Derivative Financial Instruments - Schedule of Notional Amounts and Estimated Fair Values of Commodity Derivative Positions (Detail) bbl in Thousands, MMBTU in Thousands, $ in Thousands	Sep. 30, 2020 USD ($) bbl MMBTU	Dec. 31, 2019 USD ($) bbl MMBTU
Financial Institution Counterparties [Member] | Oil Commodity Derivative [Member]
Derivative Instruments [Line Items]
Oil/Natural Gas Derivative Assets, Notional Amount | bbl	2,296	1,214
Oil/Natural Gas Derivative Liabilities, Notional Amount | bbl	3,089	2,148
Oil/Natural Gas Derivative Assets, Estimated Fair Value	$ 18,718	$ 2,796
Oil/Natural Gas Derivative Liabilities, Estimated Fair Value	$ (9,132)	$ (6,916)
Financial Institution Counterparties [Member] | Natural Gas Commodity Derivative [Member]
Derivative Instruments [Line Items]
Oil/Natural Gas Derivative Assets, Notional Amount | MMBTU	5,623	8,295
Oil/Natural Gas Derivative Liabilities, Notional Amount | MMBTU	18,181	2,689
Oil/Natural Gas Derivative Assets, Estimated Fair Value	$ 932	$ 2,131
Oil/Natural Gas Derivative Liabilities, Estimated Fair Value	$ (5,879)	$ (70)
Customer Counterparties [Member] | Oil Commodity Derivative [Member]
Derivative Instruments [Line Items]
Oil/Natural Gas Derivative Assets, Notional Amount | bbl	3,106	2,172
Oil/Natural Gas Derivative Liabilities, Notional Amount | bbl	2,279	1,190
Oil/Natural Gas Derivative Assets, Estimated Fair Value	$ 9,461	$ 7,208
Oil/Natural Gas Derivative Liabilities, Estimated Fair Value	$ (18,506)	$ (2,652)
Customer Counterparties [Member] | Natural Gas Commodity Derivative [Member]
Derivative Instruments [Line Items]
Oil/Natural Gas Derivative Assets, Notional Amount | MMBTU	19,940	2,689
Oil/Natural Gas Derivative Liabilities, Notional Amount | MMBTU	3,864	8,295
Oil/Natural Gas Derivative Assets, Estimated Fair Value	$ 6,161	$ 83
Oil/Natural Gas Derivative Liabilities, Estimated Fair Value	$ (915)	$ (2,039)