Derivative Financial Instruments (Details 3) (USD $)	3 Months Ended		12 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Dec. 31, 2012
Derivative Financial Instruments
Cash flow hedge losses to be reclassified from AOCI during the next twelve months	$ 1,000,000
Hedge ineffectiveness in realized gains	0		0
Gain (loss) recognized in OCI on derivatives during the period	3,000,000	(5,000,000)
Loss recognized in OCI on derivatives during the term of the hedging relationship	(14,000,000)	(16,000,000)
Loss reclassified from AOCI into income (realized capital gains and losses)		(1,000,000)
Derivative Instruments, Gain (Loss)
Derivatives in fair value accounting hedging relationships, total gain (loss) recognized in net income on derivatives		(1,000,000)
Derivatives not designated as accounting hedging instruments, total gain (loss) recognized in net income on derivatives	31,000,000	71,000,000
Total gain (loss) recognized in net income on derivatives		70,000,000
Net investment income
Derivative Instruments, Gain (Loss)
Derivatives in fair value accounting hedging relationships, total gain (loss) recognized in net income on derivatives		(1,000,000)
Total gain (loss) recognized in net income on derivatives		(1,000,000)
Realized capital gains and losses
Derivative Instruments, Gain (Loss)
Derivatives not designated as accounting hedging instruments, total gain (loss) recognized in net income on derivatives	7,000,000	23,000,000
Total gain (loss) recognized in net income on derivatives		23,000,000
Contract benefits
Derivative Instruments, Gain (Loss)
Derivatives not designated as accounting hedging instruments, total gain (loss) recognized in net income on derivatives	26,000,000	31,000,000
Total gain (loss) recognized in net income on derivatives		31,000,000
Interest credited to contractholder funds
Derivative Instruments, Gain (Loss)
Derivatives not designated as accounting hedging instruments, total gain (loss) recognized in net income on derivatives	(2,000,000)	17,000,000
Total gain (loss) recognized in net income on derivatives		17,000,000
Interest rate contracts
Derivative Instruments, Gain (Loss)
Derivatives in fair value accounting hedging relationships, total gain (loss) recognized in net income on derivatives		(1,000,000)
Derivatives not designated as accounting hedging instruments, total gain (loss) recognized in net income on derivatives		(1,000,000)
Interest rate contracts | Net investment income
Derivative Instruments, Gain (Loss)
Derivatives in fair value accounting hedging relationships, total gain (loss) recognized in net income on derivatives		(1,000,000)
Interest rate contracts | Realized capital gains and losses
Derivative Instruments, Gain (Loss)
Derivatives not designated as accounting hedging instruments, total gain (loss) recognized in net income on derivatives		(1,000,000)
Equity and index contracts
Derivative Instruments, Gain (Loss)
Derivatives not designated as accounting hedging instruments, total gain (loss) recognized in net income on derivatives	38,000,000	53,000,000
Equity and index contracts | Interest credited to contractholder funds
Derivative Instruments, Gain (Loss)
Derivatives not designated as accounting hedging instruments, total gain (loss) recognized in net income on derivatives	38,000,000	53,000,000
Embedded derivative financial instruments
Derivative Instruments, Gain (Loss)
Derivatives not designated as accounting hedging instruments, total gain (loss) recognized in net income on derivatives	(15,000,000)	8,000,000
Embedded derivative financial instruments | Realized capital gains and losses
Derivative Instruments, Gain (Loss)
Derivatives not designated as accounting hedging instruments, total gain (loss) recognized in net income on derivatives	(1,000,000)	15,000,000
Embedded derivative financial instruments | Contract benefits
Derivative Instruments, Gain (Loss)
Derivatives not designated as accounting hedging instruments, total gain (loss) recognized in net income on derivatives	26,000,000	31,000,000
Embedded derivative financial instruments | Interest credited to contractholder funds
Derivative Instruments, Gain (Loss)
Derivatives not designated as accounting hedging instruments, total gain (loss) recognized in net income on derivatives	(40,000,000)	(38,000,000)
Foreign currency contracts
Derivative Instruments, Gain (Loss)
Derivatives not designated as accounting hedging instruments, total gain (loss) recognized in net income on derivatives	1,000,000
Foreign currency contracts | Realized capital gains and losses
Derivative Instruments, Gain (Loss)
Derivatives not designated as accounting hedging instruments, total gain (loss) recognized in net income on derivatives	1,000,000
Credit default swaps
Derivative Instruments, Gain (Loss)
Derivatives not designated as accounting hedging instruments, total gain (loss) recognized in net income on derivatives	7,000,000	9,000,000
Credit default swaps | Realized capital gains and losses
Derivative Instruments, Gain (Loss)
Derivatives not designated as accounting hedging instruments, total gain (loss) recognized in net income on derivatives	7,000,000	9,000,000
Other contracts
Derivative Instruments, Gain (Loss)
Derivatives not designated as accounting hedging instruments, total gain (loss) recognized in net income on derivatives		2,000,000
Other contracts | Interest credited to contractholder funds
Derivative Instruments, Gain (Loss)
Derivatives not designated as accounting hedging instruments, total gain (loss) recognized in net income on derivatives		$ 2,000,000