Stock Options Outstanding (Detail)	12 Months Ended
	Mar. 31, 2021 $ / shares shares
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Options Outstanding, Number of Shares Outstanding | shares	708,501
Options Outstanding, Weighted-Average Remaining Contractual Life (in years)	6 years 11 months 26 days
Options Outstanding, Weighted-Average Exercise Price	$ 83.85
Options Exercisable , Number of Shares Outstanding | shares	416,817
Options Exercisable, Weighted-Average Exercise Price	$ 89.31
$33.43 - $37.34 [Member]
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Range of Exercise Prices, Lower Range	33.43
Range of Exercise Prices, Upper Range	$ 37.34
Options Outstanding, Number of Shares Outstanding | shares	14,373
Options Outstanding, Weighted-Average Remaining Contractual Life (in years)	1 year 2 months 12 days
Options Outstanding, Weighted-Average Exercise Price	$ 34.37
Options Exercisable , Number of Shares Outstanding | shares	14,373
Options Exercisable, Weighted-Average Exercise Price	$ 34.37
$59.32 - $81.56 [Member]
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Range of Exercise Prices, Lower Range	59.32
Range of Exercise Prices, Upper Range	$ 81.56
Options Outstanding, Number of Shares Outstanding | shares	260,670
Options Outstanding, Weighted-Average Remaining Contractual Life (in years)	7 years 8 months 19 days
Options Outstanding, Weighted-Average Exercise Price	$ 65.46
Options Exercisable , Number of Shares Outstanding | shares	96,420
Options Exercisable, Weighted-Average Exercise Price	$ 73.32
$87.34 - $106.24 [Member]
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Range of Exercise Prices, Lower Range	87.34
Range of Exercise Prices, Upper Range	$ 106.24
Options Outstanding, Number of Shares Outstanding | shares	433,458
Options Outstanding, Weighted-Average Remaining Contractual Life (in years)	6 years 8 months 26 days
Options Outstanding, Weighted-Average Exercise Price	$ 96.55
Options Exercisable , Number of Shares Outstanding | shares	306,024
Options Exercisable, Weighted-Average Exercise Price	$ 96.93