Derivative Instruments - Additional Information (Detail) $ in Thousands	3 Months Ended
	Mar. 31, 2018 USD ($) Entity	Dec. 31, 2017 USD ($)
Derivative Instruments and Hedging Activities Disclosure [Line Items]
Derivative assets	$ 52,928	$ 41,677
Commodity contracts
Derivative Instruments and Hedging Activities Disclosure [Line Items]
Derivative assets	$ 52,900
Number of derivative counterparties | Entity	5
Commodity contracts | Crude Oil
Derivative Instruments and Hedging Activities Disclosure [Line Items]
Third-party quoted forward prices	West Texas Intermediate (“WTI”) crude oil