Other Current Assets (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
VAT receivable	$ 10,298	$ 14,088
Prepaid income tax asset	6,327	2,314
Other	8,392	2,282
Total other current assets	$ 25,017	$ 18,684