XML 46 R35.htm IDEA: XBRL DOCUMENT v3.21.1
Allowance for Doubtful Accounts Activity (Detail) - Allowance for Doubtful Accounts [Member] - USD ($)
$ in Thousands
12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Allowance for Doubtful Accounts Receivable [Roll Forward]    
Balance at beginning of period $ 266 $ 417
Charged to costs and expenses 246 4
Write-offs, net of recoveries 68 155
Balance at end of period $ 444 $ 266