Derivative Financial Instruments (Details 2) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Jul. 31, 2013	Jul. 31, 2012
Gains and losses recognized in cost of products sold on derivatives not designated as qualified hedging instruments
Unrealized gains recognized in cost of products sold	$ 4.6	$ 19.7
Realized (losses) gains recognized in cost of products sold	(5.4)	(7.7)
Total (losses) gains recognized in cost of products sold	(0.8)	12.0
[CommodityContractMember]
Gains and losses recognized in cost of products sold on derivatives not designated as qualified hedging instruments
Unrealized gains recognized in cost of products sold	4.5	19.6
Realized (losses) gains recognized in cost of products sold	(6.4)	(7.8)
[ForeignExchangeContractMember]
Gains and losses recognized in cost of products sold on derivatives not designated as qualified hedging instruments
Unrealized gains recognized in cost of products sold	0.1	0.1
Realized (losses) gains recognized in cost of products sold	$ 1.0	$ 0.1