Derivative Activities - Derivative Volumes Hedged and Average Hedge Prices (Detail)	Mar. 31, 2018 MMBTU / d bbl / d $ / MMBTU $ / bbl $ / gal
2018 Commodity Contract | Swaps | Natural Gas
Derivative [Line Items]
Volume Hedged | MMBTU / d	1,001,127
Weighted Average Hedge Price | $ / MMBTU	2.96
2018 Commodity Contract | Swaps | Crude Oil
Derivative [Line Items]
Volume Hedged	8,748
Weighted Average Hedge Price | $ / bbl	53.25
2018 Commodity Contract | Swaps | NGLs (C2-Ethane)
Derivative [Line Items]
Volume Hedged	250
Weighted Average Hedge Price | $ / gal	0.29
2018 Commodity Contract | Swaps | NGLs (C3-Propane)
Derivative [Line Items]
Volume Hedged	7,451
Weighted Average Hedge Price | $ / gal	0.68
2018 Commodity Contract | Swaps | NGLs (NC4-Normal Butane)
Derivative [Line Items]
Volume Hedged	4,333
Weighted Average Hedge Price | $ / gal	0.81
2018 Commodity Contract | Swaps | NGLs (C5-Natural Gasoline)
Derivative [Line Items]
Volume Hedged	4,904
Weighted Average Hedge Price | $ / gal	1.21
2018 Commodity Contract | Swaptions | Natural Gas
Derivative [Line Items]
Volume Hedged | MMBTU / d	160,000
Weighted Average Hedge Price | $ / MMBTU	3.07	[1]
2019 Commodity Contract | Swaps | Natural Gas
Derivative [Line Items]
Volume Hedged | MMBTU / d	324,658
Weighted Average Hedge Price | $ / MMBTU	2.82
2019 Commodity Contract | Swaps | Crude Oil
Derivative [Line Items]
Volume Hedged	5,872
Weighted Average Hedge Price | $ / bbl	53.73
2019 Commodity Contract | Swaptions | Natural Gas
Derivative [Line Items]
Volume Hedged | MMBTU / d	170,137
Weighted Average Hedge Price | $ / MMBTU	2.92	[1]
October-December 2018 Commodity Contract | Calls | Natural Gas
Derivative [Line Items]
Volume Hedged | MMBTU / d	70,000
Weighted Average Hedge Price | $ / MMBTU	3.10	[2]
January-June 2020 Commodity Contract | Swaps | Crude Oil
Derivative [Line Items]
Volume Hedged	250
Weighted Average Hedge Price | $ / gal	55.00
January-June 2019 Commodity Contract | Swaps | NGLs (C5-Natural Gasoline)
Derivative [Line Items]
Volume Hedged	1,000
Weighted Average Hedge Price | $ / gal	1.24

[1] Contains a combined derivative instrument consisting of a fixed price swap and a sold option to extend or double the volume. For April through December of 2018, we have swaps in place for 160,000 Mmbtu per day on which the counterparty can elect to extend the contract through December 2019 at a weighted average price of $3.07. We have swaps in place for 2019 for 140,000 Mmbtu/day on which the counterparty can elect to double the volume at a weighted average price of $2.93. We also have swaps in place for 2019 for 40,000 Mmbtu per day on which the counterparty can elect to extend the contract through December 2020 at a weighted average price of $2.85.

[2] Weighted average deferred premium of $0.16.