Derivatives (Gains Losses Recognized in Income Not Designated or Qualifying) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	$ (64)	$ (14)	$ (56)
Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] | Net derivative gains (losses)
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	594	(2,216)	(758)
Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] | Net derivative gains (losses) | Interest rate derivatives
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	(158)	(549)	(990)
Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] | Net derivative gains (losses) | Foreign currency exchange rate derivatives
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	518	(742)	882
Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] | Net derivative gains (losses) | Credit derivatives — purchased
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	6	(24)	(40)
Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] | Net derivative gains (losses) | Credit derivatives — written
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	(132)	145	71
Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] | Net derivative gains (losses) | Equity derivatives
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	360	(1,046)	(681)
Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] | Net Investment Income
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	5	(8)	(16)
Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] | Net Investment Income | Interest rate derivatives
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	4	1	0
Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] | Net Investment Income | Foreign currency exchange rate derivatives
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	0	0	0
Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] | Net Investment Income | Credit derivatives — purchased
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	0	0	0
Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] | Net Investment Income | Credit derivatives — written
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	0	0	0
Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] | Net Investment Income | Equity derivatives
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	1	(9)	(16)
Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] | Policyholder benefits and claims
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	48	(248)	(110)
Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] | Policyholder benefits and claims | Interest rate derivatives
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	(6)	(1)	46
Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] | Policyholder benefits and claims | Foreign currency exchange rate derivatives
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	(6)	5	(18)
Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] | Policyholder benefits and claims | Credit derivatives — purchased
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	0	0	0
Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] | Policyholder benefits and claims | Credit derivatives — written
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	0	0	0
Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] | Policyholder benefits and claims | Equity derivatives
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	$ 60	$ (252)	$ (138)