Other Current Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Excise and other taxes receivable	$ 3,860	$ 1,508
Material and chemical inventories	871	986
Exchange and other receivables	831	56
Other current assets	$ 5,562	$ 2,550