Investments - Contractual Maturities (Details) - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021
Amortized Cost
Due in one year or less	$ 318
Due after one year through five years	2,249
Due after five years through ten years	364
Due after ten years	778
Amortized Cost	3,709	$ 3,208
Estimated Fair Value
Due in one year or less	315
Due after one year through five years	2,127
Due after five years through ten years	345
Due after ten years	712
Amortized Cost	$ 3,499	$ 3,202