Reserve for Life-Contingent Contract Benefits and Contractholder Funds (Details 6) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Liabilities for guarantees:
Liabilities for guarantees on long-duration contracts	$ 365	$ 366	$ 350
In the event of death | Variable annuities
Liabilities for guarantees:
Liabilities for guarantees on long-duration contracts	100	105	96
At annuitization (includes income benefit guarantees) | Variable annuities
Liabilities for guarantees:
Liabilities for guarantees on long-duration contracts	40	65	92
Accumulation at specified dates | Variable annuities
Liabilities for guarantees:
Liabilities for guarantees on long-duration contracts	34	38	32
For cumulative periodic withdrawals | Variable annuities
Liabilities for guarantees:
Liabilities for guarantees on long-duration contracts	9	14	13
Other Guarantees [Member] | Variable annuities
Liabilities for guarantees:
Liabilities for guarantees on long-duration contracts	$ 182	$ 144	$ 117