Investments - Schedule of Contractual Maturities of Investments (Details) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Amortized cost
Due in one year or less	$ 825
Due after one year through five years	4,507
Due after five years through ten years	3,522
Due after ten years	5,196
Total	14,050	$ 12,979
Fair value
Due in one year or less	814
Due after one year through five years	4,314
Due after five years through ten years	3,246
Due after ten years	4,469
Total	$ 12,843	$ 12,132
% of fair value
Due in one year or less	6.30%
Due after one year through five years	33.60%
Due after five years through ten years	25.30%
Due after ten years	34.80%
Total	100.00%