v3.26.1
Investments - Schedule of Debt Securities, Trading, and Equity Securities, FV-NI (Details) - USD ($)
$ in Thousands
Jun. 30, 2026
Mar. 31, 2026
Dec. 31, 2025
Jun. 30, 2025
Mar. 31, 2025
Dec. 31, 2024
Fixed maturity securities, available-for-sale:            
Amortized Cost $ 2,206,626   $ 1,848,755      
Gross Unrealized Gains 16,777   31,378      
Gross Unrealized Losses (24,992)   (16,830)      
Allowance for Credit Losses (6,228) $ (6,500) (7,000) $ (6,150) $ 0 $ 0
Fair Value 2,192,183   1,856,303      
Fixed maturity securities, held-to-maturity:            
Amortized Cost 30,448   33,290      
Gross Unrealized Gains 6,524   829      
Gross Unrealized Losses 0   (48)      
Allowance for Credit Losses (2,256) $ (301) (468) $ (268) $ (250) $ (243)
Fair Value 34,716   33,603      
U.S. government securities            
Fixed maturity securities, available-for-sale:            
Amortized Cost 128,460   44,190      
Gross Unrealized Gains 59   292      
Gross Unrealized Losses (1,455)   (14)      
Allowance for Credit Losses 0   0      
Fair Value 127,064   44,468      
Non U.S government securities            
Fixed maturity securities, available-for-sale:            
Amortized Cost 2,721          
Gross Unrealized Gains 0          
Gross Unrealized Losses (44)          
Allowance for Credit Losses 0          
Fair Value 2,677          
Corporate securities and miscellaneous            
Fixed maturity securities, available-for-sale:            
Amortized Cost 796,092   632,244      
Gross Unrealized Gains 7,253   14,223      
Gross Unrealized Losses (6,310)   (3,080)      
Allowance for Credit Losses (6,228)   (7,000)      
Fair Value 790,807   636,387      
Municipal securities            
Fixed maturity securities, available-for-sale:            
Amortized Cost 93,125   102,691      
Gross Unrealized Gains 1,337   1,725      
Gross Unrealized Losses (2,249)   (2,300)      
Allowance for Credit Losses 0   0      
Fair Value 92,213   102,116      
Residential mortgage-backed securities            
Fixed maturity securities, available-for-sale:            
Amortized Cost 450,728   487,145      
Gross Unrealized Gains 4,979   8,928      
Gross Unrealized Losses (10,496)   (9,486)      
Allowance for Credit Losses 0   0      
Fair Value 445,211   486,587      
Commercial mortgage-backed securities            
Fixed maturity securities, available-for-sale:            
Amortized Cost 84,645   72,631      
Gross Unrealized Gains 539   1,016      
Gross Unrealized Losses (560)   (597)      
Allowance for Credit Losses 0   0      
Fair Value 84,624   73,050      
Other asset-backed securities            
Fixed maturity securities, available-for-sale:            
Amortized Cost 650,855   509,854      
Gross Unrealized Gains 2,610   5,194      
Gross Unrealized Losses (3,878)   (1,353)      
Allowance for Credit Losses 0   0      
Fair Value 649,587   513,695      
Fixed maturity securities, held-to-maturity:            
Amortized Cost 30,448   33,290      
Gross Unrealized Gains 6,524   829      
Gross Unrealized Losses 0   (48)      
Allowance for Credit Losses (2,256)   (468)      
Fair Value $ 34,716   $ 33,603