Summary of Significant Accounting Policies, Derivative Instruments, Fair Values Derivatives, Balance Sheet Location (Details) - Foreign Exchange Contract [Member] - Not Designated as Hedging Instrument [Member] - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Estimated fair value of the contracts in the consolidated balance sheets [Abstract]
Asset derivatives	$ 141	$ 121
Liability derivatives	20	57
Net fair value	121	64
Prepaid Expenses and Other Current Assets [Member]
Estimated fair value of the contracts in the consolidated balance sheets [Abstract]
Asset derivatives	57	115
Other Assets [Member]
Estimated fair value of the contracts in the consolidated balance sheets [Abstract]
Asset derivatives	84	6
Other Current Liabilities [Member]
Estimated fair value of the contracts in the consolidated balance sheets [Abstract]
Liability derivatives	$ 20	$ 57