Annual report pursuant to Section 13 and 15(d)

DERIVATIVE INSTRUMENTS (Details)

v3.8.0.1
DERIVATIVE INSTRUMENTS (Details) - USD ($)
$ in Thousands
12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
DERIVATIVE INSTRUMENTS [Abstract]      
Feedstock and natural gas usage to operating expenses 68.30% 62.20% 69.30%
Derivative [Line Items]      
Unrealized gain (loss) $ 58 $ 119 $ 381
Interest Rate Swaps [Member]      
Derivative [Line Items]      
Term loan in pay fixed, receive variable interest rate swap 10,000    
Term loan secured by plant, pipeline and equipment $ 14,000    
Derivative, variable interest rate 5.83%    
Fair value of derivative liability $ 0 58  
Not Designated as Hedging Instrument [Member] | Commodity Financial Instruments [Member]      
Derivative [Line Items]      
Realized gain (loss) 0 0 (180)
Unrealized gain (loss) 0 0 180
Net loss $ 0 $ 0 $ 0