Derivative Financial Instruments - Schedule of Notional Amounts and Estimated Fair Values of Commodity Derivative Positions (Detail) bbl in Thousands, MMBTU in Thousands, $ in Thousands	Jun. 30, 2017 USD ($) MMBTU bbl	Dec. 31, 2016 USD ($) MMBTU bbl
Financial Institution Counterparties [Member] | Oil Commodity Derivative [Member]
Derivative Instruments [Line Items]
Oil/Natural Gas Derivative Assets, Notional Amount | bbl	935	227
Oil/Natural Gas Derivative Liabilities, Notional Amount | bbl	178	944
Oil/Natural Gas Derivative Assets, Estimated Fair Value	$ 4,684	$ 206
Oil/Natural Gas Derivative Liabilities, Estimated Fair Value	$ (153)	$ (4,400)
Financial Institution Counterparties [Member] | Natural Gas Commodity Derivative [Member]
Derivative Instruments [Line Items]
Oil/Natural Gas Derivative Assets, Notional Amount | MMBTU	1,061	0
Oil/Natural Gas Derivative Liabilities, Notional Amount | MMBTU	938	1,299
Oil/Natural Gas Derivative Assets, Estimated Fair Value	$ 109	$ 0
Oil/Natural Gas Derivative Liabilities, Estimated Fair Value	$ (85)	$ (1,357)
Customer Counterparties [Member] | Oil Commodity Derivative [Member]
Derivative Instruments [Line Items]
Oil/Natural Gas Derivative Assets, Notional Amount | bbl	178	944
Oil/Natural Gas Derivative Liabilities, Notional Amount | bbl	935	227
Oil/Natural Gas Derivative Assets, Estimated Fair Value	$ 163	$ 4,580
Oil/Natural Gas Derivative Liabilities, Estimated Fair Value	$ (4,466)	$ (206)
Customer Counterparties [Member] | Natural Gas Commodity Derivative [Member]
Derivative Instruments [Line Items]
Oil/Natural Gas Derivative Assets, Notional Amount | MMBTU	938	1,299
Oil/Natural Gas Derivative Liabilities, Notional Amount | MMBTU	1,061	0
Oil/Natural Gas Derivative Assets, Estimated Fair Value	$ 87	$ 1,393
Oil/Natural Gas Derivative Liabilities, Estimated Fair Value	$ (103)	$ 0