Annual report pursuant to Section 13 and 15(d)

FAIR VALUE MEASUREMENTS (Details)

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FAIR VALUE MEASUREMENTS (Details) - USD ($)
$ in Thousands
Dec. 31, 2017
Dec. 31, 2016
Mar. 31, 2008
FAIR VALUE MEASUREMENTS [Abstract]      
Derivative contract outstanding $ 0 $ 0  
Term loan secured by plant, pipeline and equipment     $ 10,000
Recurring [Member]      
Liabilities [Abstract]      
Interest rate swap $ 0 58  
Recurring [Member] | Level 1 [Member]      
Liabilities [Abstract]      
Interest rate swap   0  
Recurring [Member] | Level 2 [Member]      
Liabilities [Abstract]      
Interest rate swap   58  
Recurring [Member] | Level 3 [Member]      
Liabilities [Abstract]      
Interest rate swap   $ 0