Fair Value Measurements - Assets and Liabilities Table (Details) - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value, net asset (liability), total	$ 0	$ (3)
Other current assets [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other current assets	52	57
Other current liabilities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other current liabilities	(52)	(60)
Fair Value, Inputs, Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value, net asset (liability), total	0	(3)
Fair Value, Inputs, Level 1 [Member] | Other current assets [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other current assets	52	57
Fair Value, Inputs, Level 1 [Member] | Other current liabilities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other current liabilities	(52)	(60)
Fair Value, Inputs, Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value, net asset (liability), total	0	0
Fair Value, Inputs, Level 2 [Member] | Other current assets [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other current assets	0	0
Fair Value, Inputs, Level 2 [Member] | Other current liabilities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other current liabilities	0	0
Fair Value, Inputs, Level 3 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value, net asset (liability), total	0	0
Fair Value, Inputs, Level 3 [Member] | Other current assets [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other current assets	0	0
Fair Value, Inputs, Level 3 [Member] | Other current liabilities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other current liabilities	$ 0	$ 0