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Derivative Financial Instruments (Details) bbl in Thousands, BTU in Billions | Oct. 29, 2020 BTU $ / Barrels $ / EnergyContent bbl | Sep. 30, 2020 BTU $ / EnergyContent $ / Barrels bbl
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NYMEX Oil Swap Contract Fourth Quarter, 2020 [Member] |  |
Derivative Financial Instruments |  |
Derivative, Nonmonetary Notional Amount, Volume |  | 4,397
Derivative, Swap Type, Weighted-Average Contract Price | $ / Barrels |  | 57.03
NYMEX Oil Swap Contract, 2021 [Member] |  |
Derivative Financial Instruments |  |
Derivative, Nonmonetary Notional Amount, Volume |  | 17,115
Derivative, Swap Type, Weighted-Average Contract Price | $ / Barrels |  | 40.38
NYMEX Oil Swap Contract, 2022 |  |
Derivative Financial Instruments |  |
Derivative, Nonmonetary Notional Amount, Volume |  | 3,885
Derivative, Swap Type, Weighted-Average Contract Price | $ / Barrels |  | 43.58
NYMEX Oil Swap Contracts [Member] |  |
Derivative Financial Instruments |  |
Derivative, Nonmonetary Notional Amount, Volume |  | 25,397
NYMEX Oil Collar Contract Fourth Quarter, 2020 [Member] |  |
Derivative Financial Instruments |  |
Derivative, Nonmonetary Notional Amount, Volume |  | 610
Derivative, Weighted-Average Floor Price | $ / Barrels |  | 55.00
Derivative, Weighted-Average Ceiling Price | $ / Barrels |  | 61.90
NYMEX Oil Collar Contract, 2021 [Member] |  |
Derivative Financial Instruments |  |
Derivative, Nonmonetary Notional Amount, Volume |  | 551
Derivative, Weighted-Average Floor Price | $ / Barrels |  | 48.97
Derivative, Weighted-Average Ceiling Price | $ / Barrels |  | 51.96
NYMEX Oil Collar Contracts [Member] |  |
Derivative Financial Instruments |  |
Derivative, Nonmonetary Notional Amount, Volume |  | 1,161
NYMEX Oil Calendar Month Average Roll Differential Fourth Quarter, 2020 |  |
Derivative Financial Instruments |  |
Derivative, Nonmonetary Notional Amount, Volume |  | 2,503
Derivative, Roll Differential Swap Type, Weighted-Average Contract Price | $ / Barrels |  | (1.18)
NYMEX Oil Calendar Month Average Roll Differential Contract, 2021 |  |
Derivative Financial Instruments |  |
Derivative, Nonmonetary Notional Amount, Volume |  | 6,058
Derivative, Roll Differential Swap Type, Weighted-Average Contract Price | $ / Barrels |  | (0.40)
NYMEX Oil Calendar Month Average Roll Differential Contracts [Member] |  |
Derivative Financial Instruments |  |
Derivative, Nonmonetary Notional Amount, Volume |  | 8,561
WTI Midland NYMEX WTI [Member] | Oil Basis Swap Contract Fourth Quarter, 2020 [Member] |  |
Derivative Financial Instruments |  |
Derivative, Nonmonetary Notional Amount, Volume |  | 4,087
Derivative, Oil Basis Swap Type, Weighted-Average Contract Price | $ / Barrels |  | (0.38)
WTI Midland NYMEX WTI [Member] | Oil Basis Swap Contract, 2021 [Member] |  |
Derivative Financial Instruments |  |
Derivative, Nonmonetary Notional Amount, Volume |  | 13,975
Derivative, Oil Basis Swap Type, Weighted-Average Contract Price | $ / Barrels |  | 0.75
WTI Midland NYMEX WTI [Member] | Oil Basis Swap Contract, 2022 [Member] |  |
Derivative Financial Instruments |  |
Derivative, Nonmonetary Notional Amount, Volume |  | 9,500
Derivative, Oil Basis Swap Type, Weighted-Average Contract Price | $ / Barrels |  | 1.15
WTI Midland NYMEX WTI [Member] | Oil Basis Swap [Member] |  |
Derivative Financial Instruments |  |
Derivative, Nonmonetary Notional Amount, Volume |  | 27,562
NYMEX WTI ICE Brent [Member] | Oil Basis Swap Contract Fourth Quarter, 2020 [Member] |  |
Derivative Financial Instruments |  |
Derivative, Nonmonetary Notional Amount, Volume |  | 920
Derivative, Oil Basis Swap Type, Weighted-Average Contract Price | $ / Barrels |  | (8.01)
NYMEX WTI ICE Brent [Member] | Oil Basis Swap Contract, 2021 [Member] |  |
Derivative Financial Instruments |  |
Derivative, Nonmonetary Notional Amount, Volume |  | 3,650
Derivative, Oil Basis Swap Type, Weighted-Average Contract Price | $ / Barrels |  | (7.86)
NYMEX WTI ICE Brent [Member] | Oil Basis Swap Contract, 2022 [Member] |  |
Derivative Financial Instruments |  |
Derivative, Nonmonetary Notional Amount, Volume |  | 3,650
Derivative, Oil Basis Swap Type, Weighted-Average Contract Price | $ / Barrels |  | (7.78)
NYMEX WTI ICE Brent [Member] | Oil Basis Swap [Member] |  |
Derivative Financial Instruments |  |
Derivative, Nonmonetary Notional Amount, Volume |  | 8,220
IF HSC [Member] | Gas Swaps Contract Fourth Quarter, 2020 [Member] |  |
Derivative Financial Instruments |  |
Derivative, Swap Type, Weighted-Average Contract Price | $ / EnergyContent |  | 2.39
Derivative, Nonmonetary Notional Amount, Energy Measure | BTU |  | 9,327
IF HSC [Member] | Gas Swaps Contract, 2021 [Member] |  |
Derivative Financial Instruments |  |
Derivative, Swap Type, Weighted-Average Contract Price | $ / EnergyContent |  | 2.42
Derivative, Nonmonetary Notional Amount, Energy Measure | BTU |  | 47,800
IF HSC [Member] | Gas Swaps Contract, 2022 [Member] |  |
Derivative Financial Instruments |  |
Derivative, Swap Type, Weighted-Average Contract Price | $ / EnergyContent |  | 2.23
Derivative, Nonmonetary Notional Amount, Energy Measure | BTU |  | 6,104
IF HSC [Member] | Gas Swaps Contracts [Member] |  |
Derivative Financial Instruments |  |
Derivative, Nonmonetary Notional Amount, Energy Measure | BTU |  | 63,231
WAHA [Member] | Gas Swaps Contract Fourth Quarter, 2020 [Member] |  |
Derivative Financial Instruments |  |
Derivative, Swap Type, Weighted-Average Contract Price | $ / EnergyContent |  | 1.21
Derivative, Nonmonetary Notional Amount, Energy Measure | BTU |  | 4,872
WAHA [Member] | Gas Swaps Contract, 2021 [Member] |  |
Derivative Financial Instruments |  |
Derivative, Swap Type, Weighted-Average Contract Price | $ / EnergyContent |  | 1.67
Derivative, Nonmonetary Notional Amount, Energy Measure | BTU |  | 25,155
WAHA [Member] | Gas Swaps Contract, 2022 [Member] |  |
Derivative Financial Instruments |  |
Derivative, Swap Type, Weighted-Average Contract Price | $ / EnergyContent |  | 2.10
Derivative, Nonmonetary Notional Amount, Energy Measure | BTU |  | 5,904
WAHA [Member] | Gas Swaps Contracts [Member] |  |
Derivative Financial Instruments |  |
Derivative, Nonmonetary Notional Amount, Energy Measure | BTU |  | 35,931
IF WAHA [Member] |  |
Derivative Financial Instruments |  |
Index percent of natural gas fixed swaps |  | 64.00%
GD WAHA [Member] |  |
Derivative Financial Instruments |  |
Index percent of natural gas fixed swaps |  | 36.00%
OPIS Propane Mont Belvieu Non-TET [Member] | NGL Swaps Contract Fourth Quarter, 2020 [Member] |  |
Derivative Financial Instruments |  |
Derivative, Nonmonetary Notional Amount, Volume |  | 466
Derivative, Swap Type, Weighted-Average Contract Price | $ / Barrels |  | 22.29
OPIS Propane Mont Belvieu Non-TET [Member] | NGL Swaps Contract, 2021 [Member] |  |
Derivative Financial Instruments |  |
Derivative, Nonmonetary Notional Amount, Volume |  | 392
Derivative, Swap Type, Weighted-Average Contract Price | $ / Barrels |  | 19.74
OPIS Propane Mont Belvieu Non-TET [Member] | NGL Swaps Contracts [Member] |  |
Derivative Financial Instruments |  |
Derivative, Nonmonetary Notional Amount, Volume |  | 858
Subsequent Event [Member] | NYMEX Oil Swap Contracts [Member] |  |
Derivative Financial Instruments |  |
Derivative, Nonmonetary Notional Amount, Volume | 300 |
Derivative, Swap Type, Weighted-Average Contract Price | $ / Barrels | 42.53 |
Subsequent Event [Member] | IF HSC [Member] | Gas Swaps Contract, 2021 [Member] |  |
Derivative Financial Instruments |  |
Derivative, Swap Type, Weighted-Average Contract Price | $ / EnergyContent | 2.62 |
Derivative, Nonmonetary Notional Amount, Energy Measure | BTU | 1,290 |
Subsequent Event [Member] | IF HSC [Member] | Gas Swaps Contract, 2022 [Member] |  |
Derivative Financial Instruments |  |
Derivative, Swap Type, Weighted-Average Contract Price | $ / EnergyContent | 2.58 |
Derivative, Nonmonetary Notional Amount, Energy Measure | BTU | 15,015 |
Subsequent Event [Member] | GD WAHA [Member] | Gas Swaps Contract, 2021 [Member] |  |
Derivative Financial Instruments |  |
Derivative, Swap Type, Weighted-Average Contract Price | $ / EnergyContent | 2.47 |
Derivative, Nonmonetary Notional Amount, Energy Measure | BTU | 924 |
Subsequent Event [Member] | GD WAHA [Member] | Gas Swaps Contract, 2022 [Member] |  |
Derivative Financial Instruments |  |
Derivative, Swap Type, Weighted-Average Contract Price | $ / EnergyContent | 2.46 |
Derivative, Nonmonetary Notional Amount, Energy Measure | BTU | 2,911 |
Subsequent Event [Member] | OPIS Propane Mont Belvieu Non-TET [Member] | NGL Swaps Contracts [Member] |  |
Derivative Financial Instruments |  |
Derivative, Nonmonetary Notional Amount, Volume | 900 |
Derivative, Swap Type, Weighted-Average Contract Price | $ / Barrels | 20.93 |

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