Supplemental Cash Flow Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Supplemental Cash Flow Elements
Cash income tax payments, net of refunds	$ 1,351	$ 1,198	$ 1,560
Cash interest payments	$ 524	$ 370	$ 314