Derivatives Derivatives (Derivatives Pertaining to Hedged Items) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Derivative Instruments, Gain (Loss) [Line Items]
Net Derivative Gains (Losses) Recognized for Hedged Items	$ (32)	$ 2	$ (44)
Amount of Gains (Losses) deferred in AOCI	40	159	(157)
Derivatives Not Designated or Not Qualifying as Hedging Instruments
Derivative Instruments, Gain (Loss) [Line Items]
Net Derivative Gains (Losses) Recognized for Hedged Items	(3)	(8)	(33)
Amount of Gains (Losses) deferred in AOCI	0	0	0
Fair Value Hedges
Derivative Instruments, Gain (Loss) [Line Items]
Net Derivative Gains (Losses) Recognized for Hedged Items		12	(2)
Amount of Gains (Losses) deferred in AOCI		0	0
Cash Flow Hedging
Derivative Instruments, Gain (Loss) [Line Items]
Net Derivative Gains (Losses) Recognized for Hedged Items	(29)	(2)	(9)
Amount of Gains (Losses) deferred in AOCI	40	159	(157)
Net derivative gains (losses)
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	(1,956)	700	(1,576)
Net derivative gains (losses) | Derivatives Not Designated or Not Qualifying as Hedging Instruments
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	(2,013)	583	(1,590)
Net derivative gains (losses) | Fair Value Hedges
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net		(12)	2
Net derivative gains (losses) | Cash Flow Hedging
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	57	129	12
Net investment income
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	36	33	28
Net investment income | Derivatives Not Designated or Not Qualifying as Hedging Instruments
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	0	0	(1)
Net investment income | Fair Value Hedges
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net		1	2
Net investment income | Cash Flow Hedging
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	36	32	27
Policyholder benefits and claims
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	0	(8)	(341)
Policyholder benefits and claims | Derivatives Not Designated or Not Qualifying as Hedging Instruments
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	0	(8)	(341)
Policyholder benefits and claims | Fair Value Hedges
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net		0	0
Policyholder benefits and claims | Cash Flow Hedging
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	0	0	0
Interest rate derivatives | Derivatives Not Designated or Not Qualifying as Hedging Instruments
Derivative Instruments, Gain (Loss) [Line Items]
Net Derivative Gains (Losses) Recognized for Hedged Items	0	0	0
Amount of Gains (Losses) deferred in AOCI	0	0	0
Interest rate derivatives | Fair Value Hedges
Derivative Instruments, Gain (Loss) [Line Items]
Net Derivative Gains (Losses) Recognized for Hedged Items		12	(2)
Amount of Gains (Losses) deferred in AOCI		0	0
Interest rate derivatives | Cash Flow Hedging
Derivative Instruments, Gain (Loss) [Line Items]
Net Derivative Gains (Losses) Recognized for Hedged Items	0	(1)	0
Amount of Gains (Losses) deferred in AOCI	25	(5)	3
Interest rate derivatives | Net derivative gains (losses) | Derivatives Not Designated or Not Qualifying as Hedging Instruments
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	1,589	(658)	(57)
Interest rate derivatives | Net derivative gains (losses) | Fair Value Hedges
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net		(12)	2
Interest rate derivatives | Net derivative gains (losses) | Cash Flow Hedging
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	32	129	2
Interest rate derivatives | Net investment income | Derivatives Not Designated or Not Qualifying as Hedging Instruments
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	0	0	0
Interest rate derivatives | Net investment income | Fair Value Hedges
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net		1	2
Interest rate derivatives | Net investment income | Cash Flow Hedging
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	2	5	6
Interest rate derivatives | Policyholder benefits and claims | Derivatives Not Designated or Not Qualifying as Hedging Instruments
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	0	0	10
Interest rate derivatives | Policyholder benefits and claims | Fair Value Hedges
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net		0	0
Interest rate derivatives | Policyholder benefits and claims | Cash Flow Hedging
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	0	0	0
Foreign currency exchange rate derivatives | Derivatives Not Designated or Not Qualifying as Hedging Instruments
Derivative Instruments, Gain (Loss) [Line Items]
Net Derivative Gains (Losses) Recognized for Hedged Items	(3)	(8)	(33)
Amount of Gains (Losses) deferred in AOCI	0	0	0
Foreign currency exchange rate derivatives | Cash Flow Hedging
Derivative Instruments, Gain (Loss) [Line Items]
Net Derivative Gains (Losses) Recognized for Hedged Items	(29)	(1)	(9)
Amount of Gains (Losses) deferred in AOCI	15	164	(160)
Foreign currency exchange rate derivatives | Net derivative gains (losses) | Derivatives Not Designated or Not Qualifying as Hedging Instruments
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	22	82	(84)
Foreign currency exchange rate derivatives | Net derivative gains (losses) | Cash Flow Hedging
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	25	0	10
Foreign currency exchange rate derivatives | Net investment income | Derivatives Not Designated or Not Qualifying as Hedging Instruments
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	0	0	0
Foreign currency exchange rate derivatives | Net investment income | Cash Flow Hedging
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	34	27	21
Foreign currency exchange rate derivatives | Policyholder benefits and claims | Derivatives Not Designated or Not Qualifying as Hedging Instruments
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	0	0	0
Foreign currency exchange rate derivatives | Policyholder benefits and claims | Cash Flow Hedging
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	0	0	0
Credit derivatives | Derivatives Not Designated or Not Qualifying as Hedging Instruments
Derivative Instruments, Gain (Loss) [Line Items]
Net Derivative Gains (Losses) Recognized for Hedged Items	0	0	0
Amount of Gains (Losses) deferred in AOCI	0	0	0
Credit derivatives | Net derivative gains (losses) | Derivatives Not Designated or Not Qualifying as Hedging Instruments
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	44	(7)	34
Credit derivatives | Net investment income | Derivatives Not Designated or Not Qualifying as Hedging Instruments
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	0	0	0
Credit derivatives | Policyholder benefits and claims | Derivatives Not Designated or Not Qualifying as Hedging Instruments
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	0	0	0
Equity derivatives | Derivatives Not Designated or Not Qualifying as Hedging Instruments
Derivative Instruments, Gain (Loss) [Line Items]
Net Derivative Gains (Losses) Recognized for Hedged Items	0	0	0
Amount of Gains (Losses) deferred in AOCI	0	0	0
Equity derivatives | Net derivative gains (losses) | Derivatives Not Designated or Not Qualifying as Hedging Instruments
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	(2,476)	632	(2,565)
Equity derivatives | Net investment income | Derivatives Not Designated or Not Qualifying as Hedging Instruments
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	0	0	(1)
Equity derivatives | Policyholder benefits and claims | Derivatives Not Designated or Not Qualifying as Hedging Instruments
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	0	0	(335)
Net Embedded Derivatives | Derivatives Not Designated or Not Qualifying as Hedging Instruments
Derivative Instruments, Gain (Loss) [Line Items]
Net Derivative Gains (Losses) Recognized for Hedged Items	0	0	0
Amount of Gains (Losses) deferred in AOCI	0	0	0
Net Embedded Derivatives | Net derivative gains (losses) | Derivatives Not Designated or Not Qualifying as Hedging Instruments
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	(1,192)	534	1,082
Net Embedded Derivatives | Net investment income | Derivatives Not Designated or Not Qualifying as Hedging Instruments
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	0	0	0
Net Embedded Derivatives | Policyholder benefits and claims | Derivatives Not Designated or Not Qualifying as Hedging Instruments
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	$ 0	$ (8)	$ (16)