Quarterly report pursuant to Section 13 or 15(d)

Financial Instruments Measured at Fair Value and Concentrations of Credit Risk - Summary of Fair Value Measurements and Financial Statement Presentation (Detail)

v3.21.2
Financial Instruments Measured at Fair Value and Concentrations of Credit Risk - Summary of Fair Value Measurements and Financial Statement Presentation (Detail)
$ in Thousands
Dec. 31, 2020
USD ($)
Fair Value Concentration Of Risk Financial Statement Captions [Line Items]  
Fair Values of Assets $ 12,165
Short Term Investments [Member]  
Fair Value Concentration Of Risk Financial Statement Captions [Line Items]  
Fair Values of Assets 11,698
Commodity Derivative Contracts [Member]  
Fair Value Concentration Of Risk Financial Statement Captions [Line Items]  
Fair Values of Assets 467
Level 1 [Member]  
Fair Value Concentration Of Risk Financial Statement Captions [Line Items]  
Fair Values of Assets 12,165
Level 1 [Member] | Short Term Investments [Member]  
Fair Value Concentration Of Risk Financial Statement Captions [Line Items]  
Fair Values of Assets 11,698
Level 1 [Member] | Commodity Derivative Contracts [Member]  
Fair Value Concentration Of Risk Financial Statement Captions [Line Items]  
Fair Values of Assets $ 467