Estimated Liability

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- Definition

Exercise Price Of Stock Options Granted Percentage

+ References

No definition available.

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- Definition

Percentage Of Stock Options Vesting In Period Of One Year

+ References

No definition available.

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- Definition

Share Based Compensation Arrangement by Share Based Payment Award, Expiration Term

+ References

No definition available.

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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.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

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-Paragraph A240

-Subparagraph g(1)

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-Publisher SEC

-Name Staff Accounting Bulletin (SAB)

-Number Topic 14

-Section F

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- Definition

Aggregate number of common shares reserved for future issuance.

+ References

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-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 129

-Paragraph 4

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-Topic 210

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-Subparagraph (SX 210.5-02.29)

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- Definition

Amounts due to employees, not to include stockholders or officers. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer).

+ References

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-Publisher FASB

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-Subparagraph (SX 210.4-08.(k)(1))

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-Name Regulation S-X (SX)

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-Section 08

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-Subparagraph 1

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-Publisher FASB

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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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-Subparagraph (SX 210.5-02.19(a))

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-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 19

-Subparagraph a

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- Definition

As of the balance sheet date, the aggregate unrecognized cost of equity-based awards made to employees under equity-based compensation awards that have yet to vest.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

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-Paragraph A240

-Subparagraph h

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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

Aggregate unrecognized cost of option awards made to employees under a stock option plan or plans, that have yet to vest.

+ References

No definition available.

+ Details

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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 estimated dividend rate (a percentage of the share price) to be paid (expected dividends) to holders of the underlying shares over the option's term.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

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-Paragraph A240

-Subparagraph e(2)(c)

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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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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-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

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-Paragraph A240

-Subparagraph a

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

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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

The total accumulated difference between fair values of underlying shares on dates of exercise and exercise price on options which were exercised (or share units converted) into shares during the reporting period under the plan.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

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- Definition

The weighted average grant-date fair value of options granted during the reporting period as calculated by applying the disclosed option pricing methodology.

+ References

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-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 123R

-Paragraph A240

-Subparagraph c(1)

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-Publisher FASB

-Name Accounting Standards Codification

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- Definition

The number of shares reserved for issuance under stock option agreements awarded under the plan that validly exist and are outstanding as of the balance sheet date, including vested options.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

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-Topic 718

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-Name Statement of Financial Accounting Standard (FAS)

-Number 123R

-Paragraph A240

-Subparagraph b(1)(a)

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-Name Statement of Financial Accounting Standard (FAS)

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- Definition

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

+ References

No definition available.

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Stock Options - Additional Information (Detail) (USD $)	12 Months Ended
Stock Options - Additional Information (Detail) (USD $)	Apr. 30, 2013	Apr. 30, 2012	Apr. 30, 2011
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options to purchase shares of common stock outstanding	10,829,000	12,083,000	11,691,000
Expected dividend yield assumed	0.00%
Weighted-average grant date fair value of options granted	$ 5.75	$ 5.14	$ 2.81
Aggregate intrinsic value of options exercised	$ 42,800,000	$ 10,800,000	$ 4,600,000
Stock-based expense	22,500,000	7,700,000	4,700,000
Total unrecognized stock-based expense related to unvested stock options	22,500,000
Future period share-based expense period of recognition	2 years 10 months 17 days
General and Administrative Expense
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based expense	13,373,000	3,295,000	1,850,000
Estimated liability for taxes, interest and related items	2,200,000
Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Future period share-based expense period of recognition	3 years 2 months 23 days
Future period share-based expense	9,000,000
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected dividend yield assumed	0.00%	0.00%	0.00%
Stock-based expense	9,800,000
Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock share reserved to permit exercise of options outstanding	1,137,123
Stock option granted price, percentage	85.00%
Employee Stock Purchase Plan \| Accrued Expenses and Other Current Liabilities
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Amount held on behalf of employees for future stock purchases	$ 300,000
2005 Stock Option Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options to purchase shares of common stock outstanding	6,843,506
Common shares reserved for Employee Stock Purchase Plan	6,843,506
2012 Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares of common stock authorized for issuance	3,247,038
Common stock share reserved to permit exercise of options outstanding	3,247,038
Option granted , vesting percentage	25.00%
2012 Equity Incentive Plan \| Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise price as a percentage of the fair market value of common stock	100.00%
2012 Equity Incentive Plan \| Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options, maximum term	10 years
2012 Equity Incentive Plan \| Share Based Awards To More Than Ten Percent Owners \| Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise price as a percentage of the fair market value of common stock	110.00%
2012 Equity Incentive Plan \| Share Based Awards To More Than Ten Percent Owners \| Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options, maximum term	5 years
2012 Equity Incentive Plan \| Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share based award, vesting period	4 years
2012 Equity Incentive Plan \| Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share based award, vesting period	4 years
2005 Equity Incentive Plan \| Power Reviews
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options to purchase shares of common stock outstanding	738,645
Common stock share reserved to permit exercise of options outstanding	738,645