Profit Sharing Plan and 401(k) Plan - Additional Information (Detail) - USD ($) |
12 Months Ended | ||
|---|---|---|---|
Dec. 31, 2016 |
Dec. 31, 2015 |
Dec. 31, 2014 |
|
| Postemployment Benefits [Abstract] | |||
| Employer contribution for profit sharing plan | $ 339,000 | $ 314,000 | $ 284,000 |