Income Taxes (Narrative) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Jul. 31, 2014	Jul. 31, 2013	Apr. 30, 2014
Operating Loss Carryforwards [Line Items]
Unrecognized Tax Benefits	$ 128.1	$ 145.3	$ 111.5
Significant (Increase) Decrease in Unrecognized Tax Benefits is Reasonably Possible, Estimated Range of Change, Upper Bound	21
Unrecognized Tax Benefits, Period Increase (Decrease)	16.6	1.1
Effect of anticipated settlements of audit issues and expiring statutes of limitations	$ 4.4
Effective tax rate, excluding discrete tax items	38.10%	38.70%