Investments (Credit Quality of Mortgage Loans by Portfolio Segment) (Details) - Mortgage Loans - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable, originated in current FY	$ 420	$ 4,369
Financing receivable, originated in FY before latest FY	4,413	6,197
Financing receivable, originated two years before latest FY	6,173	1,089
Financing receivable, originated three years before latest FY	1,053	2,648
Financing receivable, originated four years before latest FY	2,610	2,191
Financing receivable, originated five or more years before latest FY	8,116	6,502
Financing receivable, before allowance for credit losses	22,785	22,996
Commercial
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable, originated in current FY	161	2,419
Financing receivable, originated in FY before latest FY	2,417	3,191
Financing receivable, originated two years before latest FY	3,215	445
Financing receivable, originated three years before latest FY	440	1,879
Financing receivable, originated four years before latest FY	1,862	1,377
Financing receivable, originated five or more years before latest FY	5,208	4,236
Financing receivable, before allowance for credit losses	$ 13,303	$ 13,547
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	$ 12,272	$ 12,132
Financing receivable, before allowance for credit losses by debt service coverage ratio as a percentage of financing receivable, before allowance for credit losses	92.20%	89.60%
Commercial | Debt Service Coverage Ratio, 1.00x to 1.20x
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable, before allowance for credit losses	$ 540	$ 589
Financing receivable, before allowance for credit losses by debt service coverage ratio as a percentage of financing receivable, before allowance for credit losses	4.10%	4.30%
Commercial | Debt Service Coverage Ratio, Less than 1.00x
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable, before allowance for credit losses	$ 491	$ 826
Financing receivable, before allowance for credit losses by debt service coverage ratio as a percentage of financing receivable, before allowance for credit losses	3.70%	6.10%
Commercial | Loan-to-Value Ratio, Less than 65%
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable, originated in current FY	$ 161	$ 1,916
Financing receivable, originated in FY before latest FY	1,876	2,819
Financing receivable, originated two years before latest FY	2,515	405
Financing receivable, originated three years before latest FY	224	1,493
Financing receivable, originated four years before latest FY	1,289	888
Financing receivable, originated five or more years before latest FY	2,824	3,624
Financing receivable, before allowance for credit losses	8,889	11,145
Commercial | Loan-to-Value Ratio, 65% to 75%
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable, originated in current FY	0	503
Financing receivable, originated in FY before latest FY	529	354
Financing receivable, originated two years before latest FY	650	0
Financing receivable, originated three years before latest FY	177	271
Financing receivable, originated four years before latest FY	269	367
Financing receivable, originated five or more years before latest FY	1,194	402
Financing receivable, before allowance for credit losses	2,819	1,897
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	12	18
Financing receivable, originated two years before latest FY	50	40
Financing receivable, originated three years before latest FY	39	90
Financing receivable, originated four years before latest FY	209	65
Financing receivable, originated five or more years before latest FY	508	48
Financing receivable, before allowance for credit losses	818	261
Commercial | 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	25
Financing receivable, originated four years before latest FY	95	57
Financing receivable, originated five or more years before latest FY	682	162
Financing receivable, before allowance for credit losses	777	244
Agricultural
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable, originated in current FY	160	680
Financing receivable, originated in FY before latest FY	702	1,253
Financing receivable, originated two years before latest FY	1,245	477
Financing receivable, originated three years before latest FY	463	552
Financing receivable, originated four years before latest FY	538	645
Financing receivable, originated five or more years before latest FY	1,323	726
Financing receivable, before allowance for credit losses	4,431	4,333
Agricultural | Loan-to-Value Ratio, Less than 65%
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable, originated in current FY	160	532
Financing receivable, originated in FY before latest FY	574	1,163
Financing receivable, originated two years before latest FY	1,138	418
Financing receivable, originated three years before latest FY	457	496
Financing receivable, originated four years before latest FY	507	643
Financing receivable, originated five or more years before latest FY	1,305	710
Financing receivable, before allowance for credit losses	4,141	3,962
Agricultural | Loan-to-Value Ratio, 65% to 75%
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable, originated in current FY	0	148
Financing receivable, originated in FY before latest FY	128	90
Financing receivable, originated two years before latest FY	107	59
Financing receivable, originated three years before latest FY	6	56
Financing receivable, originated four years before latest FY	31	1
Financing receivable, originated five or more years before latest FY	18	16
Financing receivable, before allowance for credit losses	290	370
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	1
Financing receivable, originated five or more years before latest FY	0	0
Financing receivable, before allowance for credit losses	0	1
Residential
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable, originated in current FY	99	1,270
Financing receivable, originated in FY before latest FY	1,294	1,753
Financing receivable, originated two years before latest FY	1,713	167
Financing receivable, originated three years before latest FY	150	217
Financing receivable, originated four years before latest FY	210	169
Financing receivable, originated five or more years before latest FY	1,585	1,540
Financing receivable, before allowance for credit losses	5,051	5,116
Residential | Performing
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable, originated in current FY	99	1,266
Financing receivable, originated in FY before latest FY	1,274	1,745
Financing receivable, originated two years before latest FY	1,693	167
Financing receivable, originated three years before latest FY	149	215
Financing receivable, originated four years before latest FY	208	168
Financing receivable, originated five or more years before latest FY	1,543	1,491
Financing receivable, before allowance for credit losses	4,966	5,052
Residential | Nonperforming
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable, originated in current FY	0	4
Financing receivable, originated in FY before latest FY	20	8
Financing receivable, originated two years before latest FY	20	0
Financing receivable, originated three years before latest FY	1	2
Financing receivable, originated four years before latest FY	2	1
Financing receivable, originated five or more years before latest FY	42	49
Financing receivable, before allowance for credit losses	$ 85	$ 64