Stock Option Activity (Detail) - $ / shares	12 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Mar. 31, 2022
Share-Based Payment Arrangement [Abstract]
Number of Shares, Outstanding Options at Beginning of Year	436,949	456,849	708,501
Number of Shares, Granted	5,558	56,621	11,316
Number of Shares, Exercised	(189,143)	(73,343)	(247,578)
Number of Shares, Cancelled	(1,000)	(3,178)	(15,390)
Number of Shares, Outstanding Options at End of Year	252,364	436,949	456,849
Number of Shares, Options Exercisable at End of Year	215,913	339,043	314,624
Weighted-Average Exercise Price, Outstanding Options at Beginning of Year	$ 89.69	$ 83.81	$ 83.85
Weighted-Average Exercise Price, Granted	172.62	125.9	140.42
Weighted-Average Exercise Price, Exercised	90.4	80.19	86.97
Weighted-Average Exercise Price, Cancelled	73.37	109.15	76.63
Weighted-Average Exercise Price, Outstanding Options at End of Year	91.28	89.69	83.81
Weighted-Average Fair Value of Options Granted During the Year	$ 69.84	$ 48.36	$ 49.18