Investments - Debt Securities by Contractual Maturity Periods (Details) $ in Millions	Dec. 31, 2021 USD ($)
Amortized Cost
Due in one year or less	$ 812
Due after one year through five years	5,218
Due after five years through ten years	5,173
Due after ten years	4,067
Mortgage and other asset-backed securities	505
Total	15,775
Fair Value
Due in one year or less	816
Due after one year through five years	5,366
Due after five years through ten years	5,453
Due after ten years	4,805
Mortgage and other asset-backed securities	518
Total	$ 16,958