Stock-Based Incentive Plan - Status of Options Granted Under Long-Term Incentive Plan (Detail) $ / shares in Units, $ in Thousands	9 Months Ended
	Sep. 30, 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	(19,018)
Shares under option, exercised | shares	(5,000)
Shares under option, outstanding, ending balance | shares	482,093
Shares under options, exercisable at September 30, 2020 | shares	428,615
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, outstanding, expired | $ / shares	28.33
Weighted average exercise price per share, outstanding, forfeited | $ / shares	24.70
Weighted average exercise price per share, outstanding, exercised | $ / shares	18.70
Weighted average exercise price per share, outstanding, ending balance | $ / shares	24.88
Weighted average exercise price per share, exercisable at September 30, 2020 | $ / shares	$ 24.43
Weighted average remaining contractual life, outstanding at September 30, 2020	5 years 10 months 24 days
Weighted average remaining contractual life, exerciseable at September 30, 2020	5 years 8 months 12 days
Aggregated intrinsic value, outstanding at September 30, 2020 | $	$ 0
Aggregated intrinsic value, exercisable at September 30, 2020 | $	$ 0