Percentage of average return on invested capital on share based compensation arrangement.

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- Definition

Reduced percentage of restricted shares.

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Reduced percentage of shares earned in stock option plan.

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- Definition

Share based compensation arrangement by share based payment award equity instruments other than options vesting date.

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- Definition

Shares earned.

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- Definition

Amount of cost not yet recognized for nonvested award under share-based payment arrangement.

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
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- Definition

Weighted-average period over which cost not yet recognized is expected to be recognized for award under share-based payment arrangement, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

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- Definition

Amount of cost to be recognized for nonvested award under share-based payment arrangement. Excludes share and unit options.

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- Definition

Amount of noncash expense for award of restricted stock or unit under share-based payment arrangement.

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Period over which grantee's right to exercise award under share-based payment arrangement is no longer contingent on satisfaction of service or performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. Includes, but is not limited to, combination of market, performance or service condition.

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Description of terms of share-based payment arrangement. Includes, but is not limited to, type of award or grantee and reason for issuance.

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- Definition

Date the equity-based award expires, in CCYY-MM-DD format.

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- Definition

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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No definition available.

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- Definition

Number of shares authorized for issuance under share-based payment arrangement.

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Amount of accumulated difference between fair value of underlying shares on dates of exercise and exercise price on options exercised (or share units converted) into shares.

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- Definition

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

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- Definition

Period from grant date that an equity-based award expires, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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- Definition

Amount of noncash expense for option under share-based payment arrangement.

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Stock Option Plans - Additional Information (Detail) - USD ($) $ in Millions	1 Months Ended		12 Months Ended
	Aug. 31, 2019	May 31, 2019	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2018	Aug. 07, 2013
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares available for future grant			3,755,871			3,000,000
Stock option expense			$ 4.5	$ 3.8	$ 4.3
Aggregate intrinsic value for outstanding options			3.8
Total intrinsic value of options exercised			2.2	2.1	18.7
Restricted stock or unit expense			$ 15.3	$ 11.3	$ 9.6
Stock Awards [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares available for future grant						1,500,000
Performance Vesting Stock Options [Member] \| Long Term Compensation Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares available for future grant		100,849
Percentage of average return on invested capital			16.40%
Reduced percentage of shares earned in stock options plan			66.70%
Shares earned			88,755
Stock based compensation plan, description			The performance criterion for the Fiscal 2019 Employee Performance Stock Option Grant is based upon the achievement of certain levels of return on equity (as defined in the option agreements), ranging from 10.0% to 20.0%, for the fiscal year ending March 31, 2020. All stock options are earned if the return on equity is 20.0% or greater, and the percentage of shares earned are reduced proportionately to approximately 66.7% if the return on equity is 10.0%. If the Company does not achieve a return on equity of at least 10.0%, all stock options granted will be forfeited. During fiscal 2020, the adjusted return on equity was approximately 16.4%; therefore, 88,755 options were earned, with the remaining options forfeited.
Share-based compensation vesting period		4 years
Share-based compensation award expiration term		10 years
Performance Vesting Stock Options [Member] \| Long Term Compensation Plan [Member] \| Minimum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Percentage of average return on invested capital		10.00%
Share-based compensation expiration date			Mar. 31, 2021
Performance Vesting Stock Options [Member] \| Long Term Compensation Plan [Member] \| Maximum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Percentage of average return on invested capital		20.00%
Share-based compensation expiration date			Mar. 31, 2023
Time Vesting Stock Options [Member] \| Long Term Compensation Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares available for future grant		84,043
Share-based compensation vesting period		4 years
Stock Options [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unrecognized compensation cost, stock options			$ 7.2
Weighted-average period of recognition of unrecognized compensation cost			2 years 4 months 24 days
Stock Options [Member] \| Long Term Compensation Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based compensation award expiration term		10 years
Performance Vesting Restricted Stock [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares available for future grant		51,112
Percentage of average return on invested capital			16.40%
Shares earned			44,985
Stock based compensation plan, description			The performance criterion for the Fiscal 2020 Employee Restricted Stock Performance Award is based upon the achievement of certain levels of return on equity (as defined in the agreement), ranging from 10.0% to 20.0%, for the fiscal year ended March 31, 2020. All restricted shares will be earned if the return on equity is 20.0% or greater, and the percentage of shares earned will be reduced proportionately to approximately 66.7% if the return on equity is 10.0%. If the Company does not achieve a return on equity of at least 10.0%, all awards will be forfeited.
Share-based compensation vesting period		4 years
Reduced percentage of restricted shares			66.70%
Performance Vesting Restricted Stock [Member] \| Minimum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Percentage of average return on invested capital		10.00%
Share-based compensation vesting date			Mar. 31, 2021
Performance Vesting Restricted Stock [Member] \| Maximum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Percentage of average return on invested capital		20.00%
Share-based compensation vesting date			Mar. 31, 2023
Time Vesting Restricted Stock [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares available for future grant		42,591
Share-based compensation vesting period		4 years
Time Vesting Restricted Stock [Member] \| Board of Director [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based compensation vesting period		6 months
Restricted Stock [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares available for future grant	24,589		233,000
Share-based compensation vesting period	6 months
Weighted-average period of recognition of unrecognized compensation cost			2 years 2 months 12 days
Unrecognized compensation cost			$ 15.4
Restricted Stock And Restricted Stock Unit [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares available for future grant			1,219,192