Business, Basis of Presentation and Summary of Significant Accounting Policies - Restructuring charges (Details) $ in Millions	12 Months Ended
Apr. 30, 2019 USD ($)
Selling, general and administrative expenses
Restructuring costs	$ 5.0

Amount of expenses associated with exit or disposal activities pursuant to an authorized plan. Excludes expenses related to a discontinued operation or an asset retirement obligation.

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration