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]
Derivative, Gain (Loss) on Derivative, Net	$ (12)	$ (23)	$ 52	$ 744
Derivatives Not Designated or Not Qualifying as Hedging Instruments: | Net derivative gains (losses)
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	(699)	(944)	(1,723)	3,018
Derivatives Not Designated or Not Qualifying as Hedging Instruments: | Net derivative gains (losses) | Interest rate derivatives
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	(148)	(710)	(466)	1,503
Derivatives Not Designated or Not Qualifying as Hedging Instruments: | Net derivative gains (losses) | Foreign currency exchange rate derivatives
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	(346)	154	(527)	1,841
Derivatives Not Designated or Not Qualifying as Hedging Instruments: | Net derivative gains (losses) | Credit derivatives — purchased
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	(2)	(21)	(17)	(48)
Derivatives Not Designated or Not Qualifying as Hedging Instruments: | Net derivative gains (losses) | Credit derivatives — written
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	35	51	111	49
Derivatives Not Designated or Not Qualifying as Hedging Instruments: | Net derivative gains (losses) | Equity derivatives
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	(238)	(418)	(824)	(327)
Derivatives Not Designated or Not Qualifying as Hedging Instruments: | Net investment income
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	(5)	(3)	(9)	(13)
Derivatives Not Designated or Not Qualifying as Hedging Instruments: | Net investment income | Interest rate derivatives
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	(2)	0	(2)	0
Derivatives Not Designated or Not Qualifying as Hedging Instruments: | Net investment income | Foreign currency exchange rate derivatives
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	0	0	0	0
Derivatives Not Designated or Not Qualifying as Hedging Instruments: | Net investment income | Credit derivatives — purchased
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	0	0	0	0
Derivatives Not Designated or Not Qualifying as Hedging Instruments: | Net investment income | Credit derivatives — written
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	0	0	0	0
Derivatives Not Designated or Not Qualifying as Hedging Instruments: | Net investment income | Equity derivatives
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	(3)	(3)	(7)	(13)
Derivatives Not Designated or Not Qualifying as Hedging Instruments: | Policyholder benefits and claims
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	(62)	(55)	(188)	(15)
Derivatives Not Designated or Not Qualifying as Hedging Instruments: | Policyholder benefits and claims | Interest rate derivatives
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	(3)	22	(16)	90
Derivatives Not Designated or Not Qualifying as Hedging Instruments: | Policyholder benefits and claims | Foreign currency exchange rate derivatives
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	2	(5)	4	(17)
Derivatives Not Designated or Not Qualifying as Hedging Instruments: | Policyholder benefits and claims | Credit derivatives — purchased
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	0	0	0	0
Derivatives Not Designated or Not Qualifying as Hedging Instruments: | Policyholder benefits and claims | Credit derivatives — written
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	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]
Derivative, Gain (Loss) on Derivative, Net	$ (61)	$ (72)	$ (176)	$ (88)