Quarterly report pursuant to Section 13 or 15(d)

Selected Balance Sheet Data - Schedule of Other Assets (Parenthetical) (Detail)

v3.19.2
Selected Balance Sheet Data - Schedule of Other Assets (Parenthetical) (Detail) - USD ($)
$ in Thousands
 3 Months Ended 6 Months Ended
Jun. 30, 2019
Jun. 30, 2018
Jun. 30, 2019
Jun. 30, 2018
Dec. 31, 2018
Other Assets [Line Items]          
Allowance of doubtful accounts $ 398   $ 398   $ 514
Provision (recovery) for bad debt expense 91 $ 77 (13) $ (29)  
Write-off receivables $ 100 $ 4 103 55  
Reduction of accrued bonuses and other employee related expenses in settlement of employee notes receivable     $ 60 $ 192  
Minimum [Member]          
Other Assets [Line Items]          
Notes receivable due period     1 year    
Maximum [Member]          
Other Assets [Line Items]          
Notes receivable due period     5 years