Investments - Debt Securities by Contractual Maturity Periods (Details) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Amortized Cost
Due in one year or less	$ 657
Due after one year through five years	3,983
Due after five years through ten years	3,306
Due after ten years	2,294
Mortgage and other asset-backed securities	394
Total	10,634	$ 10,842
Fair Value
Due in one year or less	631
Due after one year through five years	3,710
Due after five years through ten years	2,914
Due after ten years	1,938
Mortgage and other asset-backed securities	346
Total	$ 9,539	$ 9,872