Stock-Based Compensation Plans - Full Value Awards activity (Detail) - Restricted Stock [Member] - $ / shares	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of Restricted Shares, Beginning balance	160,544	162,356	162,610
Number of Restricted Shares, Granted	150,031	90,242	72,861
Number of Restricted Shares, Performance share pay-out	4,739	12,145	0
Number of Restricted Shares, Canceled	(29,581)	(5,272)	(8,513)
Number of Restricted Shares, Vested	(85,932)	(98,927)	(64,602)
Number of Restricted Shares, Ending balance	199,801	160,544	162,356
Weighted Average Grant Date Fair Value, Beginning balance	$ 346.15	$ 321.04	$ 316.56
Weighted Average Grant Date Fair Value, Ending balance	$ 276.74	$ 346.15	$ 321.04