Investments - OTTI (Details) - USD ($) $ in Millions |
6 Months Ended | |
|---|---|---|
Jun. 30, 2025 |
Jun. 30, 2024 |
|
| Available-for-sale Securities Including Securities Pledged [Line Items] | ||
| us-gaap_OtherThanTemporaryImpairmentLossDebtSecuritiesAvailableForSaleRecognizedInEarnings | $ 15 | $ 4 |