Derivatives (Primary Risks Managed by Derivatives) (Details) - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	$ 277,286	$ 173,029
Derivative assets:	4,118	3,703
Derivative liabilities:	5,248	5,080
Derivatives Designated as Hedging Instruments
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	4,278	3,895
Derivative assets:	439	339
Derivative liabilities:	25	45
Derivatives Not Designated or Not Qualifying as Hedging Instruments:
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	273,008	169,134
Derivative assets:	3,679	3,364
Derivative liabilities:	5,223	5,035
Interest rate swaps | Derivatives Not Designated or Not Qualifying as Hedging Instruments:
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	69,303	31,252
Derivative assets:	131	140
Derivative liabilities:	444	103
Interest rate swaps | Cash flow hedges: | Derivatives Designated as Hedging Instruments
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	500	0
Derivative assets:	9	0
Derivative liabilities:	0	0
Interest rate floors | Derivatives Not Designated or Not Qualifying as Hedging Instruments:
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	8,000	3,500
Derivative assets:	1	7
Derivative liabilities:	30	1
Interest rate caps | Derivatives Not Designated or Not Qualifying as Hedging Instruments:
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	7,850	7,050
Derivative assets:	14	19
Derivative liabilities:	14	1
Interest rate futures | Derivatives Not Designated or Not Qualifying as Hedging Instruments:
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	171	0
Derivative assets:	0	0
Derivative liabilities:	0	0
Interest rate options | Derivatives Not Designated or Not Qualifying as Hedging Instruments:
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	23,060	33,680
Derivative assets:	11	47
Derivative liabilities:	371	167
Interest rate forwards | Derivatives Not Designated or Not Qualifying as Hedging Instruments:
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	16,352	17,017
Derivative assets:	121	32
Derivative liabilities:	1,876	1,937
Foreign currency swaps | Derivatives Not Designated or Not Qualifying as Hedging Instruments:
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	674	735
Derivative assets:	111	99
Derivative liabilities:	0	1
Foreign currency swaps | Cash flow hedges: | Derivatives Designated as Hedging Instruments
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	3,778	3,895
Derivative assets:	430	339
Derivative liabilities:	25	45
Foreign currency forwards | Derivatives Not Designated or Not Qualifying as Hedging Instruments:
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	304	384
Derivative assets:	6	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	780	1,405
Derivative assets:	19	27
Derivative liabilities:	0	0
Equity futures | Derivatives Not Designated or Not Qualifying as Hedging Instruments:
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	316	0
Derivative assets:	0	0
Derivative liabilities:	1	0
Equity index options | Derivatives Not Designated or Not Qualifying as Hedging Instruments:
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	39,897	20,099
Derivative assets:	1,722	757
Derivative liabilities:	1,041	687
Equity total return swaps | Derivatives Not Designated or Not Qualifying as Hedging Instruments:
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	106,301	53,742
Derivative assets:	1,543	2,236
Derivative liabilities:	1,446	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