| **Investments (Narrative) (Details) - USD ($) $ in Millions**                               | 3 Months Ended | 9 Months Ended |        |
|---------------------------------------------------------------------------------------------|----------------|----------------|--------|
||
| **Gain (Loss) on Securities [Line Items]**                                                  |           |           |   |   |   |
| Investment and derivative, realized gain (loss), coinsurance agreement                      | $ (35)         |           |   |   |   |
| Debt securities, available-for-sale, realized loss                                          | 134            | $ 28           | $ 222  | $ 68 |   |
| Embedded derivative, gain on embedded derivative                                            | 24             |           |   |   |   |
| Financing receivable, credit loss, expense (reversal)                                       | 8              | 0              | 8      | 0 |   |
| Impairment losses (gains) recognized in earnings                                            | 25             | 11             | 55     | 16 |   |
| Reduction of net unrealized gains on investments included in AOCI due to shadow adjustments | 46             |           | 46     |   | $ 2,477 |
| Notional value                                                                              | 220            |           | 220    |   | 270 |
| Other liabilities                                                                           | 1              |           | 1      |   | (12) |
| Commitments to purchase or fund privately placed debt securities                            | 1,595          |           | 1,595  |   |   |
| Commitments to sell various privately placed debt securities                                | 100            |           | 100    |   |   |
| Funds Withheld Liability Securities                                                         |           |           |   |   |   |
| **Gain (Loss) on Securities [Line Items]**                                                  |           |           |   |   |   |
| Debt securities, available-for-sale, realized loss                                          | (59)           |           |   |   |   |
| Mortgage loans                                                                              |           |           |   |   |   |
| **Gain (Loss) on Securities [Line Items]**                                                  |           |           |   |   |   |
| Financing receivable, accrued interest, after allowance for credit loss                     | 3              |           | 3      |   |   |
| Fixed maturity securities                                                                   |           |           |   |   |   |
| **Gain (Loss) on Securities [Line Items]**                                                  |           |           |   |   |   |
| Debt securities, available-for-sale, accrued interest, after allowance for credit loss      | $ 401          | $ 387          | $ 401  | $ 387 | $ 369 |

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Commitments To Sell Various Privately Placed Debt Securities
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Investment and Derivative, Realized Gain (Loss), Coinsurance Agreement
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Reduction of net unrealized gains on investments included in AOCI due to shadow adjustments
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| - Definition
Amount, after allowance for credit loss, of accrued interest on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).
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Amount of realized loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).
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Nominal or face amount used to calculate payment on derivative.
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Increase in the fair value of the embedded derivative or group of embedded derivatives included in earnings in the period.
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Amount, after allowance for credit loss, of accrued interest on financing receivable.
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Fair value portion of other liabilities.
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Amount of other-than-temporary impairment (OTTI) on investment in debt security, recognized in earnings.
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Amount of credit loss expense (reversal of expense) for financing receivable.
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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.
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