v3.26.1
Investments - Schedule of Realized and Unrealized Gains (Losses) on Investments and Net Investment Income (Loss) (Details) - USD ($)
$ in Thousands
 3 Months Ended 6 Months Ended
Jun. 30, 2026
Jun. 30, 2025
Jun. 30, 2026
Jun. 30, 2025
Net realized and unrealized gains (losses) on investments:        
Net realized gains (losses) on investments $ 232,135 $ 196,129 $ 387,751 $ 314,787
Change in net unrealized gains (losses) on investments (4,279) 11,905 (8,818) 142,041
Net realized and unrealized gains (losses) on investments 227,856 208,034 378,933 456,828
Net investment income (loss):        
Interest and other 40,454 35,118 81,280 67,272
Management fees (15,643) (13,719) (30,112) (26,685)
Other expenses (371) (332) (699) (593)
Net investment income (loss) 24,440 21,067 50,469 39,994
Total net realized and unrealized gains (losses) on investments and net investment income (loss) 252,296 229,101 429,402 496,822
Total fixed maturities        
Net investment income (loss):        
Interest and other 34,307 27,317 68,785 52,604
Short-term investments        
Net investment income (loss):        
Interest and other 10 230 19 298
TS Hamilton Fund        
Net realized and unrealized gains (losses) on investments:        
Net realized gains (losses) on investments 237,376 194,786 390,083 313,920
Change in net unrealized gains (losses) on investments 2,250 (16,877) 38,353 78,772
Net investment income (loss):        
Interest and other 1,948 2,858 3,584 4,594
Cash and cash equivalents        
Net investment income (loss):        
Interest and other 4,195 3,987 8,489 8,590
Other        
Net investment income (loss):        
Interest and other (6) 726 403 1,186
Fixed maturities and short-term investments        
Net realized and unrealized gains (losses) on investments:        
Net realized gains (losses) on investments (5,241) 1,343 (2,332) 867
Change in net unrealized gains (losses) on investments $ (6,529) $ 28,782 $ (47,171) $ 63,269