Income Taxes (Narrative) (Details) - USD ($) $ in Millions	9 Months Ended
Jan. 31, 2019	Jan. 31, 2018	Apr. 30, 2018
Income Tax Disclosure [Abstract]
Effective tax rate	25.40%	7.70%
Unrecognized tax benefits	$ 178.1	$ 163.1	$ 186.1
Gross unrecognized tax benefits increase (decrease)	(8.0)	$ 13.1
Change in tax benefits that are reasonably possible	46.7
Increase in deferred tax assets	$ 107.3

Percentage of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

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The increase (decrease) during the reporting period in the account that represents the temporary difference that results from Income or Loss that is recognized for accounting purposes but not for tax purposes and vice versa.

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The amount of the unrecognized tax benefit of a position taken for which it is reasonably possible that the total amount thereof will significantly increase or decrease within twelve months of the balance sheet date.

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Amount of unrecognized tax benefits.

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Amount of increase (decrease) in unrecognized tax benefits attributable to uncertain tax positions taken in tax returns.

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