Investments - Carrying Value of Measurement Alternative Investments (Details) - USD ($) $ in Millions |
Mar. 31, 2024 |
Dec. 31, 2023 |
|---|---|---|
| Investments, Debt and Equity Securities [Abstract] | ||
| Alternative Investment, Initial Cost Basis | $ 558 | |
| Alternative Investment, Upward Price Adjustment, Cumulative Amount | 636 | |
| Alternative Investment, Downward Price Adjustment Including Impairment, Cumulative Amount | (181) | |
| Measurement alternative | $ 1,013 | $ 1,008 |