Purchase price paid by employees for common stock through an employee stock purchase plan.

No definition available.

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- Definition

Full Value Stock to Stock Options Ratio

+ References

No definition available.

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- Definition

The annual payments that will be made for five years commencing on the seventh anniversary of the grant date.

+ References

No definition available.

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- Definition

Unrecognized cost of unvested share-based compensation awards.

+ 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 (i)
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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.

+ References

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- Definition

Amount of cash outflow to satisfy an employee's income tax withholding obligation as part of a net-share settlement of a share-based award.

+ References

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- Definition

Amount of cash inflow from exercise of stock options granted under share-based compensation arrangement.

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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

The number of non-vested equity-based payment instruments, excluding stock (or unit) options, that validly exist and are outstanding as of the balance sheet date.

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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 highest percentage of annual salary that an employee is permitted to utilize with respect to the plan.

+ References

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- Definition

Number of additional shares authorized for issuance under an established share-based compensation plan.

+ References

No definition available.

+ Details

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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).

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- Definition

The difference between the maximum number of shares (or other type of equity) authorized for issuance under the plan (including the effects of amendments and adjustments), and the sum of: 1) the number of shares (or other type of equity) already issued upon exercise of options or other equity-based awards under the plan; and 2) shares (or other type of equity) reserved for issuance on granting of outstanding awards, net of cancellations and forfeitures, if applicable.

+ References

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- Definition

Purchase price of common stock expressed as a percentage of its fair value.

+ References

No definition available.

+ Details

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- Definition

For net-share settlement of share-based awards when the employer settles employees' income tax withholding obligations, this element represents the number of shares the employees use to repay the employer.

+ References

No definition available.

+ Details

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- Definition

Number of shares issued during the period as a result of an employee stock purchase plan.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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- Definition

Number of shares (or other type of equity) issued during the period as a result of any equity-based compensation plan other than an employee stock ownership plan (ESOP), net of any shares forfeited. Shares issued could result from the issuance of restricted stock, the exercise of stock options, stock issued under employee stock purchase plans, and/or other employee benefit plans.

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- Definition

Number of shares that have been repurchased during the period and are being held in treasury.

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- Definition

Equity impact of the cost of common and preferred stock that were repurchased during the period. Recorded using the cost method.

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Employee Stock Plans - Additional Information (Detail)	3 Months Ended		6 Months Ended
Employee Stock Plans - Additional Information (Detail)	Oct. 31, 2017 USD ($) shares	Oct. 31, 2016 USD ($) shares	Oct. 31, 2017 USD ($) $ / shares shares	Oct. 31, 2016 USD ($) $ / shares shares	Apr. 30, 2017 shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Payments of tax withholdings on restricted stock \| $			$ 3,461,000	$ 4,177,000
Shares repurchased during the period, value \| $	$ 25,350,000	$ 6,956,000	$ 32,722,000	$ 11,117,000
Treasury Stock, Common
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares repurchased during the period	773,923	335,500	893,279	335,500
Shares repurchased during the period, value \| $	$ 25,300,000	$ 6,900,000	$ 29,300,000	$ 6,900,000
Time Based Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period			4 years
Market Based Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period			3 years
Shares outstanding	700,000		700,000
Total unrecognized compensation cost related to non-vested awards \| $	$ 11,400,000		$ 11,400,000
Performance Based Restricted Stock Unit
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period			3 years
Shares outstanding	200,000		200,000
Total unrecognized compensation cost related to non-vested awards \| $	$ 5,600,000		$ 5,600,000
Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares outstanding	1,733,000		1,733,000		1,581,000
Total unrecognized compensation cost related to non-vested awards \| $	$ 40,500,000		$ 40,500,000
Expected cost recognized over weighted-average period			2 years 6 months
Shares repurchased during the period to pay for taxes	2,888		100,371	186,517
Payments of tax withholdings on restricted stock \| $	$ 100,000		$ 3,400,000	$ 4,200,000
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Proceeds from issuance of common stock upon exercise of employee stock options \| $		$ 200,000	$ 600,000	$ 600,000
Stock Options \| Common Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock issued for stock options exercised	0	11,620	41,075	44,090
Stock Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock incentive plan, additional number of shares			5,500,000
Maximum number of shares reserved for issuance	11,200,000		11,200,000
Issuance of full-value stock awards limitation, required ratio to stock options	2.3		2.3
ESPP
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Maximum number of shares reserved for issuance	3,000,000		3,000,000
Authorized payroll deductions	15.00%		15.00%
Authorized payroll deductions, value \| $			$ 25,000
Fair market price of common stock			85.00%
Shares available for future issuance	1,200,000		1,200,000
Employees stock purchased	0	0	116,285	114,011
Employees stock purchased, price per share \| $ / shares			$ 29.35	$ 17.60