Impairment and Restructuring Charges (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2017	Jun. 30, 2017	Dec. 31, 2018
Restructuring and asset impairment charges
Restructuring Charges	$ 6	$ 13		$ 16
Employee Severance related costs
Restructuring and asset impairment charges
Severance accrual expected to be paid within next twelve months	6			6
Restructuring accrual
Balance in severance accrual at December 31, 2016			$ 8	7
Payments made to terminated employees				(12)
Balance in severance accrual at June 30, 2017	8			8
Employee Severance related costs | Argentina employee-related severance
Restructuring and asset impairment charges
Restructuring Charges	6			17
Restructuring accrual
Restructuring charge for employee severance costs				15
Employee Severance related costs | Prior year restructuring activities
Restructuring accrual
Refinement of estimates for prior year restructuring activities	(1)			$ (2)
Employee Severance related costs | IT transformation
Restructuring and asset impairment charges
Restructuring Charges		8
Employee Severance related costs | South America employee-related severance
Restructuring and asset impairment charges
Restructuring Charges		3
Non employee severance costs
Restructuring and asset impairment charges
Restructuring Charges	$ 1
Employee Severance And Other Costs | Minimum | Forecast
Restructuring and asset impairment charges
Restructuring Charges			8		$ 1
Employee Severance And Other Costs | Maximum | Forecast
Restructuring and asset impairment charges
Restructuring Charges			$ 10		$ 2
Facility Closing | Port Colborne Ontario Canada Plant
Restructuring and asset impairment charges
Restructuring Charges		$ 2