Allowance for Expected Credit Losses (1)Gross UnrealizedFair
Value		Carrying
Value
GainsLosses
December 31, 2024
Held to maturity:
State and municipal$42,145 $(25)$1,492 $— $43,612 $42,120 
Residential mortgage-backed2,292 — 69 — 2,361 2,292 
Total held to maturity44,437 (25)1,561 — 45,973 44,412 
Available for sale:
U.S. government and government agency2,268,596 — 9,608 (42,863)2,235,341 2,235,341 
State and municipal:
Special revenue1,581,778 — 3,521 (67,591)1,517,708 1,517,708 
State general obligation272,936 — 1,439 (8,981)265,394 265,394 
Pre-refunded85,340 — 599 (347)85,592 85,592 
Corporate backed158,322 — 1,079 (5,827)153,574 153,574 
Local general obligation278,165 — 922 (6,711)272,376 272,376 
Total state and municipal2,376,541 — 7,560 (89,457)2,294,644 2,294,644 
Mortgage-backed:
Residential3,411,796 (5)11,047 (189,630)3,233,208 3,233,208 
Commercial534,936 (425)1,201 (3,430)532,282 532,282 
Total mortgage-backed3,946,732 (430)12,248 (193,060)3,765,490 3,765,490 
Asset-backed3,910,363 — 16,161 (41,512)3,885,012 3,885,012 
Corporate:
Industrial3,746,501 — 14,518 (93,820)3,667,199 3,667,199 
Financial3,339,718 — 18,871 (38,076)3,320,513 3,320,513 
Utilities795,839 — 2,970 (20,115)778,694 778,694 
Other653,194 — 2,493 (4,452)651,235 651,235 
Total corporate8,535,252 — 38,852 (156,463)8,417,641 8,417,641 
Foreign government1,928,978 (216)11,936 (185,373)1,755,325 1,755,325 
Total available for sale22,966,462 (646)96,365 (708,728)22,353,453 22,353,453 
Total investments in fixed maturity securities$23,010,899 $(671)$97,926 $(708,728)$22,399,426 $22,397,865 
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 six months ended June 30, 2025 and 2024:
(In thousands)20252024
Balance, beginning of period$25 $43 
Provision for expected credit losses(11)(9)
Balance, end of period$14 $34 
The following table presents the rollforward of the allowance for expected credit losses for held to maturity securities for the three months ended June 30, 2025 and 2024:
(In thousands)20252024
Balance, beginning of period$20 $38 
Provision for expected credit losses(6)(4)
Balance, end of period$14 $34 
Debt Securities, Available-for-sale, Allowance for Credit Loss
The following table presents the rollforward of the allowance for expected credit losses for available for sale securities for the six months ended June 30, 2025 and 2024:
20252024
(In thousands)Foreign GovernmentMortgage-backedState and MunicipalTotalForeign GovernmentCorporateMortgage-backedAsset-backedState and MunicipalTotal
Balance, beginning of period$216 $430 $— $646 $29,603 $5,026 $158 $1,164 $757 $36,708 
Change on securities for which credit losses were not previously recorded— — 10 10 300 — 1,701 — — 2,001 
Change on securities for which credit losses were previously recorded102 (430)(10)(338)(10,434)(5,026)(158)(275)(418)(16,311)
Reduction due to disposals— — — — — — (561)— — (561)
Balance, end of period$318 $— $— $318 $19,469 $— $1,140 $889 $339 $21,837 
During the six months ended June 30, 2025, the Company decreased the allowance for expected credit losses for available for sale securities primarily due to improved pricing related to mortgage-backed securities. During the six months ended June 30, 2024, the Company decreased the allowance for expected credit losses for available for sale securities primarily due to improved pricing associated with foreign government securities and corporate securities.
The following table presents the rollforward of the allowance for expected credit losses for available for sale securities for the three months ended June 30, 2025 and 2024:

20252024
(In thousands)Foreign GovernmentState and MunicipalTotalForeign GovernmentMortgage-backedAsset-backedState and MunicipalTotal
Balance, beginning of period$323 $10 $333 $20,479 $562 $1,097 $693 $22,831 
Change on securities for which credit losses were not previously recorded— — — 300 1,139 — — 1,439 
Change on securities for which credit losses were previously recorded(5)(10)(15)(1,310)— (208)(354)(1,872)
Reduction due to disposals— — — — (561)— — (561)
Balance, end of period$318 $— $318 $19,469 $1,140 $889 $339 $21,837 
Amortized cost and fair value of fixed maturity securities by contractual maturity
The amortized cost and fair value of fixed maturity securities at June 30, 2025, by contractual maturity, are shown below. Actual maturities may differ from contractual maturities because certain issuers may have the right to call or prepay obligations.  
(In thousands)Amortized
Cost (1)		Fair
Value
Due in one year or less$1,728,802 $1,720,156 
Due after one year through five years9,001,644 8,861,485 
Due after five years through ten years4,046,210 4,065,444 
Due after ten years5,144,357 5,117,452 
Mortgage-backed securities4,448,676 4,329,733 
Total$24,369,689 $24,094,270 
________________
(1) Amortized cost is reduced by the allowance for expected credit losses of $14 thousand related to held to maturity securities.
v3.25.2
Investments in Equity Securities (Tables)
 6 Months Ended
Jun. 30, 2025
Equity securities  
Debt Securities, Available-for-sale [Line Items]  
Schedule of Investments in Equity Securities At June 30, 2025 and December 31, 2024, investments in equity securities were as follows:
 
(In thousands)CostGross UnrealizedFair
Value		Carrying
Value
GainsLosses
June 30, 2025
Common stocks$528,148 $211,335 $(19,913)$719,570 $719,570 
Preferred stocks388,653 158,950 (4,981)542,622 542,622 
Total$916,801 $370,285 $(24,894)$1,262,192 $1,262,192 
December 31, 2024
Common stocks$612,479 $223,981 $(76,293)$760,167 $760,167 
Preferred stocks329,495 122,716 (8,590)443,621 443,621 
Total$941,974 $346,697 $(84,883)$1,203,788 $1,203,788 
v3.25.2
Net Investment Income (Tables)
 6 Months Ended
Jun. 30, 2025
Net Investment Income [Abstract]  
Schedule of Net Investment Income Net investment income consisted of the following: 
 For the Three Months
Ended June 30,		For the Six Months
Ended June 30,
(In thousands)2025202420252024
Investment income (loss) earned on:
Fixed maturity securities, including cash and cash equivalents and loans receivable$322,518 $324,136 $636,306 $659,384 
Investment funds27,268 25,476 54,291 (3,873)
Arbitrage trading account (1)23,672 16,682 40,001 34,693 
Equity securities12,485 12,386 23,126 23,721 
Real estate(4,092)(3,705)(8,109)(16,868)
Gross investment income381,851 374,975 745,615 697,057 
Investment expense(2,548)(2,846)(6,020)(5,090)
Net investment income$379,303 $372,129 $739,595 $691,967 
(1) Net investment income includes earnings from trading account receivables from brokers and clearing organizations.
v3.25.2
Investment Funds (Tables)
 6 Months Ended
Jun. 30, 2025
Equity Method Investments and Joint Ventures [Abstract]  
Schedule of Investment Funds Investment funds consisted of the following:
Carrying Value as of Income (Loss) from
Investment Funds
June 30,December 31,For the Six Months
Ended June 30,
(In thousands)2025202420252024
Financial services$434,518 $430,163 $12,277 $(18,231)
Transportation276,904 286,426 20,714 (3,732)
Real Estate181,509 178,685 5,614 12,880 
Infrastructure161,019 151,560 9,064 7,828 
Energy42,193 42,776 (1,234)8,505 
Other funds396,115 378,636 7,856 (11,123)
Total$1,492,258 $1,468,246 $54,291 $(3,873)
v3.25.2
Real Estate (Tables)
 6 Months Ended
Jun. 30, 2025
Real Estate [Abstract]  
Schedule of Real Estate Investments Investment in real estate represents directly owned property held for investment, as follows:
Carrying Value
June 30,December 31,
(In thousands)20252024
Properties in operation$1,066,361 $1,063,687 
Properties under development228,144 227,768 
Total$1,294,505 $1,291,455 
v3.25.2
Loans Receivable Loans Receivable (Tables)
 6 Months Ended
Jun. 30, 2025
Receivables [Abstract]  
Schedule of Loans Receivable
At June 30, 2025 and December 31, 2024, loans receivable were as follows:
(In thousands)June 30,
2025		December 31,
2024
Amortized cost (net of allowance for expected credit losses):
Real estate loans$320,309 $402,382 
Commercial loans4,056 3,071 
Total$324,365 $405,453 
Fair value:
Real estate loans$320,643 $402,177 
Commercial loans4,056 3,071 
Total$324,699 $405,248 
Financing Receivable, Allowance for Credit Loss
The following table presents the rollforward of the allowance for expected credit losses for loans receivable for the six months ended June 30, 2025 and 2024:
20252024
(In thousands)Real Estate LoansCommercial LoansTotalReal Estate LoansCommercial LoansTotal
Balance, beginning of period$1,088 $26 $1,114 $2,983 $21 $3,004 
Change in expected credit losses(754)9 (745)(1,190)(1)(1,191)
Balance, end of period$334 $35 $369 $1,793 $20 $1,813 
During six months ended June 30, 2025, the Company decreased the allowance for expected credit losses due to the redemption of one loan and a decrease in the weighted average life of the remaining loan portfolio. During the six months ended June 30, 2024, the Company decreased the allowance for expected credit losses due to a decrease in the weighted average life of the loan portfolio.
The following table presents the rollforward of the allowance for expected credit losses for loans receivable for the three months ended June 30, 2025 and 2024:
20252024
(In thousands)Real Estate LoansCommercial LoansTotalReal Estate LoansCommercial LoansTotal
Balance, beginning of period$776 $12 $788 $2,587 $22 $2,609 
Change in expected credit losses(442)23 (419)(794)(2)(796)
Balance, end of period$334 $35 $369 $1,793 $20 $1,813 
v3.25.2
Net Investment (Losses) Gains (Tables)
 6 Months Ended
Jun. 30, 2025
Realized and Unrealized Investment Gains (Losses) [Abstract]  
Realized And Unrealized Investment Gains (Losses) Net investment gains (losses) were as follows:
For the Three Months
Ended June 30,		For the Six Months
Ended June 30,
(In thousands)2025202420252024
Net investment gains (losses):  
Fixed maturity securities:  
Gains$4,209 $3,092 $6,841 $6,649 
Losses(5,654)(5,362)(8,366)(7,685)
Equity securities (1):
Net realized (losses) gains on investment sales (1,100)61,521 (3,695)101,798 
Change in unrealized gains (losses)63,630 (66,717)83,577 (40,905)
Investment funds808 217 822 1,210 
Real estate (5,256)(1,958)(1,313)(4,174)
Other (2)(26,104)(51,099)(31,622)(105,696)
Net realized and unrealized gains (losses) on investments in earnings before allowance for expected credit losses30,533 (60,306)46,244 (48,803)
Change in allowance for expected credit losses on investments:
Fixed maturity securities21 998 339 14,879 
Loans receivable419 796 745 1,191 
Change in allowance for expected credit losses on investments440 1,794 1,084 16,070 
Net investment gains (losses)30,973 (58,512)47,328 (32,733)
Income tax (expense) benefit(6,685)12,401 (10,213)5,769 
After-tax net investment gains (losses)$24,288 $(46,111)$37,115 $(26,964)
Change in unrealized investment gains (losses) on available for sale securities:  
Fixed maturity securities without allowance for expected credit losses$152,235 $(11,394)$336,222 $(99,988)
Fixed maturity securities with allowance for expected credit losses478 (7,683)(73)(6,696)
Investment funds5,110 (1,338)7,606 (3,041)
Other35 (225)(42)(212)
Total change in unrealized investment gains (losses)157,858 (20,640)343,713 (109,937)
Income tax (expense) benefit(37,593)7,302 (75,175)26,477 
Noncontrolling interests— 1 (1)1 
After-tax change in unrealized investment gains (losses) of available for sale securities$120,265 $(13,337)$268,537 $(83,459)
______________________
(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) Primarily relates to realized foreign currency losses upon the disposition of fixed maturity securities.
v3.25.2
Fixed Maturity Securities In An Unrealized Loss Position (Tables)
 6 Months Ended
Jun. 30, 2025
Investments, Debt and Equity Securities [Abstract]  
Securities in an unrealized loss position The following tables summarize all fixed maturity securities in an unrealized loss position at June 30, 2025 and December 31, 2024 by the length of time those securities have been continuously in an unrealized loss position:
  Less Than 12 Months12 Months or GreaterTotal
(In thousands)Fair
Value		Gross
Unrealized Losses		Fair
Value		Gross
Unrealized Losses		Fair
Value		Gross
Unrealized Losses
June 30, 2025
U.S. government and government agency$941,906 $11,134 $466,439 $19,315 $1,408,345 $30,449 
State and municipal200,033 3,908 1,262,830 51,312 1,462,863 55,220 
Mortgage-backed859,569 11,556 887,676 146,042 1,747,245 157,598 
Asset-backed610,864 2,675 532,828 24,130 1,143,692 26,805 
Corporate366,889 2,120 2,207,465 83,962 2,574,354 86,082 
Foreign government150,504 2,285 339,854 163,221 490,358 165,506 
Fixed maturity securities$3,129,765 $33,678 $5,697,092 $487,982 $8,826,857 $521,660 
December 31, 2024
U.S. government and government agency$767,515 $9,637 $560,260 $33,226 $1,327,775 $42,863 
State and municipal348,116 8,027 1,411,761 81,430 1,759,877 89,457 
Mortgage-backed1,541,464 21,326 1,060,823 171,734 2,602,287 193,060 
Asset-backed411,763 4,613 626,237 36,899 1,038,000 41,512 
Corporate1,791,970 21,346 2,951,377 135,117 4,743,347 156,463 
Foreign government600,103 17,933 476,479 167,440 1,076,582 185,373 
Fixed maturity securities$5,460,931 $82,882 $7,086,937 $625,846 $12,547,868 $708,728 
Non-Investment Grade Fixed Maturity Securities A summary of the Company’s non-investment grade fixed maturity securities that were in an unrealized loss position at June 30, 2025 is presented in the table below:
($ in thousands)Number of
Securities		Aggregate
Fair Value		Gross
Unrealized Loss
Foreign government50 $144,584 $155,344 
State and municipal6 28,621 1,436 
Corporate8 29,131 622 
Mortgage-backed15 2,589 193 
Asset-backed1 9 1 
Total80 $204,934 $157,596 
v3.25.2
Fair Value Measurements (Tables)
 6 Months Ended
Jun. 30, 2025
Fair Value Disclosures [Abstract]  
Assets And Liabilities Measured At Fair value, On A Recurring Basis The following tables present the assets and liabilities measured at fair value on a recurring basis as of June 30, 2025 and December 31, 2024 by level:
(In thousands)TotalLevel 1Level 2Level 3
June 30, 2025
Assets:
Fixed maturity securities available for sale:
U.S. government and government agency$3,101,062 $— $3,101,062 $— 
State and municipal2,146,601 — 2,146,601 — 
Mortgage-backed4,327,577 — 4,327,577 — 
Asset-backed3,853,435 — 3,853,435 — 
Corporate8,758,776 — 8,738,800 19,976 
Foreign government1,875,654 — 1,875,654 — 
Total fixed maturity securities available for sale24,063,105 — 24,043,129 19,976 
Equity securities:
Common stocks719,570 716,561 858 2,151 
Preferred stocks542,622 — 533,948 8,674 
Total equity securities1,262,192 716,561 534,806 10,825 
Arbitrage trading account1,034,557 905,421 125,391 3,745 
Total$26,359,854 $1,621,982 $24,703,326 $34,546 
Liabilities:
Trading account securities sold but not yet purchased$30,909 $30,909 $— $— 
December 31, 2024
Assets:
Fixed maturity securities available for sale:
U.S. government and government agency$2,235,341 $— $2,235,341 $— 
State and municipal2,294,644 — 2,294,644 — 
Mortgage-backed3,765,490 — 3,765,490 — 
Asset-backed3,885,012 — 3,885,012 — 
Corporate8,417,641 — 8,397,974 19,667 
Foreign government1,755,325 — 1,755,325 — 
Total fixed maturity securities available for sale22,353,453 — 22,333,786 19,667 
Equity securities:
Common stocks760,167 757,115 1,011 2,041 
Preferred stocks443,621 — 439,947 3,674 
Total equity securities1,203,788 757,115 440,958 5,715 
Arbitrage trading account1,122,599 1,062,459 56,630 3,510 
Total$24,679,840 $1,819,574 $22,831,374 $28,892 
Liabilities:
Trading account securities sold but not yet purchased$73,358 $73,358 $— $— 
Summarize Changes In Level 3 Assets The following tables summarize changes in Level 3 assets and liabilities for the six months ended June 30, 2025 and for the year ended December 31, 2024:
Gains (Losses) Included In:
(In thousands)Beginning
Balance		Earnings (Losses)Other
Comprehensive
Income (Losses)		ImpairmentsPurchasesSalesPaydowns / MaturitiesTransfers In / (Out)Ending
Balance
Six Months Ended June 30, 2025
Assets:
Fixed maturities securities available for sale:
Corporate$19,667 $— $309 $— $— $— $— $— $19,976 
Total19,667 — 309 — — — — — 19,976 
Equity securities:
Common stocks$2,041 $236 $— $— $— $(126)$— $— $2,151 
Preferred stocks3,674 — — — 6,160 (1,160)— — 8,674 
Total5,715 236 — — 6,160 (1,286)— — 10,825 
Arbitrage trading account3,510 235 — — — — — — 3,745 
Total$28,892 $471 $309 $— $6,160 $(1,286)$— $— $34,546 
Year Ended
December 31, 2024
Assets:
Fixed maturities securities available for sale:
Corporate$— $— $(333)$— $— $— $— $20,000 $19,667 
Total— — (333)— — — — 20,000 19,667 
Equity securities:
Common stocks$1,558 $611 $— $— $— $(128)$— $— $2,041 
Preferred stocks3,695 36 — — — (57)— — 3,674 
Total5,253 647 — — — (185)— — 5,715 
Arbitrage trading account3,772 (261)— — — (38)— 37 3,510 
Total$9,025 $386 $(333)$— $— $(223)$— $20,037 $28,892 
v3.25.2
Reserves for Loss and Loss Expenses (Tables)
 6 Months Ended
Jun. 30, 2025
Insurance [Abstract]  
Reserve Balances The table below provides a reconciliation of the beginning and ending reserve balances:
June 30,
(In thousands)20252024
Net reserves at beginning of period$17,166,641 $15,661,820 
Net provision for losses and loss expenses:
Claims occurring during the current year (1)3,822,512 3,411,888 
Increase in estimates for claims occurring in prior years (2) (3)17,823 14,700 
Loss reserve discount accretion 15,881 17,786 
Total3,856,216 3,444,374 
Net payments for claims:  
Current year431,981 383,639 
Prior years2,537,599 2,205,566 
Total2,969,580 2,589,205 
Foreign currency translation164,747 (56,143)
Net reserves at end of period18,218,024 16,460,846 
Ceded reserves at end of period3,278,099 3,106,344 
Gross reserves at end of period$21,496,123 $19,567,190 
_______________________________________
(1) Claims occurring during the current year are net of loss reserve discounts of $28 million and $26 million for the six months ended June 30, 2025 and 2024, 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 $17 million and $7 million for the six months ended June 30, 2025 and 2024, 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 $1 million and $2 million for the six months ended June 30, 2025 and 2024, respectively.
v3.25.2
Fair Value of Financial Instruments (Tables)
 6 Months Ended
Jun. 30, 2025
Fair Value Disclosures [Abstract]  
Carrying Amounts And Estimated Fair Values Of Financial Instruments The following table presents the carrying amounts and estimated fair values of the Company’s financial instruments:
  June 30, 2025December 31, 2024
(In thousands)Carrying ValueFair ValueCarrying ValueFair Value
Assets:
Fixed maturity securities$24,093,156 $24,094,270 $22,397,865 $22,399,426 
Equity securities1,262,192 1,262,192 1,203,788 1,203,788 
Arbitrage trading account1,034,557 1,034,557 1,122,599 1,122,599 
Loans receivable324,365 324,699 405,453 405,248 
Cash and cash equivalents1,984,529 1,984,529 1,974,747 1,974,747 
Trading account receivables from brokers and clearing organizations138,891 138,891 60,327 60,327 
Liabilities:
Due to broker16,160 16,160 70,483 70,483 
Trading account securities sold but not yet purchased30,909 30,909 73,358 73,358 
Senior notes and other debt1,831,638 1,438,943 1,831,158 1,425,852 
Subordinated debentures1,010,168 766,884 1,009,808 805,864 
v3.25.2
Premiums and Reinsurance Related Information (Tables)
 6 Months Ended
Jun. 30, 2025
Insurance [Abstract]  
Reinsurance Financial Information
The following is a summary of insurance and reinsurance financial information:
For the Three Months
Ended June 30,		For the Six Months
Ended June 30,
(In thousands)2025202420252024
Written premiums:
Direct$3,610,784 $3,380,470 $6,921,677 $6,419,537 
Assumed366,985 337,302 740,031 660,991 
Ceded(626,330)(590,993)(1,176,966)(1,102,458)
Total net premiums written$3,351,439 $3,126,779 $6,484,742 $5,978,070 
Earned premiums:
Direct$3,335,252 $3,048,872 $6,569,095 $5,985,516 
Assumed336,521 328,114 676,118 666,024 
Ceded(573,588)(530,571)(1,134,647)(1,040,778)
Total net premiums earned$3,098,185 $2,846,415 $6,110,566 $5,610,762 
Ceded losses and loss expenses incurred$354,923 $327,243 $669,175 $633,194 
Ceded commissions earned$135,919 $123,647 $275,523 $244,701 
Premium receivable, allowance for credit loss The following table presents the rollforward of the allowance for expected credit losses for premiums and fees receivable for the six months ended June 30, 2025 and 2024:
(In thousands)20252024
Allowance for expected credit losses, beginning of period$39,884 $35,110 
Change in expected credit losses(924)2,169 
Allowance for expected credit losses, end of period$38,960 $37,279 
The following table presents the rollforward of the allowance for expected credit losses for premiums and fees receivable for the three months ended June 30, 2025 and 2024:
(In thousands)20252024
Allowance for expected credit losses, beginning of period$38,861 $35,039 
Change in expected credit losses99 2,240 
Allowance for expected credit losses, end of period$38,960 $37,279 
Reinsurance Recoverable, Allowance for Credit Loss
The following table presents the rollforward of the allowance for expected credit losses associated with due from reinsurers for the six months ended June 30, 2025 and 2024:
(In thousands)20252024
Allowance for expected credit losses, beginning of period$8,350 $8,404 
Change in expected credit losses(1,396)1,851 
Allowance for expected credit losses, end of period$6,954 $10,255 
The following table presents the rollforward of the allowance for expected credit losses associated with due from reinsurers for the three months ended June 30, 2025 and 2024:
(In thousands)20252024
Allowance for expected credit losses, beginning of period$7,084 $9,185 
Change in expected credit losses(130)1,070 
Allowance for expected credit losses, end of period$6,954 $10,255 
v3.25.2
Restricted Stock Units (Tables)
 6 Months Ended
Jun. 30, 2025
Share-Based Payment Arrangement [Abstract]  
Summary Of Restricted Stock Units Issued A summary of RSUs issued in the six months ended June 30, 2025 and 2024 follows:
($ in thousands)
UnitsFair Value
202520,995 $1,235 
20242,277$125 
v3.25.2
Leases (Tables)
 6 Months Ended
Jun. 30, 2025
Leases [Abstract]  
Lease, Cost Further information relating to operating lease expense and other operating lease information are as follows:
 For the Three Months Ended
June 30,		For the Six Months Ended June 30,
(In thousands)2025202420252024
Leases:
Lease cost$13,220 $11,326 $25,998 $22,403 
Cash paid for amounts included in the measurement of lease liabilities reported in operating cash flows$11,832 $12,364 $25,314 $24,596 
Right-of-use assets obtained in exchange for new lease liabilities$31,224 $8,853 $44,434 $33,548 
Supplemental Balance Sheet Information
As of June 30,
($ in thousands)20252024
Right-of-use assets$210,884$190,207
Lease liabilities$249,189$231,128
Weighted-average remaining lease term7.3 years7.5 years
Weighted-average discount rate5.82 %5.51 %
Maturities of Operating Lease Liabilities
Contractual maturities of the Company’s future minimum lease payments are as follows:
(In thousands)June 30, 2025
Contractual Maturities:
2025$24,509 
202648,304 
202739,709 
202838,184 
202934,282 
Thereafter113,898 
Total undiscounted future minimum lease payments298,886 
Less: Discount impact49,697 
Total lease liability$249,189 
v3.25.2
Business Segments (Tables)
 6 Months Ended
Jun. 30, 2025
Segment Reporting [Abstract]  
Financial Information Of Company Operating Segments
  RevenuesExpenses  
(In thousands)Earned
Premiums (1)		Investment
Income
(Loss)		OtherTotal (2)Losses and Loss ExpensesPolicy Acquisition and Insurance Operating ExpensesOtherTotalPre-Tax Income (Loss)Net Income (Loss) to Common Stockholders
Three months ended June 30, 2025
Insurance$2,728,784 $299,476 $10,154 $3,038,414 $1,742,235 $772,328 $11,179 $2,525,742 $512,672 $393,450 
Reinsurance & Monoline Excess369,401 80,858 — 450,259 213,189 109,771 — 322,960 127,299 100,040 
Corporate, other and eliminations (3)— (1,031)152,193 151,162 — — 300,243 300,243 (149,081)(116,490)
Net investment gains— — 30,973 30,973 — — — — 30,973 24,288 
Total$3,098,185 $379,303 $193,320 $3,670,808 $1,955,424 $882,099 $311,422 $3,148,945 $521,863 $401,288 
Three months ended June 30, 2024
Insurance$2,484,569 $303,561 $9,591 $2,797,721 $1,589,569 $707,155 $10,944 $2,307,668 $490,053 $374,247 
Reinsurance & Monoline Excess361,846 58,472 — 420,318 191,027 104,842 — 295,869 124,449 97,638 
Corporate, other and eliminations (3)— 10,096 144,409 154,505 — — 222,822 222,822 (68,317)(53,865)
Net investment losses— — (58,512)(58,512)— — — — (58,512)(46,111)
Total$2,846,415 $372,129 $95,488 $3,314,032 $1,780,596 $811,997 $233,766 $2,826,359 $487,673 $371,909 
Six months ended June 30, 2025
Insurance$5,371,291 $590,724 $20,106 $5,982,121 $3,429,688 $1,507,989 $22,267 $4,959,944 $1,022,177 $786,572 
Reinsurance & Monoline Excess739,275 147,288 — 886,563 426,528 212,356 — 638,884 247,679 195,883 
Corporate, other and eliminations (3)— 1,583 300,612 302,195 — — 558,910 558,910 (256,715)(200,710)
Net investment gains— — 47,328 47,328 — — — — 47,328 37,115 
Total$6,110,566 $739,595 $368,046 $7,218,207 $3,856,216 $1,720,345 $581,177 $6,157,738 $1,060,469 $818,860 
Six months ended June 30, 2024
Insurance$4,883,338 $548,338 $19,014 $5,450,690 $3,071,121 $1,389,749 $21,618 $4,482,488 $968,202 $739,337 
Reinsurance & Monoline Excess727,424 111,683 — 839,107 373,253 213,780 — 587,033 252,074 199,764 
Corporate, other and eliminations (3)— 31,946 281,795 313,741 — — 439,540 439,540 (125,799)(97,757)
Net investment losses— — (32,733)(32,733)— — — — (32,733)(26,964)
Total$5,610,762 $691,967 $268,076 $6,570,805 $3,444,374 $1,603,529 $461,158 $5,509,061 $1,061,744 $814,380 
Identifiable Assets
(In thousands)June 30,
2025		December 31,
2024
Insurance$34,532,276 $32,911,507 
Reinsurance & Monoline Excess5,799,205 5,669,729 
Corporate, other and eliminations (3)2,326,576 1,867,399 
Consolidated$42,658,057 $40,448,635 
_________________
(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 June 30, 2025 and 2024 were $361 million and $368 million, respectively, and for the six months ended June 30, 2025 and 2024 were $694 million and $762 million, respectively. Revenues for Reinsurance & Monoline Excess from foreign operations for the three months ended June 30, 2025 and 2024 were $116 million and $117 million, respectively, and for the six months ended June 30, 2025 and 2024 were $246 million and $228 million, respectively.
(3) Corporate, other and eliminations represent corporate revenues and expenses and certain other items that are not allocated to business segments
Net Premiums Earned By Major Line Of Business Net premiums earned by major line of business are as follows:
 For the Three Months
Ended June 30,		For the Six Months
Ended June 30,
(In thousands)2025202420252024
Insurance:
Other liability$1,104,332 $1,001,987 $2,177,060 $1,969,247 
Short-tail lines (1)619,988 538,797 1,216,096 1,049,606 
Auto405,632 361,580 795,581 715,593 
Workers' compensation318,881 310,564 629,910 612,060 
Professional liability279,951 271,641 552,644 536,832 
Total Insurance2,728,784 2,484,569 5,371,291 4,883,338 
Reinsurance & Monoline Excess:
Casualty (2)184,903 199,080 366,670 396,924 
Property (2)113,136 97,255 233,979 199,638 
Monoline excess (3)71,362 65,511 138,626 130,862 
Total Reinsurance & Monoline Excess369,401 361,846 739,275 727,424 
Total$3,098,185 $2,846,415 $6,110,566 $5,610,762 
______________
(1) Short-tail lines include commercial multi-peril (non-liability), inland marine, accident and health, fidelity and surety, boiler and machinery, high net worth homeowners and other lines.
(2) Includes reinsurance casualty and property and certain program management business.
(3) Monoline excess includes operations that solely retain risk on an excess basis.
v3.25.2
Per Share Data (Narrative) (Details) - shares
 6 Months Ended
Jun. 30, 2025
Jun. 30, 2024
Earnings Per Share [Abstract]    
Weighted average number of shares held in grantor trust (in shares) 17,659,297,000 17,495,175
v3.25.2
Per Share Data (Weighted Average Number of Common Shares Used In the Computation of Basic and Diluted Earnings per Share) (Details) - shares
shares in Thousands
 3 Months Ended 6 Months Ended
Jun. 30, 2025
Jun. 30, 2024
Jun. 30, 2025
Jun. 30, 2024
Earnings Per Share [Abstract]        
Basic (shares) 397,016 400,273 396,972 401,295
Diluted (shares) 400,368 403,737 400,098 404,679
v3.25.2
Consolidated Statements of Comprehensive Income (Loss) (Details) - USD ($)
$ in Thousands
 3 Months Ended 6 Months Ended
Jun. 30, 2025
Jun. 30, 2024
Jun. 30, 2025
Jun. 30, 2024
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]        
Beginning of period     $ 8,407,439  
Other comprehensive income (loss) $ 189,683 $ (10,111) 361,886 $ (107,803)
End of period 9,304,808   9,304,808  
Net realized and unrealized gains (losses) on investments 30,533 (60,306) 46,244 (48,803)
Income before income taxes 521,863 487,673 1,060,469 1,061,744
Tax effect (121,155) (115,788) (242,411) (247,824)
Net income before noncontrolling interests 400,708 371,885 818,058 813,920
Total change in unrealized investment gains (losses) 157,858 (20,640) 343,713 (109,937)
Net change in period 69,418 3,227 93,348 (24,343)
Other comprehensive income (loss), pre-tax 227,276 (17,413) 437,061 (134,280)
Other comprehensive income (loss), tax effect (37,593) 7,302 (75,175) 26,477
Accumulated Other Comprehensive Income (Loss)        
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]        
Beginning of period (762,067) (1,023,530) (934,269) (925,838)
Other comprehensive income before reclassifications 167,936 (51,484) 335,968 (180,366)
Amounts reclassified from AOCI 21,747 41,373 25,918 72,563
Other comprehensive income (loss) 189,683 (10,111) 361,886 (107,803)
Unrealized investment loss related to noncontrolling interest 0 1 (1) 1
End of period (572,384) (1,033,640) (572,384) (1,033,640)
Accumulated Other Comprehensive Income (Loss) | Amounts reclassified from AOCI        
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]        
Income before income taxes 27,528 52,371 32,808 91,852
Tax effect (5,781) (10,998) (6,890) (19,289)
Net income before noncontrolling interests 21,747 41,373 25,918 72,563
Unrealized investment losses:        
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]        
Beginning of period (368,898) (656,476) (517,170) (586,354)
Other comprehensive income before reclassifications 98,518 (54,711) 242,620 (156,023)
Amounts reclassified from AOCI 21,747 41,373 25,918 72,563
Other comprehensive income (loss) 120,265 (13,338) 268,538 (83,460)
Unrealized investment loss related to noncontrolling interest 0 1 (1) 1
End of period (248,633) (669,813) (248,633) (669,813)
Total change in unrealized investment gains (losses) 157,858 (20,640) 343,713 (109,937)
Unrealized investment gains, tax effect (37,593) 7,302 (75,175) 26,477
Unrealized investment gains (losses), after-tax amounts 120,265 (13,338) 268,538 (83,460)
Unrealized investment losses: | Amounts reclassified from AOCI        
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]        
Net realized and unrealized gains (losses) on investments 27,528 52,371 32,808 91,852
Tax effect (5,781) (10,998) (6,890) (19,289)
Net income before noncontrolling interests 21,747 41,373 25,918 72,563
Currency Translation Adjustments        
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]        
Beginning of period (393,169) (367,054) (417,099) (339,484)
Other comprehensive income before reclassifications 69,418 3,227 93,348 (24,343)
Amounts reclassified from AOCI 0 0 0 0
Other comprehensive income (loss) 69,418 3,227 93,348 (24,343)
Unrealized investment loss related to noncontrolling interest 0 0 0 0
End of period (323,751) (363,827) (323,751) (363,827)
Currency translation adjustment, pre-tax 69,418 3,227 93,348 (24,343)
Currency translation adjustment, tax effect 0 0 0 0
Net change in period 69,418 3,227 93,348 (24,343)
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
v3.25.2
Statement of Cash Flows (Details) - USD ($)
 6 Months Ended
Jun. 30, 2025
Jun. 30, 2024
Cash and Cash Equivalents [Abstract]    
Interest payments $ 63,228,000 $ 63,051,000
Income taxes paid $ 164,260,000 $ 165,739,000
v3.25.2
Investments in Fixed Maturity Securities (Investments in fixed maturity securities) (Details) - USD ($)
$ in Thousands
Jun. 30, 2025
Mar. 31, 2025
Dec. 31, 2024
Jun. 30, 2024
Mar. 31, 2024
Dec. 31, 2023
Debt Securities, Available-for-sale [Line Items]            
Total held to maturity, Amortized Cost $ 30,065   $ 44,437      
Held-to-maturity, Allowance for Credit Loss (14) $ (20) (25) $ (34) $ (38) $ (43)
Held to maturity, Gross Unrealized Gains 1,114   1,561      
Held to maturity, Gross Unrealized Losses 0   0      
Total held to maturity, Fair Value 31,165   45,973      
Carrying Value 30,051   44,412      
Total available for sale, Amortized Cost 24,339,638   22,966,462      
Available-for-sale, Allowance for Credit Loss (318) (333) (646) (21,837) (22,831) (36,708)
Total available for sale, Gross Unrealized Gains 245,445   96,365      
Total available for sale, Gross Unrealized Losses (521,660)   (708,728)      
Total available for sale, Fair Value 24,063,105   22,353,453      
Total fixed maturity securities available for sale 24,063,105   22,353,453      
Fixed maturity securities, amortized cost 24,369,703   23,010,899      
Fixed maturity securities, allowance for credit loss (332)   (671)      
Total investments in fixed maturity securities, Gross Unrealized Gains 246,559   97,926      
Total investments in fixed maturity securities, Gross Unrealized Losses (521,660)   (708,728)      
Total investments in fixed maturity securities, Fair Value 24,094,270   22,399,426      
Total investments in fixed maturity securities, Carrying Value 24,093,156   22,397,865      
State and municipal            
Debt Securities, Available-for-sale [Line Items]            
Total held to maturity, Amortized Cost 27,983   42,145      
Held-to-maturity, Allowance for Credit Loss (14)   (25)      
Held to maturity, Gross Unrealized Gains 1,040   1,492      
Held to maturity, Gross Unrealized Losses 0   0      
Total held to maturity, Fair Value 29,009   43,612      
Carrying Value 27,969   42,120      
Total available for sale, Amortized Cost 2,188,603   2,376,541      
Available-for-sale, Allowance for Credit Loss 0 (10) 0 (339) (693) (757)
Total available for sale, Gross Unrealized Gains 13,218   7,560      
Total available for sale, Gross Unrealized Losses (55,220)   (89,457)      
Total available for sale, Fair Value 2,146,601   2,294,644      
Total fixed maturity securities available for sale 2,146,601   2,294,644      
Residential mortgage-backed            
Debt Securities, Available-for-sale [Line Items]            
Total held to maturity, Amortized Cost 2,082   2,292      
Held-to-maturity, Allowance for Credit Loss 0   0      
Held to maturity, Gross Unrealized Gains 74   69      
Held to maturity, Gross Unrealized Losses 0   0      
Total held to maturity, Fair Value 2,156   2,361      
Carrying Value 2,082   2,292      
Total available for sale, Amortized Cost 4,090,672   3,411,796      
Available-for-sale, Allowance for Credit Loss 0   (5)      
Total available for sale, Gross Unrealized Gains 34,670   11,047      
Total available for sale, Gross Unrealized Losses (157,265)   (189,630)      
Total available for sale, Fair Value 3,968,077   3,233,208      
Total fixed maturity securities available for sale 3,968,077   3,233,208      
U.S. government and government agency            
Debt Securities, Available-for-sale [Line Items]            
Total available for sale, Amortized Cost 3,108,090   2,268,596      
Available-for-sale, Allowance for Credit Loss 0   0      
Total available for sale, Gross Unrealized Gains 23,421   9,608      
Total available for sale, Gross Unrealized Losses (30,449)   (42,863)      
Total available for sale, Fair Value 3,101,062   2,235,341      
Total fixed maturity securities available for sale 3,101,062   2,235,341      
Special revenue            
Debt Securities, Available-for-sale [Line Items]            
Total available for sale, Amortized Cost 1,387,506   1,581,778      
Available-for-sale, Allowance for Credit Loss 0   0      
Total available for sale, Gross Unrealized Gains 6,306   3,521      
Total available for sale, Gross Unrealized Losses (40,427)   (67,591)      
Total available for sale, Fair Value 1,353,385   1,517,708      
Total fixed maturity securities available for sale 1,353,385   1,517,708      
State general obligation            
Debt Securities, Available-for-sale [Line Items]            
Total available for sale, Amortized Cost 258,795   272,936      
Available-for-sale, Allowance for Credit Loss 0   0      
Total available for sale, Gross Unrealized Gains 2,817   1,439      
Total available for sale, Gross Unrealized Losses (5,451)   (8,981)      
Total available for sale, Fair Value 256,161   265,394      
Total fixed maturity securities available for sale 256,161   265,394      
Pre-refunded            
Debt Securities, Available-for-sale [Line Items]            
Total available for sale, Amortized Cost 77,145   85,340      
Available-for-sale, Allowance for Credit Loss 0   0      
Total available for sale, Gross Unrealized Gains 555   599      
Total available for sale, Gross Unrealized Losses (223)   (347)      
Total available for sale, Fair Value 77,477   85,592      
Total fixed maturity securities available for sale 77,477   85,592      
Corporate backed            
Debt Securities, Available-for-sale [Line Items]            
Total available for sale, Amortized Cost 187,565   158,322      
Available-for-sale, Allowance for Credit Loss 0   0      
Total available for sale, Gross Unrealized Gains 1,688   1,079      
Total available for sale, Gross Unrealized Losses (5,053)   (5,827)      
Total available for sale, Fair Value 184,200   153,574      
Total fixed maturity securities available for sale 184,200   153,574      
Local general obligation            
Debt Securities, Available-for-sale [Line Items]            
Total available for sale, Amortized Cost 277,592   278,165      
Available-for-sale, Allowance for Credit Loss 0   0      
Total available for sale, Gross Unrealized Gains 1,852   922      
Total available for sale, Gross Unrealized Losses (4,066)   (6,711)      
Total available for sale, Fair Value 275,378   272,376      
Total fixed maturity securities available for sale 275,378   272,376      
Commercial            
Debt Securities, Available-for-sale [Line Items]            
Total available for sale, Amortized Cost 355,922   534,936      
Available-for-sale, Allowance for Credit Loss 0   (425)      
Total available for sale, Gross Unrealized Gains 3,911   1,201      
Total available for sale, Gross Unrealized Losses (333)   (3,430)      
Total available for sale, Fair Value 359,500   532,282      
Total fixed maturity securities available for sale 359,500   532,282      
Mortgage-backed            
Debt Securities, Available-for-sale [Line Items]            
Total available for sale, Amortized Cost 4,446,594   3,946,732      
Available-for-sale, Allowance for Credit Loss 0   (430) (1,140) (562) (158)
Total available for sale, Gross Unrealized Gains 38,581   12,248      
Total available for sale, Gross Unrealized Losses (157,598)   (193,060)      
Total available for sale, Fair Value 4,327,577   3,765,490      
Total fixed maturity securities available for sale 4,327,577   3,765,490      
Asset-backed            
Debt Securities, Available-for-sale [Line Items]            
Total available for sale, Amortized Cost 3,862,993   3,910,363      
Available-for-sale, Allowance for Credit Loss 0   0 (889) (1,097) (1,164)
Total available for sale, Gross Unrealized Gains 17,247   16,161      
Total available for sale, Gross Unrealized Losses (26,805)   (41,512)      
Total available for sale, Fair Value 3,853,435   3,885,012      
Total fixed maturity securities available for sale 3,853,435   3,885,012      
Industrial            
Debt Securities, Available-for-sale [Line Items]            
Total available for sale, Amortized Cost 3,680,399   3,746,501      
Available-for-sale, Allowance for Credit Loss 0   0      
Total available for sale, Gross Unrealized Gains 45,729   14,518      
Total available for sale, Gross Unrealized Losses (53,582)   (93,820)      
Total available for sale, Fair Value 3,672,546   3,667,199      
Total fixed maturity securities available for sale 3,672,546   3,667,199      
Financial            
Debt Securities, Available-for-sale [Line Items]            
Total available for sale, Amortized Cost 3,417,541   3,339,718      
Available-for-sale, Allowance for Credit Loss 0   0      
Total available for sale, Gross Unrealized Gains 54,356   18,871      
Total available for sale, Gross Unrealized Losses (19,722)   (38,076)      
Total available for sale, Fair Value 3,452,175   3,320,513      
Total fixed maturity securities available for sale 3,452,175   3,320,513      
Utilities            
Debt Securities, Available-for-sale [Line Items]            
Total available for sale, Amortized Cost 1,146,714   795,839      
Available-for-sale, Allowance for Credit Loss 0   0      
Total available for sale, Gross Unrealized Gains 15,476   2,970      
Total available for sale, Gross Unrealized Losses (10,772)   (20,115)      
Total available for sale, Fair Value 1,151,418   778,694      
Total fixed maturity securities available for sale 1,151,418   778,694      
Other            
Debt Securities, Available-for-sale [Line Items]            
Total available for sale, Amortized Cost 481,868   653,194      
Available-for-sale, Allowance for Credit Loss 0   0      
Total available for sale, Gross Unrealized Gains 2,775   2,493      
Total available for sale, Gross Unrealized Losses (2,006)   (4,452)      
Total available for sale, Fair Value 482,637   651,235      
Total fixed maturity securities available for sale 482,637   651,235      
Corporate            
Debt Securities, Available-for-sale [Line Items]            
Total available for sale, Amortized Cost 8,726,522   8,535,252      
Available-for-sale, Allowance for Credit Loss 0   0 0   (5,026)
Total available for sale, Gross Unrealized Gains 118,336   38,852      
Total available for sale, Gross Unrealized Losses (86,082)   (156,463)      
Total available for sale, Fair Value 8,758,776   8,417,641      
Total fixed maturity securities available for sale 8,758,776   8,417,641      
Foreign government            
Debt Securities, Available-for-sale [Line Items]            
Total available for sale, Amortized Cost 2,006,836   1,928,978      
Available-for-sale, Allowance for Credit Loss (318) $ (323) (216) $ (19,469) $ (20,479) $ (29,603)
Total available for sale, Gross Unrealized Gains 34,642   11,936      
Total available for sale, Gross Unrealized Losses (165,506)   (185,373)      
Total available for sale, Fair Value 1,875,654   1,755,325      
Total fixed maturity securities available for sale $ 1,875,654   $ 1,755,325      
v3.25.2
Investments in Fixed Maturity Securities (HTM Allowance for Credit Loss) (Details) - USD ($)
$ in Thousands
 3 Months Ended 6 Months Ended
Jun. 30, 2025
Jun. 30, 2024
Jun. 30, 2025
Jun. 30, 2024
Debt Securities, Held-to-maturity, Allowance for Credit Loss [Roll Forward]        
Balance, beginning of period $ 20 $ 38 $ 25 $ 43
Cumulative effect adjustment resulting from changes in accounting principles 14 34 14 34
Provision for expected credit losses (6) (4) (11) (9)
Balance, end of period $ 14 $ 34 $ 14 $ 34
v3.25.2
Investments in Fixed Maturity Securities (AFS Allowance for Credit Loss) (Details) - USD ($)
$ in Thousands
 3 Months Ended 6 Months Ended
Jun. 30, 2025
Jun. 30, 2024
Jun. 30, 2025
Jun. 30, 2024
Debt Securities, Available-for-sale, Allowance for Credit Loss [Roll Forward]        
Balance, beginning of period $ 333 $ 22,831 $ 646 $ 36,708
Change on securities for which credit losses were not previously recorded 0 1,439 10 2,001
Change on securities for which credit losses were previously recorded (15) (1,872) (338) (16,311)
Balance, end of period 318 21,837 318 21,837
Reduction due to disposals 0 (561) 0 (561)
Foreign government        
Debt Securities, Available-for-sale, Allowance for Credit Loss [Roll Forward]        
Balance, beginning of period 323 20,479 216 29,603
Change on securities for which credit losses were not previously recorded 0 300 0 300
Change on securities for which credit losses were previously recorded (5) (1,310) 102 (10,434)
Balance, end of period 318 19,469 318 19,469
Reduction due to disposals 0 0 0 0
Mortgage-backed        
Debt Securities, Available-for-sale, Allowance for Credit Loss [Roll Forward]        
Balance, beginning of period   562 430 158
Change on securities for which credit losses were not previously recorded   1,139 0 1,701
Change on securities for which credit losses were previously recorded   0 (430) (158)
Balance, end of period 0 1,140 0 1,140
Reduction due to disposals   (561) 0 (561)
State and municipal        
Debt Securities, Available-for-sale, Allowance for Credit Loss [Roll Forward]        
Balance, beginning of period 10 693 0 757
Change on securities for which credit losses were not previously recorded 0 0 10 0
Change on securities for which credit losses were previously recorded (10) (354) (10) (418)
Balance, end of period 0 339 0 339
Reduction due to disposals 0 0 0 0
Corporate        
Debt Securities, Available-for-sale, Allowance for Credit Loss [Roll Forward]        
Balance, beginning of period     0 5,026
Change on securities for which credit losses were not previously recorded       0
Change on securities for which credit losses were previously recorded       (5,026)
Balance, end of period 0 0 0 0
Reduction due to disposals       0
Asset-backed        
Debt Securities, Available-for-sale, Allowance for Credit Loss [Roll Forward]        
Balance, beginning of period   1,097 0 1,164
Change on securities for which credit losses were not previously recorded   0   0
Change on securities for which credit losses were previously recorded   (208)   (275)
Balance, end of period $ 0 889 $ 0 889
Reduction due to disposals   $ 0   $ 0
v3.25.2
Investments in Fixed Maturity Securities (Amortized cost and fair value of fixed maturity securities) (Details) - USD ($)
$ in Thousands
Jun. 30, 2025
Mar. 31, 2025
Dec. 31, 2024
Jun. 30, 2024
Mar. 31, 2024
Dec. 31, 2023
Investments, Debt and Equity Securities [Abstract]            
Amortized Cost, Due in one year or less $ 1,728,802          
Amortized Cost, Due after one year through five years 9,001,644          
Amortized Cost, Due after five years through ten years 4,046,210          
Amortized Cost, Due after ten years 5,144,357          
Amortized Cost, Mortgaged-backed securities 4,448,676          
Total investments in fixed maturity securities, Amortized Value 24,369,689          
Fair Value, Due in one year or less 1,720,156          
Fair Value, Due after one year through five years 8,861,485          
Fair Value, Due after five years through ten years 4,065,444          
Fair Value, Due after ten years 5,117,452          
Fair Value, Mortgage-backed securities 4,329,733          
Total investments in fixed maturity securities, Fair Value 24,094,270   $ 22,399,426      
Cumulative effect adjustment resulting from changes in accounting principles $ 14 $ 20 $ 25 $ 34 $ 38 $ 43
v3.25.2
Investments in Equity Securities (Details) - USD ($)
$ in Thousands
 3 Months Ended 6 Months Ended
Mar. 31, 2025
Jun. 30, 2025
Dec. 31, 2024
Debt Securities, Available-for-sale [Line Items]      
Equity securities   $ 1,262,192 $ 1,203,788
Fair Value      
Debt Securities, Available-for-sale [Line Items]      
Cost   916,801 941,974
Gross Unrealized, Gains $ 346,697 370,285  
Gross Unrealized, Losses (84,883) (24,894)  
Equity securities   1,262,192 1,203,788
Fair Value | Common stock      
Debt Securities, Available-for-sale [Line Items]      
Cost   528,148 612,479
Gross Unrealized, Gains 223,981 211,335  
Gross Unrealized, Losses (76,293) (19,913)  
Equity securities   719,570 760,167
Fair Value | Preferred stocks      
Debt Securities, Available-for-sale [Line Items]      
Cost   388,653 329,495
Gross Unrealized, Gains 122,716 158,950  
Gross Unrealized, Losses $ (8,590) (4,981)  
Equity securities   542,622 443,621
Carrying Value      
Debt Securities, Available-for-sale [Line Items]      
Equity securities   1,262,192 1,203,788
Carrying Value | Common stock      
Debt Securities, Available-for-sale [Line Items]      
Equity securities   719,570 760,167
Carrying Value | Preferred stocks      
Debt Securities, Available-for-sale [Line Items]      
Equity securities   $ 542,622 $ 443,621
v3.25.2
Arbitrage Trading Account (Details) - USD ($)
$ in Millions
Jun. 30, 2025
Dec. 31, 2024
Derivative [Line Items]    
Arbitrage trading account $ 1,035 $ 1,123
Long | Options held    
Derivative [Line Items]    
Fair value of derivative 5  
Notional amount of derivative 270  
Short | Options held    
Derivative [Line Items]    
Fair value of derivative 31  
Notional amount of derivative $ 271  
v3.25.2
Net Investment Income (Details) - USD ($)
$ in Thousands
 3 Months Ended 6 Months Ended
Jun. 30, 2025
Jun. 30, 2024
Jun. 30, 2025
Jun. 30, 2024
Net Investment Income [Line Items]        
Gross investment income $ 381,851 $ 374,975 $ 745,615 $ 697,057
Investment expense (2,548) (2,846) (6,020) (5,090)
Net investment income 379,303 372,129 739,595 691,967
Fixed maturity securities, including cash and cash equivalents and loans receivable        
Net Investment Income [Line Items]        
Gross investment income 322,518 324,136 636,306 659,384
Investment funds        
Net Investment Income [Line Items]        
Gross investment income 27,268 25,476 54,291 (3,873)
Arbitrage Trading Account        
Net Investment Income [Line Items]        
Gross investment income 23,672 16,682 40,001 34,693
Equity securities        
Net Investment Income [Line Items]        
Gross investment income 12,485 12,386 23,126 23,721
Real estate        
Net Investment Income [Line Items]        
Gross investment income $ (4,092) $ (3,705) $ (8,109) $ (16,868)
v3.25.2
Investment Funds (Details) - USD ($)
$ in Thousands
 3 Months Ended 6 Months Ended 12 Months Ended
Jan. 01, 2025
Jun. 30, 2025
Jun. 30, 2024
Jun. 30, 2025
Jun. 30, 2024
Dec. 31, 2024
Schedule of Equity Method Investments [Line Items]            
Unfunded commitments   $ 272,000   $ 272,000    
Investment funds   1,492,258   1,492,258   $ 1,468,246
Income (Loss) from Investment Funds       54,291 $ (3,873)  
Written premiums ceded   626,330 $ 590,993 1,176,966 1,102,458  
Fair Value            
Schedule of Equity Method Investments [Line Items]            
Trading account receivables from brokers and clearing organizations   138,891   138,891   $ 60,327
Lifson Re            
Schedule of Equity Method Investments [Line Items]            
Percentage of reinsurance placements of share placed amounts 32.50%         30.00%
Written premiums ceded       362,000 206,000  
Financial services            
Schedule of Equity Method Investments [Line Items]            
Investment funds   181,509   181,509   $ 178,685
Income (Loss) from Investment Funds       5,614 12,880  
Transportation            
Schedule of Equity Method Investments [Line Items]            
Investment funds   434,518   434,518   430,163
Income (Loss) from Investment Funds       12,277 (18,231)  
Real Estate            
Schedule of Equity Method Investments [Line Items]            
Investment funds   276,904   276,904   286,426
Income (Loss) from Investment Funds       20,714 (3,732)  
Energy            
Schedule of Equity Method Investments [Line Items]            
Investment funds   42,193   42,193   42,776
Income (Loss) from Investment Funds       (1,234) 8,505  
Infrastructure            
Schedule of Equity Method Investments [Line Items]            
Investment funds   161,019   161,019   151,560
Income (Loss) from Investment Funds       9,064 7,828  
Other funds            
Schedule of Equity Method Investments [Line Items]            
Investment funds   396,115   396,115   378,636
Income (Loss) from Investment Funds       7,856 $ (11,123)  
Deferred compensation trust assets   $ 42,000   $ 42,000   $ 38,000
v3.25.2
Real Estate (Details) - USD ($)
$ in Thousands
Jun. 30, 2025
Dec. 31, 2024
Real Estate [Abstract]    
Properties in operation $ 1,066,361 $ 1,063,687
Properties under development 228,144 227,768
Total $ 1,294,505 $ 1,291,455
v3.25.2
Real Estate (Narrative) (Details) - USD ($)
 6 Months Ended
Jun. 30, 2025
Jun. 30, 2024
Dec. 31, 2024
Real Estate [Abstract]      
Accumulated depreciation and amortization on properties $ 39,761,000   $ 38,671,000
Real estate depreciation expense 4,547,000 $ 4,164,000  
Lease future minimum payments 2021 17,986,813    
Lease future minimum payments 2022 37,365,898    
Lease future minimum payments 2023 37,887,121    
Lease future minimum payments 2024 38,646,570    
Lease future minimum payments 2025 33,546,284    
Lease future minimum payments 2026 27,798,317    
Lease future minimum payments there after $ 411,072,017    
v3.25.2
Loans Receivable (Details) - USD ($)
$ in Thousands
 6 Months Ended
Jun. 30, 2025
Dec. 31, 2024
Accounts, Notes, Loans and Financing Receivable [Line Items]    
Loans receivable, gross $ 324,365 $ 405,453
Loans receivable 324,699 405,248
Real estate loans    
Accounts, Notes, Loans and Financing Receivable [Line Items]    
Loans receivable, gross 320,309 402,382
Loans receivable 320,643 402,177
Commercial loans    
Accounts, Notes, Loans and Financing Receivable [Line Items]    
Loans receivable, gross 4,056 3,071
Loans receivable $ 4,056 $ 3,071
Loans receivable maturity term 5 years  
v3.25.2
Loans Receivable - Allowance For Credit Loss (Details) - USD ($)
$ in Thousands
 3 Months Ended 6 Months Ended
Jun. 30, 2025
Jun. 30, 2024
Jun. 30, 2025
Jun. 30, 2024
Financing Receivable, Allowance for Credit Loss [Line Items]        
Balance, beginning of period $ 788 $ 2,609 $ 1,114 $ 3,004
Change in expected credit losses (419) (796) (745) (1,191)
Balance, end of period 369 1,813 369 1,813
Real estate loans        
Financing Receivable, Allowance for Credit Loss [Line Items]        
Balance, beginning of period 776 2,587 1,088 2,983
Change in expected credit losses (442) (794) (754) (1,190)
Balance, end of period 334 1,793 334 1,793
Commercial loans        
Financing Receivable, Allowance for Credit Loss [Line Items]        
Balance, beginning of period 12 22 26 21
Change in expected credit losses 23 (2) 9 (1)
Balance, end of period $ 35 $ 20 $ 35 $ 20
v3.25.2
Net Investment (Losses) Gains (Net Investment Gains (Losses)) (Details) - USD ($)
$ in Thousands
 3 Months Ended 6 Months Ended
Jun. 30, 2025
Jun. 30, 2024
Jun. 30, 2025
Jun. 30, 2024
Investments, Debt and Equity Securities [Abstract]        
Fixed maturity securities, gains $ 4,209 $ 3,092 $ 6,841 $ 6,649
Fixed maturity securities, losses (5,654) (5,362) (8,366) (7,685)
Net realized (losses) gains on investment sales (1,100) 61,521 (3,695) 101,798
Change in unrealized gains (losses) 63,630 (66,717) 83,577 (40,905)
Investment funds 808 217 822 1,210
Real estate (5,256) (1,958) (1,313) (4,174)
Other (2) (26,104) (51,099) (31,622) (105,696)
Net realized and unrealized gains (losses) on investments in earnings before allowance for expected credit losses 30,533 (60,306) 46,244 (48,803)
Fixed maturity securities 21 998 339 14,879
Loans receivable 419 796 745 1,191
Change in allowance for expected credit losses on investments 440 1,794 1,084 16,070
Net investment gains (losses) 30,973 (58,512) 47,328 (32,733)
Income tax (expense) benefit (6,685) 12,401 (10,213) 5,769
After-tax net investment gains (losses) $ 24,288 $ (46,111) $ 37,115 $ (26,964)
v3.25.2
Net Investment (Losses) Gains (Change in Unrealized Gains (Losses) of Available For Sales Securities) (Details) - USD ($)
$ in Thousands
 3 Months Ended 6 Months Ended
Jun. 30, 2025
Jun. 30, 2024
Jun. 30, 2025
Jun. 30, 2024
Realized and Unrealized Investment Gains Losses [Line Items]        
Total change in unrealized investment gains (losses) $ 157,858 $ (20,640) $ 343,713 $ (109,937)
Income tax (expense) benefit (37,593) 7,302 (75,175) 26,477
Noncontrolling interests 0 1 (1) 1
Total change in unrealized gains 120,265 (13,337) 268,537 (83,459)
Debt securities        
Realized and Unrealized Investment Gains Losses [Line Items]        
Total change in unrealized investment gains (losses) 152,235 (11,394) 336,222 (99,988)
Fixed maturity securities with allowance for expected credit losses        
Realized and Unrealized Investment Gains Losses [Line Items]        
Total change in unrealized investment gains (losses) 478 (7,683) (73) (6,696)
Investment funds        
Realized and Unrealized Investment Gains Losses [Line Items]        
Total change in unrealized investment gains (losses) 5,110 (1,338) 7,606 (3,041)
Other        
Realized and Unrealized Investment Gains Losses [Line Items]        
Total change in unrealized investment gains (losses) $ 35 $ (225) $ (42) $ (212)
v3.25.2
Fixed Maturity Securities In An Unrealized Loss Position (Securities in an Unrealized Loss Position) (Details) - USD ($)
$ in Thousands
Jun. 30, 2025
Dec. 31, 2024
Debt Securities, Available-for-sale [Line Items]    
Fair Value, Less than 12 Months $ 3,129,765 $ 5,460,931
Gross Unrealized Losses, Less than 12 Months 33,678 82,882
Fair Value, 12 Months or Greater 5,697,092 7,086,937
Gross Unrealized Losses, 12 Months or Greater 487,982 625,846
Fair Value, Total 8,826,857 12,547,868
Gross Unrealized Losses, Total 521,660 708,728
U.S. government and government agency    
Debt Securities, Available-for-sale [Line Items]    
Fair Value, Less than 12 Months 941,906 767,515
Gross Unrealized Losses, Less than 12 Months 11,134 9,637
Fair Value, 12 Months or Greater 466,439 560,260
Gross Unrealized Losses, 12 Months or Greater 19,315 33,226
Fair Value, Total 1,408,345 1,327,775
Gross Unrealized Losses, Total 30,449 42,863
State and municipal    
Debt Securities, Available-for-sale [Line Items]    
Fair Value, Less than 12 Months 200,033 348,116
Gross Unrealized Losses, Less than 12 Months 3,908 8,027
Fair Value, 12 Months or Greater 1,262,830 1,411,761
Gross Unrealized Losses, 12 Months or Greater 51,312 81,430
Fair Value, Total 1,462,863 1,759,877
Gross Unrealized Losses, Total 55,220 89,457
Mortgage-backed    
Debt Securities, Available-for-sale [Line Items]    
Fair Value, Less than 12 Months 859,569 1,541,464
Gross Unrealized Losses, Less than 12 Months 11,556 21,326
Fair Value, 12 Months or Greater 887,676 1,060,823
Gross Unrealized Losses, 12 Months or Greater 146,042 171,734
Fair Value, Total 1,747,245 2,602,287
Gross Unrealized Losses, Total 157,598 193,060
Asset-backed    
Debt Securities, Available-for-sale [Line Items]    
Fair Value, Less than 12 Months 610,864 411,763
Gross Unrealized Losses, Less than 12 Months 2,675 4,613
Fair Value, 12 Months or Greater 532,828 626,237
Gross Unrealized Losses, 12 Months or Greater 24,130 36,899
Fair Value, Total 1,143,692 1,038,000
Gross Unrealized Losses, Total 26,805 41,512
Corporate    
Debt Securities, Available-for-sale [Line Items]    
Fair Value, Less than 12 Months 366,889 1,791,970
Gross Unrealized Losses, Less than 12 Months 2,120 21,346
Fair Value, 12 Months or Greater 2,207,465 2,951,377
Gross Unrealized Losses, 12 Months or Greater 83,962 135,117
Fair Value, Total 2,574,354 4,743,347
Gross Unrealized Losses, Total 86,082 156,463
Foreign government    
Debt Securities, Available-for-sale [Line Items]    
Fair Value, Less than 12 Months 150,504 600,103
Gross Unrealized Losses, Less than 12 Months 2,285 17,933
Fair Value, 12 Months or Greater 339,854 476,479
Gross Unrealized Losses, 12 Months or Greater 163,221 167,440
Fair Value, Total 490,358 1,076,582
Gross Unrealized Losses, Total $ 165,506 $ 185,373
v3.25.2
Fixed Maturity Securities In An Unrealized Loss Position (Non-Investment Grade Fixed Maturity Securities) (Details) - External Credit Rating, Noninvestment Grade
$ in Thousands
Jun. 30, 2025
USD ($)
Debt Securities, Available-for-sale [Line Items]  
Number of Securities 80
Aggregate Fair Value $ 204,934
Gross Unrealized Loss $ 157,596
Foreign government  
Debt Securities, Available-for-sale [Line Items]  
Number of Securities 50
Aggregate Fair Value $ 144,584
Gross Unrealized Loss $ 155,344
State and municipal  
Debt Securities, Available-for-sale [Line Items]  
Number of Securities 6
Aggregate Fair Value $ 28,621
Gross Unrealized Loss $ 1,436
Corporate  
Debt Securities, Available-for-sale [Line Items]  
Number of Securities 8
Aggregate Fair Value $ 29,131
Gross Unrealized Loss $ 622
Mortgage-backed  
Debt Securities, Available-for-sale [Line Items]  
Number of Securities 15
Aggregate Fair Value $ 2,589
Gross Unrealized Loss $ 193
Asset-backed  
Debt Securities, Available-for-sale [Line Items]  
Number of Securities 1
Aggregate Fair Value $ 9
Gross Unrealized Loss $ 1
v3.25.2
Fair Value Measurements (Assets and Liabilities Measured At Fair Value, On a Recurring Basis) (Details) - USD ($)
$ in Thousands
Jun. 30, 2025
Dec. 31, 2024
Assets:    
Total fixed maturity securities available for sale $ 24,063,105 $ 22,353,453
Equity securities 1,262,192 1,203,788
Arbitrage trading account 1,035,000 1,123,000
Fair Value, Measurements, Recurring    
Assets:    
Total fixed maturity securities available for sale 24,063,105 22,353,453
Equity securities 1,262,192 1,203,788
Arbitrage trading account 1,034,557 1,122,599
Total 26,359,854 24,679,840
Liabilities:    
Trading account securities sold but not yet purchased 30,909 73,358
Fair Value, Measurements, Recurring | U.S. government and government agency    
Assets:    
Total fixed maturity securities available for sale 3,101,062 2,235,341
Fair Value, Measurements, Recurring | State and municipal    
Assets:    
Total fixed maturity securities available for sale 2,146,601 2,294,644
Fair Value, Measurements, Recurring | Mortgage-backed    
Assets:    
Total fixed maturity securities available for sale 4,327,577 3,765,490
Fair Value, Measurements, Recurring | Asset-backed    
Assets:    
Total fixed maturity securities available for sale 3,853,435 3,885,012
Fair Value, Measurements, Recurring | Corporate    
Assets:    
Total fixed maturity securities available for sale 8,758,776 8,417,641
Fair Value, Measurements, Recurring | Foreign government    
Assets:    
Total fixed maturity securities available for sale 1,875,654 1,755,325
Fair Value, Measurements, Recurring | Common stocks    
Assets:    
Equity securities 719,570 760,167
Fair Value, Measurements, Recurring | Preferred stocks    
Assets:    
Equity securities 542,622 443,621
Level 1 | Fair Value, Measurements, Recurring    
Assets:    
Total fixed maturity securities available for sale 0 0
Equity securities 716,561 757,115
Arbitrage trading account 905,421 1,062,459
Total 1,621,982 1,819,574
Liabilities:    
Trading account securities sold but not yet purchased 30,909 73,358
Level 1 | Fair Value, Measurements, Recurring | U.S. government and government agency    
Assets:    
Total fixed maturity securities available for sale 0 0
Level 1 | Fair Value, Measurements, Recurring | State and municipal    
Assets:    
Total fixed maturity securities available for sale 0 0
Level 1 | Fair Value, Measurements, Recurring | Mortgage-backed    
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 716,561 757,115
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 24,043,129 22,333,786
Equity securities 534,806 440,958
Arbitrage trading account 125,391 56,630
Total 24,703,326 22,831,374
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 3,101,062 2,235,341
Level 2 | Fair Value, Measurements, Recurring | State and municipal    
Assets:    
Total fixed maturity securities available for sale 2,146,601 2,294,644
Level 2 | Fair Value, Measurements, Recurring | Mortgage-backed    
Assets:    
Total fixed maturity securities available for sale 4,327,577 3,765,490
Level 2 | Fair Value, Measurements, Recurring | Asset-backed    
Assets:    
Total fixed maturity securities available for sale 3,853,435 3,885,012
Level 2 | Fair Value, Measurements, Recurring | Corporate    
Assets:    
Total fixed maturity securities available for sale 8,738,800 8,397,974
Level 2 | Fair Value, Measurements, Recurring | Foreign government    
Assets:    
Total fixed maturity securities available for sale 1,875,654 1,755,325
Level 2 | Fair Value, Measurements, Recurring | Common stocks    
Assets:    
Equity securities 858 1,011
Level 2 | Fair Value, Measurements, Recurring | Preferred stocks    
Assets:    
Equity securities 533,948 439,947
Level 3 | Fair Value, Measurements, Recurring    
Assets:    
Total fixed maturity securities available for sale 19,976 19,667
Equity securities 10,825 5,715
Arbitrage trading account 3,745 3,510
Total 34,546 28,892
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 19,976 19,667
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 2,151 2,041
Level 3 | Fair Value, Measurements, Recurring | Preferred stocks    
Assets:    
Equity securities $ 8,674 $ 3,674
v3.25.2
Fair Value Measurements (Summarize Changes in Level 3 Assets) (Details) - USD ($)
$ in Thousands
 6 Months Ended 12 Months Ended
Jun. 30, 2025
Dec. 31, 2024
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]    
Assets, Impairments   $ 0
Level 3    
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]    
Assets, beginning balance $ 28,892 9,025
Assets, earnings 471 386
Assets, other comprehensive income 309 (333)
Assets, Impairments 0  
Assets, purchases 6,160 0
Assets, (sales) (1,286) (223)
Assets, maturities 0 0
Assets. transfers out   20,037
Securities transferred into or out of level 3, net 0  
Assets, ending balance 34,546 28,892
Level 3 | Debt securities    
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]    
Assets, beginning balance 19,667 0
Assets, earnings 0 0
Assets, other comprehensive income 309 (333)
Assets, Impairments 0  
Assets, Impairments   0
Assets, purchases 0 0
Assets, (sales) 0 0
Assets, maturities 0 0
Assets. transfers out   20,000
Securities transferred into or out of level 3, net 0  
Assets, ending balance 19,976 19,667
Level 3 | Equity securities    
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]    
Assets, beginning balance 5,715 5,253
Assets, earnings 236 647
Assets, other comprehensive income 0 0
Assets, Impairments 0 0
Assets, purchases 6,160 0
Assets, (sales) (1,286) (185)
Assets, maturities 0 0
Assets. transfers out 0 0
Assets, ending balance 10,825 5,715
Level 3 | Common stock    
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]    
Assets, beginning balance 2,041 1,558
Assets, earnings 236 611
Assets, other comprehensive income 0 0
Assets, Impairments 0 0
Assets, purchases 0 0
Assets, (sales) (126) (128)
Assets, maturities 0 0
Assets. transfers out 0 0
Assets, ending balance 2,151 2,041
Level 3 | Preferred stocks    
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]    
Assets, beginning balance 3,674 3,695
Assets, earnings 0 36
Assets, other comprehensive income 0 0
Assets, Impairments 0 0
Assets, purchases 6,160 0
Assets, (sales) (1,160) (57)
Assets, maturities 0 0
Assets. transfers out 0 0
Assets, ending balance 8,674 3,674
Level 3 | Arbitrage trading account    
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]    
Assets, beginning balance 3,510 3,772
Assets, earnings 235 (261)
Assets, other comprehensive income 0 0
Assets, Impairments 0  
Assets, Impairments   0
Assets, purchases 0 0
Assets, (sales) 0 (38)
Assets, maturities 0 0
Assets. transfers out   37
Securities transferred into or out of level 3, net 0  
Assets, ending balance 3,745 3,510
Level 3 | Corporate    
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]    
Assets, beginning balance 19,667 0
Assets, earnings 0 0
Assets, other comprehensive income 309 (333)
Assets, Impairments 0 0
Assets, purchases 0 0
Assets, (sales) 0 0
Assets, maturities 0 0
Securities transferred into or out of level 3, net 0 20,000
Assets, ending balance $ 19,976 $ 19,667
v3.25.2
Reserves for Loss and Loss Expenses (Details) - USD ($)
$ in Thousands
 6 Months Ended
Jun. 30, 2025
Jun. 30, 2024
Dec. 31, 2024
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]      
Net reserves at beginning of period $ 17,166,641 $ 15,661,820  
Net provision for losses and loss expenses:      
Claims occurring during the current year 3,822,512 3,411,888  
Decrease in estimates for claims occurring in prior years 17,823 14,700  
Loss reserve discount accretion 15,881 17,786  
Liability for Unpaid Claims and Claims Adjustment Expense, Incurred Claims 3,856,216 3,444,374  
Net payments for claims:      
Current year 431,981 383,639  
Prior years 2,537,599 2,205,566  
Total 2,969,580 2,589,205  
Foreign currency translation 164,747 (56,143)  
Net reserves at end of period 18,218,024 16,460,846 $ 17,166,641
Ceded reserves at end of period 3,278,099 3,106,344  
Gross reserves at end of period $ 21,496,123 $ 19,567,190 $ 20,368,030
v3.25.2
Reserves for Loss and Loss Expenses (Narrative) (Details) - USD ($)
 6 Months Ended
Jun. 30, 2025
Jun. 30, 2024
Liability for Claims and Claims Adjustment Expense [Line Items]    
Net of loss reserves discount $ 28,000,000 $ 26,000,000
Increase (decrease) in estimates for claims 17,000,000 (7,000,000)
Adjustment expense 1,000,000 2,000,000
Insurance    
Liability for Claims and Claims Adjustment Expense [Line Items]    
Unfavorable reserve development net of premium offsets 19,000,000 5,000,000
Reinsurance and Monoline Excess Segment    
Liability for Claims and Claims Adjustment Expense [Line Items]    
Unfavorable reserve development net of premium offsets   $ 7,000,000
Favorable reserve development net of premium offsets $ 20,000,000  
v3.25.2
Fair Value of Financial Instruments (Carrying Amounts and Estimated Fair Values of Financial Instruments) (Details) - USD ($)
$ in Thousands
Jun. 30, 2025
Dec. 31, 2024
Assets:    
Equity securities $ 1,262,192 $ 1,203,788
Arbitrage trading account 1,035,000 1,123,000
Loans receivable 324,699 405,248
Carrying Value    
Assets:    
Fixed maturity securities 24,093,156 22,397,865
Equity securities 1,262,192 1,203,788
Arbitrage trading account 1,034,557 1,122,599
Loans receivable 324,365 405,453
Cash and cash equivalents 1,984,529 1,974,747
Trading account receivables from brokers and clearing organizations 138,891 60,327
Liabilities:    
Due to broker 16,160 70,483
Trading account securities sold but not yet purchased 30,909 73,358
Senior notes and other debt 1,831,638 1,831,158
Subordinated debentures 1,010,168 1,009,808
Fair Value    
Assets:    
Fixed maturity securities 24,094,270 22,399,426
Equity securities 1,262,192 1,203,788
Arbitrage trading account 1,034,557 1,122,599
Loans receivable 324,699 405,248
Cash and cash equivalents 1,984,529 1,974,747
Trading account receivables from brokers and clearing organizations 138,891 60,327
Liabilities:    
Due to broker 16,160 70,483
Trading account securities sold but not yet purchased 30,909 73,358
Senior notes and other debt 1,438,943 1,425,852
Subordinated debentures $ 766,884 $ 805,864
v3.25.2
Premiums and Reinsurance Related Information (Details) - USD ($)
$ in Thousands
 3 Months Ended 6 Months Ended
Jun. 30, 2025
Jun. 30, 2024
Jun. 30, 2025
Jun. 30, 2024
Written premiums:        
Written premiums, direct $ 3,610,784 $ 3,380,470 $ 6,921,677 $ 6,419,537
Written premiums, assumed 366,985 337,302 740,031 660,991
Written premiums, ceded (626,330) (590,993) (1,176,966) (1,102,458)
Total net premiums written 3,351,439 3,126,779 6,484,742 5,978,070
Earned premiums:        
Earned premiums, direct 3,335,252 3,048,872 6,569,095 5,985,516
Earned premiums, assumed 336,521 328,114 676,118 666,024
Earned premiums, ceded (573,588) (530,571) (1,134,647) (1,040,778)
Net premiums earned 3,098,185 2,846,415 6,110,566 5,610,762
Ceded losses and loss expenses incurred 354,923 327,243 669,175 633,194
Ceded commissions earned $ 135,919 $ 123,647 $ 275,523 $ 244,701
v3.25.2
Premiums and Reinsurance Related Information - Premiums and Reinsurance, Allowance For Credit Loss (Details) - USD ($)
$ in Thousands
 3 Months Ended 6 Months Ended
Jun. 30, 2025
Jun. 30, 2024
Jun. 30, 2025
Jun. 30, 2024
Premium Receivable, Allowance for Credit Loss [Roll Forward]        
Allowance for expected credit losses, beginning of period $ 38,861 $ 35,039 $ 39,884 $ 35,110
Cumulative effect adjustment resulting from changes in accounting principles 38,960 37,279 38,960 37,279
Change in expected credit losses 99 2,240 (924) 2,169
Allowance for expected credit losses, end of period 38,960 37,279 38,960 37,279
Reinsurance Recoverable, Allowance for Credit Loss [Roll Forward]        
Allowance for expected credit losses, beginning of period 7,084 9,185 8,350 8,404
Cumulative effect adjustment resulting from changes in accounting principles 6,954 10,255 6,954 10,255
Reinsurance Recoverable, Credit Loss Expense (Reversal) (130) 1,070 (1,396) 1,851
Allowance for expected credit losses, end of period $ 6,954 $ 10,255 $ 6,954 $ 10,255
v3.25.2
Restricted Stock Units (Summary of Restricted Stock Units Issued) (Details) - USD ($)
$ in Thousands
 6 Months Ended
Jun. 30, 2025
Jun. 30, 2024
Share-Based Compensation Arrangement by Share-based Payment Award [Line Item]    
Share based compensation expense $ 25,000 $ 25,000
Restricted stock    
Share-Based Compensation Arrangement by Share-based Payment Award [Line Item]    
Restricted stock units (in units) 20,995 2,277
Fair Value $ 1,235 $ 125
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  
v3.25.2
Leases (Lease Cost) (Details) - USD ($)
$ in Thousands
 3 Months Ended 6 Months Ended
Jun. 30, 2025
Jun. 30, 2024
Jun. 30, 2025
Jun. 30, 2024
Leases [Abstract]        
Lease cost $ 13,220 $ 11,326 $ 25,998 $ 22,403
Cash paid for amounts included in the measurement of lease liabilities reported in operating cash flows 11,832 12,364 25,314 24,596
Right-of-use assets obtained in exchange for new lease liabilities $ 31,224 $ 8,853 $ 44,434 $ 33,548
v3.25.2
Leases (Supplemental Balance Sheet Information) (Details) - USD ($)
$ in Thousands
Jun. 30, 2025
Jun. 30, 2024
Leases [Abstract]    
Operating lease, right-of-use asset $ 210,884 $ 190,207
Operating lease, liability $ 249,189 $ 231,128
Weighted-average remaining lease term 7 years 3 months 18 days 7 years 6 months
Weighted-average discount rate 5.82% 5.51%
v3.25.2
Leases (Maturities of Operating Lease Liabilities) (Details) - USD ($)
$ in Thousands
Jun. 30, 2025
Jun. 30, 2024
Leases [Abstract]    
2025 $ 24,509  
2026 48,304  
2027 39,709  
2028 38,184  
2029 34,282  
Thereafter 113,898  
Total undiscounted future minimum lease payments 298,886  
Less: Discount impact 49,697  
Total lease liability $ 249,189 $ 231,128
v3.25.2
Business Segments (Financial Information of Company Operating Segments) (Details)
$ in Thousands
 3 Months Ended 6 Months Ended
Jun. 30, 2025
USD ($)
Jun. 30, 2024
USD ($)
Jun. 30, 2025
USD ($)
segment
Jun. 30, 2024
USD ($)
Segment Reporting [Abstract]        
Number of reportable segments | segment     2  
Segment Reporting Information [Line Items]        
Earned Premiums (1) $ 3,098,185 $ 2,846,415 $ 6,110,566 $ 5,610,762
Investment Income (Loss) 379,303 372,129 739,595 691,967
Other 193,320 95,488 368,046 268,076
Total revenues 3,670,808 3,314,032 7,218,207 6,570,805
Net Income (Loss) to Common Stockholders 401,288 371,909 818,860 814,380
Net investment gains 30,973 (58,512) 47,328 (32,733)
Net investment gains, net of tax 24,288 (46,111) 37,115 (26,964)
Income before income taxes 521,863 487,673 1,060,469 1,061,744
Policyholder Benefits and Claims Incurred, Net 1,955,424 1,780,596 3,856,216 3,444,374
Policy Acquisition And Insurance Operating Expenses 882,099 811,997 1,720,345 1,603,529
Segment Reporting, Other Segment Item, Amount 311,422 233,766 581,177 461,158
Total 3,148,945 2,826,359 6,157,738 5,509,061
Net investment gains (losses) 30,973 (58,512) 47,328 (32,733)
Corporate Reconciling Items And Eliminations        
Segment Reporting Information [Line Items]        
Investment Income (Loss) (1,031) 10,096 1,583 31,946
Other 152,193 144,409 300,612 281,795
Total revenues 151,162 154,505 302,195 313,741
Net Income (Loss) to Common Stockholders (116,490) (53,865) (200,710) (97,757)
Income before income taxes (149,081) (68,317) (256,715) (125,799)
Segment Reporting, Other Segment Item, Amount 300,243 222,822 558,910 439,540
Total 300,243 222,822 558,910 439,540
Segment Reporting, Reconciling Item, Corporate Nonsegment        
Segment Reporting Information [Line Items]        
Income before income taxes 30,973 (58,512) 47,328 (32,733)
Net investment gains (losses) 30,973      
Insurance        
Segment Reporting Information [Line Items]        
Earned Premiums (1)   2,484,569   4,883,338
Insurance | Operating Segments        
Segment Reporting Information [Line Items]        
Earned Premiums (1) 2,728,784 2,484,569 5,371,291 4,883,338
Investment Income (Loss) 299,476 303,561 590,724 548,338
Other 10,154 9,591 20,106 19,014
Total revenues 3,038,414 2,797,721 5,982,121 5,450,690
Net Income (Loss) to Common Stockholders 393,450 374,247 786,572 739,337
Income before income taxes 512,672 490,053 1,022,177 968,202
Policyholder Benefits and Claims Incurred, Net 1,742,235 1,589,569 3,429,688 3,071,121
Policy Acquisition And Insurance Operating Expenses 772,328 707,155 1,507,989 1,389,749
Segment Reporting, Other Segment Item, Amount 11,179 10,944 22,267 21,618
Total 2,525,742 2,307,668 4,959,944 4,482,488
Insurance | Operating Segments | Non-US        
Segment Reporting Information [Line Items]        
Total revenues 361,000 368,000 694,000 762,000
Reinsurance and Monoline Excess Segment        
Segment Reporting Information [Line Items]        
Earned Premiums (1)   361,846   727,424
Reinsurance and Monoline Excess Segment | Operating Segments        
Segment Reporting Information [Line Items]        
Earned Premiums (1) 369,401 361,846 739,275 727,424
Investment Income (Loss) 80,858 58,472 147,288 111,683
Other 0 0 0 0
Total revenues 450,259 420,318 886,563 839,107
Net Income (Loss) to Common Stockholders 100,040 97,638 195,883 199,764
Income before income taxes 127,299 124,449 247,679 252,074
Policyholder Benefits and Claims Incurred, Net 213,189 191,027 426,528 373,253
Policy Acquisition And Insurance Operating Expenses 109,771 104,842 212,356 213,780
Total 322,960 295,869 638,884 587,033
Reinsurance and Monoline Excess Segment | Operating Segments | Non-US        
Segment Reporting Information [Line Items]        
Total revenues $ 116,000 $ 117,000 $ 246,000 $ 228,000
v3.25.2
Business Segments (Identifiable Assets by Segment) (Details) - USD ($)
$ in Thousands
Jun. 30, 2025
Dec. 31, 2024
Segment Reporting, Asset Reconciling Item [Line Items]    
Consolidated Assets $ 42,658,057 $ 40,448,635
Operating Segments | Insurance    
Segment Reporting, Asset Reconciling Item [Line Items]    
Consolidated Assets 34,532,276 32,911,507
Operating Segments | Reinsurance and Monoline Excess Segment    
Segment Reporting, Asset Reconciling Item [Line Items]    
Consolidated Assets 5,799,205 5,669,729
Corporate Reconciling Items And Eliminations    
Segment Reporting, Asset Reconciling Item [Line Items]    
Consolidated Assets $ 2,326,576 $ 1,867,399
v3.25.2
Business Segments (Net Premiums Earned By Major Line of Business) (Details) - USD ($)
$ in Thousands
 3 Months Ended 6 Months Ended
Jun. 30, 2025
Jun. 30, 2024
Jun. 30, 2025
Jun. 30, 2024
Revenue from External Customer [Line Items]        
Net premiums earned $ 3,098,185 $ 2,846,415 $ 6,110,566 $ 5,610,762
Insurance        
Revenue from External Customer [Line Items]        
Net premiums earned   2,484,569   4,883,338
Insurance | Operating Segments        
Revenue from External Customer [Line Items]        
Net premiums earned 2,728,784 2,484,569 5,371,291 4,883,338
Insurance | Other liability        
Revenue from External Customer [Line Items]        
Net premiums earned 1,104,332 1,001,987 2,177,060 1,969,247
Insurance | Short-tail lines        
Revenue from External Customer [Line Items]        
Net premiums earned 619,988 538,797 1,216,096 1,049,606
Insurance | Auto        
Revenue from External Customer [Line Items]        
Net premiums earned 405,632 361,580 795,581 715,593
Insurance | Workers' compensation        
Revenue from External Customer [Line Items]        
Net premiums earned 318,881 310,564 629,910 612,060
Insurance | Professional liability        
Revenue from External Customer [Line Items]        
Net premiums earned 279,951 271,641 552,644 536,832
Reinsurance and Monoline Excess Segment        
Revenue from External Customer [Line Items]        
Net premiums earned   361,846   727,424
Reinsurance and Monoline Excess Segment | Operating Segments        
Revenue from External Customer [Line Items]        
Net premiums earned 369,401 361,846 739,275 727,424
Reinsurance and Monoline Excess Segment | Casualty        
Revenue from External Customer [Line Items]        
Net premiums earned 184,903 199,080 366,670 396,924
Reinsurance and Monoline Excess Segment | Monoline excess        
Revenue from External Customer [Line Items]        
Net premiums earned 71,362 65,511 138,626 130,862
Reinsurance and Monoline Excess Segment | Property        
Revenue from External Customer [Line Items]        
Net premiums earned $ 113,136 $ 97,255 $ 233,979 $ 199,638