Investments - Holding gains (losses) on equity securities still held (Details) - USD ($) $ in Millions |
3 Months Ended | 6 Months Ended | ||
|---|---|---|---|---|
Jun. 30, 2026 |
Jun. 30, 2025 |
Jun. 30, 2026 |
Jun. 30, 2025 |
|
| Holding Gains (Losses) on Equity Securities Still Held [Line Items] | ||||
| Holding gains (losses) on equity securities | $ 14 | $ 11 | $ (7) | $ 19 |
| Income Statement Location [Axis]: us-gaap:DebtAndEquitySecuritiesRealizedGainLoss | ||||
| Holding Gains (Losses) on Equity Securities Still Held [Line Items] | ||||
| Holding gains (losses) on equity securities | 12 | 9 | (2) | 16 |
| Income Statement Location [Axis]: us-gaap:NetInvestmentIncome | ||||
| Holding Gains (Losses) on Equity Securities Still Held [Line Items] | ||||
| Holding gains (losses) on equity securities | $ 2 | $ 2 | $ (5) | $ 3 |