Supplemental Financial Information (Components of Other Items, Net) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Additional Financial Information Disclosure [Abstract]
Pension and postretirement benefit costs	$ (69)	$ (99)	$ (65)
Foreign exchange losses	(35)	(18)	(19)
Other	3	5	(8)
Other items, net	$ (101)	$ (112)	$ (92)