Schedule of Interest Expense on Note Payable to Principal Stockholder (Detail) - USD ($) $ in Thousands |
3 Months Ended | 9 Months Ended | ||
---|---|---|---|---|
Sep. 30, 2017 |
Sep. 30, 2016 |
Sep. 30, 2017 |
Sep. 30, 2016 |
|
Related Party Transactions [Abstract] | ||||
Interest expense on note payable to principal stockholder | $ 1,173 | $ 729 | $ 2,608 | $ 2,172 |