v3.26.1
Investments (Tables)
 6 Months Ended
Jun. 30, 2026
Investments, Debt and Equity Securities [Abstract]  
Available-For-Sale Investments The following tables summarize the Company's available-for-sale investments. Agency mortgage-backed securities include securities issued by U.S. government-sponsored enterprises and U.S. government agencies. The net unrealized holding gains (losses) in the tables below are presented before taxes.
 June 30, 2026
(dollars in thousands)Amortized
Cost		Gross
Unrealized
Holding
Gains		Gross
Unrealized
Holding
Losses		Estimated
Fair
Value
Fixed maturity securities:
U.S. Treasury securities$5,975,754 $12,558 $(41,807)$5,946,505 
U.S. government-sponsored enterprises1,710,419 7,853 (69,829)1,648,443 
Obligations of states, municipalities, and political subdivisions3,655,327 15,280 (121,372)3,549,235 
Foreign governments, agencies, and supranationals3,440,886 54,137 (101,592)3,393,431 
Agency mortgage-backed securities2,994,204 7,938 (76,404)2,925,738 
Non-agency mortgage-backed securities47,706 — (710)46,996 
Corporate and university bonds220,312 202 (22,255)198,259 
Total fixed maturity securities18,044,608 97,968 (433,969)17,708,607 
Short-term investments2,337,159 1,286 (5,026)2,333,419 
Investments, available-for-sale$20,381,767 $99,254 $(438,995)$20,042,026 

 December 31, 2025
(dollars in thousands)Amortized
Cost		Gross
Unrealized
Holding
Gains		Gross
Unrealized
Holding
Losses		Estimated
Fair
Value
Fixed maturity securities:
U.S. Treasury securities$5,877,779 $63,769 $(13,641)$5,927,907 
U.S. government-sponsored enterprises1,678,599 19,378 (57,743)1,640,234 
Obligations of states, municipalities, and political subdivisions3,743,154 34,871 (105,557)3,672,468 
Foreign governments, agencies, and supranationals3,359,014 89,595 (73,694)3,374,915 
Agency mortgage-backed securities2,935,758 24,903 (59,541)2,901,120 
Non-agency mortgage-backed securities66,296 — (538)65,758 
Corporate and university bonds235,318 368 (20,102)215,584 
Total fixed maturity securities17,895,918 232,884 (330,816)17,797,986 
Short-term investments2,029,650 4,632 (620)2,033,662 
Investments, available-for-sale$19,925,568 $237,516 $(331,436)$19,831,648 
Unrealized Gain (Loss) on Investments The following tables summarize gross unrealized investment losses on available-for-sale investments by the length of time that securities have continuously been in an unrealized loss position.
June 30, 2026
Less than 12 months12 months or longerTotal
(dollars in thousands)Estimated
Fair
Value		Gross
Unrealized
Holding Losses		Estimated
Fair
Value		Gross
Unrealized
Holding Losses		Estimated
Fair
Value
Gross
Unrealized
Holding
Losses
Fixed maturity securities:
U.S. Treasury securities$2,250,496 $(19,252)$1,010,529 $(22,555)$3,261,025 $(41,807)
U.S. government-sponsored enterprises357,578 (2,998)749,419 (66,831)1,106,997 (69,829)
Obligations of states, municipalities, and political subdivisions774,473 (8,720)1,581,088 (112,652)2,355,561 (121,372)
Foreign governments, agencies, and supranationals1,095,865 (17,396)995,623 (84,196)2,091,488 (101,592)
Agency mortgage-backed securities821,781 (12,529)1,282,216 (63,875)2,103,997 (76,404)
Non-agency mortgage-backed securities5,847 (55)41,148 (655)46,995 (710)
Corporate and university bonds20,971 (392)174,842 (21,863)195,813 (22,255)
Total fixed maturity securities5,327,011 (61,342)5,834,865 (372,627)11,161,876 (433,969)
Short-term investments1,513,336 (5,026)— — 1,513,336 (5,026)
Total$6,840,347 $(66,368)$5,834,865 $(372,627)$12,675,212 $(438,995)

At June 30, 2026, the Company held 1,215 available-for-sale securities in an unrealized loss position with a total estimated fair value of $12.7 billion and gross unrealized losses of $439.0 million. Of these 1,215 securities, 745 securities had been in a continuous unrealized loss position for one year or longer and had a total estimated fair value of $5.8 billion and gross unrealized losses of $372.6 million.

December 31, 2025
Less than 12 months12 months or longerTotal
(dollars in thousands)Estimated
Fair
Value
Gross
Unrealized
Holding
Losses
Estimated
Fair
Value
Gross
Unrealized
Holding 
Losses
Estimated
Fair
Value
Gross
Unrealized
Holding 
Losses
Fixed maturity securities:
U.S. Treasury securities$197,135 $(470)$1,275,453 $(13,171)$1,472,588 $(13,641)
U.S. government-sponsored enterprises108,490 (112)802,349 (57,631)910,839 (57,743)
Obligations of states, municipalities, and political subdivisions184,124 (970)1,871,154 (104,587)2,055,278 (105,557)
Foreign governments, agencies, and supranationals214,787 (1,008)1,181,298 (72,686)1,396,085 (73,694)
Agency mortgage-backed securities156,553 (701)1,446,048 (58,840)1,602,601 (59,541)
Non-agency mortgage-backed securities5,889 (6)59,869 (532)65,758 (538)
Corporate and university bonds20,488 (174)180,290 (19,928)200,778 (20,102)
Total fixed maturity securities887,466 (3,441)6,816,461 (327,375)7,703,927 (330,816)
Short-term investments59,179 (620)— — 59,179 (620)
Total$946,645 $(4,061)$6,816,461 $(327,375)$7,763,106 $(331,436)

At December 31, 2025, the Company held 948 available-for-sale securities in an unrealized loss position with a total estimated fair value of $7.8 billion and gross unrealized losses of $331.4 million. Of these 948 securities, 851 securities had been in a continuous unrealized loss position for one year or longer and had a total estimated fair value of $6.8 billion and gross unrealized losses of $327.4 million.
Schedule Of Amortized Cost And Estimated Fair Value Of Fixed Maturity Securities By Contractual Maturity Date The amortized cost and estimated fair value of fixed maturity securities at June 30, 2026 are shown below by contractual maturity.
(dollars in thousands)Amortized
Cost		Estimated
Fair Value
Due in one year or less$2,231,948 $2,232,541 
Due after one year through five years6,442,642 6,357,047 
Due after five years through ten years5,151,631 5,063,447 
Due after ten years1,176,477 1,082,838 
15,002,698 14,735,873 
Mortgage-backed securities
3,041,910 2,972,734 
Total fixed maturity securities$18,044,608 $17,708,607 
Components Of Net Investment Income The following table presents the components of net investment income.
Quarter Ended June 30, Six Months Ended June 30,
(dollars in thousands)2026202520262025
Interest:
Fixed maturity securities$169,196 $145,829 $333,520 $289,174 
Short-term investments17,699 19,580 34,803 39,253 
Cash and cash equivalents and restricted cash and cash equivalents28,297 35,723 59,253 75,497 
Dividends on equity securities43,827 34,812 93,163 75,007 
259,019 235,944 520,739 478,931 
Investment expenses(2,896)(5,935)(8,726)(11,827)
Net investment income$256,123 $230,009 $512,013 $467,104 
Summary Of Net Investment Gains (Losses) And The Change In Net Unrealized Gains On Available-For-Sale Investments The following table presents the components of net investment gains included in net income and the change in net unrealized losses included in other comprehensive income (loss). Gross realized investment gains and losses on fixed maturity securities and short-term investments were not material to the consolidated financial statements and are presented on a net basis in the following table.
Quarter Ended June 30, Six Months Ended June 30,
(dollars in thousands)2026202520262025
Fixed maturity securities and short-term investments:
Net realized investment losses$(2,933)$(16,596)$(890)$(18,397)
Equity securities:
Change in fair value of securities sold during the period40,142 1,134 18,241 (188)
Change in fair value of securities held at the end of the period1,130,316 595,685 422,612 449,737 
Total change in fair value1,170,458 596,819 440,853 449,549 
Net investment gains$1,167,525 $580,223 $439,963 $431,152 
Change in net unrealized losses on available-for-sale investments included in other comprehensive income (loss):
Fixed maturity securities$(72,465)$251,805 $(238,069)$525,018 
Short-term investments(2,805)6,524 (7,752)10,538 
Net increase (decrease)$(75,270)$258,329 $(245,821)$535,556