Certain Long-Duration Contracts with Guarantees (Sales Inducements) (Details) - USD ($) $ in Millions |
12 Months Ended | ||
|---|---|---|---|
Dec. 31, 2017 |
Dec. 31, 2016 |
Dec. 31, 2015 |
|
| Movement in Deferred Sales Inducements [Roll Forward] | |||
| Beginning balance | $ 1,127 | $ 1,189 | $ 1,514 |
| Capitalization | 2 | 47 | 8 |
| Amortization—Impact of assumption and experience unlocking and true-ups | 157 | 118 | 43 |
| Amortization—All other | (105) | (231) | (392) |
| Change in unrealized investment gains and losses | (13) | 4 | 16 |
| Ending balance | $ 1,168 | $ 1,127 | $ 1,189 |