Investments - Net Realized Gains (Losses) on Investments (Details) - USD ($) $ in Thousands |
3 Months Ended | 9 Months Ended | ||
|---|---|---|---|---|
Sep. 30, 2026 |
Sep. 30, 2025 |
Sep. 30, 2026 |
Sep. 30, 2025 |
|
| Marketable Securities [Line Items] | ||||
| Net realized gains (losses) on investments | $ 166,722 | $ 109,355 | $ 554,472 | $ 424,142 |
| Fixed maturities and short-term investments | ||||
| Marketable Securities [Line Items] | ||||
| Net realized gains (losses) on investments | (6,983) | 3,274 | (9,316) | 4,140 |
| TS Hamilton Fund | ||||
| Marketable Securities [Line Items] | ||||
| Net realized gains (losses) on investments | $ 173,705 | $ 106,081 | $ 563,788 | $ 420,002 |