Restructuring and Asset Related Charges - Net (Details) - USD ($) $ in Millions	3 Months Ended				6 Months Ended
	Jun. 30, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Restructuring Cost and Reserve [Line Items]
Restructuring and asset related charges - net	$ 1			$ 2	$ 2	$ 2
2017 Restructuring [Member] | Employee Severance [Member]
Restructuring Cost and Reserve [Line Items]
Payments for Restructuring					(6)
Restructuring Reserve	6				6
Restructuring and asset related charges - net	$ 1	$ 2	$ 8		$ 2
2017 Restructuring [Member] | Impairment of Long-Lived Assets and Other Assets [Member]
Restructuring Cost and Reserve [Line Items]
Asset Impairment Charges		$ 62