Derivative Activities - Derivative Volumes Hedged and Average Hedge Prices (Detail)	Sep. 30, 2019 MMBTU / d bbl / d $ / MMBTU $ / bbl $ / gal
2019 Commodity Contract | Swaps | Natural Gas
Derivative [Line Items]
Volume Hedged | MMBTU / d	1,271,739
Weighted Average Hedge Price | $ / MMBTU	2.82
2019 Commodity Contract | Swaps | Crude Oil
Derivative [Line Items]
Volume Hedged	9,168
Weighted Average Hedge Price | $ / bbl	56.11
2019 Commodity Contract | Swaps | NGLs (C3-Propane)
Derivative [Line Items]
Volume Hedged	500
Weighted Average Hedge Price | $ / gal	0.53
2019 Commodity Contract | Swaps | NGLs (NC4-Normal Butane)
Derivative [Line Items]
Volume Hedged	1,000
Weighted Average Hedge Price | $ / gal	0.60
2019 Commodity Contract | Swaps | NGLs (C5-Natural Gasoline)
Derivative [Line Items]
Volume Hedged	5,500
Weighted Average Hedge Price | $ / gal	1.30
2019 Commodity Contract | Swaps | NGLs (iC4-Iso Butane)
Derivative [Line Items]
Volume Hedged	500
Weighted Average Hedge Price | $ / gal	0.75
2019 Commodity Contract | Swaptions | Natural Gas
Derivative [Line Items]
Volume Hedged | MMBTU / d	140,000
Weighted Average Hedge Price | $ / MMBTU	2.81	[1]
2019 Commodity Contract | Collars | Crude Oil
Derivative [Line Items]
Volume Hedged	1,000
2019 Commodity Contract | Collars | Crude Oil | Minimum
Derivative [Line Items]
Weighted Average Hedge Price | $ / gal	63.00
2019 Commodity Contract | Collars | Crude Oil | Maximum
Derivative [Line Items]
Weighted Average Hedge Price | $ / gal	73.00
2020 Commodity Contract | Swaps | Natural Gas
Derivative [Line Items]
Volume Hedged | MMBTU / d	674,208
Weighted Average Hedge Price | $ / MMBTU	2.64
2020 Commodity Contract | Swaps | Crude Oil
Derivative [Line Items]
Volume Hedged	6,738
Weighted Average Hedge Price | $ / bbl	58.53
2020 Commodity Contract | Swaptions | Natural Gas
Derivative [Line Items]
Volume Hedged | MMBTU / d	147,568
Weighted Average Hedge Price | $ / MMBTU	2.77	[1]
2020 Commodity Contract | Swaptions | Crude Oil
Derivative [Line Items]
Volume Hedged	1,000
Weighted Average Hedge Price | $ / gal	57.00	[2]
2020 Commodity Contract | Calls | Crude Oil
Derivative [Line Items]
Volume Hedged	500
Weighted Average Hedge Price | $ / gal	59.00
2021 Commodity Contract | Swaptions | Natural Gas
Derivative [Line Items]
Volume Hedged | MMBTU / d	30,000
Weighted Average Hedge Price | $ / MMBTU	2.70	[1]
2021 Commodity Contract | Swaptions | Crude Oil
Derivative [Line Items]
Volume Hedged	1,000
Weighted Average Hedge Price | $ / gal	55.00	[2]

[1] Contains a combined derivative instrument consisting of a fixed price swap and a sold option to extend or double the volumes. We have swaps in place for 2019 for 140,000 Mmbtu/day on which the counterparty can elect to extend the contract through December 2020 at a weighted average price of $2.81. In 2020, if the counterparty elects to double the volume, we would have additional swaps in place for 110,000 Mmbtu/day at a weighted average price of $2.78. We also have swaps in place for 2020 for 50,000 Mmbtu/day on which the counterparty can elect to extend the contract through December 2021 at a weighted average price of $2.75. In 2021, if the counterparty elects to double the volume, we would have additional swaps in place for 30,000 Mmbtu/day at a weighted average price of $2.70.

[2] Contains a combined derivative instrument consisting of a fixed price swap and a sold option to extend or double the volumes. We have swaps in place for 2020 for 1,000 bbls/day on which the counterparty can elect to extend the contract through 2021 at a weighted average price of $57.00. In 2021, if the counterparty elects to double the volume, we would have additional swaps in place for 1,000 bbls/day at a weighted average price of $55.00.