Share-Based Compensation - Activity in Company's Plan - Incentive Plan (Detail) - 2016 Incentive Plan Stock Option [Member] - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Outstanding at January 1, 2023, Number of Shares	60,300
Granted, Number of Shares	0	26,500	3,000
Exercised, Number of Shares	(37,800)	(13,150)	(7,000)
Forfeited, Number of Shares	0
Outstanding (vested and expected to vest) at December 31, 2023, Number of Shares	22,500
Exercisable at December 31, 2023, Number of Shares	8,500
Outstanding at January 1, 2023, Weighted Average Exercise Price per Share	$ 57.75
Granted, Weighted Average Exercise Price per Share	0
Exercised, Weighted Average Exercise Price per Share	57.07
Forfeited, Weighted Average Exercise Price per Share	0
Outstanding (vested and expected to vest) at December 31, 2023, Weighted Average Exercise Price per Share	58.89
Exercisable at December 31, 2023, Weighted Average Exercise Price per Share	$ 54.26
Outstanding (vested and expected to vest) at December 31, 2023, Weighted Average Remaining Contractual Term	8 years
Exercisable at December 31, 2023, Weighted Average Remaining Contractual Term	7 years 1 month 6 days
Outstanding (vested and expected to vest) at December 31, 2023, Aggregate Intrinsic Value	$ 1,687
Exercisable at December 31, 2023, Aggregate Intrinsic Value	$ 677