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Employee Benefit Plans - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified | 12 Months Ended
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Apr. 30, 2014 | Apr. 30, 2013 | Apr. 30, 2012
Employee Stock Purchase Plan [Line Items] |  |  |
Employer contributions | $ 784 | $ 645 | $ 603
Defined contribution plan , description | We provide an employer matching contribution equal to fifty cents for every dollar an employee invests in the 401(k) Plan up to our maximum match of one thousand dollars per calendar year, subject to revision. |  |
Employer contributions vesting period | Three year |  |
Class A Common Stock [Member] |  |  |
Employee Stock Purchase Plan [Line Items] |  |  |
Discount rate | 15.00% |  |
Reserve for stock issuance | 900 |  |
Stock issued under stock purchase plan | 70 | 76 | 65
Stock available for distribution under stock purchase plan | 113 |  |

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- Definition The minimum period that the individual is required to perform services in order to be fully vested under the deferred compensation arrangement. + 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 (a)(1) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition Amount of discretionary contributions made by an employer to a defined contribution plan. + References No definition available. + Details
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- Definition Description of the terms and benefits provided by the employer's defined contribution plans. A defined contribution plan provides benefits in return for services rendered, provides an individual account for each participant, and has terms that specify how contributions to the individual's account are to be determined rather than the amount of benefits the individual is to receive. Under a defined contribution pension plan, the benefits a participant will receive depend solely on the amount contributed to the participant's account, the returns earned on investments of those contributions, and forfeitures of other participants' benefits that may be allocated to such participant's account. A description of the plan(s) including employee groups covered, the basis for determining contributions, and the nature and effects of significant matters affecting comparability of information for all periods presented. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 70 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6414718&loc=d3e28014-114942 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Defined Contribution Postretirement Plan -URI http://asc.fasb.org/extlink&oid=6510416 + Details
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- Definition Discount rate from fair value on purchase date that participants pay for 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 -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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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 Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (a)(3) -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 Number of shares issued during the period as a result of an employee stock purchase plan. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 04 -Article 3 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21463-112644 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.3-04) -URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 29, 30 -Article 5 + Details
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