v3.26.1
Investments - Gross Unrealized Losses and Fair Value of Available for Sale Securities (Details) - USD ($)
$ in Thousands
Mar. 31, 2026
Dec. 31, 2025
Debt Securities, Available-for-sale [Line Items]    
Fair value, less than 12 months $ 2,755,478 $ 228,242
Unrealized losses, less than 12 months (24,531) (2,636)
Fair value, 12 months or greater 1,972,965 2,142,209
Unrealized losses, 12 months or greater (325,056) (314,736)
Fair value, total 4,728,443 2,370,451
Unrealized losses, total (349,587) (317,372)
U.S. government and agency securities    
Debt Securities, Available-for-sale [Line Items]    
Fair value, less than 12 months 187,863 0
Unrealized losses, less than 12 months (1,351) 0
Fair value, 12 months or greater 97,504 98,287
Unrealized losses, 12 months or greater (28,635) (27,958)
Fair value, total 285,367 98,287
Unrealized losses, total (29,986) (27,958)
State and municipal obligations    
Debt Securities, Available-for-sale [Line Items]    
Fair value, less than 12 months 85,436 10,256
Unrealized losses, less than 12 months (514) (167)
Fair value, 12 months or greater 96,049 96,240
Unrealized losses, 12 months or greater (14,087) (13,938)
Fair value, total 181,485 106,496
Unrealized losses, total (14,601) (14,105)
Corporate bonds and notes    
Debt Securities, Available-for-sale [Line Items]    
Fair value, less than 12 months 1,490,636 100,367
Unrealized losses, less than 12 months (15,697) (1,739)
Fair value, 12 months or greater 1,017,671 1,102,930
Unrealized losses, 12 months or greater (205,664) (195,916)
Fair value, total 2,508,307 1,203,297
Unrealized losses, total (221,361) (197,655)
RMBS    
Debt Securities, Available-for-sale [Line Items]    
Fair value, less than 12 months 527,449 27,202
Unrealized losses, less than 12 months (4,678) (105)
Fair value, 12 months or greater 517,600 567,936
Unrealized losses, 12 months or greater (63,889) (62,325)
Fair value, total 1,045,049 595,138
Unrealized losses, total (68,567) (62,430)
CMBS    
Debt Securities, Available-for-sale [Line Items]    
Fair value, less than 12 months 62,116 2,820
Unrealized losses, less than 12 months (545) (122)
Fair value, 12 months or greater 211,509 232,409
Unrealized losses, 12 months or greater (11,072) (12,875)
Fair value, total 273,625 235,229
Unrealized losses, total (11,617) (12,997)
CLO    
Debt Securities, Available-for-sale [Line Items]    
Fair value, less than 12 months 285,682 56,480
Unrealized losses, less than 12 months (765) (125)
Fair value, 12 months or greater 0 5,650
Unrealized losses, 12 months or greater 0 (30)
Fair value, total 285,682 62,130
Unrealized losses, total (765) (155)
Other ABS    
Debt Securities, Available-for-sale [Line Items]    
Fair value, less than 12 months 114,253 31,117
Unrealized losses, less than 12 months (979) (378)
Fair value, 12 months or greater 32,632 38,757
Unrealized losses, 12 months or greater (1,709) (1,694)
Fair value, total 146,885 69,874
Unrealized losses, total (2,688) $ (2,072)
Mortgage insurance-linked notes    
Debt Securities, Available-for-sale [Line Items]    
Fair value, less than 12 months 2,043  
Unrealized losses, less than 12 months (2)  
Fair value, 12 months or greater 0  
Unrealized losses, 12 months or greater 0  
Fair value, total 2,043  
Unrealized losses, total $ (2)