| **SUPPLEMENTAL INFORMATION - NATURAL GAS AND CRUDE OIL PROPERTIES Standardized Measure of Discounted Future Cash Flows Relating to Proved Reserves (Unaudited) (Details) - USD ($) $ in Thousands** | Dec. 31, 2016 | Dec. 31, 2015 | Dec. 31, 2014 |
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| **Discounted Future Net Cash Flows Relating to Proved Oil and Gas Reserves [Line Items]**                                                                                                           |          |          |          |
| Future Estimated Cash Flows                                                                                                                                                                         | $ 7,122,525   | $ 6,297,298   | $ 12,550,515  |
| Future Estimated Production Costs                                                                                                                                                                   | (1,624,167)   | (1,493,040)   | (2,746,811)   |
| Future Estimated Development Costs                                                                                                                                                                  | (2,219,914)   | (2,036,685)   | (2,528,755)   |
| Future Estimated Income Tax Expense                                                                                                                                                                 | (597,476)     | (508,332)     | (2,336,510)   |
| Future Net Cash Flows                                                                                                                                                                               | 2,680,968     | 2,259,241     | 4,938,439     |
| 10% Annual Discount for Estimated Timing of Cash Flows                                                                                                                                              | (1,260,339)   | (1,162,377)   | (2,631,974)   |
| Standardized Measure of Disconted Future Estimated Net Cash Flows                                                                                                                                   | $ 1,420,629   | $ 1,096,864   | $ 2,306,465   |

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| - Definition
Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.
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No definition available.
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Amount of estimated future accumulated cash inflow from the sale of proved oil and gas reserves.
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Amount of estimated future accumulated cash outflow for costs to be incurred in developing proved oil and gas reserves.
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Amount of estimated future accumulated cash outflow for income tax, based on the future income less future expense derived from production and sale of proved oil and gas reserves.
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Amount, after future accumulated cash outflow for development and production costs and future income tax, of estimated future accumulated cash inflow from the sale of proved oil and gas reserves.
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Amount of estimated future accumulated cash outflow for costs to be incurred in producing proved oil and gas reserves.
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Amount of discount on future accumulated cash inflow, after deducting future accumulated cash outflow for development and production costs and future income tax, from sale of proved oil and gas reserves, using a discount rate of ten percent a year.
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| - Definition
Amount of discounted future accumulated cash inflow relating to proved oil and gas reserves.
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