Derivatives (Primary Risks) (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	$ 308,215	$ 299,154
Estimated Fair Value Assets	10,466	11,866
Estimated Fair Value Liabilities	3,852	4,229
Derivatives Designated as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	61,088	60,723
Estimated Fair Value Assets	4,009	5,432
Estimated Fair Value Liabilities	1,764	2,222
Derivatives Designated as Hedging Instruments [Member] | Fair Value Hedges [Member]
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	5,987	6,228
Estimated Fair Value Assets	2,175	3,256
Estimated Fair Value Liabilities	87	82
Derivatives Designated as Hedging Instruments [Member] | Fair Value Hedges [Member] | Interest rate swaps
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	3,550	3,186
Estimated Fair Value Assets	2,164	3,224
Estimated Fair Value Liabilities	6	4
Derivatives Designated as Hedging Instruments [Member] | Fair Value Hedges [Member] | Foreign currency swaps
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	801	1,106
Estimated Fair Value Assets	11	8
Estimated Fair Value Liabilities	23	78
Derivatives Designated as Hedging Instruments [Member] | Fair Value Hedges [Member] | Foreign currency forwards
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	1,636	1,936
Estimated Fair Value Assets	0	24
Estimated Fair Value Liabilities	58	0
Derivatives Designated as Hedging Instruments [Member] | Cash Flow Hedges [Member]
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	52,101	50,731
Estimated Fair Value Assets	1,695	2,106
Estimated Fair Value Liabilities	1,677	2,137
Derivatives Designated as Hedging Instruments [Member] | Cash Flow Hedges [Member] | Interest rate swaps
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	4,117	4,750
Estimated Fair Value Assets	6	44
Estimated Fair Value Liabilities	1	0
Derivatives Designated as Hedging Instruments [Member] | Cash Flow Hedges [Member] | Interest rate forwards
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	6,889	7,377
Estimated Fair Value Assets	89	513
Estimated Fair Value Liabilities	119	120
Derivatives Designated as Hedging Instruments [Member] | Cash Flow Hedges [Member] | Foreign currency swaps
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	41,095	38,604
Estimated Fair Value Assets	1,600	1,549
Estimated Fair Value Liabilities	1,557	2,017
Derivatives Designated as Hedging Instruments [Member] | Foreign Operations Hedges [Member]
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	3,000	3,764
Estimated Fair Value Assets	139	70
Estimated Fair Value Liabilities	0	3
Derivatives Designated as Hedging Instruments [Member] | Foreign Operations Hedges [Member] | Foreign currency forwards
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	0	164
Estimated Fair Value Assets	0	0
Estimated Fair Value Liabilities	0	3
Derivatives Designated as Hedging Instruments [Member] | Foreign Operations Hedges [Member] | Currency options
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	3,000	3,600
Estimated Fair Value Assets	139	70
Estimated Fair Value Liabilities	0	0
Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	247,127	238,431
Estimated Fair Value Assets	6,457	6,434
Estimated Fair Value Liabilities	2,088	2,007
Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] | Interest rate swaps
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	38,860	49,561
Estimated Fair Value Assets	3,644	3,683
Estimated Fair Value Liabilities	115	38
Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] | Interest rate forwards
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	374	351
Estimated Fair Value Assets	0	0
Estimated Fair Value Liabilities	26	10
Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] | Interest rate floors
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	7,701	12,701
Estimated Fair Value Assets	145	350
Estimated Fair Value Liabilities	0	0
Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] | Interest rate caps
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	65,559	40,730
Estimated Fair Value Assets	124	13
Estimated Fair Value Liabilities	0	0
Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] | Interest rate futures
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	1,615	1,498
Estimated Fair Value Assets	4	0
Estimated Fair Value Liabilities	0	2
Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] | Interest rate options
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	11,754	17,746
Estimated Fair Value Assets	493	502
Estimated Fair Value Liabilities	10	5
Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] | Synthetic GICs
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	40,121	38,646
Estimated Fair Value Assets	0	0
Estimated Fair Value Liabilities	0	0
Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] | Foreign currency swaps
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	12,787	13,265
Estimated Fair Value Assets	768	603
Estimated Fair Value Liabilities	614	693
Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] | Foreign currency forwards
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	16,230	15,643
Estimated Fair Value Assets	36	209
Estimated Fair Value Liabilities	666	310
Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] | Currency futures
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	839	914
Estimated Fair Value Assets	0	3
Estimated Fair Value Liabilities	2	0
Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] | Currency options
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	900	1,350
Estimated Fair Value Assets	0	0
Estimated Fair Value Liabilities	0	0
Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] | Credit default swaps — purchased
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	3,042	2,978
Estimated Fair Value Assets	13	9
Estimated Fair Value Liabilities	113	121
Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] | Credit default swaps — written
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	8,626	9,609
Estimated Fair Value Assets	177	196
Estimated Fair Value Liabilities	12	0
Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] | Equity futures
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	4,204	5,427
Estimated Fair Value Assets	12	14
Estimated Fair Value Liabilities	5	38
Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] | Equity index options
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	29,743	22,954
Estimated Fair Value Assets	1,004	834
Estimated Fair Value Liabilities	458	437
Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] | Equity variance swaps
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	699	716
Estimated Fair Value Assets	17	15
Estimated Fair Value Liabilities	13	12
Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] | Total rate of return swaps [Member]
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	1,048	1,048
Estimated Fair Value Assets	9	0
Estimated Fair Value Liabilities	4	59
Derivatives Not Designated or Not Qualifying as Hedging Instruments [Member] | Equity Total Return Swaps [Member]
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	3,025	3,294
Estimated Fair Value Assets	11	3
Estimated Fair Value Liabilities	$ 50	$ 282