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Stockholders' Equity - Summary of Grant Activity for Stock Options, Restricted Stock Units, Performance Stock Units and Restricted Stock Awards (Detail) (USD $) | 12 Months Ended
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Apr. 30, 2013 | Apr. 30, 2012 | Apr. 30, 2011
Schedule Of Stock Option Activity [Line Items] |  |  |
Stock Options, Granted | 388 |  |
Total grant activity | 1,123 | 618 | 1,310
Total grant activity, unissued | 920 | 346 | 333
Stock Options [Member] |  |  |
Schedule Of Stock Option Activity [Line Items] |  |  |
Stock Options, Granted | 388 | 7 | 280
Stock options, Weighted Average Grant Date Fair Value | 3.03 | 4.14 | 2.85
Unissued | 388 | 7 | 250
Restricted Stock Units [Member] |  |  |
Schedule Of Stock Option Activity [Line Items] |  |  |
Performance stock units, Granted | 340 | 305 | 499
Performance stock units, Weighted Average Grant Date Fair Value | 5.15 | 6.12 | 3.57
Unissued | 273 | 143 | 83
Unissued | 1,088 | 1,380 |
Performance Stock Units [Member] |  |  |
Schedule Of Stock Option Activity [Line Items] |  |  |
Performance stock units, Granted | 316 | 255 | 469
Performance stock units, Weighted Average Grant Date Fair Value | 5.17 | 6.06 | 4.20
Unissued | 259 | 196 |
Restricted Stock Awards [Member] |  |  |
Schedule Of Stock Option Activity [Line Items] |  |  |
Performance stock units, Granted | 79 | 51 | 62
Performance stock units, Weighted Average Grant Date Fair Value | 4.45 | 5.83 | 4.81
Unissued |  |  |

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- Definition The total number of equity based compensation grants including stock options, PSUs, RSUs and RSAs. + References No definition available. + Details
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- Definition The total number of equity based compensation grants including stock options, PSUs, RSUs and RSAs that remain unvested and unissued at the balance sheet date. + References No definition available. + Details
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- Definition The number of non-vested stock options that validly exist and are outstanding as of the balance sheet date. + References No definition available. + Details
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- Details
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- Definition The number of non-vested RSUs that validly exist and are outstanding as of the balance sheet date. + References No definition available. + Details
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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). + 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)(iii)(1) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 123R -Paragraph A240 -Subparagraph b(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. + Details
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- Definition The weighted average fair value at grant date for nonvested equity-based awards issued 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). + 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)(iii)(1) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 123R -Paragraph A240 -Subparagraph c(1) -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. Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 123R -Paragraph A240 -Subparagraph b(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. + 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 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 123R -Paragraph A240 -Subparagraph b(2)(b) -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. Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 123R -Paragraph A240 -Subparagraph b(2)(a) -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. + Details
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- Definition Gross number of share options (or share units) granted during the period. + References No definition available. + 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 Statement of Financial Accounting Standard (FAS) -Number 123R -Paragraph A240 -Subparagraph c(1) -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. Reference 2: 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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