Investments - Schedule of Payment Status of Mortgage Loans (Details) - Mortgage loans - USD ($) $ in Millions	Sep. 30, 2026	Dec. 31, 2025
Debt Securities, Available-for-Sale [Line Items]
Amortized cost before allowance	$ 1,052	$ 889
Allowance	(12)	(10)
Total mortgage loans	1,040	879
Less than 90 days past due
Debt Securities, Available-for-Sale [Line Items]
Amortized cost before allowance	2	2
90 days or greater past due
Debt Securities, Available-for-Sale [Line Items]
Amortized cost before allowance	3	2
Total past due before allowance
Debt Securities, Available-for-Sale [Line Items]
Amortized cost before allowance	5	4
Current before allowance
Debt Securities, Available-for-Sale [Line Items]
Amortized cost before allowance	1,047	885
Commercial
Debt Securities, Available-for-Sale [Line Items]
Amortized cost before allowance	680	628
Allowance	(9)	(9)
Total mortgage loans	671	619
Commercial \| Less than 90 days past due
Debt Securities, Available-for-Sale [Line Items]
Amortized cost before allowance	0	0
Commercial \| 90 days or greater past due
Debt Securities, Available-for-Sale [Line Items]
Amortized cost before allowance	0	0
Commercial \| Total past due before allowance
Debt Securities, Available-for-Sale [Line Items]
Amortized cost before allowance	0	0
Commercial \| Current before allowance
Debt Securities, Available-for-Sale [Line Items]
Amortized cost before allowance	680	628
Residential
Debt Securities, Available-for-Sale [Line Items]
Amortized cost before allowance	372	261
Allowance	(3)	(1)
Total mortgage loans	369	260
Residential \| Less than 90 days past due
Debt Securities, Available-for-Sale [Line Items]
Amortized cost before allowance	2	2
Residential \| 90 days or greater past due
Debt Securities, Available-for-Sale [Line Items]
Amortized cost before allowance	3	2
Residential \| Total past due before allowance
Debt Securities, Available-for-Sale [Line Items]
Amortized cost before allowance	5	4
Residential \| Current before allowance
Debt Securities, Available-for-Sale [Line Items]
Amortized cost before allowance	$ 367	$ 257