Stock Options and Stock-Based Compensation - Outstanding Options (Detail) - USD ($)	12 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Mar. 31, 2020
Share-based Payment Arrangement [Abstract]
Options outstanding, beginning balance, Shares	937,158	1,029,103	1,058,411
Granted, Number of Options	130,200	234,175	271,575
Exercised, Number of Options	(298,570)	(278,094)	(235,932)
Cancelled - forfeited, Number of Options	(44,546)
Cancelled - expired, Number of Options	(366)
Options outstanding, ending balance, Shares	723,876	937,158	1,029,103
Options vested and expected to vest, Number of Options	659,402
Ending exercisable, Number of Options	354,460
Options outstanding, beginning balance, Weighted Average Exercise Price	$ 64.28	$ 54.87
Granted, Weighted Average Exercise Price per Share	161.95	81.12	$ 79.49
Exercised, Weighted Average Exercise Price per Share	55.44	44.17	38.34
Cancelled - forfeited, Weighted Average Exercise Price per Share	79.37
Cancelled - expired, Weighted Average Exercise Price per Share	70.98
Options outstanding, ending balance, Weighted Average Exercise Price	84.55	$ 64.28	$ 54.87
Options vested and expected to vest, Weighted Average Exercise Price per Share	82.53
Ending exercisable, Weighted Average Exercise Price per Share	$ 59.28
Option outstanding, Weighted Average Remaining Contractual Life (Years)	3 years 3 months 21 days
Options vested and expected to vest, Weighted Average Remaining Contractual Life (Years)	3 years 3 months 18 days
Ending exercisable, Weighted Average Remaining Contractual Life (Years)	2 years 6 months 25 days
Option outstanding, Aggregate Intrinsic Value	$ 62,156,642
Options vested and expected to vest, Aggregate Intrinsic Value	57,717,373
Ending exercisable, Aggregate Intrinsic Value	$ 38,692,989