v3.26.3
Investments (Tables)
 9 Months Ended
Sep. 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.
September 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$5,950,970 $288 $(158,604)$5,792,654 
U.S. government-sponsored enterprises1,704,119 793 (122,563)1,582,349 
Obligations of states, municipalities, and political subdivisions3,619,917 572 (244,861)3,375,628 
Foreign governments, agencies, and supranationals3,542,488 25,387 (190,045)3,377,830 
Agency mortgage-backed securities3,116,267 95 (166,613)2,949,749 
Non-agency mortgage-backed securities44,236 — (974)43,262 
Corporate and university bonds204,892 39 (31,341)173,590 
Total fixed maturity securities18,182,889 27,174 (915,001)17,295,062 
Short-term investments2,771,422 2,791 (5,121)2,769,092 
Investments, available-for-sale$20,954,311 $29,965 $(920,122)$20,064,154 

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.
September 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$4,389,125 $(113,882)$986,030 $(44,722)$5,375,155 $(158,604)
U.S. government-sponsored enterprises789,093 (32,862)722,508 (89,701)1,511,601 (122,563)
Obligations of states, municipalities, and political subdivisions1,754,504 (83,762)1,455,084 (161,099)3,209,588 (244,861)
Foreign governments, agencies, and supranationals1,491,510 (68,271)1,038,467 (121,774)2,529,977 (190,045)
Agency mortgage-backed securities1,662,303 (78,033)1,230,123 (88,580)2,892,426 (166,613)
Non-agency mortgage-backed securities5,760 (102)37,502 (872)43,262 (974)
Corporate and university bonds6,626 (272)164,275 (31,069)170,901 (31,341)
Total fixed maturity securities10,098,921 (377,184)5,633,989 (537,817)15,732,910 (915,001)
Short-term investments2,537,436 (5,121)— — 2,537,436 (5,121)
Total$12,636,357 $(382,305)$5,633,989 $(537,817)$18,270,346 $(920,122)

At September 30, 2026, the Company held 1,663 available-for-sale securities in an unrealized loss position with a total estimated fair value of $18.3 billion and gross unrealized losses of $920.1 million. Of these 1,663 securities, 716 securities had been in a continuous unrealized loss position for one year or longer and had a total estimated fair value of $5.6 billion and gross unrealized losses of $537.8 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 September 30, 2026 are shown below by contractual maturity.
(dollars in thousands)Amortized
Cost		Estimated
Fair Value
Due in one year or less$2,084,296 $2,083,791 
Due after one year through five years6,576,638 6,341,782 
Due after five years through ten years5,156,621 4,836,669 
Due after ten years1,204,831 1,039,809 
15,022,386 14,302,051 
Mortgage-backed securities
3,160,503 2,993,011 
Total fixed maturity securities$18,182,889 $17,295,062 
Components Of Net Investment Income The following table presents the components of net investment income.
Quarter Ended September 30, Nine Months Ended September 30,
(dollars in thousands)2026202520262025
Interest:
Fixed maturity securities$171,041 $155,645 $504,561 $444,819 
Short-term investments21,981 19,406 56,784 58,659 
Cash and cash equivalents and restricted cash and cash equivalents30,054 37,483 89,307 112,980 
Dividends on equity securities38,182 35,762 131,345 110,769 
261,258 248,296 781,997 727,227 
Investment expenses(3,143)(2,621)(11,869)(14,448)
Net investment income$258,115 $245,675 $770,128 $712,779 
Summary Of Net Investment Gains (Losses) And The Change In Net Unrealized Gains On Available-For-Sale Investments The following table presents the components of net investment gains (losses) included in net income and the change in net unrealized losses included in other comprehensive income (loss). Gross realized investment gains and losses on fixed maturity securities and short-term investments were not material to the consolidated financial statements and are presented on a net basis in the following table.
Quarter Ended September 30, Nine Months Ended September 30,
(dollars in thousands)2026202520262025
Fixed maturity securities and short-term investments:
Net realized investment gains (losses)$(523)$4,695 $(1,413)$(13,702)
Equity securities:
Change in fair value of securities sold during the period(177)(1,795)20,750 1,345 
Change in fair value of securities held at the end of the period(280,209)429,986 139,717 876,395 
Total change in fair value(280,386)428,191 160,467 877,740 
Net investment gains (losses)$(280,909)$432,886 $159,054 $864,038 
Change in net unrealized losses on available-for-sale investments included in other comprehensive income (loss):
Fixed maturity securities$(551,827)$60,844 $(789,895)$585,862 
Short-term investments1,411 (1,021)(6,342)9,517 
Net increase (decrease)$(550,416)$59,823 $(796,237)$595,379