Other Assets and Liabilities - Prepaid Expenses and Other Current Assets (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Prepaid Expenses and Other Current Assets:
Valued-added tax recoverable	$ 1,031	$ 1,206
Prepaid expenses	8,497	7,106
Advance to suppliers and other current assets	612	128
Guarantee from Armistice	467	0
Income tax receivable	521	518
Total	$ 11,128	$ 8,958