Quarterly report pursuant to Section 13 or 15(d)

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

v3.19.1
Fair Value of Derivative Instruments on Condensed Consolidated Balance Sheets (Detail) - USD ($)
$ in Thousands
3 Months Ended
Mar. 31, 2019
Dec. 31, 2018
Derivatives, Fair Value [Line Items]    
Derivative Asset, Current $ 2,658 $ 34,932
Document Period End Date Mar. 31, 2019  
Derivative liabilities $ 25,107 991
Derivative Asset, Noncurrent 229 10,100
Derivative Liability, Noncurrent 6,150 0
Derivative Liability 31,257 991
Derivative Asset 2,887 45,032
Commodity contracts    
Derivatives, Fair Value [Line Items]    
Derivative Liability 28,400  
Commodity contracts | Current Derivative Contract [Member]    
Derivatives, Fair Value [Line Items]    
Derivative Asset, Current 2,658 34,932
Derivative liabilities 25,107 991
Commodity contracts | Noncurrent Derivative Contract [Member]    
Derivatives, Fair Value [Line Items]    
Derivative Asset, Noncurrent 229 10,100
Derivative Liability, Noncurrent 6,150 0
Fair Value, Measurements, Recurring | Commodity contracts    
Derivatives, Fair Value [Line Items]    
Derivative Asset, Current 2,658 34,932
Derivative liabilities (25,107) (991)
Derivative Asset, Noncurrent 229 10,100
Derivative Liability, Noncurrent $ 6,150 $ 0