Income Taxes (Narrative) (Details) (USD $) In Millions, unless otherwise specified	6 Months Ended
	Oct. 31, 2014	Oct. 31, 2013	Apr. 30, 2014
Income Tax Disclosure [Abstract]
Unrecognized Tax Benefits	$ 112.9	$ 129.8	$ 111.5
Significant (Increase) Decrease in Unrecognized Tax Benefits is Reasonably Possible, Estimated Range of Change, Upper Bound	18
Unrecognized Tax Benefits, Period Increase (Decrease)	1.4	16.6
Effect of anticipated settlements of audit issues and expiring statutes of limitations	11.6
Effective tax rate, excluding discrete tax items	37.80%	38.70%
Effective Income Tax Rate Reconciliation, Percent	41.00%	40.60%
Net Discreet Tax Expense (Benefit)	$ (12.1)	$ (6.9)