Income Taxes - Provision for Income Taxes (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Currently payable
Federal	$ 720	$ 534	$ 698
State	123	59	109
International	633	673	763
Tax Cuts and Jobs Act (TCJA) non-current transition tax provision			176
Deferred
Federal	(59)	(32)	(38)
State	(20)	(26)	(17)
International	(79)	(78)	(54)
Total provision for income taxes	$ 1,318	$ 1,130	$ 1,637