Reinsurance (Reinsurance Recoverable) (Details) - USD ($) $ in Millions |
Dec. 31, 2017 |
Dec. 31, 2016 |
|---|---|---|
| Effects of Reinsurance [Line Items] | ||
| Total reinsurance recoverables | $ 5,159 | $ 4,211 |
| Individual and group annuities | ||
| Effects of Reinsurance [Line Items] | ||
| Total reinsurance recoverables | 698 | 658 |
| Life insurance | ||
| Effects of Reinsurance [Line Items] | ||
| Total reinsurance recoverables | 4,290 | 3,388 |
| Other reinsurance | ||
| Effects of Reinsurance [Line Items] | ||
| Total reinsurance recoverables | 171 | 165 |
| CIGNA | Individual and group annuities | ||
| Effects of Reinsurance [Line Items] | ||
| Total reinsurance recoverables | 682 | 656 |
| Hartford Life Business | Life insurance | ||
| Effects of Reinsurance [Line Items] | ||
| Total reinsurance recoverables | 2,145 | 2,049 |
| Reinsurance Payable | 1,301 | 1,205 |
| Union Hamilton | Individual and group annuities | ||
| Effects of Reinsurance [Line Items] | ||
| Total reinsurance recoverables | $ 13 | $ 0 |