Stock-Based Incentive Plan - Status of Options Granted Under Long-Term Incentive Plan (Detail) - USD ($) $ / shares in Units, $ in Thousands	9 Months Ended
	Sep. 30, 2021
Shares Under Option
Shares under option, outstanding, beginning balance	453,785
Shares under option, forfeited	(9,500)
Shares under option, exercised	(49,527)
Shares under option, outstanding, ending balance	394,758
Shares under options, exercisable at September 30, 2021	394,758
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	21.07
Weighted average exercise price per share, outstanding, ending balance	25.48
Weighted average exercise price per share, exercisable at September 30, 2021	$ 25.48
Weighted average remaining contractual life, outstanding at September 30, 2021	5 years 2 months 12 days
Weighted average remaining contractual life, exerciseable at September 30, 2021	5 years 2 months 12 days
Aggregated intrinsic value, outstanding at September 30, 2021	$ 1,015
Aggregated intrinsic value, exercisable at September 30, 2021	$ 1,015