Derivatives (Primary Risks Managed by Derivatives) (Details) - USD ($) $ in Millions	Jun. 30, 2025	Dec. 31, 2024
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	$ 289,379	$ 277,286
Derivative assets	7,795	4,118
Derivative liabilities	7,398	5,248
Derivatives Designated as Hedging Instruments:
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	4,219	4,278
Derivative assets	248	439
Derivative liabilities	105	25
Derivatives Not Designated or Not Qualifying as Hedging Instruments:
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	285,160	273,008
Derivative assets	7,547	3,679
Derivative liabilities	7,293	5,223
Interest rate swaps | Derivatives Not Designated or Not Qualifying as Hedging Instruments:
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	37,501	69,303
Derivative assets	176	131
Derivative liabilities	315	444
Interest rate floors | Derivatives Not Designated or Not Qualifying as Hedging Instruments:
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	8,000	8,000
Derivative assets	4	1
Derivative liabilities	19	30
Interest rate caps | Derivatives Not Designated or Not Qualifying as Hedging Instruments:
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	5,350	7,850
Derivative assets	3	14
Derivative liabilities	9	14
Interest rate futures | Derivatives Not Designated or Not Qualifying as Hedging Instruments:
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	0	171
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	28,700	23,060
Derivative assets	13	11
Derivative liabilities	407	371
Interest rate forwards | Derivatives Not Designated or Not Qualifying as Hedging Instruments:
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	11,481	16,352
Derivative assets	70	121
Derivative liabilities	1,280	1,876
Interest rate forwards | Cash flow hedges: | Derivatives Designated as Hedging Instruments:
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	500	500
Derivative assets	0	9
Derivative liabilities	3	0
Foreign currency swaps | Derivatives Not Designated or Not Qualifying as Hedging Instruments:
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	585	674
Derivative assets	70	111
Derivative liabilities	5	0
Foreign currency swaps | Cash flow hedges: | Derivatives Designated as Hedging Instruments:
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	3,719	3,778
Derivative assets	248	430
Derivative liabilities	102	25
Foreign currency forwards | Derivatives Not Designated or Not Qualifying as Hedging Instruments:
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	309	304
Derivative assets	0	6
Derivative liabilities	7	0
Credit default swaps — written | Derivatives Not Designated or Not Qualifying as Hedging Instruments:
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	1,230	780
Derivative assets	28	19
Derivative liabilities	0	0
Equity futures | Derivatives Not Designated or Not Qualifying as Hedging Instruments:
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	395	316
Derivative assets	0	0
Derivative liabilities	1	1
Equity index options | Derivatives Not Designated or Not Qualifying as Hedging Instruments:
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	84,568	39,897
Derivative assets	2,929	1,722
Derivative liabilities	1,344	1,041
Equity total return swaps | Derivatives Not Designated or Not Qualifying as Hedging Instruments:
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	107,041	106,301
Derivative assets	4,254	1,543
Derivative liabilities	$ 3,906	$ 1,446