Derivative Instruments and Fair Value Measurements - Summary of Change in Fair Value of Commodity Derivatives (Detail) - USD ($) $ in Thousands |
3 Months Ended | |
|---|---|---|
Mar. 31, 2016 |
Mar. 31, 2015 |
|
| Derivatives Fair Value [Line Items] | ||
| Total gain (loss) on commodity derivatives | $ 3,500 | $ 15,901 |
| Derivatives Not Designated as Hedging Instruments [Member] | ||
| Derivatives Fair Value [Line Items] | ||
| Total gain (loss) on commodity derivatives | 2,543 | 6,580 |
| Derivatives Not Designated as Hedging Instruments [Member] | Unrealized Loss on Commodity Derivatives [Member] | ||
| Derivatives Fair Value [Line Items] | ||
| Total gain (loss) on commodity derivatives | (957) | (9,321) |
| Derivatives Not Designated as Hedging Instruments [Member] | Realized Gain on Commodity Derivatives [Member] | ||
| Derivatives Fair Value [Line Items] | ||
| Total gain (loss) on commodity derivatives | $ 3,500 | $ 15,901 |