Derivative Instruments And Hedging Activities - Derivative Instruments Not Designated As Hedging Instruments (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Derivative [Line Items]
Liability derivative instruments not designated as hedging instruments	$ 6,440	$ 10,731
Accrued Liabilities [Member] | Foreign Exchange Contracts [Member]
Derivative [Line Items]
Liability derivative instruments not designated as hedging instruments	2,900	3,923
Other Liabilities [Member] | Foreign Exchange Contracts [Member]
Derivative [Line Items]
Liability derivative instruments not designated as hedging instruments	$ 3,540	$ 6,808