Fair Value of Financial Instruments (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2017 USD ($) Letter	Dec. 31, 2016 USD ($)
Performance Bond [Abstract]
Unrestricted cash	$ 2,300	$ 15,300
Number of standby letters of credit | Letter	3
Letter of credit and surety bonds	$ 900
Assets and liabilities measured at fair value [Abstract]
Money market funds	3,240	16,435
Foreign exchange contracts - Assets	201	141
Total assets	3,441	16,576
Foreign exchange contracts - Liabilities		(20)
Contingent consideration liability	(1,701)	(2,105)
Total liabilities	(1,701)	(2,125)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Gain (Loss) Included in Earnings, Description	446
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Settlements	(850)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability Value, Beginning Balance	2,105
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Assets and liabilities measured at fair value [Abstract]
Money market funds	3,240	16,435
Foreign exchange contracts - Assets	0	0
Total assets	3,240	16,435
Foreign exchange contracts - Liabilities		0
Contingent consideration liability	0	0
Total liabilities	0	0
Significant Other Observable Inputs (Level 2) [Member]
Assets and liabilities measured at fair value [Abstract]
Money market funds	0	0
Foreign exchange contracts - Assets	201	141
Total assets	201	141
Foreign exchange contracts - Liabilities		(20)
Contingent consideration liability	0	0
Total liabilities	0	(20)
Significant Unobservable Inputs (Level 3) [Member]
Assets and liabilities measured at fair value [Abstract]
Money market funds	0	0
Foreign exchange contracts - Assets	0	0
Total assets	0	0
Foreign exchange contracts - Liabilities		0
Contingent consideration liability	(1,701)	(2,105)
Total liabilities	(1,701)	$ (2,105)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability Value, Ending Balance	$ 1,701