Interest Cost Components (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Debt Disclosure [Abstract]
Amount charged to expense	$ 381	$ 338	$ 377
Amount capitalized	11	33	23
Interest costs	$ 392	$ 371	$ 400