Restructuring of Operations - Additional Information (Details) $ in Millions		12 Months Ended
	Dec. 31, 2016 employee	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Restructuring Cost and Reserve [Line Items]
Restructuring expense		$ 36	$ 15	$ 21
Estimated reduction of employees | employee	800
Restructuring And Related Activities, Completion Period Duration	2 years
Employee Termination Benefits [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring expense		33	12	15
Exit Costs [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring expense		$ 3	$ 3	$ 6