v3.26.1
Investments - Schedule of Fixed Maturity Securities in a Continuous Unrealized Loss Position (Details)
$ in Thousands
Mar. 31, 2026
USD ($)
security
Dec. 31, 2025
USD ($)
security
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss [Abstract]    
Less than 12 months, Fair value $ 1,664,525 $ 484,377
Less than 12 months, Gross unrealized losses $ (25,158) $ (7,734)
Less than 12 months, Number of securities | security 550 166
12 months or more, Fair value $ 1,683,592 $ 1,908,289
12 months or more, Gross unrealized losses $ (124,451) $ (121,192)
12 months or more, Number of securities | security 347 389
Fair value $ 3,348,117 $ 2,392,666
Gross unrealized losses $ (149,609) $ (128,926)
Number of securities | security 897 555
U.S. government, agencies and GSEs    
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss [Abstract]    
Less than 12 months, Fair value $ 73,162 $ 34,142
Less than 12 months, Gross unrealized losses $ (1,151) $ (384)
Less than 12 months, Number of securities | security 17 6
12 months or more, Fair value $ 19,544 $ 22,664
12 months or more, Gross unrealized losses $ (1,128) $ (908)
12 months or more, Number of securities | security 6 7
Fair value $ 92,706 $ 56,806
Gross unrealized losses $ (2,279) $ (1,292)
Number of securities | security 23 13
State and political subdivisions    
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss [Abstract]    
Less than 12 months, Fair value $ 30,838 $ 18,053
Less than 12 months, Gross unrealized losses $ (1,808) $ (1,483)
Less than 12 months, Number of securities | security 14 9
12 months or more, Fair value $ 405,008 $ 422,895
12 months or more, Gross unrealized losses $ (51,235) $ (49,043)
12 months or more, Number of securities | security 80 83
Fair value $ 435,846 $ 440,948
Gross unrealized losses $ (53,043) $ (50,526)
Number of securities | security 94 92
Non-U.S. government    
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss [Abstract]    
Less than 12 months, Fair value $ 58,513 $ 15,323
Less than 12 months, Gross unrealized losses $ (1,444) $ (146)
Less than 12 months, Number of securities | security 70 20
12 months or more, Fair value $ 9,892 $ 10,525
12 months or more, Gross unrealized losses $ (236) $ (237)
12 months or more, Number of securities | security 1 2
Fair value $ 68,405 $ 25,848
Gross unrealized losses $ (1,680) $ (383)
Number of securities | security 71 22
U.S. corporate    
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss [Abstract]    
Less than 12 months, Fair value $ 713,576 $ 182,483
Less than 12 months, Gross unrealized losses $ (11,733) $ (2,790)
Less than 12 months, Number of securities | security 194 49
12 months or more, Fair value $ 802,476 $ 908,852
12 months or more, Gross unrealized losses $ (48,551) $ (47,552)
12 months or more, Number of securities | security 148 163
Fair value $ 1,516,052 $ 1,091,335
Gross unrealized losses $ (60,284) $ (50,342)
Number of securities | security 342 212
Non-U.S. corporate    
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss [Abstract]    
Less than 12 months, Fair value $ 199,918 $ 38,506
Less than 12 months, Gross unrealized losses $ (3,742) $ (1,800)
Less than 12 months, Number of securities | security 73 16
12 months or more, Fair value $ 188,776 $ 230,778
12 months or more, Gross unrealized losses $ (10,484) $ (10,804)
12 months or more, Number of securities | security 39 50
Fair value $ 388,694 $ 269,284
Gross unrealized losses $ (14,226) $ (12,604)
Number of securities | security 112 66
Residential mortgage-backed    
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss [Abstract]    
Less than 12 months, Fair value $ 73,911 $ 24,879
Less than 12 months, Gross unrealized losses $ (709) $ (78)
Less than 12 months, Number of securities | security 33 11
12 months or more, Fair value $ 0 $ 0
12 months or more, Gross unrealized losses $ 0 $ 0
12 months or more, Number of securities | security 0 0
Fair value $ 73,911 $ 24,879
Gross unrealized losses $ (709) $ (78)
Number of securities | security 33 11
Commercial mortgage-backed    
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss [Abstract]    
Less than 12 months, Fair value $ 116,575 $ 56,000
Less than 12 months, Gross unrealized losses $ (1,748) $ (485)
Less than 12 months, Number of securities | security 33 14
12 months or more, Fair value $ 0 $ 0
12 months or more, Gross unrealized losses $ 0 $ 0
12 months or more, Number of securities | security 0 0
Fair value $ 116,575 $ 56,000
Gross unrealized losses $ (1,748) $ (485)
Number of securities | security 33 14
Other asset-backed    
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss [Abstract]    
Less than 12 months, Fair value $ 398,032 $ 114,991
Less than 12 months, Gross unrealized losses $ (2,823) $ (568)
Less than 12 months, Number of securities | security 116 41
12 months or more, Fair value $ 257,896 $ 312,575
12 months or more, Gross unrealized losses $ (12,817) $ (12,648)
12 months or more, Number of securities | security 73 84
Fair value $ 655,928 $ 427,566
Gross unrealized losses $ (15,640) $ (13,216)
Number of securities | security 189 125