Investments (Credit Quality of Mortgage Loans by Portfolio Segment) (Details) - Mortgage Loans - USD ($) $ in Millions	Sep. 30, 2025	Dec. 31, 2024
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable, originated in current FY	$ 1,313	$ 1,843
Financing receivable, originated in FY before latest FY	1,898	642
Financing receivable, originated two years before latest FY	565	4,376
Financing receivable, originated three years before latest FY	3,923	5,999
Financing receivable, originated four years before latest FY	5,651	986
Financing receivable, originated five or more years before latest FY	9,689	9,586
Financing receivable, before allowance for credit losses	23,039	23,432
Commercial
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable, originated in current FY	519	848
Financing receivable, originated in FY before latest FY	848	199
Financing receivable, originated two years before latest FY	158	2,390
Financing receivable, originated three years before latest FY	2,051	3,152
Financing receivable, originated four years before latest FY	2,931	432
Financing receivable, originated five or more years before latest FY	6,124	6,305
Financing receivable, before allowance for credit losses	$ 12,631	$ 13,326
Financing receivable, before allowance for credit losses by debt service coverage ratio as a percentage of financing receivable, before allowance for credit losses	100.00%	100.00%
Commercial | Debt Service Coverage Ratio, Greater than 1.20x
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable, before allowance for credit losses	$ 11,301	$ 12,029
Financing receivable, before allowance for credit losses by debt service coverage ratio as a percentage of financing receivable, before allowance for credit losses	89.50%	90.30%
Commercial | Debt Service Coverage Ratio, 1.00x to 1.20x
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable, before allowance for credit losses	$ 821	$ 801
Financing receivable, before allowance for credit losses by debt service coverage ratio as a percentage of financing receivable, before allowance for credit losses	6.50%	6.00%
Commercial | Debt Service Coverage Ratio, Less than 1.00x
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable, before allowance for credit losses	$ 509	$ 496
Financing receivable, before allowance for credit losses by debt service coverage ratio as a percentage of financing receivable, before allowance for credit losses	4.00%	3.70%
Commercial | Loan-to-Value Ratio, Less than 65%
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable, originated in current FY	$ 346	$ 640
Financing receivable, originated in FY before latest FY	591	199
Financing receivable, originated two years before latest FY	158	279
Financing receivable, originated three years before latest FY	331	1,850
Financing receivable, originated four years before latest FY	1,671	196
Financing receivable, originated five or more years before latest FY	2,843	2,844
Financing receivable, before allowance for credit losses	5,940	6,008
Commercial | Loan-to-Value Ratio, 65% to 75%
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable, originated in current FY	142	208
Financing receivable, originated in FY before latest FY	257	0
Financing receivable, originated two years before latest FY	0	1,022
Financing receivable, originated three years before latest FY	815	713
Financing receivable, originated four years before latest FY	874	62
Financing receivable, originated five or more years before latest FY	974	1,171
Financing receivable, before allowance for credit losses	3,062	3,176
Commercial | Loan-to-Value Ratio, 76% to 80%
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable, originated in current FY	0	0
Financing receivable, originated in FY before latest FY	0	0
Financing receivable, originated two years before latest FY	0	117
Financing receivable, originated three years before latest FY	296	201
Financing receivable, originated four years before latest FY	239	174
Financing receivable, originated five or more years before latest FY	715	601
Financing receivable, before allowance for credit losses	1,250	1,093
Commercial | Loan-to-Value Ratio, Greater than 80%
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable, originated in current FY	31	0
Financing receivable, originated in FY before latest FY	0	0
Financing receivable, originated two years before latest FY	0	972
Financing receivable, originated three years before latest FY	609	388
Financing receivable, originated four years before latest FY	147	0
Financing receivable, originated five or more years before latest FY	1,592	1,689
Financing receivable, before allowance for credit losses	2,379	3,049
Agricultural
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable, originated in current FY	229	408
Financing receivable, originated in FY before latest FY	356	221
Financing receivable, originated two years before latest FY	211	674
Financing receivable, originated three years before latest FY	656	1,186
Financing receivable, originated four years before latest FY	1,156	407
Financing receivable, originated five or more years before latest FY	1,933	1,667
Financing receivable, before allowance for credit losses	4,541	4,563
Agricultural | Loan-to-Value Ratio, Less than 65%
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable, originated in current FY	187	408
Financing receivable, originated in FY before latest FY	356	203
Financing receivable, originated two years before latest FY	194	594
Financing receivable, originated three years before latest FY	573	1,073
Financing receivable, originated four years before latest FY	1,053	400
Financing receivable, originated five or more years before latest FY	1,909	1,632
Financing receivable, before allowance for credit losses	4,272	4,310
Agricultural | Loan-to-Value Ratio, 65% to 75%
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable, originated in current FY	42	0
Financing receivable, originated in FY before latest FY	0	18
Financing receivable, originated two years before latest FY	17	80
Financing receivable, originated three years before latest FY	83	113
Financing receivable, originated four years before latest FY	103	6
Financing receivable, originated five or more years before latest FY	20	19
Financing receivable, before allowance for credit losses	265	236
Agricultural | Loan-to-Value Ratio, 76% to 80%
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable, originated in current FY	0	0
Financing receivable, originated in FY before latest FY	0	0
Financing receivable, originated two years before latest FY	0	0
Financing receivable, originated three years before latest FY	0	0
Financing receivable, originated four years before latest FY	0	1
Financing receivable, originated five or more years before latest FY	3	0
Financing receivable, before allowance for credit losses	3	1
Agricultural | Loan-to-Value Ratio, Greater than 80%
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable, originated in current FY	0	0
Financing receivable, originated in FY before latest FY	0	0
Financing receivable, originated two years before latest FY	0	0
Financing receivable, originated three years before latest FY	0	0
Financing receivable, originated four years before latest FY	0	0
Financing receivable, originated five or more years before latest FY	1	16
Financing receivable, before allowance for credit losses	1	16
Residential
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable, originated in current FY	565	587
Financing receivable, originated in FY before latest FY	694	222
Financing receivable, originated two years before latest FY	196	1,312
Financing receivable, originated three years before latest FY	1,216	1,661
Financing receivable, originated four years before latest FY	1,564	147
Financing receivable, originated five or more years before latest FY	1,632	1,614
Financing receivable, before allowance for credit losses	5,867	5,543
Residential | Performing
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable, originated in current FY	565	586
Financing receivable, originated in FY before latest FY	694	222
Financing receivable, originated two years before latest FY	196	1,268
Financing receivable, originated three years before latest FY	1,170	1,640
Financing receivable, originated four years before latest FY	1,537	146
Financing receivable, originated five or more years before latest FY	1,592	1,563
Financing receivable, before allowance for credit losses	5,754	5,425
Residential | Nonperforming
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable, originated in current FY	0	1
Financing receivable, originated in FY before latest FY	0	0
Financing receivable, originated two years before latest FY	0	44
Financing receivable, originated three years before latest FY	46	21
Financing receivable, originated four years before latest FY	27	1
Financing receivable, originated five or more years before latest FY	40	51
Financing receivable, before allowance for credit losses	$ 113	$ 118