v2.4.0.8

Income Taxes - Additional Information (Detail) (USD $) | 12 Months Ended |
--- | --- | ---
Apr. 30, 2014 | Apr. 30, 2013 | Apr. 30, 2012
Schedule Of Income Taxes [Line Items] |  |  |
Research and development credit carry-forwards | $ 3,497,000 | $ 3,169,000 |
Excess stock based compensation tax deductions | 32,100,000 |  |
Net deferred tax assets | 19,710,000 | 19,941,000 |
Income tax benefit | 1,400,000 | 2,500,000 |
Deferred tax assets, valuation allowance increase | 14,800,000 | 18,000,000 |
Permanently reinvested undistributed earnings | 5,100,000 | 3,700,000 | 2,700,000
Permanently reinvested undistributed earnings, tax impact of distribution | 1,700,000 | 1,300,000 | 900,000
Statutory income tax rate | 34.00% |  |
Unrecognized tax benefits if recognized, that would affect the effective tax rate | 1,900,000 |  |
Internal Revenue Service (IRS) |  |  |
Schedule Of Income Taxes [Line Items] |  |  |
Net operating loss carry-forwards | 190,900,000 | 148,500,000 |
Net operating loss carry-forwards, beginning expiration year | 2026 |  |
Research and development credit carry-forwards | 4,800,000 | 4,000,000 |
Tax credit carry-forwards, beginning expiration year | 2026 |  |
State and Local Jurisdiction |  |  |
Schedule Of Income Taxes [Line Items] |  |  |
Net operating loss carry-forwards | 83,500,000 | 46,200,000 |
Net operating loss carry-forwards, beginning expiration year | 2015 |  |
Research and development credit carry-forwards | $ 1,400,000 | $ 800,000 |
Tax credit carry-forwards, beginning expiration year | 2033 |  |

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- Definition Amount after allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences and carryforwards. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (b),(c) -URI http://asc.fasb.org/extlink&oid=6907707&loc=d3e32537-109319 + Details
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- Definition Amount before allocation of valuation allowances of deferred tax asset attributable to deductible research tax credit carryforwards. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 6 -URI http://asc.fasb.org/extlink&oid=6907707&loc=d3e32621-109319 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 8 -URI http://asc.fasb.org/extlink&oid=6907707&loc=d3e32632-109319 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 3 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=6907707&loc=d3e32559-109319 + Details
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- Definition Amount of deferred tax liability not recognized because of the exceptions to comprehensive recognition of deferred taxes related to undistributed earnings of foreign subsidiaries. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 30 -Section 50 -Paragraph 2 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=6424122&loc=d3e41874-109331 + Details
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- Definition The total amount of unrecognized tax benefits that, if recognized, would affect the effective tax rate. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 15A -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=6907707&loc=SL6600010-109319 + Details
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