Stock-Based Incentive Plan - Status of Options Granted Under Long-Term Incentive Plan (Detail) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2020 USD ($) $ / shares shares
Shares Under Option
Shares under option, outstanding, beginning balance | shares	508,111
Shares under option, expired | shares	(2,000)
Shares under option, forfeited | shares	(30,826)
Shares under option, exercised | shares	(21,500)
Share under option, outstanding, ending balance | shares	453,785
Shares under options, exercisable at December 31 | shares	404,014
Weighted Average Exercise Price Per Share [Abstract]
Weighted average exercise price per share, outstanding, beginning balance | $ / shares	$ 24.83
Weighted average exercise price per share, expired | $ / shares	28.33
Weighted average exercise price per share, forfeited | $ / shares	26.10
Weighted average exercise price per share, exercised | $ / shares	17.84
Weighted average exercise price per share, outstanding, ending balance | $ / shares	25.06
Weighted average exercise price per share, exercisable at December 31, 2020 | $ / shares	$ 24.63
Weighted average remaining contractual life, outstanding at December 31, 2020	5 years 9 months 18 days
Weighted average remaining contractual life, exercisable at December 31, 2020	5 years 7 months 6 days
Aggregate intrinsic value, outstanding at December 31, 2020 | $	$ 268
Aggregate intrinsic Value, exercisable at December 31, 2020 | $	$ 268