v3.26.1
Investments - Schedule of Fixed Maturity Securities in a Continuous Unrealized Loss Position (Details)
$ in Thousands
Jun. 30, 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 $ 1,714,637 $ 484,377
Less than 12 months, Gross unrealized losses $ (24,318) $ (7,734)
Less than 12 months, Number of securities | security 565 166
12 months or more, Fair value $ 1,598,281 $ 1,908,289
12 months or more, Gross unrealized losses $ (120,421) $ (121,192)
12 months or more, Number of securities | security 327 389
Fair value $ 3,312,918 $ 2,392,666
Gross unrealized losses $ (144,739) $ (128,926)
Number of securities | security 892 555
U.S. government, agencies and GSEs    
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss [Abstract]    
Less than 12 months, Fair value $ 134,416 $ 34,142
Less than 12 months, Gross unrealized losses $ (1,836) $ (384)
Less than 12 months, Number of securities | security 36 6
12 months or more, Fair value $ 17,837 $ 22,664
12 months or more, Gross unrealized losses $ (1,116) $ (908)
12 months or more, Number of securities | security 5 7
Fair value $ 152,253 $ 56,806
Gross unrealized losses $ (2,952) $ (1,292)
Number of securities | security 41 13
State and political subdivisions    
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss [Abstract]    
Less than 12 months, Fair value $ 21,175 $ 18,053
Less than 12 months, Gross unrealized losses $ (461) $ (1,483)
Less than 12 months, Number of securities | security 7 9
12 months or more, Fair value $ 411,146 $ 422,895
12 months or more, Gross unrealized losses $ (53,076) $ (49,043)
12 months or more, Number of securities | security 85 83
Fair value $ 432,321 $ 440,948
Gross unrealized losses $ (53,537) $ (50,526)
Number of securities | security 92 92
Non-U.S. government    
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss [Abstract]    
Less than 12 months, Fair value $ 62,498 $ 15,323
Less than 12 months, Gross unrealized losses $ (920) $ (146)
Less than 12 months, Number of securities | security 73 20
12 months or more, Fair value $ 9,912 $ 10,525
12 months or more, Gross unrealized losses $ (178) $ (237)
12 months or more, Number of securities | security 1 2
Fair value $ 72,410 $ 25,848
Gross unrealized losses $ (1,098) $ (383)
Number of securities | security 74 22
U.S. corporate    
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss [Abstract]    
Less than 12 months, Fair value $ 763,534 $ 182,483
Less than 12 months, Gross unrealized losses $ (10,995) $ (2,790)
Less than 12 months, Number of securities | security 210 49
12 months or more, Fair value $ 754,674 $ 908,852
12 months or more, Gross unrealized losses $ (43,974) $ (47,552)
12 months or more, Number of securities | security 138 163
Fair value $ 1,518,208 $ 1,091,335
Gross unrealized losses $ (54,969) $ (50,342)
Number of securities | security 348 212
Non-U.S. corporate    
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss [Abstract]    
Less than 12 months, Fair value $ 222,697 $ 38,506
Less than 12 months, Gross unrealized losses $ (2,809) $ (1,800)
Less than 12 months, Number of securities | security 74 16
12 months or more, Fair value $ 183,175 $ 230,778
12 months or more, Gross unrealized losses $ (10,245) $ (10,804)
12 months or more, Number of securities | security 37 50
Fair value $ 405,872 $ 269,284
Gross unrealized losses $ (13,054) $ (12,604)
Number of securities | security 111 66
Residential mortgage-backed    
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss [Abstract]    
Less than 12 months, Fair value $ 133,763 $ 24,879
Less than 12 months, Gross unrealized losses $ (1,054) $ (78)
Less than 12 months, Number of securities | security 55 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 $ 133,763 $ 24,879
Gross unrealized losses $ (1,054) $ (78)
Number of securities | security 55 11
Commercial mortgage-backed    
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss [Abstract]    
Less than 12 months, Fair value $ 128,839 $ 56,000
Less than 12 months, Gross unrealized losses $ (3,216) $ (485)
Less than 12 months, Number of securities | security 28 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 $ 128,839 $ 56,000
Gross unrealized losses $ (3,216) $ (485)
Number of securities | security 28 14
Other asset-backed    
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss [Abstract]    
Less than 12 months, Fair value $ 247,715 $ 114,991
Less than 12 months, Gross unrealized losses $ (3,027) $ (568)
Less than 12 months, Number of securities | security 82 41
12 months or more, Fair value $ 221,537 $ 312,575
12 months or more, Gross unrealized losses $ (11,832) $ (12,648)
12 months or more, Number of securities | security 61 84
Fair value $ 469,252 $ 427,566
Gross unrealized losses $ (14,859) $ (13,216)
Number of securities | security 143 125