v3.26.1
Investments (Tables)
 3 Months Ended
Mar. 31, 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.
 March 31, 2026
(dollars in thousands)Amortized
Cost		Gross
Unrealized
Holding
Gains		Gross
Unrealized
Holding
Losses		Estimated
Fair
Value
Fixed maturity securities:
U.S. Treasury securities$5,992,327 $33,328 $(23,853)$6,001,802 
U.S. government-sponsored enterprises1,715,840 13,140 (64,358)1,664,622 
Obligations of states, municipalities, and political subdivisions3,759,474 24,502 (111,523)3,672,453 
Foreign governments, agencies, and supranationals3,484,109 51,406 (111,258)3,424,257 
Agency mortgage-backed securities2,978,312 15,434 (66,982)2,926,764 
Non-agency mortgage-backed securities54,756 — (701)54,055 
Corporate and university bonds222,498 189 (22,859)199,828 
Total fixed maturity securities18,207,316 137,999 (401,534)17,943,781 
Short-term investments2,027,082 1,526 (2,461)2,026,147 
Investments, available-for-sale$20,234,398 $139,525 $(403,995)$19,969,928 

 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.
March 31, 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$1,109,592 $(5,438)$1,165,863 $(18,415)$2,275,455 $(23,853)
U.S. government-sponsored enterprises181,210 (1,027)766,475 (63,331)947,685 (64,358)
Obligations of states, municipalities, and political subdivisions511,759 (3,887)1,762,168 (107,636)2,273,927 (111,523)
Foreign governments, agencies, and supranationals798,190 (17,276)1,131,345 (93,982)1,929,535 (111,258)
Agency mortgage-backed securities529,219 (5,626)1,359,971 (61,356)1,889,190 (66,982)
Non-agency mortgage-backed securities5,857 (42)48,198 (659)54,055 (701)
Corporate and university bonds21,097 (535)176,540 (22,324)197,637 (22,859)
Total fixed maturity securities3,156,924 (33,831)6,410,560 (367,703)9,567,484 (401,534)
Short-term investments1,189,488 (2,461)— — 1,189,488 (2,461)
Total$4,346,412 $(36,292)$6,410,560 $(367,703)$10,756,972 $(403,995)

At March 31, 2026, the Company held 1,102 available-for-sale securities in an unrealized loss position with a total estimated fair value of $10.8 billion and gross unrealized losses of $404.0 million. Of these 1,102 securities, 808 securities had been in a continuous unrealized loss position for one year or longer and had a total estimated fair value of $6.4 billion and gross unrealized losses of $367.7 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 March 31, 2026 are shown below by contractual maturity.
(dollars in thousands)Amortized
Cost		Estimated
Fair Value
Due in one year or less$2,172,638 $2,171,438 
Due after one year through five years6,579,483 6,530,862 
Due after five years through ten years5,237,767 5,169,709 
Due after ten years1,184,360 1,090,953 
15,174,248 14,962,962 
Mortgage-backed securities
3,033,068 2,980,819 
Total fixed maturity securities$18,207,316 $17,943,781 
Components Of Net Investment Income The following table presents the components of net investment income.
Three Months Ended March 31,
(dollars in thousands)20262025
Interest:
Fixed maturity securities$164,324 $143,345 
Short-term investments17,104 19,673 
Cash and cash equivalents and restricted cash and cash equivalents30,956 39,774 
Dividends on equity securities49,336 40,195 
261,720 242,987 
Investment expenses(5,830)(5,892)
Net investment income$255,890 $237,095 
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 losses included in net income (loss) and the change in net unrealized losses included in other comprehensive income (loss). Gross realized investment gains and losses on fixed maturity securities, short-term investments, and other investments were not material to the consolidated financial statements and are presented on a net basis in the following table.
Three Months Ended March 31,
(dollars in thousands)20262025
Fixed maturity securities and short-term investments:
Net realized investment gains (losses)$2,043 $(1,801)
Equity securities:
Change in fair value of securities sold during the period(1,620)(1,322)
Change in fair value of securities held at the end of the period(727,985)(145,948)
Total change in fair value(729,605)(147,270)
Net investment losses$(727,562)$(149,071)
Change in net unrealized losses on available-for-sale investments included in other comprehensive income (loss):
Fixed maturity securities$(165,604)$273,213 
Short-term investments(4,947)4,014 
Net increase (decrease)$(170,551)$277,227