v3.26.1
Fair Value Measurements - Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis (Details) - USD ($)
$ in Thousands
Mar. 31, 2026
Dec. 31, 2025
Fixed maturity securities, available-for-sale:    
Total fixed maturity securities, available-for-sale $ 2,195,107 $ 1,856,303
Total fixed maturity securities, held-to-maturity 34,290 33,603
Total equity securities 1,140 1,174
Mortgage loans 9,088 9,902
Short-term investments 386,514 264,299
Derivatives 24,401 34,857
Total 2,650,540 2,200,138
U.S. government securities    
Fixed maturity securities, available-for-sale:    
Total fixed maturity securities, available-for-sale 159,548 44,468
Non U.S government securities    
Fixed maturity securities, available-for-sale:    
Total fixed maturity securities, available-for-sale 2,671  
Corporate securities and miscellaneous    
Fixed maturity securities, available-for-sale:    
Total fixed maturity securities, available-for-sale 800,485 636,387
Municipal securities    
Fixed maturity securities, available-for-sale:    
Total fixed maturity securities, available-for-sale 95,629 102,116
Residential mortgage-backed securities    
Fixed maturity securities, available-for-sale:    
Total fixed maturity securities, available-for-sale 471,175 486,587
Commercial mortgage-backed securities    
Fixed maturity securities, available-for-sale:    
Total fixed maturity securities, available-for-sale 79,672 73,050
Other asset-backed securities    
Fixed maturity securities, available-for-sale:    
Total fixed maturity securities, available-for-sale 585,927 513,695
Total fixed maturity securities, held-to-maturity 34,290 33,603
Preferred stocks    
Fixed maturity securities, available-for-sale:    
Total equity securities 1,140 1,174
Level 1    
Fixed maturity securities, available-for-sale:    
Total fixed maturity securities, available-for-sale 159,548 44,468
Total fixed maturity securities, held-to-maturity 0 0
Total equity securities 0 0
Mortgage loans 0 0
Short-term investments 386,514 264,299
Derivatives 24,401 34,857
Total 570,463 343,624
Level 1 | U.S. government securities    
Fixed maturity securities, available-for-sale:    
Total fixed maturity securities, available-for-sale 159,548 44,468
Level 1 | Non U.S government securities    
Fixed maturity securities, available-for-sale:    
Total fixed maturity securities, available-for-sale 0  
Level 1 | Corporate securities and miscellaneous    
Fixed maturity securities, available-for-sale:    
Total fixed maturity securities, available-for-sale 0 0
Level 1 | Municipal securities    
Fixed maturity securities, available-for-sale:    
Total fixed maturity securities, available-for-sale 0 0
Level 1 | Residential mortgage-backed securities    
Fixed maturity securities, available-for-sale:    
Total fixed maturity securities, available-for-sale 0 0
Level 1 | Commercial mortgage-backed securities    
Fixed maturity securities, available-for-sale:    
Total fixed maturity securities, available-for-sale 0 0
Level 1 | Other asset-backed securities    
Fixed maturity securities, available-for-sale:    
Total fixed maturity securities, available-for-sale 0 0
Total fixed maturity securities, held-to-maturity 0 0
Level 1 | Preferred stocks    
Fixed maturity securities, available-for-sale:    
Total equity securities 0 0
Level 2    
Fixed maturity securities, available-for-sale:    
Total fixed maturity securities, available-for-sale 1,876,109 1,660,918
Total fixed maturity securities, held-to-maturity 0 0
Total equity securities 1,140 1,174
Mortgage loans 0 0
Short-term investments 0 0
Derivatives 0 0
Total 1,877,249 1,662,092
Level 2 | U.S. government securities    
Fixed maturity securities, available-for-sale:    
Total fixed maturity securities, available-for-sale 0 0
Level 2 | Non U.S government securities    
Fixed maturity securities, available-for-sale:    
Total fixed maturity securities, available-for-sale 2,671  
Level 2 | Corporate securities and miscellaneous    
Fixed maturity securities, available-for-sale:    
Total fixed maturity securities, available-for-sale 658,638 503,274
Level 2 | Municipal securities    
Fixed maturity securities, available-for-sale:    
Total fixed maturity securities, available-for-sale 95,629 102,116
Level 2 | Residential mortgage-backed securities    
Fixed maturity securities, available-for-sale:    
Total fixed maturity securities, available-for-sale 471,175 486,587
Level 2 | Commercial mortgage-backed securities    
Fixed maturity securities, available-for-sale:    
Total fixed maturity securities, available-for-sale 79,672 73,050
Level 2 | Other asset-backed securities    
Fixed maturity securities, available-for-sale:    
Total fixed maturity securities, available-for-sale 568,324 495,891
Total fixed maturity securities, held-to-maturity 0 0
Level 2 | Preferred stocks    
Fixed maturity securities, available-for-sale:    
Total equity securities 1,140 1,174
Level 3    
Fixed maturity securities, available-for-sale:    
Total fixed maturity securities, available-for-sale 159,450 150,917
Total fixed maturity securities, held-to-maturity 34,290 33,603
Total equity securities 0 0
Mortgage loans 9,088 9,902
Short-term investments 0 0
Derivatives 0 0
Total 202,828 194,422
Level 3 | U.S. government securities    
Fixed maturity securities, available-for-sale:    
Total fixed maturity securities, available-for-sale 0 0
Level 3 | Non U.S government securities    
Fixed maturity securities, available-for-sale:    
Total fixed maturity securities, available-for-sale 0  
Level 3 | Corporate securities and miscellaneous    
Fixed maturity securities, available-for-sale:    
Total fixed maturity securities, available-for-sale 141,847 133,113
Level 3 | Municipal securities    
Fixed maturity securities, available-for-sale:    
Total fixed maturity securities, available-for-sale 0 0
Level 3 | Residential mortgage-backed securities    
Fixed maturity securities, available-for-sale:    
Total fixed maturity securities, available-for-sale 0 0
Level 3 | Commercial mortgage-backed securities    
Fixed maturity securities, available-for-sale:    
Total fixed maturity securities, available-for-sale 0 0
Level 3 | Other asset-backed securities    
Fixed maturity securities, available-for-sale:    
Total fixed maturity securities, available-for-sale 17,603 17,804
Total fixed maturity securities, held-to-maturity 34,290 33,603
Level 3 | Preferred stocks    
Fixed maturity securities, available-for-sale:    
Total equity securities $ 0 $ 0