Derivatives (Primary Risks Managed by Derivatives) (Details) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	$ 166,524	$ 116,742
Derivative assets	2,500	2,271
Derivative liabilities	4,991	3,911
Derivatives Designated as Hedging Instruments:
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	3,898	4,041
Derivative assets	462	584
Derivative liabilities	14	20
Derivatives Not Designated or Not Qualifying as Hedging Instruments:
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	162,626	112,701
Derivative assets	2,038	1,687
Derivative liabilities	4,977	3,891
Interest rate swaps | Derivatives Not Designated or Not Qualifying as Hedging Instruments:
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	30,527	3,145
Derivative assets	168	98
Derivative liabilities	280	46
Interest rate floors | Derivatives Not Designated or Not Qualifying as Hedging Instruments:
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	3,000	3,250
Derivative assets	2	12
Derivative liabilities	1	3
Interest rate caps | Derivatives Not Designated or Not Qualifying as Hedging Instruments:
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	5,800	6,350
Derivative assets	80	137
Derivative liabilities	27	43
Interest rate options | Derivatives Not Designated or Not Qualifying as Hedging Instruments:
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	31,080	28,688
Derivative assets	19	22
Derivative liabilities	303	232
Interest rate forwards | Derivatives Not Designated or Not Qualifying as Hedging Instruments:
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	16,441	18,168
Derivative assets	178	35
Derivative liabilities	2,867	2,466
Interest rate forwards | Cash flow hedges: | Derivatives Designated as Hedging Instruments:
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	0	60
Derivative assets	0	0
Derivative liabilities	0	12
Foreign currency swaps | Derivatives Not Designated or Not Qualifying as Hedging Instruments:
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	759	810
Derivative assets	124	147
Derivative liabilities	0	0
Foreign currency swaps | Cash flow hedges: | Derivatives Designated as Hedging Instruments:
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	3,898	3,981
Derivative assets	462	584
Derivative liabilities	14	8
Foreign currency forwards | Derivatives Not Designated or Not Qualifying as Hedging Instruments:
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	312	295
Derivative assets	0	1
Derivative liabilities	1	1
Credit default swaps — written | Derivatives Not Designated or Not Qualifying as Hedging Instruments:
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	1,530	1,757
Derivative assets	21	18
Derivative liabilities	1	2
Credit default swaptions | Derivatives Not Designated or Not Qualifying as Hedging Instruments:
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	0	100
Derivative assets	0	0
Derivative liabilities	0	0
Equity index options | Derivatives Not Designated or Not Qualifying as Hedging Instruments:
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	16,215	17,229
Derivative assets	508	697
Derivative liabilities	436	351
Equity total return swaps | Derivatives Not Designated or Not Qualifying as Hedging Instruments:
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	56,332	32,909
Derivative assets	931	520
Derivative liabilities	1,061	747
Hybrid options | Derivatives Not Designated or Not Qualifying as Hedging Instruments:
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	630	0
Derivative assets	7	0
Derivative liabilities	$ 0	$ 0