Quarterly report pursuant to Section 13 or 15(d)

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

v3.10.0.1
Selected Balance Sheet Data - Schedule of Other Assets (Parenthetical) (Detail) - USD ($)
$ in Thousands
 3 Months Ended 6 Months Ended
Jun. 30, 2018
Jun. 30, 2017
Jun. 30, 2018
Jun. 30, 2017
Dec. 31, 2017
Other Assets [Line Items]          
Allowance of doubtful accounts $ 409   $ 409   $ 494
(Recovery) provision for bad debt expense 77 $ (10) (29) $ (54)  
Write-off receivables $ 4 $ (6) $ 55 $ 10  
Minimum [Member]          
Other Assets [Line Items]          
Notes receivable due period     1 year    
Maximum [Member]          
Other Assets [Line Items]          
Notes receivable due period     5 years