Annual report pursuant to Section 13 and 15(d)

Retirement Plan - Additional Information (Detail)

v3.10.0.1
Retirement Plan - Additional Information (Detail) - USD ($)
12 Months Ended
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
Defined Contribution Pension And Other Postretirement Plans Disclosure [Abstract]      
Employer contribution, percentage 33.00% 33.00% 33.00%
Percentage of employee wage contributions matched by the employer 5.00% 5.00% 5.00%
Retirement Plan, Total expense $ 769,000 $ 703,000 $ 505,000