Income Taxes - Significant Components of Provision for Income Taxes Attributable to Continuing Operations (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Current income tax provision:
Federal taxes	$ 1,676	$ 1,207	$ 210
State taxes	370	301	234
International taxes	67	129	135
Total current provision	2,113	1,637	579
Deferred income tax provision (benefit):
Federal taxes	(1,357)	(222)	620
State taxes	(266)	(45)	115
International taxes	(4)	(29)	(21)
Total deferred provision (benefit)	(1,627)	(296)	714
Total income tax provision	$ 486	$ 1,341	$ 1,293