Derivatives (Primary Risks) (Details) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	$ 312,491		$ 308,215
Estimated Fair Value Assets	10,148		10,466
Estimated Fair Value Liabilities	4,631		$ 3,852
Gain (Loss) on Discontinuation of Cash Flow Hedge Due to Forecasted Transaction Probable of Not Occurring, Net	$ (2)	$ (2)
Maximum Length of Time Hedged in Cash Flow Hedge	7 years		7 years
Accumulated Other Comprehensive Income Loss	$ 1,900		$ 2,100
Derivatives Designated as Hedging Instruments:
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	63,452		61,088
Estimated Fair Value Assets	3,969		4,009
Estimated Fair Value Liabilities	2,024		1,764
Derivatives Designated as Hedging Instruments: | Fair Value Hedges [Member]
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	6,623		5,987
Estimated Fair Value Assets	1,901		2,175
Estimated Fair Value Liabilities	223		87
Derivatives Designated as Hedging Instruments: | Fair Value Hedges [Member] | Interest rate swaps
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	4,347		3,550
Estimated Fair Value Assets	1,875		2,164
Estimated Fair Value Liabilities	124		6
Derivatives Designated as Hedging Instruments: | Fair Value Hedges [Member] | Foreign currency swaps
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	740		801
Estimated Fair Value Assets	25		11
Estimated Fair Value Liabilities	6		23
Derivatives Designated as Hedging Instruments: | Fair Value Hedges [Member] | Foreign currency forwards
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	1,536		1,636
Estimated Fair Value Assets	1		0
Estimated Fair Value Liabilities	93		58
Derivatives Designated as Hedging Instruments: | Cash Flow Hedges [Member]
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	53,537		52,101
Estimated Fair Value Assets	1,884		1,695
Estimated Fair Value Liabilities	1,799		1,677
Derivatives Designated as Hedging Instruments: | Cash Flow Hedges [Member] | Interest rate swaps
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	3,778		4,117
Estimated Fair Value Assets	26		6
Estimated Fair Value Liabilities	0		1
Derivatives Designated as Hedging Instruments: | Cash Flow Hedges [Member] | Interest rate forwards
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	7,425		6,889
Estimated Fair Value Assets	6		89
Estimated Fair Value Liabilities	460		119
Derivatives Designated as Hedging Instruments: | Cash Flow Hedges [Member] | Foreign currency swaps
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	42,334		41,095
Estimated Fair Value Assets	1,852		1,600
Estimated Fair Value Liabilities	1,339		1,557
Derivatives Designated as Hedging Instruments: | Foreign Operations Hedges [Member]
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	3,292		3,000
Estimated Fair Value Assets	184		139
Estimated Fair Value Liabilities	2		0
Derivatives Designated as Hedging Instruments: | Foreign Operations Hedges [Member] | Foreign currency forwards
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	292		0
Estimated Fair Value Assets	7		0
Estimated Fair Value Liabilities	2		0
Derivatives Designated as Hedging Instruments: | Foreign Operations Hedges [Member] | Currency options
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	3,000		3,000
Estimated Fair Value Assets	177		139
Estimated Fair Value Liabilities	0		0
Derivatives Not Designated or Not Qualifying as Hedging Instruments:
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	249,039		247,127
Estimated Fair Value Assets	6,179		6,457
Estimated Fair Value Liabilities	2,607		2,088
Derivatives Not Designated or Not Qualifying as Hedging Instruments: | Interest rate swaps
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	34,867		38,860
Estimated Fair Value Assets	2,850		3,644
Estimated Fair Value Liabilities	502		115
Derivatives Not Designated or Not Qualifying as Hedging Instruments: | Interest rate forwards
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	439		374
Estimated Fair Value Assets	0		0
Estimated Fair Value Liabilities	63		26
Derivatives Not Designated or Not Qualifying as Hedging Instruments: | Interest rate floors
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	7,451		7,701
Estimated Fair Value Assets	66		145
Estimated Fair Value Liabilities	0		0
Derivatives Not Designated or Not Qualifying as Hedging Instruments: | Interest rate caps
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	66,410		65,559
Estimated Fair Value Assets	567		124
Estimated Fair Value Liabilities	0		0
Derivatives Not Designated or Not Qualifying as Hedging Instruments: | Interest rate futures
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	1,225		1,615
Estimated Fair Value Assets	0		4
Estimated Fair Value Liabilities	6		0
Derivatives Not Designated or Not Qualifying as Hedging Instruments: | Interest rate options
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	13,054		11,754
Estimated Fair Value Assets	490		493
Estimated Fair Value Liabilities	16		10
Derivatives Not Designated or Not Qualifying as Hedging Instruments: | Equity total return swaps
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	1,048		1,048
Estimated Fair Value Assets	0		9
Estimated Fair Value Liabilities	118		4
Derivatives Not Designated or Not Qualifying as Hedging Instruments: | Synthetic GICs
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	43,485		40,121
Estimated Fair Value Assets	0		0
Estimated Fair Value Liabilities	0		0
Derivatives Not Designated or Not Qualifying as Hedging Instruments: | Foreign currency swaps
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	12,893		12,787
Estimated Fair Value Assets	866		768
Estimated Fair Value Liabilities	394		614
Derivatives Not Designated or Not Qualifying as Hedging Instruments: | Foreign currency forwards
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	17,537		16,230
Estimated Fair Value Assets	117		36
Estimated Fair Value Liabilities	913		666
Derivatives Not Designated or Not Qualifying as Hedging Instruments: | Currency futures
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	828		839
Estimated Fair Value Assets	7		0
Estimated Fair Value Liabilities	0		2
Derivatives Not Designated or Not Qualifying as Hedging Instruments: | Currency options
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	450		900
Estimated Fair Value Assets	2		0
Estimated Fair Value Liabilities	0		0
Derivatives Not Designated or Not Qualifying as Hedging Instruments: | Credit default swaps — purchased
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	3,064		3,042
Estimated Fair Value Assets	50		13
Estimated Fair Value Liabilities	106		113
Derivatives Not Designated or Not Qualifying as Hedging Instruments: | Credit default swaps — written
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	10,518		8,626
Estimated Fair Value Assets	146		177
Estimated Fair Value Liabilities	17		12
Derivatives Not Designated or Not Qualifying as Hedging Instruments: | Equity futures
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	3,944		4,204
Estimated Fair Value Assets	32		12
Estimated Fair Value Liabilities	4		5
Derivatives Not Designated or Not Qualifying as Hedging Instruments: | Equity index options
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	28,067		29,743
Estimated Fair Value Assets	945		1,004
Estimated Fair Value Liabilities	444		458
Derivatives Not Designated or Not Qualifying as Hedging Instruments: | Equity variance swaps
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	699		699
Estimated Fair Value Assets	18		17
Estimated Fair Value Liabilities	13		13
Derivatives Not Designated or Not Qualifying as Hedging Instruments: | Equity total return swaps
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	3,060		3,025
Estimated Fair Value Assets	23		11
Estimated Fair Value Liabilities	$ 11		$ 50