Annual report pursuant to Section 13 and 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
 12 Months Ended
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
Other Assets [Line Items]      
Allowance of doubtful accounts $ 514 $ 494  
Provision for bad debt expense 291 219 $ 47
Write-off receivables $ 271 $ 38 $ 93
Minimum [Member]      
Other Assets [Line Items]      
Notes receivable due period 1 year    
Maximum [Member]      
Other Assets [Line Items]      
Notes receivable due period 4 years