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)	$ 3	$ (43)
Amount of Gains (Losses) deferred in AOCI	37	156	(152)
Derivatives Not Designated or Not Qualifying as hedging Instruments
Derivative Instruments, Gain (Loss) [Line Items]
Net Derivative Gains (Losses) Recognized for Hedged Items	(3)	(7)	(32)
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	37	156	(152)
Net derivative gains (losses)
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	(2,014)	742	(1,425)
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	(2,070)	625	(1,435)
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	56	129	8
Net investment income
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	34	32	26
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	34	31	25
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)	1
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	(659)	(58)
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	31	129	0
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)	(7)	(32)
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	12	161	(153)
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	81	(83)
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	8
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	32	26	19
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)	631	(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)
Embedded Derivative Financial Instruments [Member] | 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
Embedded Derivative Financial Instruments [Member] | 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	(1,249)	579	1,237
Embedded Derivative Financial Instruments [Member] | 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
Embedded Derivative Financial Instruments [Member] | 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)