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:
Liability for guarantees	$ 364	$ 365	$ 350
Variable annuities | In the event of death
Liabilities for guarantees:
Liability for guarantees	100	105	96
Variable annuities | Liability for guarantees related to income benefits
Liabilities for guarantees:
Liability for guarantees	40	64	92
Variable annuities | Guaranteed accumulation benefits
Liabilities for guarantees:
Liability for guarantees	34	38	32
Variable annuities | For cumulative periodic withdrawals
Liabilities for guarantees:
Liability for guarantees	9	14	13
Variable annuities | Other guarantees
Liabilities for guarantees:
Liability for guarantees	$ 181	$ 144	$ 117