Derivative Activities - Derivative Volumes Hedged and Average Hedge Prices (Parenthetical) (Detail) - Call Swaptions	Dec. 31, 2019 MMBTU / d bbl / d $ / MMBTU $ / bbl
2020 Commodity Contract | Natural Gas
Derivative [Line Items]
Volume Hedged | MMBTU / d	140,000
Weighted average price of hedge | $ / MMBTU	2.53
2021 Commodity Contract | Natural Gas
Derivative [Line Items]
Volume Hedged | MMBTU / d	100,000
Weighted average price of hedge | $ / MMBTU	2.69
2021 Commodity Contract | Crude Oil
Derivative [Line Items]
Volume Hedged | bbl / d	3,000
Weighted average price of hedge | $ / bbl	56.50