Quarterly report pursuant to Section 13 or 15(d)

Fair Value of Derivative Instruments on Condensed Consolidated Balance Sheets (Detail)

v3.7.0.1
Fair Value of Derivative Instruments on Condensed Consolidated Balance Sheets (Detail) - USD ($)
$ in Thousands
Mar. 31, 2017
Dec. 31, 2016
Derivatives, Fair Value [Line Items]    
Derivative assets $ 0 $ 0
Commodity derivative liabilities – current 4,667 12,932
Derivative Liability, Noncurrent 3,694 14,437
Derivative Liability 8,361 27,369
Commodity contracts    
Derivatives, Fair Value [Line Items]    
Derivative Liability 8,400  
Commodity contracts | Derivative assets/liabilities - current    
Derivatives, Fair Value [Line Items]    
Derivative assets, current 0 0
Commodity derivative liabilities – current 4,667 12,932
Commodity contracts | Noncurrent Derivative Contract [Member]    
Derivatives, Fair Value [Line Items]    
Derivative Asset, Noncurrent 0 0
Derivative Liability, Noncurrent $ 3,694 $ 14,437