Quarterly report pursuant to Section 13 or 15(d)

Derivative Instruments - Additional Information (Detail)

v3.19.1
Derivative Instruments - Additional Information (Detail)
$ in Thousands
3 Months Ended
Mar. 31, 2019
USD ($)
bbl
$ / bbl
Entity
Dec. 31, 2018
USD ($)
Derivative Instruments and Hedging Activities Disclosure [Line Items]    
Document Period End Date Mar. 31, 2019  
Derivative assets $ 31,257 $ 991
Second Quarter 2019 [Member] | Crude Oil    
Derivative Instruments and Hedging Activities Disclosure [Line Items]    
Derivative, Type of Instrument Swaps-WTI  
Derivative, Nonmonetary Notional Amount | bbl 6,421  
Derivative, Swap Type, Average Fixed Price | $ / bbl 54.48  
Derivative Instruments Not Designated as Hedging Instruments, Asset, at Fair Value $ 0  
Derivative Instruments Not Designated as Hedging Instruments, Liability, at Fair Value $ 3,361  
Second Quarter 2019 [Member] | Louisiana Light Sweet [Member]    
Derivative Instruments and Hedging Activities Disclosure [Line Items]    
Derivative, Type of Instrument Swaps-LLS  
Derivative, Nonmonetary Notional Amount | bbl 5,000  
Derivative, Swap Type, Average Fixed Price | $ / bbl 59.17  
Derivative Instruments Not Designated as Hedging Instruments, Asset, at Fair Value $ 0  
Derivative Instruments Not Designated as Hedging Instruments, Liability, at Fair Value $ 3,109  
Second Quarter 2019 [Member] | MEH [Domain]    
Derivative Instruments and Hedging Activities Disclosure [Line Items]    
Derivative, Type of Instrument 1000  
Derivative, Nonmonetary Notional Amount | $ / bbl 64.00  
Derivative, Swap Type, Average Fixed Price | $ / bbl 0  
Derivative Instruments Not Designated as Hedging Instruments, Asset, at Fair Value $ 183  
Commodity contracts    
Derivative Instruments and Hedging Activities Disclosure [Line Items]    
Derivative assets $ 28,400  
Number of derivative counterparties | Entity 7  
Commodity contracts | Crude Oil    
Derivative Instruments and Hedging Activities Disclosure [Line Items]    
Third-party quoted forward prices WTI  
Commodity contracts | Louisiana Light Sweet [Member]    
Derivative Instruments and Hedging Activities Disclosure [Line Items]    
Third-party quoted forward prices LLS  
Commodity contracts | MEH [Domain]    
Derivative Instruments and Hedging Activities Disclosure [Line Items]    
Third-party quoted forward prices MEH  
Third Quarter 2019 [Member] | Crude Oil    
Derivative Instruments and Hedging Activities Disclosure [Line Items]    
Derivative, Type of Instrument Swaps-WTI  
Derivative, Nonmonetary Notional Amount | bbl 6,397  
Derivative, Swap Type, Average Fixed Price | $ / bbl 54.50  
Derivative Instruments Not Designated as Hedging Instruments, Asset, at Fair Value $ 0  
Derivative Instruments Not Designated as Hedging Instruments, Liability, at Fair Value $ 3,430  
Third Quarter 2019 [Member] | Louisiana Light Sweet [Member]    
Derivative Instruments and Hedging Activities Disclosure [Line Items]    
Derivative, Type of Instrument Swaps-LLS  
Derivative, Nonmonetary Notional Amount | bbl 5,000  
Derivative, Swap Type, Average Fixed Price | $ / bbl 59.17  
Derivative Instruments Not Designated as Hedging Instruments, Asset, at Fair Value $ 0  
Derivative Instruments Not Designated as Hedging Instruments, Liability, at Fair Value $ 2,592  
Third Quarter 2019 [Member] | MEH [Domain]    
Derivative Instruments and Hedging Activities Disclosure [Line Items]    
Derivative, Nonmonetary Notional Amount | bbl 1,000  
Derivative, Swap Type, Average Fixed Price | $ / bbl 64.00  
Derivative Instruments Not Designated as Hedging Instruments, Asset, at Fair Value $ 0  
Derivative Instruments Not Designated as Hedging Instruments, Liability, at Fair Value $ 34  
Fourth Quarter 2019 [Member] | Crude Oil    
Derivative Instruments and Hedging Activities Disclosure [Line Items]    
Derivative, Type of Instrument Swaps-WTI  
Derivative, Nonmonetary Notional Amount | bbl 6,398  
Derivative, Swap Type, Average Fixed Price | $ / bbl 54.50  
Derivative Instruments Not Designated as Hedging Instruments, Asset, at Fair Value $ 0  
Derivative Instruments Not Designated as Hedging Instruments, Liability, at Fair Value $ 3,130  
Fourth Quarter 2019 [Member] | Louisiana Light Sweet [Member]    
Derivative Instruments and Hedging Activities Disclosure [Line Items]    
Derivative, Type of Instrument Swaps-LLS  
Derivative, Nonmonetary Notional Amount | bbl 5,000  
Derivative, Swap Type, Average Fixed Price | $ / bbl 59.17  
Derivative Instruments Not Designated as Hedging Instruments, Asset, at Fair Value $ 0  
Derivative Instruments Not Designated as Hedging Instruments, Liability, at Fair Value $ 1,995  
Fourth Quarter 2019 [Member] | MEH [Domain]    
Derivative Instruments and Hedging Activities Disclosure [Line Items]    
Derivative, Nonmonetary Notional Amount | bbl 1,000  
Derivative, Swap Type, Average Fixed Price | $ / bbl 64.00  
Derivative Instruments Not Designated as Hedging Instruments, Asset, at Fair Value $ 68  
Derivative Instruments Not Designated as Hedging Instruments, Liability, at Fair Value $ 0  
First Quarter 2020 [Member] | Crude Oil    
Derivative Instruments and Hedging Activities Disclosure [Line Items]    
Derivative, Type of Instrument Swaps-WTI  
Derivative, Nonmonetary Notional Amount | bbl 6,000  
Derivative, Swap Type, Average Fixed Price | $ / bbl 54.09  
Derivative Instruments Not Designated as Hedging Instruments, Asset, at Fair Value $ 0  
Derivative Instruments Not Designated as Hedging Instruments, Liability, at Fair Value $ 2,904  
First Quarter 2020 [Member] | MEH [Domain]    
Derivative Instruments and Hedging Activities Disclosure [Line Items]    
Derivative, Nonmonetary Notional Amount | bbl 2,000  
Derivative, Swap Type, Average Fixed Price | $ / bbl 61.03  
Derivative Instruments Not Designated as Hedging Instruments, Asset, at Fair Value $ 0  
Derivative Instruments Not Designated as Hedging Instruments, Liability, at Fair Value $ 58  
Second Quarter 2020 [Member] | Crude Oil    
Derivative Instruments and Hedging Activities Disclosure [Line Items]    
Derivative, Type of Instrument Swaps-WTI  
Derivative, Nonmonetary Notional Amount | bbl 6,000  
Derivative, Swap Type, Average Fixed Price | $ / bbl 54.09  
Derivative Instruments Not Designated as Hedging Instruments, Asset, at Fair Value $ 0  
Derivative Instruments Not Designated as Hedging Instruments, Liability, at Fair Value $ 2,369  
Second Quarter 2020 [Member] | MEH [Domain]    
Derivative Instruments and Hedging Activities Disclosure [Line Items]    
Derivative, Nonmonetary Notional Amount | bbl 2,000  
Derivative, Swap Type, Average Fixed Price | $ / bbl 61.03  
Derivative Instruments Not Designated as Hedging Instruments, Asset, at Fair Value $ 0  
Derivative Instruments Not Designated as Hedging Instruments, Liability, at Fair Value $ 57  
Third Quarter 2020 [Member] | Crude Oil    
Derivative Instruments and Hedging Activities Disclosure [Line Items]    
Derivative, Type of Instrument Swaps-WTI  
Derivative, Nonmonetary Notional Amount | bbl 6,000  
Derivative, Swap Type, Average Fixed Price | $ / bbl 54.09  
Derivative Instruments Not Designated as Hedging Instruments, Asset, at Fair Value $ 0  
Derivative Instruments Not Designated as Hedging Instruments, Liability, at Fair Value $ 1,898  
Third Quarter 2020 [Member] | MEH [Domain]    
Derivative Instruments and Hedging Activities Disclosure [Line Items]    
Derivative, Nonmonetary Notional Amount | bbl 2,000  
Derivative, Swap Type, Average Fixed Price | $ / bbl 61.03  
Derivative Instruments Not Designated as Hedging Instruments, Asset, at Fair Value $ 0  
Derivative Instruments Not Designated as Hedging Instruments, Liability, at Fair Value $ 40  
Fourth Quarter 2020 [Member] | Crude Oil    
Derivative Instruments and Hedging Activities Disclosure [Line Items]    
Derivative, Type of Instrument Swaps-WTI  
Derivative, Nonmonetary Notional Amount | bbl 6,000  
Derivative, Swap Type, Average Fixed Price | $ / bbl 54.09  
Derivative Instruments Not Designated as Hedging Instruments, Asset, at Fair Value $ 0  
Derivative Instruments Not Designated as Hedging Instruments, Liability, at Fair Value $ 1,518  
Fourth Quarter 2020 [Member] | MEH [Domain]    
Derivative Instruments and Hedging Activities Disclosure [Line Items]    
Derivative, Nonmonetary Notional Amount | bbl 2,000  
Derivative, Swap Type, Average Fixed Price | $ / bbl 61.03  
Derivative Instruments Not Designated as Hedging Instruments, Asset, at Fair Value $ 0  
Derivative Instruments Not Designated as Hedging Instruments, Liability, at Fair Value $ 39