v3.25.2
Investments - Schedule of Fixed Maturity Securities in a Continuous Unrealized Loss Position (Details)
$ in Thousands
Jun. 30, 2025
USD ($)
security
Dec. 31, 2024
USD ($)
security
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss [Abstract]    
Less than 12 months, Fair value $ 809,616 $ 1,444,660
Less than 12 months, Gross unrealized losses $ (16,544) $ (34,364)
Less than 12 months, Number of securities | security 264 544
12 months or more, Fair value $ 2,148,648 $ 2,722,049
12 months or more, Gross unrealized losses $ (158,343) $ (238,076)
12 months or more, Number of securities | security 426 566
Fair value $ 2,958,264 $ 4,166,709
Gross unrealized losses $ (174,887) $ (272,440)
Number of securities | security 690 1,110
U.S. government, agencies and GSEs    
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss [Abstract]    
Less than 12 months, Fair value $ 69,908 $ 157,596
Less than 12 months, Gross unrealized losses $ (1,670) $ (4,704)
Less than 12 months, Number of securities | security 13 32
12 months or more, Fair value $ 18,086 $ 19,998
12 months or more, Gross unrealized losses $ (196) $ (381)
12 months or more, Number of securities | security 6 9
Fair value $ 87,994 $ 177,594
Gross unrealized losses $ (1,866) $ (5,085)
Number of securities | security 19 41
State and political subdivisions    
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss [Abstract]    
Less than 12 months, Fair value $ 65,525 $ 48,280
Less than 12 months, Gross unrealized losses $ (5,002) $ (2,366)
Less than 12 months, Number of securities | security 21 17
12 months or more, Fair value $ 383,015 $ 396,638
12 months or more, Gross unrealized losses $ (56,093) $ (73,261)
12 months or more, Number of securities | security 76 84
Fair value $ 448,540 $ 444,918
Gross unrealized losses $ (61,095) $ (75,627)
Number of securities | security 97 101
Non-U.S. government    
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss [Abstract]    
Less than 12 months, Fair value $ 16,110 $ 56,631
Less than 12 months, Gross unrealized losses $ (211) $ (1,236)
Less than 12 months, Number of securities | security 24 76
12 months or more, Fair value $ 9,836 $ 9,692
12 months or more, Gross unrealized losses $ (404) $ (622)
12 months or more, Number of securities | security 1 1
Fair value $ 25,946 $ 66,323
Gross unrealized losses $ (615) $ (1,858)
Number of securities | security 25 77
U.S. corporate    
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss [Abstract]    
Less than 12 months, Fair value $ 392,199 $ 881,643
Less than 12 months, Gross unrealized losses $ (6,967) $ (20,844)
Less than 12 months, Number of securities | security 95 265
12 months or more, Fair value $ 1,043,840 $ 1,379,860
12 months or more, Gross unrealized losses $ (67,274) $ (108,740)
12 months or more, Number of securities | security 186 264
Fair value $ 1,436,039 $ 2,261,503
Gross unrealized losses $ (74,241) $ (129,584)
Number of securities | security 281 529
Non-U.S. corporate    
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss [Abstract]    
Less than 12 months, Fair value $ 84,807 $ 195,648
Less than 12 months, Gross unrealized losses $ (1,500) $ (4,015)
Less than 12 months, Number of securities | security 33 102
12 months or more, Fair value $ 270,004 $ 385,508
12 months or more, Gross unrealized losses $ (15,133) $ (26,035)
12 months or more, Number of securities | security 52 74
Fair value $ 354,811 $ 581,156
Gross unrealized losses $ (16,633) $ (30,050)
Number of securities | security 85 176
Residential mortgage-backed    
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss [Abstract]    
Less than 12 months, Fair value $ 100,554 $ 3,313
Less than 12 months, Gross unrealized losses $ (559) $ (31)
Less than 12 months, Number of securities | security 32 3
12 months or more, Fair value $ 0 $ 2,822
12 months or more, Gross unrealized losses $ 0 $ (26)
12 months or more, Number of securities | security 0 4
Fair value $ 100,554 $ 6,135
Gross unrealized losses $ (559) $ (57)
Number of securities | security 32 7
Other asset-backed    
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss [Abstract]    
Less than 12 months, Fair value $ 77,194 $ 101,549
Less than 12 months, Gross unrealized losses $ (632) $ (1,168)
Less than 12 months, Number of securities | security 43 49
12 months or more, Fair value $ 423,867 $ 527,531
12 months or more, Gross unrealized losses $ (19,243) $ (29,011)
12 months or more, Number of securities | security 105 130
Fair value $ 501,061 $ 629,080
Gross unrealized losses $ (19,875) $ (30,179)
Number of securities | security 148 179
Commercial mortgage-backed    
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss [Abstract]    
Less than 12 months, Fair value $ 3,319  
Less than 12 months, Gross unrealized losses $ (3)  
Less than 12 months, Number of securities | security 3  
12 months or more, Fair value $ 0  
12 months or more, Gross unrealized losses $ 0  
12 months or more, Number of securities | security 0  
Fair value $ 3,319  
Gross unrealized losses $ (3)  
Number of securities | security 3