Other Current Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
VAT receivable	$ 7,854	$ 14,088
Prepaid income tax asset	5,090	2,314
Other	2,664	2,282
Total other current assets	$ 15,608	$ 18,684