Investments - Investments - Mortgage Loans by Region and Property Type (Details) - USD ($) $ in Millions	Mar. 31, 2024	Dec. 31, 2023	Mar. 31, 2023	Dec. 31, 2022
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, after Allowance for Credit Loss	$ 6,197	$ 6,087
Commercial Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	$ 6,245	$ 6,138
Percent of Total	100.00%	100.00%
Financing Receivable, Allowance for Credit Loss	$ (48)	$ (51)	$ (36)	$ (36)
Financing Receivable, after Allowance for Credit Loss	6,197	6,087
Commercial Loan [Member] | Industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	$ 2,478	$ 2,363
Percent of Total	39.70%	38.50%
Commercial Loan [Member] | Multifamily
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	$ 2,192	$ 2,200
Percent of Total	35.10%	35.90%
Commercial Loan [Member] | Office
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	$ 568	$ 578
Percent of Total	9.10%	9.40%
Commercial Loan [Member] | Retail
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	$ 927	$ 917
Percent of Total	14.80%	14.90%
Commercial Loan [Member] | Residential Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	$ 80	$ 80
Percent of Total	1.30%	1.30%
East North Central [Member] | Commercial Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	$ 371	$ 368
Percent of Total	5.90%	6.00%
Middle Atlantic [Member] | Commercial Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	$ 246	$ 238
Percent of Total	3.90%	3.90%
Mountain [Member] | Commercial Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	$ 728	$ 699
Percent of Total	11.70%	11.40%
New England [Member] | Commercial Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	$ 350	$ 351
Percent of Total	5.60%	5.70%
Pacific [Member] | Commercial Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	$ 1,330	$ 1,326
Percent of Total	21.30%	21.60%
South Atlantic [Member] | Commercial Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	$ 1,780	$ 1,776
Percent of Total	28.50%	28.90%
West North Central [Member] | Commercial Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	$ 104	$ 103
Percent of Total	1.70%	1.70%
West South Central [Member] | Commercial Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	$ 498	$ 445
Percent of Total	8.00%	7.20%
Region Others [Member] | Commercial Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	$ 838	$ 832
Percent of Total	13.40%	13.60%