Income Taxes - Components of Income Tax Expense (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Current taxes
U.S. income taxes	$ 2,128	$ 1,476	$ 804
Foreign income taxes	334	173	185
State income taxes	303	114	47
Total current taxes	2,765	1,763	1,036
Deferred taxes (benefits)
U.S. income taxes (benefits)	(217)	(236)	(75)
Foreign income taxes	11	16	8
State income tax (benefits)	(180)	(93)	(34)
Total deferred taxes (benefits)	(386)	(313)	(101)
Total income taxes	$ 2,379	$ 1,450	$ 935