Allowance for Expected Credit Losses (Details) - Changes in the Allowance for Estimated Uncollectible Reinsurance - USD ($) $ in Millions |
3 Months Ended | |
|---|---|---|
Mar. 31, 2024 |
Mar. 31, 2023 |
|
| Credit Loss [Abstract] | ||
| Reinsurance recoverables (net of allowance for estimated uncollectible reinsurance), balance, beginning of period | $ 8,143 | $ 8,063 |
| Reinsurance recoverables (net of allowance for estimated uncollectible reinsurance), balance, end of period | 8,100 | 8,091 |
| Reinsurance recoverables, allowance for uncollectible reinsurance [Roll Forward] | ||
| Reinsurance recoverables, allowance for uncollectible reinsurance, beginning balance | 118 | 132 |
| Current period change for estimated uncollectible reinsurance | (1) | (1) |
| Write-offs of uncollectible reinsurance recoverables | 0 | 0 |
| Reinsurance recoverables, allowance for uncollectible reinsurance, ending balance | $ 117 | $ 131 |