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, 2016 USD ($) bbl MMBTU	Dec. 31, 2015 USD ($) bbl MMBTU
Financial Institution Counterparties [Member] | Oil Commodity Derivative [Member]
Derivative Instruments [Line Items]
Oil/Natural Gas Derivative Assets, Notional Amount | bbl	912	1,184
Oil/Natural Gas Derivative Liabilities, Notional Amount | bbl	627	45
Oil/Natural Gas Derivative Assets, Estimated Fair Value	$ 3,176	$ 12,650
Oil/Natural Gas Derivative Liabilities, Estimated Fair Value	$ (3,023)	$ (352)
Financial Institution Counterparties [Member] | Natural Gas Commodity Derivative [Member]
Derivative Instruments [Line Items]
Oil/Natural Gas Derivative Assets, Notional Amount | MMBTU	0	760
Oil/Natural Gas Derivative Liabilities, Notional Amount | MMBTU	3,325	0
Oil/Natural Gas Derivative Assets, Estimated Fair Value	$ 0	$ 560
Oil/Natural Gas Derivative Liabilities, Estimated Fair Value	$ (1,946)	$ 0
Customer Counterparties [Member] | Oil Commodity Derivative [Member]
Derivative Instruments [Line Items]
Oil/Natural Gas Derivative Assets, Notional Amount | bbl	627	45
Oil/Natural Gas Derivative Liabilities, Notional Amount | bbl	912	1,184
Oil/Natural Gas Derivative Assets, Estimated Fair Value	$ 3,128	$ 354
Oil/Natural Gas Derivative Liabilities, Estimated Fair Value	$ (3,044)	$ (12,454)
Customer Counterparties [Member] | Natural Gas Commodity Derivative [Member]
Derivative Instruments [Line Items]
Oil/Natural Gas Derivative Assets, Notional Amount | MMBTU	3,325	0
Oil/Natural Gas Derivative Liabilities, Notional Amount | MMBTU	0	760
Oil/Natural Gas Derivative Assets, Estimated Fair Value	$ 2,031	$ 0
Oil/Natural Gas Derivative Liabilities, Estimated Fair Value	$ 0	$ (549)