Stockholders' Equity - Share Based Payment Award Performance Shares Valuation Assumptions (Parenthetical) (Detail)	12 Months Ended
Apr. 30, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance based restricted stock unit performance period	3 years
PSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance based restricted stock unit performance period	3 years

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

No definition available.

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