Derivatives Derivatives (Derivatives Pertaining to Hedged Items) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Derivative Instruments, Gain (Loss) [Line Items]
Net Derivative Gains (Losses) Recognized for Hedged Items	$ (14)	$ (32)	$ 2
Amount of Gains (Losses) Deferred in AOCI	(52)	40	159
Derivatives Not Designated or Not Qualifying as Hedging Instruments
Derivative Instruments, Gain (Loss) [Line Items]
Net Derivative Gains (Losses) Recognized for Hedged Items	(7)	(3)	(8)
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
Amount of Gains (Losses) Deferred in AOCI			0
Cash Flow Hedging
Derivative Instruments, Gain (Loss) [Line Items]
Net Derivative Gains (Losses) Recognized for Hedged Items	(7)	(29)	(2)
Amount of Gains (Losses) Deferred in AOCI	(52)	40	159
Net Derivative Gains (Losses)
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	(4)	(1,956)	700
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	(21)	(2,013)	583
Net Derivative Gains (Losses) | Fair Value Hedges
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net			(12)
Net Derivative Gains (Losses) | Cash Flow Hedging
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	17	57	129
Net Investment Income
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	40	36	33
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 Investment Income | Fair Value Hedges
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net			1
Net Investment Income | Cash Flow Hedging
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	40	36	32
Policyholder Benefits and Claims
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	0	0	(8)
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	(8)
Policyholder Benefits and Claims | Fair Value Hedges
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net			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
Amount of Gains (Losses) Deferred in AOCI			0
Interest rate derivatives | Cash Flow Hedging
Derivative Instruments, Gain (Loss) [Line Items]
Net Derivative Gains (Losses) Recognized for Hedged Items	0	0	(1)
Amount of Gains (Losses) Deferred in AOCI	77	25	(5)
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	3,565	1,589	(658)
Interest rate derivatives | Net Derivative Gains (Losses) | Fair Value Hedges
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net			(12)
Interest rate derivatives | Net Derivative Gains (Losses) | Cash Flow Hedging
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	2	32	129
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
Interest rate derivatives | Net Investment Income | Cash Flow Hedging
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	3	2	5
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	0
Interest rate derivatives | Policyholder Benefits and Claims | Fair Value Hedges
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net			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	(7)	(3)	(8)
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	(7)	(29)	(1)
Amount of Gains (Losses) Deferred in AOCI	(129)	15	164
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	(16)	22	82
Foreign currency exchange rate derivatives | Net Derivative Gains (Losses) | Cash Flow Hedging
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	15	25	0
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	37	34	27
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	18	44	(7)
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	(1,367)	(2,476)	632
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	0
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	0
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	(2,221)	(1,192)	534
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	$ 0	$ (8)