Investments (Credit Quality of Mortgage Loans by Portfolio Segment) (Details) - Mortgage Loans - USD ($) $ in Millions	Mar. 31, 2023	Dec. 31, 2022
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable, originated in current FY	$ 85	$ 4,369
Financing receivable, originated in FY before latest FY	4,390	6,197
Financing receivable, originated two years before latest FY	6,189	1,091
Financing receivable, originated three years before latest FY	1,078	2,648
Financing receivable, originated four years before latest FY	2,626	2,191
Financing receivable, originated five or more years before latest FY	8,591	6,559
Financing receivable, before allowance for credit losses	22,959	23,055
Commercial
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable, originated in current FY	47	2,419
Financing receivable, originated in FY before latest FY	2,417	3,191
Financing receivable, originated two years before latest FY	3,212	445
Financing receivable, originated three years before latest FY	443	1,879
Financing receivable, originated four years before latest FY	1,866	1,377
Financing receivable, originated five or more years before latest FY	5,544	4,263
Financing receivable, before allowance for credit losses	$ 13,529	$ 13,574
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	$ 12,365	$ 12,157
Financing receivable, before allowance for credit losses by debt service coverage ratio as a percentage of financing receivable, before allowance for credit losses	91.40%	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	$ 421	$ 590
Financing receivable, before allowance for credit losses by debt service coverage ratio as a percentage of financing receivable, before allowance for credit losses	3.10%	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	$ 743	$ 827
Financing receivable, before allowance for credit losses by debt service coverage ratio as a percentage of financing receivable, before allowance for credit losses	5.50%	6.10%
Commercial | Loan-to-Value Ratio, Less than 65%
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable, originated in current FY	$ 47	$ 1,916
Financing receivable, originated in FY before latest FY	1,914	2,819
Financing receivable, originated two years before latest FY	2,840	405
Financing receivable, originated three years before latest FY	404	1,493
Financing receivable, originated four years before latest FY	1,481	888
Financing receivable, originated five or more years before latest FY	4,492	3,627
Financing receivable, before allowance for credit losses	11,178	11,148
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	503	354
Financing receivable, originated two years before latest FY	354	0
Financing receivable, originated three years before latest FY	0	271
Financing receivable, originated four years before latest FY	270	367
Financing receivable, originated five or more years before latest FY	714	425
Financing receivable, before allowance for credit losses	1,841	1,920
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	18
Financing receivable, originated two years before latest FY	18	40
Financing receivable, originated three years before latest FY	39	90
Financing receivable, originated four years before latest FY	40	65
Financing receivable, originated five or more years before latest FY	119	48
Financing receivable, before allowance for credit losses	216	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	75	57
Financing receivable, originated five or more years before latest FY	219	163
Financing receivable, before allowance for credit losses	294	245
Agricultural
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable, originated in current FY	36	680
Financing receivable, originated in FY before latest FY	699	1,253
Financing receivable, originated two years before latest FY	1,254	479
Financing receivable, originated three years before latest FY	471	552
Financing receivable, originated four years before latest FY	547	645
Financing receivable, originated five or more years before latest FY	1,381	756
Financing receivable, before allowance for credit losses	4,388	4,365
Agricultural | Loan-to-Value Ratio, Less than 65%
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable, originated in current FY	36	532
Financing receivable, originated in FY before latest FY	560	1,163
Financing receivable, originated two years before latest FY	1,138	420
Financing receivable, originated three years before latest FY	412	496
Financing receivable, originated four years before latest FY	498	643
Financing receivable, originated five or more years before latest FY	1,362	740
Financing receivable, before allowance for credit losses	4,006	3,994
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	139	90
Financing receivable, originated two years before latest FY	116	59
Financing receivable, originated three years before latest FY	59	56
Financing receivable, originated four years before latest FY	49	1
Financing receivable, originated five or more years before latest FY	18	16
Financing receivable, before allowance for credit losses	381	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	1	0
Financing receivable, before allowance for credit losses	1	1
Residential
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable, originated in current FY	2	1,270
Financing receivable, originated in FY before latest FY	1,274	1,753
Financing receivable, originated two years before latest FY	1,723	167
Financing receivable, originated three years before latest FY	164	217
Financing receivable, originated four years before latest FY	213	169
Financing receivable, originated five or more years before latest FY	1,666	1,540
Financing receivable, before allowance for credit losses	5,042	5,116
Residential | Performing
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable, originated in current FY	2	1,266
Financing receivable, originated in FY before latest FY	1,269	1,745
Financing receivable, originated two years before latest FY	1,713	167
Financing receivable, originated three years before latest FY	163	215
Financing receivable, originated four years before latest FY	211	168
Financing receivable, originated five or more years before latest FY	1,613	1,491
Financing receivable, before allowance for credit losses	4,971	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	5	8
Financing receivable, originated two years before latest FY	10	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	53	49
Financing receivable, before allowance for credit losses	$ 71	$ 64