Business, Basis of Presentation and Summary of Significant Accounting Policies - Recent Accounting Pronouncements (Details) $ in Millions	6 Months Ended
Oct. 31, 2017 USD ($)
ASU 2016 09
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Excess tax benefits	$ 1.1

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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Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration