Quarterly report pursuant to Section 13 or 15(d)

Notes Payable to Former Stockholders - Schedule of Interest Expense Pertaining to Notes (Detail)

v3.10.0.1
Notes Payable to Former Stockholders - Schedule of Interest Expense Pertaining to Notes (Detail) - USD ($)
$ in Thousands
 3 Months Ended 9 Months Ended
Sep. 30, 2018
Sep. 30, 2017
Sep. 30, 2018
Sep. 30, 2017
Interest Expense [Line Items]        
Interest expense $ 342 $ 370 $ 1,054 $ 1,126
Notes Payable to Former Stockholders [Member]        
Interest Expense [Line Items]        
Interest expense $ 96 $ 110 $ 307 $ 345