Derivative Financial Instruments Derivative Instruments and Hedging Activities - Cash Flow Hedge Activity Included in Accumulated Other Comprehensive Income (Loss) (Details) - Cost of Sales [Member] - Foreign Exchange Forward [Member] - Cash Flow Hedging [Member] - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative Instruments, Loss Recognized in Other Comprehensive Income (Loss), Effective Portion	$ (2,109)
Derivative Instruments, Gain Recognized in Other Comprehensive Income (Loss), Effective Portion		$ 1,826	$ 514	$ 1,826
Derivative Instruments, Gain Reclassified from Accumulated OCI into Income, Effective Portion	$ 261	$ 22	$ 496	$ 22