Derivatives (Gains Losses Recognized in Income Not Designated or Qualifying) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Derivative Instruments, Gain (Loss) [Line Items]
Net Derivative Gains (Losses) Recognized for Derivatives	$ 1	$ 3	$ 2	$ 24
Derivatives Not Designated or Not Qualifying as Hedging Instruments: | Net derivative gains (losses)
Derivative Instruments, Gain (Loss) [Line Items]
Net Derivative Gains (Losses) Recognized for Derivatives	(817)	(1,165)	(2,324)	(69)
Derivatives Not Designated or Not Qualifying as Hedging Instruments: | Net derivative gains (losses) | Interest rate derivatives
Derivative Instruments, Gain (Loss) [Line Items]
Net Derivative Gains (Losses) Recognized for Derivatives	(81)	(372)	(145)	1,044
Derivatives Not Designated or Not Qualifying as Hedging Instruments: | Net derivative gains (losses) | Foreign currency exchange rate derivatives
Derivative Instruments, Gain (Loss) [Line Items]
Net Derivative Gains (Losses) Recognized for Derivatives	(30)	(8)	(72)	24
Derivatives Not Designated or Not Qualifying as Hedging Instruments: | Net derivative gains (losses) | Credit default swaps — purchased
Derivative Instruments, Gain (Loss) [Line Items]
Net Derivative Gains (Losses) Recognized for Derivatives	0	(1)	0	(1)
Derivatives Not Designated or Not Qualifying as Hedging Instruments: | Net derivative gains (losses) | Credit default swaps — written
Derivative Instruments, Gain (Loss) [Line Items]
Net Derivative Gains (Losses) Recognized for Derivatives	5	9	16	8
Derivatives Not Designated or Not Qualifying as Hedging Instruments: | Net derivative gains (losses) | Equity derivatives
Derivative Instruments, Gain (Loss) [Line Items]
Net Derivative Gains (Losses) Recognized for Derivatives	(711)	(793)	(2,123)	(1,144)
Derivatives Not Designated or Not Qualifying as Hedging Instruments: | Net Investment Income
Derivative Instruments, Gain (Loss) [Line Items]
Net Derivative Gains (Losses) Recognized for Derivatives	0	(2)	(1)	(6)
Derivatives Not Designated or Not Qualifying as Hedging Instruments: | Net Investment Income | Interest rate derivatives
Derivative Instruments, Gain (Loss) [Line Items]
Net Derivative Gains (Losses) Recognized for Derivatives	0	0	0	0
Derivatives Not Designated or Not Qualifying as Hedging Instruments: | Net Investment Income | Foreign currency exchange rate derivatives
Derivative Instruments, Gain (Loss) [Line Items]
Net Derivative Gains (Losses) Recognized for Derivatives	0	0	0	0
Derivatives Not Designated or Not Qualifying as Hedging Instruments: | Net Investment Income | Credit default swaps — purchased
Derivative Instruments, Gain (Loss) [Line Items]
Net Derivative Gains (Losses) Recognized for Derivatives	0	0	0	0
Derivatives Not Designated or Not Qualifying as Hedging Instruments: | Net Investment Income | Credit default swaps — written
Derivative Instruments, Gain (Loss) [Line Items]
Net Derivative Gains (Losses) Recognized for Derivatives	0	0	0	0
Derivatives Not Designated or Not Qualifying as Hedging Instruments: | Net Investment Income | Equity derivatives
Derivative Instruments, Gain (Loss) [Line Items]
Net Derivative Gains (Losses) Recognized for Derivatives	0	(2)	(1)	(6)
Derivatives Not Designated or Not Qualifying as Hedging Instruments: | Policyholder benefits and claims
Derivative Instruments, Gain (Loss) [Line Items]
Net Derivative Gains (Losses) Recognized for Derivatives	(58)	(191)	(333)	(179)
Derivatives Not Designated or Not Qualifying as Hedging Instruments: | Policyholder benefits and claims | Interest rate derivatives
Derivative Instruments, Gain (Loss) [Line Items]
Net Derivative Gains (Losses) Recognized for Derivatives	6	(3)	8	26
Derivatives Not Designated or Not Qualifying as Hedging Instruments: | Policyholder benefits and claims | Foreign currency exchange rate derivatives
Derivative Instruments, Gain (Loss) [Line Items]
Net Derivative Gains (Losses) Recognized for Derivatives	0	0	0	0
Derivatives Not Designated or Not Qualifying as Hedging Instruments: | Policyholder benefits and claims | Credit default swaps — purchased
Derivative Instruments, Gain (Loss) [Line Items]
Net Derivative Gains (Losses) Recognized for Derivatives	0	0	0	0
Derivatives Not Designated or Not Qualifying as Hedging Instruments: | Policyholder benefits and claims | Credit default swaps — written
Derivative Instruments, Gain (Loss) [Line Items]
Net Derivative Gains (Losses) Recognized for Derivatives	0	0	0	0
Derivatives Not Designated or Not Qualifying as Hedging Instruments: | Policyholder benefits and claims | Equity derivatives
Derivative Instruments, Gain (Loss) [Line Items]
Net Derivative Gains (Losses) Recognized for Derivatives	$ (64)	$ (188)	$ (341)	$ (205)