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Restructuring and Asset Related Charges - Net (Details) - USD ($) $ in Millions	3 Months Ended			9 Months Ended		13 Months Ended
	Sep. 30, 2018	Dec. 31, 2017	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018
Restructuring Cost and Reserve [Line Items]
Restructuring and asset related charges - net	$ 1		$ 8	$ 3	$ 10
2017 Restructuring [Member] \| Employee Severance [Member]
Restructuring Cost and Reserve [Line Items]
Payments for Restructuring						$ (8)
Restructuring Reserve	5			5		$ 5
Restructuring and asset related charges - net	$ 1	$ 2	$ 8	$ 3
2017 Restructuring [Member] \| Impairment of Long-Lived Assets and Other Assets [Member]
Restructuring Cost and Reserve [Line Items]
Asset Impairment Charges		$ 62