Short-term and Long-term Investments, Restricted Deposits - Contractual Maturities of Short-Term and Long-Term Investments and Restricted Deposits (Details) - USD ($) $ in Millions	Mar. 31, 2023	Dec. 31, 2022
Investments
Amortized Cost
One year or less	$ 2,011	$ 2,207
One year through five years	8,008	7,651
Five years through ten years	4,131	4,066
Greater than ten years	144	135
Asset-backed securities	3,746	3,522
Amortized Cost	18,040	17,581
Fair Value
One year or less	1,981	2,179
One year through five years	7,556	7,147
Five years through ten years	3,821	3,613
Greater than ten years	140	129
Asset-backed securities	3,504	3,234
Fair Value	17,002	16,302
Restricted Deposits
Amortized Cost
One year or less	570	534
One year through five years	546	524
Five years through ten years	245	224
Greater than ten years	2	0
Asset-backed securities	0	0
Amortized Cost	1,363	1,282
Fair Value
One year or less	569	532
One year through five years	518	490
Five years through ten years	224	195
Greater than ten years	2	0
Asset-backed securities	0	0
Fair Value	$ 1,313	$ 1,217