Reserve for Life-Contingent Contract Benefits and Contractholder Funds (Details 4) (Variable annuities, USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Variable annuity contracts with guarantees
Account balances of separate accounts with guarantees, invested in equity, fixed income and balanced mutual funds	$ 5,200,000,000	$ 5,230,000,000
Account balances of separate accounts with guarantees, invested in money market mutual funds	748,000,000	721,000,000
In the event of death
Variable annuity contracts with guarantees
Separate account value in the event of death	5,951,000,000	5,947,000,000
Net amount at risk in the event of death	636,000,000	1,044,000,000
Average attained age of contractholders	68 years	67 years
Liability for guarantees related to income benefits
Variable annuity contracts with guarantees
Separate account value at annuitization	1,463,000,000	1,416,000,000
Net amount at risk at annuitization	252,000,000	418,000,000
Weighted average waiting period until annuitization or guarantee date	0 years	0 years
For cumulative periodic withdrawals
Variable annuity contracts with guarantees
Separate account value	488,000,000	532,000,000
Net amount at risk	9,000,000	16,000,000
Accumulation at specified dates
Variable annuity contracts with guarantees
Separate account value	732,000,000	811,000,000
Net amount at risk	$ 27,000,000	$ 50,000,000
Weighted average waiting period until annuitization or guarantee date	5 years	6 years