Quarterly report pursuant to Section 13 or 15(d)

EQUITY INVESTMENTS (Narrative) (Details)

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EQUITY INVESTMENTS (Narrative) (Details)
a in Thousands
3 Months Ended
Mar. 31, 2021
USD ($)
a
shares
Mar. 31, 2020
USD ($)
Dec. 31, 2020
USD ($)
Schedule of Equity Method Investments [Line Items]      
Equity investments $ 27,044,000   $ 24,816,000
Investment in Grizzly Oil Sands ULC      
Schedule of Equity Method Investments [Line Items]      
Equity investment, ownership interest 24.50%    
Equity method investment, impairment $ 0 $ 0  
Amount of cash paid for equity investments 0    
Increase (decrease) due to foreign currency translation adjustment 2,600,000 (14,700,000)  
Equity investments $ 27,044,000   24,816,000
Investment in Mammoth Energy Services, Inc.      
Schedule of Equity Method Investments [Line Items]      
Equity investment, ownership interest 21.50%    
Equity method investment, ownership (in shares) | shares 9,829,548    
Approximate fair value, quoted market price $ 52,300,000    
Equity investments 0 0 $ 0
Distributions from equity method investments $ 0 $ 0  
Athabasca, Peace River And Cold Lake Oil Sands Regions | Investment in Grizzly Oil Sands ULC      
Schedule of Equity Method Investments [Line Items]      
Gas and oil area, reserve (in acres) | a 830