Leases - Additional Information (Detail) - USD ($) $ in Thousands |
9 Months Ended | ||
---|---|---|---|
Sep. 30, 2018 |
Jan. 19, 2018 |
Dec. 31, 2017 |
|
Leases [Abstract] | |||
Operating lease expiration date | 2018-05 | ||
Operating lease, initial term | 10 years | ||
Operating lease, option to extend additional term | 7 years | ||
Operating lease assets | $ 14,147 | $ 472 |