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Restructuring and Asset Related Charges - Net (Details) - USD ($) $ in Millions	3 Months Ended		19 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2019
Restructuring Cost and Reserve [Line Items]
Restructuring and asset related charges - net	$ 1	$ 1
2017 Restructuring [Member] \| Employee Severance [Member]
Restructuring Cost and Reserve [Line Items]
Payments for Restructuring			$ (10)
Restructuring Reserve	4		4
Restructuring and asset related charges - net	$ 1	$ 1
2017 Restructuring [Member] \| Impairment of Long-Lived Assets and Other Assets [Member]
Restructuring Cost and Reserve [Line Items]
Asset Impairment Charges			62
2017 Restructuring [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and asset related charges - net			76
2017 Restructuring [Member] \| Employee Severance [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and asset related charges - net			$ 14