Derivative Financial Instruments - Balance Sheet Location and Fair Value of Assets Associated with Derivative Financial Instruments (Details) - Not Designated as Hedging Instrument - Foreign exchange contract - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Other Current Liabilities
Derivatives, Fair Value [Line Items]
Foreign exchange contracts: other current liabilities	$ 887	$ 258
Other Current Assets
Derivatives, Fair Value [Line Items]
Foreign exchange contracts: other current assets	$ 43	$ 566