Annual report pursuant to Section 13 and 15(d)

DERIVATIVE FINANCIAL INSTRUMENTS (Details Textual)

v3.8.0.1
DERIVATIVE FINANCIAL INSTRUMENTS (Details Textual)
Dec. 31, 2018
$ / Rate
Dec. 31, 2017
$ / Rate
Oct. 31, 2017
Sep. 30, 2017
Number Of Barrels Per Day       1,000
Addititional Derivative Contracts [Member]        
Number Of Barrels Per Day     1,000  
Call Option [Member]        
Derivative, Price Risk Option Strike Price   55.35    
Call Option [Member] | Scenario, Forecast [Member]        
Derivative, Price Risk Option Strike Price 54.60      
Call Option [Member] | Addititional Derivative Contracts [Member] | Scenario, Forecast [Member]        
Derivative, Price Risk Option Strike Price 54.80      
Put Option [Member]        
Derivative, Price Risk Option Strike Price   49.00    
Put Option [Member] | Scenario, Forecast [Member]        
Derivative, Price Risk Option Strike Price 49.00      
Put Option [Member] | Addititional Derivative Contracts [Member] | Scenario, Forecast [Member]        
Derivative, Price Risk Option Strike Price 51.00