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EQUITY INVESMENTS (Narrative) (Details) $ / shares in Units, a in Thousands |  |  |  | 1 Months Ended | 3 Months Ended | 9 Months Ended | 12 Months Ended |  |  |  |  |
--- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | ---
Jul. 26, 2018 USD ($) shares | Jun. 29, 2018 USD ($) shares | May 01, 2018 USD ($) | Dec. 31, 2017 USD ($) | Sep. 30, 2018 USD ($) | Sep. 30, 2017 USD ($) | Jun. 30, 2017 USD ($) | Dec. 31, 2014 entity | Sep. 30, 2018 USD ($) a project $ / shares | Sep. 30, 2017 USD ($) | Dec. 31, 2014 a | Jun. 05, 2017 $ / shares shares | Feb. 17, 2017 $ / shares | Dec. 15, 2016 $ / shares | Apr. 30, 2015 bbl | Jun. 30, 2014 bbl
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
(Income) loss from equity method investments, net |  |  |  |  | $ (12,858,000) | $ 2,737,000 |  |  | $ (35,282,000) | $ 33,468,000 |  |  |  |  |  |
Distributions from equity method investments |  |  |  |  |  |  |  |  | 446,000 | 4,114,000 |  |  |  |  |  |
Share price (in usd per share) | $ / shares |  |  |  |  |  |  |  |  |  |  |  |  | $ 19.48 | $ 20.96 |  |
Gain on sale of equity method investments |  |  |  |  | 2,733,000 | 0 |  |  | 124,768,000 | 12,523,000 |  |  |  |  |  |
Proceeds from sale of equity method investments |  |  |  |  |  |  |  |  | 226,487,000 | 0 |  |  |  |  |  |
Payments for equity method investments |  |  |  |  |  |  |  |  | 2,318,000 | 44,844,000 |  |  |  |  |  |
Mammoth Energy Services LP |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Distributions from equity method investments |  |  |  |  |  |  |  |  | 1,200,000 |  |  |  |  |  |  |
Equity method investment, ownership interest, percent | 22.00% |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Shares owned (in shares) | shares | 9,829,548 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Gain (loss) on disposition of stock from equity method investee |  |  |  |  | 2,700,000 |  |  |  | $ 28,300,000 |  |  |  |  |  |  |
Share dividend (in usd per share) | $ / shares |  |  |  |  |  |  |  |  | $ 0.125 |  |  |  |  |  |  |
Tatex Thailand II, LLC |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
(Income) loss from equity method investments, net |  |  |  |  | $ (137,000) | (95,000) |  |  | $ (241,000) | (549,000) |  |  |  |  |  |
Equity method investment, ownership interest, percent |  |  |  |  | 23.50% |  |  |  | 23.50% |  |  |  |  |  |  |
Tatex Thailand III LLC |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Distributions from equity method investments |  |  |  | $ 200,000 |  |  |  |  |  |  |  |  |  |  |  |
Grizzly Oil Sands ULC |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Gas and oil area, reserve (in acres) | a |  |  |  |  |  |  |  |  | 830 |  |  |  |  |  |  |
(Income) loss from equity method investments, net |  |  |  |  | $ 275,000 | 296,000 |  |  | $ 833,000 | 869,000 |  |  |  |  |  |
Number of oil sand projects | project |  |  |  |  |  |  |  |  | 3 |  |  |  |  |  |  |
Production volume (in bbls/day) | bbl |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 2,200 | 11,300
Other than temporary impairment loss |  |  |  |  |  |  |  |  | $ 0 | 0 |  |  |  |  |  |
Equity method investment, amount of cash calls, based on proportionate ownership interest |  |  |  |  |  |  |  |  | 2,300,000 |  |  |  |  |  |  |
Equity method investments, increase (decrease) due to foreign currency translation adjustment |  |  |  |  | $ 2,900,000 | 6,700,000 |  |  | $ (5,700,000) | 12,500,000 |  |  |  |  |  |
Equity method investment, ownership interest, percent |  |  |  |  | 24.9999% |  |  |  | 24.9999% |  |  |  |  |  |  |
Timber Wolf Terminals LLC |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
(Income) loss from equity method investments, net |  |  |  |  | $ 0 | 4,000 |  |  | $ 536,000 | 8,000 |  |  |  |  |  |
Distributions from equity method investments |  |  |  |  |  |  |  |  | $ 400,000 |  |  |  |  |  |  |
Equity method investment, ownership interest, percent |  |  |  |  | 50.00% |  |  |  | 50.00% |  |  |  |  |  |  |
Windsor Midstream LLC |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
(Income) loss from equity method investments, net |  |  |  |  | $ 0 | (2,000) |  |  | $ (9,000) | 25,232,000 |  |  |  |  |  |
Distributions from equity method investments |  |  |  |  |  |  |  |  | $ 0 | 500,000 |  |  |  |  |  |
Equity method investment, ownership interest, percent |  |  |  |  | 22.50% |  |  |  | 22.50% |  |  |  |  |  |  |
Sturgeon Acquisitions LLC |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
(Income) loss from equity method investments, net |  |  |  |  | $ 0 | 0 |  |  | $ 0 | (71,000) |  |  |  |  |  |
Equity method investment, ownership interest, percent |  |  |  |  | 0.00% |  |  | 25.00% | 0.00% |  | 25.00% |  |  |  |  |
Gain on sale of equity method investments |  |  |  |  |  |  | $ 12,500,000 |  |  |  |  |  |  |  |  |
Mammoth Energy Services LP |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Equity method investments, increase (decrease) due to foreign currency translation adjustment |  |  |  |  | $ 100,000 | 160,000 |  |  | $ (200,000) | 230,000 |  |  |  |  |  |
Equity method investment, ownership interest, percent |  |  |  |  |  |  |  | 30.50% |  |  | 30.50% |  |  |  |  |
Number of entities contributed for ownership interest (in entities) | entity |  |  |  |  |  |  |  | 4 |  |  |  |  |  |  |  |
Shares received from equity method investee in exchange for ownership interest (in shares) | shares |  |  |  |  |  |  |  |  |  |  |  | 2,000,000 |  |  |  |
Share price (in usd per share) | $ / shares |  |  |  |  |  |  |  |  |  |  |  | $ 18.50 |  |  |  |
Strike Force Midstream LLC |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
(Income) loss from equity method investments, net |  |  |  |  | $ 0 | $ 127,000 |  |  | (693,000) | 2,585,000 |  |  |  |  |  |
Distributions from equity method investments |  |  | $ 175,000,000 |  |  |  |  |  | $ 800,000 | 3,600,000 |  |  |  |  |  |
Equity method investment, ownership interest, percent |  |  | 25.00% |  | 0.00% |  |  |  | 0.00% |  |  |  |  |  |  |
Gain on sale of equity method investments |  |  | $ 96,400,000 |  |  |  |  |  |  |  |  |  |  |  |  |
Payments for equity method investments |  |  |  |  |  |  |  |  |  | $ 43,000,000 |  |  |  |  |  |
Over-allotment option | Mammoth Energy Services LP |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Proceeds from sale of equity method investments | $ 4,500,000 | $ 47,000,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |
Over-allotment option | Common Stock | Mammoth Energy Services LP |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of shares sold (in shares) | shares | 118,974 | 1,235,600 |  |  |  |  |  |  |  |  |  |  |  |  |  |
Phu Horm Field | Apico Llc |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Gas and oil area, reserve (in acres) | a |  |  |  |  |  |  |  |  | 180 |  |  |  |  |  |  |
Concession Acreage in Southeast Asia | Tatex Thailand III LLC |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Gas and oil area, reserve (in acres) | a |  |  |  |  |  |  |  |  |  |  | 245 |  |  |  |  |
Apico Llc | Tatex Thailand II, LLC |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Ownership percentage |  |  |  |  | 8.50% |  |  |  | 8.50% |  |  |  |  |  |  |
Strike Force Midstream LLC | Rice Energy Inc |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Ownership percentage by parent |  |  |  | 75.00% |  |  |  |  |  |  |  |  |  |  |  |

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