Stock-Based Compensation and Stock Options - Stock Options (Detail) - $ / shares	3 Months Ended		6 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Options outstanding, beginning balance, Shares	846,625	1,017,494	937,158	1,029,103
Options granted, Shares	27,250	41,650	60,250	86,825
Options exercised, Shares	(67,915)	(80,455)	(186,671)	(124,818)
Options cancelled/forfeited, Shares	(26,978)	(2,772)	(31,755)	(15,193)
Options outstanding, ending balance, Shares	778,982	975,917	778,982	975,917
Options outstanding, beginning balance, Weighted Average Exercise Price	$ 68.50	$ 55.54	$ 64.28	$ 54.87
Options granted, Weighted Average Exercise Price	154.97	79.49	135.53	65.55
Options exercised, Weighted Average Exercise Price	56.83	38.66	51.95	37.77
Options cancelled/forfeited, Weighted Average Exercise Price	79.26	54.70	78.31	57.09
Options outstanding, ending balance, Weighted Average Exercise Price	$ 72.17	$ 57.97	$ 72.17	$ 57.97