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

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- Definition

Reduced percentage of restricted shares.

+ References

No definition available.

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- Definition

Reduced percentage of shares earned in stock option plan.

+ References

No definition available.

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- Definition

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

+ References

No definition available.

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- Definition

Shares earned.

+ References

No definition available.

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- Definition

Unrecognized cost of unvested share-based compensation awards.

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- Definition

Weighted average period over which unrecognized compensation is expected to be recognized for equity-based compensation plans, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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- Definition

Unrecognized cost of unvested share-based awards, other than options, awarded to employees as compensation.

+ References

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- Definition

The noncash expense that represents the cost of restricted stock or unit distributed to employees as compensation.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3602-108585

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- Definition

Period which an employee's right to exercise an award is no longer contingent on satisfaction of either a service condition, market condition or a performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

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- Definition

General descriptive information regarding an arrangement under which employees and directors receive: (a) awards of equity shares, equity share options, or other equity instruments; or (b) the entity incurs liabilities to them: (1) in amounts based, at least in part, on the price of the entity's shares or other equity instruments; or (2) that require or may require settlement by issuance of the entity's shares. Such an arrangement is usually provided to employees and directors to compensate them, provide performance incentives to them, and to attract or retain their services. May also include pertinent information particular to a plan that is not elsewhere specified in the taxonomy.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5047-113901

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- Definition

The weighted average fair value at grant date for nonvested equity-based awards issued during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

+ References

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- Definition

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

+ References

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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.

+ References

No definition available.

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- Definition

The maximum number of shares (or other type of equity) originally approved (usually by shareholders and board of directors), net of any subsequent amendments and adjustments, for awards under the equity-based compensation plan. As stock or unit options and equity instruments other than options are awarded to participants, the shares or units remain authorized and become reserved for issuance under outstanding awards (not necessarily vested).

+ References

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- Definition

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.

+ References

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- Definition

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

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901

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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.

+ References

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- Definition

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.

+ References

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- Definition

The noncash expense that accounts for the value of stock or unit options distributed to employees as compensation.

+ References

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Stock Option Plans - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Millions	1 Months Ended		12 Months Ended
	Aug. 31, 2017	May 31, 2017	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2016	Aug. 07, 2013
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares available for future grant			4,176,195			3,000,000
Stock option expense			$ 4.3	$ 5.3	$ 7.5
Aggregate intrinsic value for outstanding options			29.3
Aggregate intrinsic value of exercisable options			23.8
Total intrinsic value of options exercised			18.7
Restricted stock or unit expense			$ 9.6	$ 6.8	$ 9.8
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		58,055
Percentage of average return on invested capital			17.20%
Reduced percentage of shares earned in stock options plan			66.70%
Shares earned			55,858
Stock based compensation plan, description			The performance criterion for the Fiscal 2018 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 11.0% to 18.0%, for the fiscal year ending March 31, 2018. All stock options will be earned if the return on equity is 18.0% or greater, and the percentage of shares earned will be reduced proportionately to approximately 66.7% if the return on equity is 11.0%. If the Company does not achieve a return on equity of at least 11.0%, all stock options granted will be forfeited. During fiscal 2018, the adjusted return on equity was approximately 17.2%; therefore, 55,858 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		11.00%
Share-based compensation expiration date			Mar. 31, 2019
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		18.00%
Share-based compensation expiration date			Mar. 31, 2021
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		48,379
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			$ 6.8
Weighted-average period of recognition of unrecognized compensation cost			2 years 6 months
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
Board of Directors Stock Option [Member] \| Long Term Compensation Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares available for future grant	6,052
Performance Vesting Restricted Stock [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares available for future grant		52,646
Percentage of average return on invested capital			17.20%
Shares earned			50,656
Stock based compensation plan, description			The performance criterion for the Fiscal 2018 Employee Restricted Stock Performance Award is based upon the achievement of certain levels of return on equity (as defined in the agreement), ranging from 11.0% to 18.0%, for the fiscal year ended March 31, 2018. All restricted shares will be earned if the return on equity is 18.0% or greater, and the percentage of shares earned will be reduced proportionately to approximately 66.7% if the return on equity is 11.0%. If the Company does not achieve a return on equity of at least 11.0%, 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		11.00%
Share-based compensation vesting date			Mar. 31, 2019
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		18.00%
Share-based compensation vesting date			Mar. 31, 2021
Time Vesting Restricted Stock [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares available for future grant		43,874
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	11,444		330,000
Share-based compensation vesting period	6 months
Weighted-average period of recognition of unrecognized compensation cost			2 years 3 months 18 days
Weighted average grant date fair value, shares granted			$ 100.05	$ 76.67	$ 81.30
Unrecognized compensation cost			$ 17.0
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			1,386,296