Quarterly report pursuant to Section 13 or 15(d)

Commodity Derivative Positions (Detail)

v3.7.0.1
Commodity Derivative Positions (Detail)
$ in Thousands
6 Months Ended
Jun. 30, 2017
USD ($)
bbl
$ / bbl
Dec. 31, 2016
USD ($)
Derivative Instruments Related to Oil and Gas Production [Line Items]    
Derivative Liability $ 90 $ 27,369
Settlement Agreement [Member]    
Derivative Instruments Related to Oil and Gas Production [Line Items]    
Fair Value Asset 457,245  
Fair Value Liability  
Crude Oil | Third Quarter 2017 [Member]    
Derivative Instruments Related to Oil and Gas Production [Line Items]    
Instrument Swaps  
Notional Volume, per day | bbl 4,408  
Derivative, Swap Type, Average Fixed Price | $ / bbl 48.59  
Fair Value Asset $ 903,636  
Fair Value Liability $ 0  
Crude Oil | Fourth Quarter 2017 [Member]    
Derivative Instruments Related to Oil and Gas Production [Line Items]    
Instrument Swaps  
Notional Volume, per day | bbl 4,408  
Derivative, Swap Type, Average Fixed Price | $ / bbl 48.59  
Fair Value Asset $ 591,129  
Fair Value Liability $ 0  
Crude Oil | First Quarter 2018 [Member]    
Derivative Instruments Related to Oil and Gas Production [Line Items]    
Instrument Swaps  
Notional Volume, per day | bbl 3,476  
Derivative, Swap Type, Average Fixed Price | $ / bbl 49.10  
Fair Value Asset $ 419,761  
Fair Value Liability $ 0  
Crude Oil | Second Quarter 2018 [Member]    
Derivative Instruments Related to Oil and Gas Production [Line Items]    
Instrument Swaps  
Notional Volume, per day | bbl 3,476  
Derivative, Swap Type, Average Fixed Price | $ / bbl 49.10  
Fair Value Asset $ 299,826  
Fair Value Liability $ 0  
Crude Oil | Third Quarter 2018 [Member]    
Derivative Instruments Related to Oil and Gas Production [Line Items]    
Instrument Swaps  
Notional Volume, per day | bbl 3,476  
Derivative, Swap Type, Average Fixed Price | $ / bbl 49.10  
Fair Value Asset $ 193,534  
Fair Value Liability $ 0  
Crude Oil | Fourth Quarter 2018 [Member]    
Derivative Instruments Related to Oil and Gas Production [Line Items]    
Instrument Swaps  
Notional Volume, per day | bbl 3,476  
Derivative, Swap Type, Average Fixed Price | $ / bbl 49.10  
Fair Value Asset $ 82,328  
Fair Value Liability $ 0  
Crude Oil | First Quarter 2019 [Member]    
Derivative Instruments Related to Oil and Gas Production [Line Items]    
Instrument Swaps  
Notional Volume, per day | bbl 2,916  
Derivative, Swap Type, Average Fixed Price | $ / bbl 49.75  
Fair Value Asset $ 160,594  
Fair Value Liability $ 0  
Crude Oil | Second Quarter 2019 [Member]    
Derivative Instruments Related to Oil and Gas Production [Line Items]    
Instrument Swaps  
Notional Volume, per day | bbl 2,916  
Derivative, Swap Type, Average Fixed Price | $ / bbl 49.75  
Fair Value Asset $ 88,824  
Fair Value Liability $ 0  
Crude Oil | Third Quarter 2019 [Member]    
Derivative Instruments Related to Oil and Gas Production [Line Items]    
Instrument Swaps  
Notional Volume, per day | bbl 2,916  
Derivative, Swap Type, Average Fixed Price | $ / bbl 49.75  
Fair Value Asset $ 24,775  
Fair Value Liability $ 0  
Crude Oil | Fourth Quarter 2019 [Member]    
Derivative Instruments Related to Oil and Gas Production [Line Items]    
Instrument Swaps  
Notional Volume, per day | bbl 2,916  
Derivative, Swap Type, Average Fixed Price | $ / bbl 49.75  
Fair Value Asset $ 0  
Fair Value Liability $ 56,550