Quarterly report pursuant to Section 13 or 15(d)

Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail)

v3.7.0.1
Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) - USD ($)
$ in Thousands
Jun. 30, 2017
Dec. 31, 2016
Assets:    
Derivative Asset, Current $ 2,672 $ 0
Derivative Asset, Noncurrent 584 0
Liabilities:    
Commodity derivative liabilities – current 0 12,932
Derivative Liability, Noncurrent 90 14,437
Fair Value, Measurements, Recurring | Commodity contracts    
Assets:    
Derivative Asset, Current 2,672  
Derivative Asset, Noncurrent 584  
Liabilities:    
Commodity derivative liabilities – current 0 12,932
Derivative Liability, Noncurrent 90 14,437
Fair Value, Measurements, Recurring | Commodity contracts | Level 1    
Assets:    
Derivative Asset, Current 0  
Derivative Asset, Noncurrent 0  
Liabilities:    
Commodity derivative liabilities – current 0 0
Derivative Liability, Noncurrent 0 0
Fair Value, Measurements, Recurring | Commodity contracts | Level 2    
Assets:    
Derivative Asset, Current 2,672  
Derivative Asset, Noncurrent 584  
Liabilities:    
Commodity derivative liabilities – current 0 12,932
Derivative Liability, Noncurrent 90 14,437
Fair Value, Measurements, Recurring | Commodity contracts | Level 3    
Assets:    
Derivative Asset, Current 0  
Derivative Asset, Noncurrent 0  
Liabilities:    
Commodity derivative liabilities – current 0 0
Derivative Liability, Noncurrent $ 0 $ 0