Derivatives (Gains Losses Recognized in Income Not Designated or Qualifying) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Derivative Instruments, Gain (Loss) [Line Items]
Net Derivative Gains (Losses) Recognized for Derivatives	$ 383	$ (851)	$ (39)
Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] | Net derivative gains (losses)
Derivative Instruments, Gain (Loss) [Line Items]
Net Derivative Gains (Losses) Recognized for Derivatives	876	(1,728)	(302)
Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] | Net derivative gains (losses) | Interest rate derivatives
Derivative Instruments, Gain (Loss) [Line Items]
Net Derivative Gains (Losses) Recognized for Derivatives	314	(1,753)	(83)
Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] | Net derivative gains (losses) | Foreign currency [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Net Derivative Gains (Losses) Recognized for Derivatives	554	(69)	(252)
Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] | Net derivative gains (losses) | Credit derivatives — purchased
Derivative Instruments, Gain (Loss) [Line Items]
Net Derivative Gains (Losses) Recognized for Derivatives	(2)	(6)	(72)
Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] | Net derivative gains (losses) | Credit derivatives — written
Derivative Instruments, Gain (Loss) [Line Items]
Net Derivative Gains (Losses) Recognized for Derivatives	(1)	100	105
Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] | Net derivative gains (losses) | Equity market [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Net Derivative Gains (Losses) Recognized for Derivatives	11	0	0
Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] | Net Investment Gains (Losses) [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Net Derivative Gains (Losses) Recognized for Derivatives	(10)	(35)	(27)
Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] | Net Investment Gains (Losses) [Member] | Interest rate derivatives
Derivative Instruments, Gain (Loss) [Line Items]
Net Derivative Gains (Losses) Recognized for Derivatives	0	0	0
Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] | Net Investment Gains (Losses) [Member] | Foreign currency [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Net Derivative Gains (Losses) Recognized for Derivatives	0	0	0
Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] | Net Investment Gains (Losses) [Member] | Credit derivatives — purchased
Derivative Instruments, Gain (Loss) [Line Items]
Net Derivative Gains (Losses) Recognized for Derivatives	0	(14)	(15)
Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] | Net Investment Gains (Losses) [Member] | Credit derivatives — written
Derivative Instruments, Gain (Loss) [Line Items]
Net Derivative Gains (Losses) Recognized for Derivatives	0	1	0
Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] | Net Investment Gains (Losses) [Member] | Equity market [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Net Derivative Gains (Losses) Recognized for Derivatives	(10)	(22)	(12)
Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] | Policyholder Benefit And Claim [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Net Derivative Gains (Losses) Recognized for Derivatives	(10)	0	0
Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] | Policyholder Benefit And Claim [Member] | Interest rate derivatives
Derivative Instruments, Gain (Loss) [Line Items]
Net Derivative Gains (Losses) Recognized for Derivatives	0	0	0
Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] | Policyholder Benefit And Claim [Member] | Foreign currency [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Net Derivative Gains (Losses) Recognized for Derivatives	0	0	0
Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] | Policyholder Benefit And Claim [Member] | Credit derivatives — purchased
Derivative Instruments, Gain (Loss) [Line Items]
Net Derivative Gains (Losses) Recognized for Derivatives	0	0	0
Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] | Policyholder Benefit And Claim [Member] | Credit derivatives — written
Derivative Instruments, Gain (Loss) [Line Items]
Net Derivative Gains (Losses) Recognized for Derivatives	0	0	0
Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] | Policyholder Benefit And Claim [Member] | Equity market [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Net Derivative Gains (Losses) Recognized for Derivatives	$ (10)	$ 0	$ 0