Company Restructuring - Narrative (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Restructuring Cost and Reserve [Line Items]
Restructuring and related charges	$ 22	$ 10
Employee costs
Restructuring Cost and Reserve [Line Items]
Cumulative amount incurred to date for active programs	113
Exit costs
Restructuring Cost and Reserve [Line Items]
Cumulative amount incurred to date for active programs	$ 109