Other Assets (Details 1) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Spare parts inventory	$ 2,700	$ 2,764
Catalysts	2,410	2,962
Deposits	381	381
Other	1,784	933
Total	$ 7,275	$ 7,040