Derivative Instruments And Hedging Activities - Derivative Instruments Not Designated As Hedging Instruments (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Derivative [Line Items]
Liability derivative instruments not designated as hedging instruments	$ 3,984	$ 6,308
Accrued Liabilities | Foreign Exchange Contracts
Derivative [Line Items]
Liability derivative instruments not designated as hedging instruments	3,454	3,133
Other Non-Current Liabilities | Foreign Exchange Contracts
Derivative [Line Items]
Liability derivative instruments not designated as hedging instruments	$ 530	$ 3,175