Derivative Financial Instruments Derivative Instruments and Hedging Activities - FV of Derivative Instruments Included Within Consolidated Balance Sheet (Details) - Foreign Exchange Forward [Member] - Designated as Hedging Instrument [Member] - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Prepaid Expenses and Other Current Assets [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset	$ 874	$ 187
Other Assets [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset	713	545
Derivative Financial Instruments, Assets [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset	$ 1,587
Derivative Financial Instruments, Liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivative Liability		$ 732