Quarterly report pursuant to Section 13 or 15(d)

Derivative Instruments - Additional Information (Detail)

v3.10.0.1
Derivative Instruments - Additional Information (Detail)
$ in Thousands
9 Months Ended
Sep. 30, 2018
USD ($)
Entity
Dec. 31, 2017
USD ($)
Derivative Instruments and Hedging Activities Disclosure [Line Items]    
Derivative assets $ 118,211 $ 41,677
Commodity contracts    
Derivative Instruments and Hedging Activities Disclosure [Line Items]    
Derivative assets $ 118,200  
Number of derivative counterparties | Entity 8  
Commodity contracts | Crude Oil    
Derivative Instruments and Hedging Activities Disclosure [Line Items]    
Third-party quoted forward prices West Texas Intermediate (“WTI”)