Earnings Per Share and Stock Plans (Summary of Option Transactions) (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Exercised	(296,027)	(187,907)	(363,091)
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Number of options, Outstanding, at Beginning of the year	834,777	922,450	1,063,894
Granted	171,515	133,743	227,783
Exercised	(296,027)	(187,907)	(363,091)
Cancelled	(183,471)	(33,509)	(6,136)
Number of options, Outstanding, Closing Balance	526,794	834,777	922,450	1,063,894
Exercisable at end of period	225,337
Beginning of year, Average Option Price	$ 23.52	$ 21.04	$ 19.10
Granted	35.16	38.70	24.33
Exercised	20.26	22.09	17.43
Cancelled	31.01	23.94	19.83
End of year, Average Option Price	26.53	$ 23.52	$ 21.04	$ 19.10
End of year, Average Exercisable Price	$ 22.67
Outstanding at period end, Weighted average Remaining Contractual Life (in years)	6 years 11 months 4 days	7 years 14 days	7 years 6 months 21 days	6 years 11 months 23 days
Exercisable at period end, Weighted average Remaining Contractual Life (in years)	5 years 8 months 26 days
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Intrinsic Value	$ 1,518	$ 9,602	$ 13,654	$ 6,477
Exercisable at end of period, Aggregate Intrinsic Value	$ 858

The number of shares into which fully or partially vested stock options outstanding as of the balance sheet date can be currently converted under the option plan.

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The weighted-average price as of the balance sheet date at which grantees can acquire the shares reserved for issuance on vested portions of options outstanding and currently exercisable under the stock option plan.

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

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Amount by which the current fair value of the underlying stock exceeds the exercise price of options outstanding.

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

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A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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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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Amount of difference between fair value of the underlying shares reserved for issuance and exercise price of vested portions of options outstanding and currently exercisable.

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Weighted average remaining contractual term for vested portions of options outstanding and currently exercisable or convertible, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Weighted average remaining contractual term for option awards outstanding, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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

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