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Equity Investments (Narrative) (Details) a in Thousands |  |  | 1 Months Ended | 3 Months Ended | 9 Months Ended | 12 Months Ended |  |  |  |
--- | --- | --- | --- | --- | --- | --- | --- | --- | --- | ---
Oct. 19, 2016 | Jan. 28, 2014 USD ($) | Mar. 31, 2015 USD ($) | Sep. 30, 2016 USD ($) | Mar. 31, 2016 USD ($) | Sep. 30, 2015 USD ($) | Mar. 31, 2015 USD ($) | Sep. 30, 2016 USD ($) a shares | Sep. 30, 2015 USD ($) | Dec. 31, 2014 USD ($) | Oct. 18, 2016 | Feb. 01, 2016 USD ($) | Dec. 31, 2012 | Oct. 05, 2012 USD ($)
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
(Income) loss from equity method investments |  |  |  | $ (5,997,000) |  | $ 61,891,000 |  | $ 25,576,000 | $ 57,036,000 |  |  |  |  |
Distributions from equity method investments |  |  |  |  |  |  |  | 14,220,000 | 4,761,000 |  |  |  |  |
Payments for equity method investments |  |  |  |  |  |  |  | $ 18,510,000 | 13,837,000 |  |  |  |  |
Investment in Tatex Thailand II, LLC |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Equity shares owned by affiliate (shares) | shares |  |  |  |  |  |  |  | 85,122 |  |  |  |  |  |
Total shares owned of subaffiliate (shares) | shares |  |  |  |  |  |  |  | 1,000,000 |  |  |  |  |  |
Gas and oil area, reserve (acres) | a |  |  |  |  |  |  |  | 243 |  |  |  |  |  |
(Income) loss from equity method investments |  |  |  | $ (253,000) |  | 0 |  | $ (412,000) | 189,000 |  |  |  |  |
Ownership interest, percent |  |  |  | 23.50% |  |  |  | 23.50% |  |  |  |  |  |
Investment in Tatex Thailand III, LLC |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Gas and oil area, reserve (acres) | a |  |  |  |  |  |  |  | 245 |  |  |  |  |  |
(Income) loss from equity method investments |  |  |  | $ 0 |  | 0 |  | $ 0 | 0 |  |  |  |  |
Ownership interest, percent |  |  |  | 17.90% |  |  |  | 17.90% |  |  |  |  |  |
Investment in Grizzly Oil Sands ULC |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Gas and oil area, reserve (acres) | a |  |  |  |  |  |  |  | 830 |  |  |  |  |  |
(Income) loss from equity method investments |  |  |  | $ 363,000 |  | 58,653,000 |  | $ 24,811,000 | 71,289,000 |  |  |  |  |
Impairment of oil and gas properties |  |  |  |  | $ 23,100,000 |  |  |  |  |  |  |  |  |
Equity method investment, amount of cash calls, based on proportionate ownership interest |  |  |  |  |  |  |  | 14,500,000 |  |  |  |  |  |
Equity method investments, increase (decrease) due to foreign currency translation adjustment |  |  |  | $ (1,400,000) |  | (11,600,000) |  | $ 8,300,000 | (23,300,000) |  |  |  |  |
Ownership interest, percent |  |  |  | 24.9999% |  |  |  | 24.9999% |  |  |  |  |  |
Investment in Windsor Midstream LLC |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
(Income) loss from equity method investments |  |  |  | $ (9,014,000) |  | (323,000) |  | $ (12,062,000) | (18,229,000) |  |  |  |  |
Ownership interest, percent |  |  |  | 22.50% |  |  |  | 22.50% |  |  |  |  |  |
Distributions from equity method investments |  |  |  |  |  |  |  | $ 14,200,000 |  |  |  |  |  |
Investment in Windsor Midstream LLC | MidMar Gas LLC |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Ownership interest, percent |  |  |  |  |  |  |  |  |  |  |  |  | 28.40% |
Coronado Midstream | Investment in Windsor Midstream LLC |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Proceeds from sale of interest in partnership unit |  |  | $ 600,000,000 |  |  |  |  |  |  |  |  |  |  |
Gain on sale on investment |  |  | $ 81,600,000 |  |  |  |  |  |  |  |  |  |  |
Investment in Blackhawk Midstream LLC |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
(Income) loss from equity method investments |  |  |  | $ 0 |  | 0 |  | $ 0 | (7,217,000) |  |  |  |  |
Ownership interest, percent |  |  |  | 48.50% |  |  |  | 48.50% |  |  |  |  |  |
Investment in Blackhawk Midstream LLC | Ohio Gathering Company, LLC and Ohio Condensate Company, LLC |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Amount put in escrow |  | $ 14,300,000 |  |  |  |  |  |  |  |  |  |  |  |
Proceeds from release of escrow deposits |  |  |  |  |  |  | $ 7,200,000 |  |  |  |  |  |  |
Purchase price of sold equity interests |  | $ 190,000,000 |  |  |  |  |  |  |  |  |  |  |  |
Investment in Sturgeon Acquisitions LLC |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
(Income) loss from equity method investments |  |  |  | $ 112,000 |  | (257,000) |  | $ 623,000 | (1,316,000) |  |  |  |  |
Ownership interest, percent |  |  |  | 25.00% |  |  |  | 25.00% |  |  |  |  |  |
Payments for equity method investments |  |  |  |  |  |  |  |  |  | $ 20,700,000 |  |  |  |
Investment in Mammoth Energy Partners LP |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
(Income) loss from equity method investments |  |  |  | $ 2,518,000 |  | 3,612,000 |  | $ 11,527,000 | 11,608,000 |  |  |  |  |
Equity method investments, increase (decrease) due to foreign currency translation adjustment |  |  |  | $ 200,000 |  |  |  | $ (1,100,000) |  |  |  |  |  |
Ownership interest, percent |  |  |  | 30.50% |  |  |  | 30.50% |  | 30.50% |  |  |  |
Investment in Strike Force Midstream LLC |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
(Income) loss from equity method investments |  |  |  | $ (99,000) |  | $ 0 |  | $ (40,000) | $ 0 |  |  |  |  |
Equity method investment, amount of cash calls, based on proportionate ownership interest |  |  |  |  |  |  |  | $ 4,000,000 |  |  |  |  |  |
Ownership interest, percent |  |  |  | 25.00% |  |  |  | 25.00% |  |  |  |  |  |
Investment in Strike Force Midstream LLC | Rice Energy Inc |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Ownership interest, percent |  |  |  | 75.00% |  |  |  | 75.00% |  |  |  |  |  |
Revolving Credit Facility | Investment in Grizzly Oil Sands ULC |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Revolving credit facility |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 125,000,000.0
Level 3 | Investment in Grizzly Oil Sands ULC |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Equity method investments, fair value of minority interest |  |  |  |  | $ 39,100,000 |  |  |  |  |  |  |  |  |
Level 3 | Investment in Strike Force Midstream LLC |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Equity method investments, fair value of minority interest |  |  |  |  |  |  |  |  |  |  |  | $ 22,500,000 |  |
Subsequent event | Investment in Mammoth Energy Partners LP |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Ownership interest, percent | 24.20% |  |  |  |  |  |  |  |  |  | 30.50% |  |  |
Sale of stock, percentage of ownership after transaction | 24.20% |  |  |  |  |  |  |  |  |  |  |  |  |

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