Investments - Components of Equity Realized Gains (Losses) (Details) - USD ($) $ in Millions |
3 Months Ended | 9 Months Ended | ||
|---|---|---|---|---|
Sep. 30, 2026 |
Sep. 30, 2025 |
Sep. 30, 2026 |
Sep. 30, 2025 |
|
| Investments, Debt and Equity Securities [Abstract] | ||||
| Total net gains (losses) recognized during the period on equity securities | $ 82 | $ 289 | $ 489 | $ 462 |
| Less: Net gains (losses) recognized on equity securities sold during the period | 25 | 9 | 50 | 41 |
| Net holding period gains (losses) recognized during the period on equity securities held at period end | $ 57 | $ 280 | $ 439 | $ 421 |