Derivatives (Primary Risks) (Details) - USD ($) $ in Millions	Mar. 31, 2026	Dec. 31, 2025
Derivatives, Fair Value [Line Items]
Estimated Fair Value Assets	$ 5,744	$ 5,388
Estimated Fair Value Liabilities	2,713	2,915
Derivative, Notional Amount	138,820	130,335
Accrued Liabilities [Member]
Derivatives, Fair Value [Line Items]
Estimated Fair Value Assets	98	87
Estimated Fair Value Liabilities	38	(7)
Derivatives Designated as Hedging Instruments:
Derivatives, Fair Value [Line Items]
Estimated Fair Value Assets	3,245	3,232
Estimated Fair Value Liabilities	1,720	1,820
Derivative, Notional Amount	45,173	43,513
Derivatives Designated as Hedging Instruments: \| Fair Value Hedges [Member]
Derivatives, Fair Value [Line Items]
Estimated Fair Value Assets	980	956
Estimated Fair Value Liabilities	657	675
Derivative, Notional Amount	6,586	5,405
Derivatives Designated as Hedging Instruments: \| Fair Value Hedges [Member] \| Interest rate swaps
Derivatives, Fair Value [Line Items]
Estimated Fair Value Assets	924	923
Estimated Fair Value Liabilities	644	667
Derivative, Notional Amount	4,283	4,446
Derivatives Designated as Hedging Instruments: \| Fair Value Hedges [Member] \| Foreign currency swaps
Derivatives, Fair Value [Line Items]
Estimated Fair Value Assets	56	33
Estimated Fair Value Liabilities	13	8
Derivative, Notional Amount	2,303	959
Derivatives Designated as Hedging Instruments: \| Cash Flow Hedges [Member]
Derivatives, Fair Value [Line Items]
Estimated Fair Value Assets	2,265	2,276
Estimated Fair Value Liabilities	1,063	1,145
Derivative, Notional Amount	38,587	38,108
Derivatives Designated as Hedging Instruments: \| Cash Flow Hedges [Member] \| Interest rate swaps
Derivatives, Fair Value [Line Items]
Estimated Fair Value Assets	0	0
Estimated Fair Value Liabilities	230	249
Derivative, Notional Amount	3,241	3,337
Derivatives Designated as Hedging Instruments: \| Cash Flow Hedges [Member] \| Foreign currency swaps
Derivatives, Fair Value [Line Items]
Estimated Fair Value Assets	2,265	2,276
Estimated Fair Value Liabilities	833	896
Derivative, Notional Amount	35,346	34,771
Derivatives Not Designated or Not Qualifying as Hedging Instruments:
Derivatives, Fair Value [Line Items]
Estimated Fair Value Assets	2,499	2,156
Estimated Fair Value Liabilities	993	1,095
Derivative, Notional Amount	93,647	86,822
Derivatives Not Designated or Not Qualifying as Hedging Instruments: \| Interest rate swaps
Derivatives, Fair Value [Line Items]
Estimated Fair Value Assets	1,407	1,403
Estimated Fair Value Liabilities	632	614
Derivative, Notional Amount	13,759	13,092
Derivatives Not Designated or Not Qualifying as Hedging Instruments: \| Interest rate floors
Derivatives, Fair Value [Line Items]
Estimated Fair Value Assets	42	30
Estimated Fair Value Liabilities	0	0
Derivative, Notional Amount	5,890	5,390
Derivatives Not Designated or Not Qualifying as Hedging Instruments: \| Interest rate caps
Derivatives, Fair Value [Line Items]
Estimated Fair Value Assets	65	46
Estimated Fair Value Liabilities	0	0
Derivative, Notional Amount	12,950	12,950
Derivatives Not Designated or Not Qualifying as Hedging Instruments: \| Interest rate futures
Derivatives, Fair Value [Line Items]
Estimated Fair Value Assets	0	0
Estimated Fair Value Liabilities	0	0
Derivative, Notional Amount	87	90
Derivatives Not Designated or Not Qualifying as Hedging Instruments: \| Interest rate options
Derivatives, Fair Value [Line Items]
Estimated Fair Value Assets	96	99
Estimated Fair Value Liabilities	66	85
Derivative, Notional Amount	19,541	20,368
Derivatives Not Designated or Not Qualifying as Hedging Instruments: \| Synthetic GICs
Derivatives, Fair Value [Line Items]
Estimated Fair Value Assets	0	0
Estimated Fair Value Liabilities	0	0
Derivative, Notional Amount	3,146	3,156
Derivatives Not Designated or Not Qualifying as Hedging Instruments: \| Foreign currency swaps
Derivatives, Fair Value [Line Items]
Estimated Fair Value Assets	283	240
Estimated Fair Value Liabilities	63	106
Derivative, Notional Amount	4,012	3,770
Derivatives Not Designated or Not Qualifying as Hedging Instruments: \| Foreign currency forwards
Derivatives, Fair Value [Line Items]
Estimated Fair Value Assets	23	5
Estimated Fair Value Liabilities	8	18
Derivative, Notional Amount	2,817	2,859
Derivatives Not Designated or Not Qualifying as Hedging Instruments: \| Credit default swaps — purchased
Derivatives, Fair Value [Line Items]
Estimated Fair Value Assets	2	2
Estimated Fair Value Liabilities	1	5
Derivative, Notional Amount	605	685
Derivatives Not Designated or Not Qualifying as Hedging Instruments: \| Credit default swaps — written
Derivatives, Fair Value [Line Items]
Estimated Fair Value Assets	145	101
Estimated Fair Value Liabilities	1	1
Derivative, Notional Amount	11,692	6,619
Derivatives Not Designated or Not Qualifying as Hedging Instruments: \| Equity futures
Derivatives, Fair Value [Line Items]
Estimated Fair Value Assets	1	3
Estimated Fair Value Liabilities	10	0
Derivative, Notional Amount	342	393
Derivatives Not Designated or Not Qualifying as Hedging Instruments: \| Equity index options
Derivatives, Fair Value [Line Items]
Estimated Fair Value Assets	331	220
Estimated Fair Value Liabilities	212	232
Derivative, Notional Amount	16,465	15,032
Derivatives Not Designated or Not Qualifying as Hedging Instruments: \| Equity Total Return Swaps [Member]
Derivatives, Fair Value [Line Items]
Estimated Fair Value Assets	104	7
Estimated Fair Value Liabilities	0	34
Derivative, Notional Amount	2,336	2,413
Derivatives Not Designated or Not Qualifying as Hedging Instruments: \| Variance Swap
Derivatives, Fair Value [Line Items]
Estimated Fair Value Assets	0	0
Estimated Fair Value Liabilities	0	0
Derivative, Notional Amount	$ 5	$ 5