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DERIVATIVE INSTRUMENTS (Schedule of Derivative Instruments) (Details) |  | 9 Months Ended
--- | --- | ---
Sep. 30, 2017 MMBTU | Sep. 30, 2019 MMBTU $ / bbl $ / MMBTU bbl
NYMEX Henry Hub Swap - 2019 |  |
Derivative [Line Items] |  |
Daily Volume (MMBtu/day) | MMBTU |  | 1,380,000
Weighted average price (in usd per MMBtu or Bbl) | $ / MMBTU |  | 2.81
NYMEX Henry Hub Swap - 2019 | Short | Call Option |  |
Derivative [Line Items] |  |
Daily Volume (MMBtu/day) | MMBTU |  | 30,000
Weighted average price (in usd per MMBtu or Bbl) | $ / MMBTU |  | 3.10
NYMEX Henry Hub Swap - 2020 |  |
Derivative [Line Items] |  |
Daily Volume (MMBtu/day) | MMBTU |  | 519,000
Weighted average price (in usd per MMBtu or Bbl) | $ / MMBTU |  | 2.88
NYMEX Henry Hub Swap - 2022 | Short | Call Option |  |
Derivative [Line Items] |  |
Daily Volume (MMBtu/day) | MMBTU |  | 628,000
Weighted average price (in usd per MMBtu or Bbl) | $ / MMBTU |  | 2.90
NYMEX Henry Hub Swap - 2023 | Short | Call Option |  |
Derivative [Line Items] |  |
Daily Volume (MMBtu/day) | MMBTU | 628,000 |
Weighted average price (in usd per MMBtu or Bbl) | $ / MMBTU |  | 2.90
NYMEX WTI Swap - 2019 |  |
Derivative [Line Items] |  |
Daily Volume (Bbls/day) | bbl |  | 6,000
Weighted average price (in usd per MMBtu or Bbl) | $ / bbl |  | 60.81
NYMEX WTI Swap - 2020 |  |
Derivative [Line Items] |  |
Daily Volume (Bbls/day) | bbl |  | 6,000
Weighted average price (in usd per MMBtu or Bbl) | $ / bbl |  | 59.82
Mont Belvieu C2 - 2019 |  |
Derivative [Line Items] |  |
Daily Volume (Bbls/day) | bbl |  | 1,000
Weighted average price (in usd per MMBtu or Bbl) | $ / bbl |  | 18.48
Mont Belvieu C3 Swap - 2019 |  |
Derivative [Line Items] |  |
Daily Volume (Bbls/day) | bbl |  | 4,000
Weighted average price (in usd per MMBtu or Bbl) | $ / bbl |  | 29.02
Mont Belvieu C5 Swap - 2019 |  |
Derivative [Line Items] |  |
Daily Volume (Bbls/day) | bbl |  | 1,000
Weighted average price (in usd per MMBtu or Bbl) | $ / bbl |  | 53.71
Transco Zone 4 - 2019 | Long |  |
Derivative [Line Items] |  |
Daily Volume (MMBtu/day) | MMBTU |  | 60,000
Weighted average price (in usd per MMBtu or Bbl) | $ / MMBTU |  | 0.05
Transco Zone 4 - 2020 | Long |  |
Derivative [Line Items] |  |
Daily Volume (MMBtu/day) | MMBTU |  | 60,000
Weighted average price (in usd per MMBtu or Bbl) | $ / MMBTU |  | 0.05
Fixed Spread - 2020 | Long |  |
Derivative [Line Items] |  |
Daily Volume (MMBtu/day) | MMBTU |  | 10,000
Weighted average price (in usd per MMBtu or Bbl) | $ / MMBTU |  | 0.54

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