Investments - Schedule of Total Investments (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Total Investments [Line Items]
Current	$ 3,117	$ 3,000
Long-term	23,025	20,812
Total	26,142	23,812
Debt securities available for sale
Total Investments [Line Items]
Current	3,009	2,774
Long-term	20,231	18,414
Total	23,240	21,188
Mortgage loans
Total Investments [Line Items]
Current	58	226
Long-term	844	821
Total	902	1,047
Other investments
Total Investments [Line Items]
Current	50	0
Long-term	1,950	1,577
Total	$ 2,000	$ 1,577