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EQUITY INVESTMENTS (Narrative) (Details) $ / shares in Units, a in Thousands | 1 Months Ended | 3 Months Ended | 9 Months Ended |  |
--- | --- | --- | --- | --- | ---
May 31, 2019 $ / shares | Feb. 28, 2019 $ / shares | Sep. 30, 2020 USD ($) shares | Sep. 30, 2019 USD ($) | Sep. 30, 2020 USD ($) a shares | Sep. 30, 2019 USD ($) | Mar. 31, 2020 USD ($) | Dec. 31, 2019 USD ($)
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |
Equity investments |  |  | $ 16,560,000 |  | $ 16,560,000 |  |  | $ 32,044,000
Investment in Mammoth Energy Services, Inc. |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |
Equity method investment, ownership (in shares) | shares |  |  | 9,829,548 |  | 9,829,548 |  |  |
Approximate fair value, quoted market price |  |  | $ 15,700,000 |  | $ 15,700,000 |  |  |
Share dividend (in usd per share) | $ / shares | $ 0.125 | $ 0.125 |  |  |  |  |  |
Investment in Grizzly Oil Sands ULC |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |
Equity method investment, ownership interest, percent |  |  | 24.60% |  | 24.60% |  |  |
Equity method investment, impairment |  |  |  |  | $ 0 | $ 0 |  |
Equity method investment, amount of cash calls, based on proportionate ownership interest |  |  |  |  |  | 400,000 |  |
Equity Method Investments, Increase (Decrease) Due To Foreign Currency Translation Adjustment |  |  | $ (3,700,000) | $ 2,000,000.0 | 4,100,000 | (5,200,000) |  |
Equity investments |  |  | $ 16,521,000 |  | $ 16,521,000 |  |  | 21,000,000
Investment in Mammoth Energy Services, Inc. |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |
Equity method investment, ownership interest, percent |  |  | 21.50% |  | 21.50% |  |  |
Equity investments |  |  | $ 0 |  | $ 0 |  | $ 0 | 11,005,000
Distributions from equity method investments |  |  |  |  | $ 0 | 2,500,000 |  |
Windsor Midstream LLC |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |
Equity method investment, ownership interest, percent |  |  | 22.50% |  | 22.50% |  |  |
Equity investments |  |  | $ 39,000 |  | $ 39,000 |  |  | 39,000
Distributions from equity method investments |  |  |  |  | $ 0 |  |  |
Tatex Thailand II, LLC |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |
Equity method investment, ownership interest, percent |  |  | 23.50% |  | 23.50% |  |  |
Equity investments |  |  | $ 0 |  | $ 0 |  |  | $ 0
Distributions from equity method investments |  |  |  |  | $ 0 | $ 2,100,000 |  |
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 |  |  |
Phu Horm Field | Apico Llc |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |
Gas and oil area, reserve (in acres) | a |  |  |  |  | 108 |  |  |
Apico Llc | Tatex Thailand II, LLC |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |
Ownership percentage | 8.50% |  |  |  |  |  |  |

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