Fair Value of Assets and Liabilities - Schedule of Financial Instruments Not Carried at Fair Value (Details) - USD ($) $ in Millions	Mar. 31, 2026	Dec. 31, 2025	Mar. 31, 2025	Dec. 31, 2024
Financial assets
Mortgage loans	$ 868	$ 879
Financial liabilities
Debt	7,491	7,490
Liability for collateral	2,074	1,934	$ 2,137	$ 2,041
Significant unobservable inputs (Level 3) | Amortized cost, net
Financial assets
Mortgage loans	868	879
Bank loans	520	473
Significant unobservable inputs (Level 3) | Fair value
Financial assets
Mortgage loans	854	868
Bank loans	528	487
Significant other observable inputs (Level 2) | Amortized cost, net
Financial liabilities
Debt	7,491	7,490
Liability for collateral	2,074	1,934
Significant other observable inputs (Level 2) | Fair value
Financial liabilities
Debt	7,245	7,367
Liability for collateral	$ 2,074	$ 1,934