Derivatives (Primary Risks Managed by Derivatives) (Details) - USD ($) $ in Millions	Jun. 30, 2024	Dec. 31, 2023
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	$ 197,521	$ 173,029
Derivative assets	3,293	3,703
Derivative liabilities	4,129	5,080
Derivatives Designated as Hedging Instruments:
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	4,368	3,895
Derivative assets	412	339
Derivative liabilities	23	45
Derivatives Not Designated or Not Qualifying as Hedging Instruments:
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	193,153	169,134
Derivative assets	2,881	3,364
Derivative liabilities	4,106	5,035
Interest rate swaps | Derivatives Not Designated or Not Qualifying as Hedging Instruments:
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	53,524	31,252
Derivative assets	130	140
Derivative liabilities	179	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	2	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	12	19
Derivative liabilities	2	1
Interest rate options | Derivatives Not Designated or Not Qualifying as Hedging Instruments:
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	23,050	33,680
Derivative assets	38	47
Derivative liabilities	222	167
Interest rate forwards | Derivatives Not Designated or Not Qualifying as Hedging Instruments:
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	13,886	17,017
Derivative assets	25	32
Derivative liabilities	1,653	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	12	0
Derivative liabilities	0	0
Foreign currency swaps | Derivatives Not Designated or Not Qualifying as Hedging Instruments:
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	712	735
Derivative assets	104	99
Derivative liabilities	0	1
Foreign currency swaps | Cash flow hedges: | Derivatives Designated as Hedging Instruments:
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	3,868	3,895
Derivative assets	400	339
Derivative liabilities	23	45
Foreign currency forwards | Derivatives Not Designated or Not Qualifying as Hedging Instruments:
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	626	384
Derivative assets	0	0
Derivative liabilities	0	1
Credit default swaps — written | Derivatives Not Designated or Not Qualifying as Hedging Instruments:
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	1,096	1,405
Derivative assets	20	27
Derivative liabilities	0	0
Equity index options | Derivatives Not Designated or Not Qualifying as Hedging Instruments:
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	20,883	20,099
Derivative assets	1,234	757
Derivative liabilities	940	687
Equity total return swaps | Derivatives Not Designated or Not Qualifying as Hedging Instruments:
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	68,976	53,742
Derivative assets	1,316	2,236
Derivative liabilities	1,110	2,137
Hybrid options | Derivatives Not Designated or Not Qualifying as Hedging Instruments:
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	20	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	80	0
Derivative assets	0	0
Derivative liabilities	$ 0	$ 0