Investments - Investments - Mortgage Loans by Region and Property Type (Details) - USD ($) $ in Millions	Sep. 30, 2026	Jun. 30, 2026	Dec. 31, 2025	Sep. 30, 2025	Jun. 30, 2025	Dec. 31, 2024
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, after Allowance for Credit Loss	$ 7,181		$ 6,837
Commercial Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	$ 7,230		$ 6,886
Percent of Total	100.00%		100.00%
Financing Receivable, Allowance for Credit Loss	$ (49)	$ (49)	$ (49)	$ (49)	$ (43)	$ (44)
Financing Receivable, after Allowance for Credit Loss	7,181		6,837
Commercial Loan [Member] \| Industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	$ 3,652		$ 3,208
Percent of Total	50.50%		46.60%
Commercial Loan [Member] \| Multifamily
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	$ 2,138		$ 2,209
Percent of Total	29.60%		32.10%
Commercial Loan [Member] \| Office
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	$ 370		$ 399
Percent of Total	5.10%		5.80%
Commercial Loan [Member] \| Retail
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	$ 990		$ 992
Percent of Total	13.70%		14.40%
Commercial Loan [Member] \| Residential Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	$ 80		$ 78
Percent of Total	1.10%		1.10%
Commercial Loan [Member] \| Regional Shopping Malls
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	$ 0		$ 0
East North Central [Member] \| Commercial Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	$ 371		$ 401
Percent of Total	5.10%		5.80%
Middle Atlantic [Member] \| Commercial Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	$ 251		$ 275
Percent of Total	3.50%		4.00%
Mountain [Member] \| Commercial Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	$ 919		$ 903
Percent of Total	12.70%		13.10%
New England [Member] \| Commercial Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	$ 327		$ 351
Percent of Total	4.50%		5.10%
Pacific [Member] \| Commercial Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	$ 1,421		$ 1,417
Percent of Total	19.70%		20.60%
South Atlantic [Member] \| Commercial Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	$ 2,106		$ 2,005
Percent of Total	29.10%		29.10%
West North Central [Member] \| Commercial Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	$ 152		$ 128
Percent of Total	2.10%		1.90%
West South Central [Member] \| Commercial Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	$ 797		$ 720
Percent of Total	11.00%		10.40%
Region Others [Member] \| Commercial Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	$ 886		$ 686
Percent of Total	12.30%		10.00%