Stock Plans - Summary of Restricted Stock Activity (Detail) - Restricted stock - $ / shares	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Shares
Beginning balance (in shares)	118,343	146,191	172,701
Granted (in shares)	87,697	43,146	51,468
Vested (in shares)	(51,369)	(65,225)	(70,399)
Forfeited (in shares)	(8,785)	(5,769)	(7,579)
Ending balance (in shares)	145,886	118,343	146,191
Weighted Average Grant Date Fair Value
Beginning balance (in dollars per share)	$ 132.62	$ 105.83	$ 90.38
Granted (in dollars per share)	130.28	167.13	124.61
Vested (in dollars per share)	113.96	95.43	81.58
Forfeited (in dollars per share)	139.66	132.54	106.54
Ending balance (in dollars per share)	$ 137.36	$ 132.62	$ 105.83