Restructuring Charges/Other - Restructuring Reserve (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Restructuring And Related Activities [Abstract]
Balance, January 1		$ 29	$ 40	$ 32
Restructuring charges	[1]	6	11	25
Non-cash items	[2]	(3)	(1)	(6)
Payments		(4)	(21)	(11)
Balance, December 31		$ 28	$ 29	$ 40

[1] Includes severance and benefits, accelerated depreciation, changes in estimates or other exit costs.

[2] Reflects charges for impacts of accelerated depreciation and changes in exchange rates.