| **Investments (Narrative) (Details) - USD ($)**                                             | 3 Months Ended  | 6 Months Ended |                 |
|---------------------------------------------------------------------------------------------|-----------------|----------------|-----------------|
||
| **Gain (Loss) on Securities [Line Items]**                                                  |            |           |            |   |   |
| Reduction of net unrealized gains on investments included in AOCI due to shadow adjustments | $ 2,342,000,000 |           | $ 2,342,000,000 |   | $ 2,198,000,000 |
| Notional value                                                                              | 197,000,000     |           | 197,000,000     |   | 182,000,000 |
| Derivative liability, fair value, gross liability                                           | (12,000,000)    |           | (12,000,000)    |   | (7,000,000) |
| Commitments to purchase or fund privately placed debt securities                            | 1,205,000,000   |           | 1,205,000,000   |   |   |
| Commitments to sell various privately placed debt securities                                | 50,000,000      |           | 50,000,000      |   |   |
| Debt securities, amortized cost                                                             | 38,392,000,000  |           | 38,392,000,000  |   | $ 38,126,000,000 |
| Common Stock                                                                                |            |           |            |   |   |
| **Gain (Loss) on Securities [Line Items]**                                                  |            |           |            |   |   |
| Equity securities, FV-NI, gain (loss)                                                       | 23,000,000      | $ 4,000,000    | 10,000,000      | $ 21,000,000 |   |
| Preferred stock                                                                             |            |           |            |   |   |
| **Gain (Loss) on Securities [Line Items]**                                                  |            |           |            |   |   |
| Equity securities, FV-NI, gain (loss)                                                       | 63,000,000      | 11,000,000     | (70,000,000)    | 53,000,000 |   |
| Fixed maturity securities                                                                   |            |           |            |   |   |
| **Gain (Loss) on Securities [Line Items]**                                                  |            |           |            |   |   |
| Interest receivable                                                                         | 373,000,000     |           | 373,000,000     |   |   |
| Mortgage loans                                                                              |            |           |            |   |   |
| **Gain (Loss) on Securities [Line Items]**                                                  |            |           |            |   |   |
| Interest receivable                                                                         | 4,000,000       |           | 4,000,000       |   |   |
| Debt securities, amortized cost                                                             | $ 22,000,000    |           | 22,000,000      |   |   |
| Financing receivable, allowance for credit loss, writeoff                                   |            |           | $ 0             |   |   |
| Senior Notes | 5.875%, face amount of $500, due August 15, 2020                             |            |           |            |   |   |
| **Gain (Loss) on Securities [Line Items]**                                                  |            |           |            |   |   |
| Realized investment gains (losses)                                                          |            | 21,000,000     |            | 21,000,000 |   |
| Face amount                                                                                 |            | $ 500,000,000  |            | $ 500,000,000 |   |

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Face (par) amount of debt instrument at time of issuance.
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Nominal or face amount used to calculate payment on derivative.
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