Certain Nontraditional Long-Duration Contracts (Account Balances of Variable Annuity Contracts with Guarantees Invested in General and Separate Account Investment Options) (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
Net Amount At Risk By Product And Guarantee [Line Items]
NetAmountAtRiskByProductAndGuaranteeSeparateAccountValue	$ 43,819,126,000	$ 46,347,647,000
variableannuity
Net Amount At Risk By Product And Guarantee [Line Items]
netamountatriskbyproductandguaranteegeneralaccountvalue	2,500,000,000	2,900,000,000
variableannuity | EquityFundsMember
Net Amount At Risk By Product And Guarantee [Line Items]
NetAmountAtRiskByProductAndGuaranteeSeparateAccountValue	28,191,315,000	28,992,157,000
variableannuity | BondFundsMember [Member]
Net Amount At Risk By Product And Guarantee [Line Items]
NetAmountAtRiskByProductAndGuaranteeSeparateAccountValue	12,844,788,000	14,924,698,000
variableannuity | MoneyMarketFundsMember
Net Amount At Risk By Product And Guarantee [Line Items]
NetAmountAtRiskByProductAndGuaranteeSeparateAccountValue	$ 2,783,023,000	$ 2,430,792,000