Fair Value Measurements - Derivative Financial Instruments Designated and Non-designated as Hedging Instruments (Details) - Fair Value, Measurements, Recurring - USD ($)	Jun. 30, 2018	Dec. 31, 2017
Derivative Not Designated as Hedging Instruments
Derivatives Fair Value [Line Items]
Nominal Value	$ 105,000,000
Derivative Not Designated as Hedging Instruments | Foreign Exchange Swaps | Less Than Six Months
Derivatives Fair Value [Line Items]
Nominal Value	$ 105,000,000
Derivatives Designated as Hedging Instruments
Derivatives Fair Value [Line Items]
Nominal Value		$ 67,000,000
Derivatives Designated as Hedging Instruments | Other Current and Non Current Liabilities
Derivatives Fair Value [Line Items]
Derivative Liability		1,000,000
Derivatives Designated as Hedging Instruments | Foreign Exchange Forward | Less Than One Year | Cash Flow Hedging
Derivatives Fair Value [Line Items]
Nominal Value		67,000,000
Derivatives Designated as Hedging Instruments | Foreign Exchange Forward | Less Than One Year | Other Current and Non Current Liabilities | Cash Flow Hedging
Derivatives Fair Value [Line Items]
Derivative Liability		$ 1,000,000