Acquisitions (Details Textual) $ in Thousands, gal in Millions	Mar. 15, 2016 USD ($) shares gal	Jun. 30, 2018 USD ($) gal	Dec. 31, 2017 USD ($)
Business Acquisition [Line Items]
Production capacity per year | gal		520
Long-term contingent consideration for acquisitions		$ 3,311	$ 8,849
Sanimax Energy, LLC
Business Acquisition [Line Items]
Production capacity per year | gal	20
Shares of common stock issued (in shares) | shares	500,000
Long-term contingent consideration for acquisitions	$ 5,000	2,527
Earnout payment period	7 years
Maximum Earnout Payment per year	$ 1,700
Current contingent liability		$ 1,663