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Trade Accounts Receivable - Summary of Trade Accounts Receivable (Detail) - USD ($)
$ in Thousands
Mar. 31, 2021
Dec. 31, 2020
Accounts Receivable Net Current [Abstract]    
Trade accounts receivable $ 4,166 $ 3,932
Allowance for doubtful accounts (25) (25)
Trade accounts receivable, net 4,141 3,907
Unpaid deferred revenue included in trade accounts receivable $ 800 $ 1,711