Fair Value Measurements (Schedule of Assets and Liabilities Measured at Fair Value on a Recurring Basis) (Details) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset	$ 13	$ 6
Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	15	9
Total liabilities	(3)	(3)
Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	0	0
Total liabilities	0	0
Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	15	9
Total liabilities	(3)	(3)
Current Other Assets [Member] | Fair Value, Measurements, Recurring [Member] | Designated as Hedging Instrument [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset	6	2
Current Other Assets [Member] | Fair Value, Measurements, Recurring [Member] | Designated as Hedging Instrument [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset	0	0
Current Other Assets [Member] | Fair Value, Measurements, Recurring [Member] | Designated as Hedging Instrument [Member] | Significant Other Observable Inputs (Level 2) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset	6	2
Current Other Assets [Member] | Fair Value, Measurements, Recurring [Member] | Not Designated as Hedging Instrument [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Foreign currency forwards and swaps	4	5
Current Other Assets [Member] | Fair Value, Measurements, Recurring [Member] | Not Designated as Hedging Instrument [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Foreign currency forwards and swaps	0	0
Current Other Assets [Member] | Fair Value, Measurements, Recurring [Member] | Not Designated as Hedging Instrument [Member] | Significant Other Observable Inputs (Level 2) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Foreign currency forwards and swaps	4	5
Other Noncurrent Assets [Member] | Fair Value, Measurements, Recurring [Member] | Designated as Hedging Instrument [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset	3	2
Other Noncurrent Assets [Member] | Fair Value, Measurements, Recurring [Member] | Designated as Hedging Instrument [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset	0	0
Interest Rate Derivative Assets, at Fair Value	0
Other Noncurrent Assets [Member] | Fair Value, Measurements, Recurring [Member] | Designated as Hedging Instrument [Member] | Significant Other Observable Inputs (Level 2) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset	3	2
Interest Rate Derivative Assets, at Fair Value	2
Current Other liabilities [Member] | Fair Value, Measurements, Recurring [Member] | Not Designated as Hedging Instrument [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Foreign currency forwards and swaps	(3)	(3)
Current Other liabilities [Member] | Fair Value, Measurements, Recurring [Member] | Not Designated as Hedging Instrument [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Foreign currency forwards and swaps	0	0
Current Other liabilities [Member] | Fair Value, Measurements, Recurring [Member] | Not Designated as Hedging Instrument [Member] | Significant Other Observable Inputs (Level 2) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Foreign currency forwards and swaps	$ (3)	$ (3)