v3.5.0.1

Stockholders' Equity - Additional Information (Details) - USD ($) $ / shares in Units, $ in Millions | 12 Months Ended
--- | ---
Apr. 30, 2016 | Apr. 30, 2015 | Apr. 30, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number | 6,688,000 | 5,093,000 | 7,091,000
Number of non-vested shares | 4,967,000 | 3,488,000 | 2,977,000
Options granted | 2,947,000 | 939,000 |
Other Stock Related Expense Benefit |  | $ 0.4 |
Restricted shares |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition | 2 years 9 months 18 days |  |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Fair Value | $ 8.5 | $ 6.2 | $ 3.6
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized | $ 19.8 |  |
Stock Options |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value | $ 2.06 | $ 3.47 | $ 4.32
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Intrinsic Value | $ 0.4 | $ 4.5 | $ 18.6
Employee Service Share-based Compensation, Cash Received from Exercise of Stock Options | 0.9 | 5.2 |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested in Period, Fair Value | 4.2 | 6.1 | $ 9.7
Employee Service Share-based Compensation, Nonvested Awards, Compensation Not yet Recognized, Stock Options | $ 6.5 |  |
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition | 2 years 5 months 24 days |  |
Two Thousand Five Stock Option Plan [Member] |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage | 25.00% |  |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number | 1,150,119 |  |
Common Stock, Capital Shares Reserved for Future Issuance | 1,150,119 |  |
2012 Equity incentive plan [Member] |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage | 25.00% |  |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number | 5,525,724 |  |
Share-based Compensation Arrangement by Share-based Payment Award, Purchase Price of Common Stock, Percent | 110.00% |  |
Number of non-vested shares | 4,753,516 |  |
Options granted | 6,193,865 |  |
Employee Stock Purchase Plan [Member] |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Purchase Price of Common Stock, Percent | 85.00% |  |
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant | 2,612,952 |  |
Share Based Compensation Arrangement By Share Based Payment Award Amount Held For Future Purchases | $ 0.3 |  |
Share-based Compensation Arrangement by Share-based Payment Award, Shares Purchased for Award | 660,036 |  |
Share-based Compensation Arrangement by Share-based Payment Award, Per Share Weighted Average Price of Shares Purchased | $ 3.52 |  |
2005 Equity Incentive Plan [Member] |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number | 12,357 |  |
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant | 12,357 |  |
General and Administrative Expense [Member] |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Estimated Liability For Taxes Interest And Related Items |  | 2.2 |
Loss From Discontinued Operations, Net Of Tax [Member] |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Estimated Liability For Taxes Interest And Related Items |  | $ 0.8 |

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- Definition Aggregate number of common shares reserved for future issuance. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.29) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
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- Definition Aggregate proceeds received by the entity during the annual period from exercises of stock or unit options and conversion of similar instruments granted under equity-based payment arrangements. + 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 (j) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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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 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) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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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. + 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 (c)(2)(i)-(ii) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition Fair value of share-based awards for which the grantee gained the right by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash. + 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 (d)(2) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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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 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=6415400&loc=d3e5070-113901 + Details
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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 Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (d)(2) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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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 Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (d)(1) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition Number of options outstanding, including both vested and non-vested options. + 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=6415400&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 2 -Subparagraph (c)(1)(i)-(ii) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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