Derivative Instruments And Hedging Activities - Derivative Instruments Designated As Hedging Instruments (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Derivatives, Fair Value [Line Items]
Asset derivative instruments designated as hedging instruments	$ 1,535	$ 966
Liability derivative instruments designated as hedging instruments	6,964	12,467
Other Current Assets | Interest Rate Swaps
Derivatives, Fair Value [Line Items]
Asset derivative instruments designated as hedging instruments	972	311
Other Assets, Net | Interest Rate Swaps
Derivatives, Fair Value [Line Items]
Asset derivative instruments designated as hedging instruments	563	655
Accrued Liabilities | Foreign Exchange Contracts
Derivatives, Fair Value [Line Items]
Liability derivative instruments designated as hedging instruments	6,235	7,492
Other Noncurrent Liabilities | Foreign Exchange Contracts
Derivatives, Fair Value [Line Items]
Liability derivative instruments designated as hedging instruments	$ 729	$ 4,975