Derivatives (Primary Risks) (Details) - USD ($) $ in Millions	Jun. 30, 2026	Dec. 31, 2025
Derivatives, Fair Value [Line Items]
Estimated Fair Value Assets	$ 5,611	$ 5,388
Estimated Fair Value Liabilities	2,959	2,915
Derivative, Notional Amount	136,329	130,335
StatementOfFinancialPositionLocationBalance [Axis]: us-gaap:DerivativeAssets
Derivatives, Fair Value [Line Items]
Estimated Fair Value Assets	78	87
StatementOfFinancialPositionLocationBalance [Axis]: us-gaap:DerivativeLiabilities
Derivatives, Fair Value [Line Items]
Estimated Fair Value Liabilities	36	(7)
Derivatives Designated as Hedging Instruments:
Derivatives, Fair Value [Line Items]
Estimated Fair Value Assets	3,154	3,232
Estimated Fair Value Liabilities	1,782	1,820
Derivative, Notional Amount	46,463	43,513
Derivatives Designated as Hedging Instruments: \| Fair Value Hedges [Member]
Derivatives, Fair Value [Line Items]
Estimated Fair Value Assets	972	956
Estimated Fair Value Liabilities	683	675
Derivative, Notional Amount	7,702	5,405
Derivatives Designated as Hedging Instruments: \| Fair Value Hedges [Member] \| Interest rate swaps
Derivatives, Fair Value [Line Items]
Estimated Fair Value Assets	909	923
Estimated Fair Value Liabilities	672	667
Derivative, Notional Amount	4,508	4,446
Derivatives Designated as Hedging Instruments: \| Fair Value Hedges [Member] \| Foreign currency swaps
Derivatives, Fair Value [Line Items]
Estimated Fair Value Assets	63	33
Estimated Fair Value Liabilities	11	8
Derivative, Notional Amount	3,194	959
Derivatives Designated as Hedging Instruments: \| Cash Flow Hedges [Member]
Derivatives, Fair Value [Line Items]
Estimated Fair Value Assets	2,182	2,276
Estimated Fair Value Liabilities	1,099	1,145
Derivative, Notional Amount	38,761	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	233	249
Derivative, Notional Amount	3,330	3,337
Derivatives Designated as Hedging Instruments: \| Cash Flow Hedges [Member] \| Foreign currency swaps
Derivatives, Fair Value [Line Items]
Estimated Fair Value Assets	2,182	2,276
Estimated Fair Value Liabilities	866	896
Derivative, Notional Amount	35,431	34,771
Derivatives Not Designated or Not Qualifying as Hedging Instruments:
Derivatives, Fair Value [Line Items]
Estimated Fair Value Assets	2,457	2,156
Estimated Fair Value Liabilities	1,177	1,095
Derivative, Notional Amount	89,866	86,822
Derivatives Not Designated or Not Qualifying as Hedging Instruments: \| Interest rate swaps
Derivatives, Fair Value [Line Items]
Estimated Fair Value Assets	1,339	1,403
Estimated Fair Value Liabilities	626	614
Derivative, Notional Amount	12,338	13,092
Derivatives Not Designated or Not Qualifying as Hedging Instruments: \| Interest rate floors
Derivatives, Fair Value [Line Items]
Estimated Fair Value Assets	27	30
Estimated Fair Value Liabilities	0	0
Derivative, Notional Amount	4,890	5,390
Derivatives Not Designated or Not Qualifying as Hedging Instruments: \| Interest rate caps
Derivatives, Fair Value [Line Items]
Estimated Fair Value Assets	80	46
Estimated Fair Value Liabilities	0	0
Derivative, Notional Amount	13,200	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	86	99
Estimated Fair Value Liabilities	59	85
Derivative, Notional Amount	19,790	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	3,167	3,156
Derivatives Not Designated or Not Qualifying as Hedging Instruments: \| Foreign currency swaps
Derivatives, Fair Value [Line Items]
Estimated Fair Value Assets	254	240
Estimated Fair Value Liabilities	73	106
Derivative, Notional Amount	4,231	3,770
Derivatives Not Designated or Not Qualifying as Hedging Instruments: \| Foreign currency forwards
Derivatives, Fair Value [Line Items]
Estimated Fair Value Assets	18	5
Estimated Fair Value Liabilities	8	18
Derivative, Notional Amount	1,401	2,859
Derivatives Not Designated or Not Qualifying as Hedging Instruments: \| Credit default swaps — purchased
Derivatives, Fair Value [Line Items]
Estimated Fair Value Assets	1	2
Estimated Fair Value Liabilities	5	5
Derivative, Notional Amount	576	685
Derivatives Not Designated or Not Qualifying as Hedging Instruments: \| Credit default swaps — written
Derivatives, Fair Value [Line Items]
Estimated Fair Value Assets	184	101
Estimated Fair Value Liabilities	3	1
Derivative, Notional Amount	11,689	6,619
Derivatives Not Designated or Not Qualifying as Hedging Instruments: \| Equity futures
Derivatives, Fair Value [Line Items]
Estimated Fair Value Assets	0	3
Estimated Fair Value Liabilities	2	0
Derivative, Notional Amount	330	393
Derivatives Not Designated or Not Qualifying as Hedging Instruments: \| Equity index options
Derivatives, Fair Value [Line Items]
Estimated Fair Value Assets	468	220
Estimated Fair Value Liabilities	310	232
Derivative, Notional Amount	16,795	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	0	7
Estimated Fair Value Liabilities	91	34
Derivative, Notional Amount	1,367	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