v3.5.0.2
Derivative Instruments and Fair Value Measurements - Summary of Fair Value of Open Commodity Derivatives (Detail) - Commodity Derivatives [Member] - USD ($)
$ in Thousands
Sep. 30, 2016
Dec. 31, 2015
Unrealized Gain on Commodity Derivatives [Member]    
Derivatives Fair Value [Line Items]    
Derivatives not designated as hedging instruments, fair value of assets derivative $ 1,057 $ 6,737
Unrealized Loss on Commodity Derivatives [Member]    
Derivatives Fair Value [Line Items]    
Derivatives not designated as hedging instruments, fair value of Liability derivative $ (2,594)