Allowance for Expected Credit Losses (Details) - Changes in the Allowance for Estimated Uncollectible Reinsurance - USD ($) $ in Millions |
3 Months Ended | 6 Months Ended | ||
|---|---|---|---|---|
Jun. 30, 2024 |
Jun. 30, 2023 |
Jun. 30, 2024 |
Jun. 30, 2023 |
|
| Credit Loss [Abstract] | ||||
| Reinsurance recoverables (net of allowance for estimated uncollectible reinsurance), balance, beginning of period | $ 8,100 | $ 8,091 | $ 8,143 | $ 8,063 |
| Reinsurance recoverables (net of allowance for estimated uncollectible reinsurance), balance, end of period | 8,132 | 8,121 | 8,132 | 8,121 |
| Reinsurance recoverables, allowance for uncollectible reinsurance [Roll Forward] | ||||
| Reinsurance recoverables, allowance for uncollectible reinsurance, beginning balance | 117 | 131 | 118 | 132 |
| Current period change for estimated uncollectible reinsurance | 0 | (10) | (1) | (11) |
| Write-offs of uncollectible reinsurance recoverables | 0 | 0 | 0 | 0 |
| Reinsurance recoverables, allowance for uncollectible reinsurance, ending balance | $ 117 | $ 121 | $ 117 | $ 121 |