Other Current Assets (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
VAT receivable	$ 14,454	$ 14,088
Prepaid income tax asset	2,289	2,314
Other	5,097	2,282
Total other current assets	$ 21,840	$ 18,684