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Financial Instruments and Fair Value - 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
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
Commodity Derivative Contracts [Member]
Fair Value Concentration Of Risk Financial Statement Captions [Line Items]
Fair Values of Assets	467
Commodity Derivative Contracts [Member] | Level 1 [Member]
Fair Value Concentration Of Risk Financial Statement Captions [Line Items]
Fair Values of Assets	$ 467

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- Definition

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- Definition

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