Derivative Financial Instruments and Off-balance sheet Financial Instruments (Details 4) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Contractholder funds
Derivative Instruments Change in Fair Value of Fair Value Hedges
Gain (loss) on hedged risk		$ 41
Contractholder funds | Interest credited to contractholder funds
Derivative Instruments Change in Fair Value of Fair Value Hedges
Gain (loss) on hedged risk		41
Interest rate contracts
Derivative Instruments Change in Fair Value of Fair Value Hedges
Gain (loss) on derivatives	3	11
Interest rate contracts | Interest credited to contractholder funds
Derivative Instruments Change in Fair Value of Fair Value Hedges
Gain (loss) on derivatives		(7)
Interest rate contracts | Net investment income
Derivative Instruments Change in Fair Value of Fair Value Hedges
Gain (loss) on derivatives	3	26
Interest rate contracts | Realized capital gains and losses
Derivative Instruments Change in Fair Value of Fair Value Hedges
Gain (loss) on derivatives		(8)
Investments
Derivative Instruments Change in Fair Value of Fair Value Hedges
Gain (loss) on hedged risk	(3)	(26)
Investments | Net investment income
Derivative Instruments Change in Fair Value of Fair Value Hedges
Gain (loss) on hedged risk	(3)	(26)
Foreign currency and interest rate contracts
Derivative Instruments Change in Fair Value of Fair Value Hedges
Gain (loss) on derivatives		(34)
Foreign currency and interest rate contracts | Interest credited to contractholder funds
Derivative Instruments Change in Fair Value of Fair Value Hedges
Gain (loss) on derivatives		$ (34)