Derivatives (Details 2) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Settlement Payments By Hedge Classification And Income Statement Location
Total earned income	$ 667	$ 803	$ 480
Derivatives Designated as Hedging Instruments [Member] | Net Investment Income [Member]
Settlement Payments By Hedge Classification And Income Statement Location
Total earned income	111	98	83
Derivatives Designated as Hedging Instruments [Member] | Interest Credited to Policyholder Account Balance [Member]
Settlement Payments By Hedge Classification And Income Statement Location
Total earned income	164	214	233
Derivatives Designated as Hedging Instruments [Member] | Other Expenses [Member]
Settlement Payments By Hedge Classification And Income Statement Location
Total earned income	(5)	(4)	(6)
Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] | Net Investment Income [Member]
Settlement Payments By Hedge Classification And Income Statement Location
Total earned income	(6)	(8)	(3)
Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] | Other Revenues [Member]
Settlement Payments By Hedge Classification And Income Statement Location
Total earned income	47	75	108
Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] | Net Derivative Gains (Losses) [Member]
Settlement Payments By Hedge Classification And Income Statement Location
Total earned income	476	411	65
Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] | Policyholder Benefits and Claims [Member]
Settlement Payments By Hedge Classification And Income Statement Location
Total earned income	$ (120)	$ 17	$ 0