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Financial Instruments, Fair Value, and Concentrations of Credit Risk - Additional Information (Detail) - USD ($)
$ in Millions
12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Fair Value Concentration Of Risk Financial Statement Captions [Line Items]    
Fair value of financing leases $ 15.2 $ 15.7
Commodity Contracts [Member]    
Fair Value Concentration Of Risk Financial Statement Captions [Line Items]    
Commodity derivative assets, notional amount 12.8  
Unrealized commodity derivative losses from hedging contracts sold $ 2.0