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Summary of the Changes in Allowance for Doubtful Accounts (Detail) - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2019
Dec. 31, 2018
Dec. 31, 2017
Receivables [Abstract]      
Balance at beginning of year $ 5 $ 12 $ 32
Additions: Bad debt expense 24 23 127
Less: Write-off (26) (29) (149)
Translation adjustment   (1) 2
Balance at end of year $ 3 $ 5 $ 12