Stock-Based Incentive Plan - Status of Options Granted Under Long-Term Incentive Plan (Detail) - USD ($) $ / shares in Units, $ in Thousands	6 Months Ended
	Jun. 30, 2021
Shares Under Option
Shares under option, outstanding, beginning balance	453,785
Shares under option, forfeited	(9,500)
Shares under option, exercised	(46,527)
Shares under option, outstanding, ending balance	397,758
Shares under options, exercisable at June 30, 2021	397,758
Weighted Average Exercise Price Per Share [Abstract]
Weighted average exercise price per share, outstanding, beginning balance	$ 25.06
Weighted average exercise price per share, outstanding, forfeited	28.33
Weighted average exercise price per share, outstanding, exercised	21.13
Weighted average exercise price per share, outstanding, ending balance	25.44
Weighted average exercise price per share, exercisable at June 30, 2021	$ 25.44
Weighted average remaining contractual life, outstanding at June 30, 2021	5 years 4 months 24 days
Weighted average remaining contractual life, exerciseable at June 30, 2021	5 years 4 months 24 days
Aggregated intrinsic value, outstanding at June 30, 2021	$ 912
Aggregated intrinsic value, exercisable at June 30, 2021	$ 912