v3.10.0.1
Derivative Instruments and Fair Value Measurements - Summary of Commodity Derivatives (Loss) Gain (Detail) - USD ($)
$ in Thousands
3 Months Ended 6 Months Ended
Jun. 30, 2018
Jun. 30, 2017
Jun. 30, 2018
Jun. 30, 2017
Derivatives Not Designated as Hedging Instruments [Member]        
Derivatives Fair Value [Line Items]        
Commodity derivative (loss) gain $ (4,884) $ 1,231 $ (6,812) $ 4,675
Derivatives Not Designated as Hedging Instruments [Member] | Net Cash (Payment) Receipt on Derivatives Settlements [Member]        
Derivatives Fair Value [Line Items]        
Commodity derivative (loss) gain (1,982) 3 (3,513) (958)
Derivatives Not Designated as Hedging Instruments [Member] | Non-Cash Fair Value (Loss) Gain on Derivatives [Member]        
Derivatives Fair Value [Line Items]        
Commodity derivative (loss) gain (2,902) $ 1,228 (3,299) $ 5,633
Derivatives Designated as Hedging [Member] | Cash Flow Hedges [Member] | Oil, NGLs and Gas Sales [Member]        
Derivatives Fair Value [Line Items]        
Commodity derivative (loss) gain $ 62   $ 62