Stock Options and Stock-Based Compensation - Stock Options (Detail) - $ / shares	12 Months Ended
Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options outstanding, beginning balance, Shares	1,029,103	1,058,411	1,064,439
Options granted, Shares	234,175	271,575	290,300
Options exercised, Shares	(278,094)	(235,932)	(250,604)
Options cancelled/forfeited, Shares	(48,026)	(64,951)	(45,724)
Options outstanding, ending balance, Shares	937,158	1,029,103	1,058,411
Options granted, weighted average exercise price	$ 81.12	$ 79.49	$ 57.27
Options exercised, weighted average exercise price	44.17	38.34	36.44
Options cancelled/forfeited, weighted average exercise price	61.26	59.87	36.71
Weighted average exercise price per share	$ 64.28	$ 54.87	$ 45.17
Options available for future grants	880,542	316,691	523,415
Exercisable options	421,964	468,107	440,386
Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Price range of outstanding options	$ 21.87	$ 20.08	$ 12.71
Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Price range of outstanding options	$ 103.31	$ 88.22	$ 62.31

Share based compensation shares authorized under stock option plans options available for future grants.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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For presentations that combine terminations, the number of shares under options that were cancelled during the reporting period as a result of occurrence of a terminating event specified in contractual agreements pertaining to the stock option plan or that expired.

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Weighted average price of options that were either forfeited or expired.

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Gross number of share options (or share units) granted during the period.

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Number of options outstanding, including both vested and non-vested options.

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Weighted average price at which grantees can acquire the shares reserved for issuance under the stock option plan.

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Weighted average price at which option holders acquired shares when converting their stock options into shares.

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Weighted average per share amount at which grantees can acquire shares of common stock by exercise of options.

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The number of shares reserved for issuance pertaining to the outstanding exercisable stock options as of the balance sheet date in the customized range of exercise prices for which the market and performance vesting condition has been satisfied.

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The weighted average price as of the balance sheet date at which grantees could acquire the underlying shares with respect to all outstanding stock options which are in the customized range of exercise prices.

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Number of share options (or share units) exercised during the current period.

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