Statements of Consolidated Shareholders' Equity (Parenthetical) - USD ($) $ in Millions	12 Months Ended
Apr. 30, 2017	Apr. 30, 2016	Apr. 30, 2015
Statement of Stockholders' Equity [Abstract]
Tax benefit of stock plans	$ 0.0	$ 2.7	$ 5.9

Amount of increase (decrease) in additional paid in capital (APIC) resulting from a tax benefit (deficiency) associated with an share-based compensation plan other than an employee stock ownership plan (ESOP).

No definition available.

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