Reserve for Life-Contingent Contract Benefits and Contractholder Funds (Details 6) (USD $) In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Liabilities for guarantees:
Liability for guarantees	$ 350	$ 555	$ 673
Liability for guarantees related to income benefits
Liabilities for guarantees:
Liability for guarantees	95	113	235
Variable annuities | In the event of death
Liabilities for guarantees:
Liability for guarantees	96	98	112
Variable annuities | Liability for guarantees related to income benefits
Liabilities for guarantees:
Liability for guarantees	92	99	221
Variable annuities | Accumulation at specified dates
Liabilities for guarantees:
Liability for guarantees	32	43	86
Variable annuities | For cumulative periodic withdrawals
Liabilities for guarantees:
Liability for guarantees	13	13	39
Variable annuities | Other guarantees
Liabilities for guarantees:
Liability for guarantees	$ 117	$ 302	$ 215