Derivatives (Primary Risks Managed by Derivatives) (Details) - USD ($) $ in Millions	Sep. 30, 2024	Dec. 31, 2023
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	$ 237,986	$ 173,029
Derivative assets	3,439	3,703
Derivative liabilities	4,002	5,080
Derivatives Designated as Hedging Instruments:
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	4,297	3,895
Derivative assets	316	339
Derivative liabilities	52	45
Derivatives Not Designated or Not Qualifying as Hedging Instruments:
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	233,689	169,134
Derivative assets	3,123	3,364
Derivative liabilities	3,950	5,035
Interest rate swaps | Derivatives Not Designated or Not Qualifying as Hedging Instruments:
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	58,535	31,252
Derivative assets	160	140
Derivative liabilities	194	103
Interest rate floors | Derivatives Not Designated or Not Qualifying as Hedging Instruments:
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	3,500	3,500
Derivative assets	4	7
Derivative liabilities	0	1
Interest rate caps | Derivatives Not Designated or Not Qualifying as Hedging Instruments:
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	6,800	7,050
Derivative assets	0	19
Derivative liabilities	16	1
Interest rate options | Derivatives Not Designated or Not Qualifying as Hedging Instruments:
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	21,400	33,680
Derivative assets	39	47
Derivative liabilities	208	167
Interest rate forwards | Derivatives Not Designated or Not Qualifying as Hedging Instruments:
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	16,692	17,017
Derivative assets	69	32
Derivative liabilities	1,162	1,937
Interest rate forwards | Cash flow hedges: | Derivatives Designated as Hedging Instruments:
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	500	0
Derivative assets	0	0
Derivative liabilities	6	0
Foreign currency swaps | Derivatives Not Designated or Not Qualifying as Hedging Instruments:
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	681	735
Derivative assets	85	99
Derivative liabilities	1	1
Foreign currency swaps | Cash flow hedges: | Derivatives Designated as Hedging Instruments:
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	3,797	3,895
Derivative assets	316	339
Derivative liabilities	46	45
Foreign currency forwards | Derivatives Not Designated or Not Qualifying as Hedging Instruments:
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	335	384
Derivative assets	0	0
Derivative liabilities	3	1
Credit default swaps — written | Derivatives Not Designated or Not Qualifying as Hedging Instruments:
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	1,095	1,405
Derivative assets	20	27
Derivative liabilities	0	0
Equity Futures | Derivatives Not Designated or Not Qualifying as Hedging Instruments:
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	2	0
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	15,943	20,099
Derivative assets	855	757
Derivative liabilities	443	687
Equity total return swaps | Derivatives Not Designated or Not Qualifying as Hedging Instruments:
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	108,706	53,742
Derivative assets	1,891	2,236
Derivative liabilities	1,923	2,137
Hybrid options | Derivatives Not Designated or Not Qualifying as Hedging Instruments:
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	0	270
Derivative assets	0	0
Derivative liabilities	0	0
Interest rate futures | Derivatives Not Designated or Not Qualifying as Hedging Instruments:
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	0	0
Derivative assets	0	0
Derivative liabilities	$ 0	$ 0