v3.26.1
Investments (Details) - USD ($)
$ in Thousands
Jun. 30, 2026
Dec. 31, 2025
Debt Securities, Available-for-sale [Line Items]    
Amortized Cost $ 5,897,786 $ 5,944,001
Gross Unrealized Gains 33,484 61,897
Gross Unrealized Losses (230,212) (214,667)
Fair Value 5,701,058 5,791,231
Assets held by insurance regulatory requirements 12,500 12,600
Assets held in trust for the benefit of contractual counterparties 188,500 185,700
U.S. Treasury securities and obligations of U.S. government corporations and agencies    
Debt Securities, Available-for-sale [Line Items]    
Amortized Cost 284,121 279,359
Gross Unrealized Gains 113 958
Gross Unrealized Losses (3,046) (2,505)
Fair Value 281,188 277,812
Obligations of U.S. states and political subdivisions    
Debt Securities, Available-for-sale [Line Items]    
Amortized Cost 1,849,688 1,961,841
Gross Unrealized Gains 9,958 10,958
Gross Unrealized Losses (139,081) (134,035)
Fair Value 1,720,565 1,838,764
Corporate debt securities    
Debt Securities, Available-for-sale [Line Items]    
Amortized Cost 2,722,787 2,712,348
Gross Unrealized Gains 16,908 36,781
Gross Unrealized Losses (65,022) (57,857)
Fair Value 2,674,673 2,691,272
ABS    
Debt Securities, Available-for-sale [Line Items]    
Amortized Cost 290,072 225,478
Gross Unrealized Gains 862 2,418
Gross Unrealized Losses (2,813) (1,335)
Fair Value 288,121 226,561
RMBS    
Debt Securities, Available-for-sale [Line Items]    
Amortized Cost 373,594 366,671
Gross Unrealized Gains 4,760 8,169
Gross Unrealized Losses (16,758) (16,816)
Fair Value 361,596 358,024
CMBS    
Debt Securities, Available-for-sale [Line Items]    
Amortized Cost 235,738 237,974
Gross Unrealized Gains 750 2,484
Gross Unrealized Losses (3,008) (1,675)
Fair Value 233,480 238,783
CLOs    
Debt Securities, Available-for-sale [Line Items]    
Amortized Cost 124,168 99,182
Gross Unrealized Gains 133 129
Gross Unrealized Losses (52) (24)
Fair Value 124,249 99,287
Foreign government debt    
Debt Securities, Available-for-sale [Line Items]    
Amortized Cost 4,488 4,487
Gross Unrealized Gains 0 0
Gross Unrealized Losses (431) (420)
Fair Value 4,057 4,067
Commercial paper    
Debt Securities, Available-for-sale [Line Items]    
Amortized Cost 13,130 56,661
Gross Unrealized Gains 0 0
Gross Unrealized Losses (1) 0
Fair Value $ 13,129 $ 56,661