Prepayments and Other Current Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Insurance premiums	$ 425	$ 1,403
Rents, licenses and other	839	694
Total	$ 1,264	$ 2,097