Insurance (Details 3) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Variable Annuity Guarantees [Member] | Guaranteed Death Benefits [Member]
Net Amount at Risk by Product and Guarantee [Line Items]
Account value	$ 184,095,000,000	$ 163,845,000,000
Separate account value in event of death	143,893,000,000	121,841,000,000
Net amount at risk in event of death	9,501,000,000	16,641,000,000
Average attained age of contractholders	62 years	62 years
Variable Annuity Guarantees [Member] | Guaranteed Annuitization Benefits [Member]
Net Amount at Risk by Product and Guarantee [Line Items]
Account value	89,137,000,000	72,016,000,000
Average attained age of contractholders	62 years	61 years
Separate account value at annuitization	84,354,000,000	66,739,000,000
Net amount at risk at annuitization	4,593,000,000	2,686,000,000
Net amount at risk at annuitization for variable annuity guarantees based on the excess of the benefit base over the contractholder's total contract account value on the balance sheet date	9,700,000,000	12,100,000,000
Two Tier Annuities [Member] | Guaranteed Annuitization Benefits [Member]
Net Amount at Risk by Product and Guarantee [Line Items]
Account value	848,000,000	386,000,000
Average attained age of contractholders	51 years	60 years
Net amount at risk at annuitization	$ 232,000,000	$ 60,000,000