Derivatives (Primary Risks Managed by Derivatives) (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	$ 173,029	$ 116,742
Derivative assets	3,703	2,271
Derivative liabilities	5,080	3,911
Derivatives Designated as Hedging Instruments:
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	3,895	4,041
Derivative assets	339	584
Derivative liabilities	45	20
Derivatives Not Designated or Not Qualifying as Hedging Instruments:
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	169,134	112,701
Derivative assets	3,364	1,687
Derivative liabilities	5,035	3,891
Interest rate swaps | Derivatives Not Designated or Not Qualifying as Hedging Instruments:
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	31,252	3,145
Derivative assets	140	98
Derivative liabilities	103	46
Interest rate floors | Derivatives Not Designated or Not Qualifying as Hedging Instruments:
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	3,500	3,250
Derivative assets	7	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	7,050	6,350
Derivative assets	19	137
Derivative liabilities	1	43
Interest rate options | Derivatives Not Designated or Not Qualifying as Hedging Instruments:
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	33,680	28,688
Derivative assets	47	22
Derivative liabilities	167	232
Interest rate forwards | Derivatives Not Designated or Not Qualifying as Hedging Instruments:
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	17,017	18,168
Derivative assets	32	35
Derivative liabilities	1,937	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	735	810
Derivative assets	99	147
Derivative liabilities	1	0
Foreign currency swaps | Cash flow hedges: | Derivatives Designated as Hedging Instruments:
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	3,895	3,981
Derivative assets	339	584
Derivative liabilities	45	8
Foreign currency forwards | Derivatives Not Designated or Not Qualifying as Hedging Instruments:
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	384	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	1,405	1,757
Derivative assets	27	18
Derivative liabilities	0	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	20,099	17,229
Derivative assets	757	697
Derivative liabilities	687	351
Equity total return swaps | Derivatives Not Designated or Not Qualifying as Hedging Instruments:
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	53,742	32,909
Derivative assets	2,236	520
Derivative liabilities	2,137	747
Hybrid options | Derivatives Not Designated or Not Qualifying as Hedging Instruments:
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	270	0
Derivative assets	0	0
Derivative liabilities	$ 0	$ 0