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Financial Instruments - Schedule of Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) - USD ($)
$ in Thousands
Dec. 31, 2020
Dec. 31, 2019
Assets    
Derivative assets $ 97 $ 272
Liabilities    
Derivative liabilities (768) (753)
Fair Value, Measurements, Recurring [Member]    
Assets    
Derivative assets 97 272
Liabilities    
Derivative liabilities (768) (753)
Commodity Contract [Member] | Fair Value, Measurements, Recurring [Member]    
Assets    
Derivative assets 97 272
Liabilities    
Derivative liabilities (768) (753)
Significant Unobservable Inputs (Level 3) [Member] | Fair Value, Measurements, Recurring [Member]    
Assets    
Derivative assets 97 272
Liabilities    
Derivative liabilities (768) (753)
Significant Unobservable Inputs (Level 3) [Member] | Commodity Contract [Member] | Fair Value, Measurements, Recurring [Member]    
Assets    
Derivative assets 97 272
Liabilities    
Derivative liabilities $ (768) $ (753)