Number of stock option plans.

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Percentage of stock outperform in order for target award to vest.

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Share based compensation arrangement by share based payment award award exercisable period.

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Share based compensation arrangement by share based payment award percentage of award achieved.

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Share based compensation arrangement by share based payment award performance period.

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Share based compensation percentage of target award granted for calculating maximum aggregate award of performance share.

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- Definition

Represents the expense recognized during the period arising from equity-based compensation arrangements (for example, shares of stock, unit, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees.

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-Publisher SEC
-Name Staff Accounting Bulletin (SAB)
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- Definition

Securities (including those issuable pursuant to contingent stock agreements) that could potentially dilute basic earnings per share (EPS) or earnings per unit (EPU) in the future that were not included in the computation of diluted EPS or EPU because to do so would increase EPS or EPU amounts or decrease loss per share or unit amounts for the period presented.

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-Name Accounting Standards Codification
-Glossary Antidilution
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-Name Accounting Standards Codification
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-Name Accounting Standards Codification
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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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Unrecognized cost of unvested share-based awards, other than options, awarded to employees as compensation.

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No definition available.

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Unrecognized cost of unvested options awarded to employees as compensation.

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No definition available.

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The aggregate amount of noncash, equity-based employee remuneration. This may include the value of stock or unit options, amortization of restricted stock or units, and adjustment for officers' compensation. As noncash, this element is an add back when calculating net cash generated by operating activities using the indirect method.

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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.

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- Definition

The number of grants made 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).

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The number of equity-based payment instruments, excluding stock (or unit) options, that vested during the reporting period.

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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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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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-Section 50
-Paragraph 2
-Subparagraph (d)(2)
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- Definition

Amount of difference between fair value of the underlying shares reserved for issuance and exercise price of fully vested and expected to vest options that are exercisable.

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- Definition

Amount by which the current fair value of the underlying stock exceeds the exercise price of fully vested and expected to vest options outstanding.

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-Name Accounting Standards Codification
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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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-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 02
-Paragraph 29, 30
-Article 5

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Gross value of stock (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). Stock 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

Amount of stock repurchase plan authorized.

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

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Stockholders' Equity - Additional Information (Detail)	3 Months Ended	9 Months Ended		12 Months Ended
Stockholders' Equity - Additional Information (Detail)	Jan. 31, 2015 USD ($) shares	Jan. 31, 2016 USD ($) OptionPlan shares	Jan. 31, 2015 USD ($) shares	Apr. 30, 2015	Apr. 30, 2014	Apr. 30, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Senior Notes Indenture, number of shares allowed for repurchase \| $		$ 50,000,000
Repurchase of common stock		0
Number of stock option plans \| OptionPlan		2
Intrinsic value of stock outstanding \| $	$ 12,700,000	$ 19,200,000	$ 12,700,000
Intrinsic value of stock exercisable \| $	$ 12,400,000	19,200,000	12,400,000
Intrinsic value of stock exercised \| $		9,100,000	$ 1,700,000
Unrecognized compensation cost of outstanding options \| $		$ 0
Shares issued under employee stock purchase plan		92,249	84,081
Stock-based compensation expense \| $		$ 4,885,000	$ 4,249,000
Performance period		3 years
Percentage of maximum aggregate award granted		200.00%
Percentage of stock outperform in order for target award to vest				5.00%	10.00%	10.00%
2013 Incentive Stock Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Period of award vested exercisable		10 years
Minimum \| 2013 Incentive Stock Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Period to award vested and calculate volatility rate		3 years
Maximum \| 2013 Incentive Stock Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Period to award vested and calculate volatility rate		4 years
2011 ESPP
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of common stock issuable with antidilutive effect	134,866		70,978
RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock units, awarded			452,600
RSUs \| Without Market Conditions
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock units, awarded		201,242
RSUs \| Non-Executive Employees
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock units, awarded		170,826
RSUs \| Director
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock units, awarded		30,416	50,500
RSUs \| Executive Officer
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock units, awarded			25,000
PSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock units, awarded		104,000	46,600
Share based payment award percentage of award achieved		173.30%
PSUs \| Without Market Conditions
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock units, awarded		5,379
PSUs \| Executive Officer
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock units, vested		180,231	93,200
PSUs \| Non-Executive Officer
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock units, awarded		5,379
RSUs and PSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock units, awarded		282,852	499,200
Stock units, vested		363,285	318,171
Stock-based compensation expense \| $		$ 4,500,000	$ 3,700,000
Value of shares issued for vested awards \| $		$ 6,300,000	$ 3,700,000
Weighted average remaining contractual term		1 year 4 months 24 days
Unrecognized compensation cost related to unvested RSUs and PSUs \| $		$ 5,800,000