Derivative Financial Instruments (Details 1) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jan. 31, 2016	Jan. 31, 2015	Jan. 31, 2016	Jan. 31, 2015
Cash flow hedging derivative instruments gain loss
Change in accumulated other comprehensive loss	$ 0.1	$ (9.5)	$ 0.4	$ (28.0)
Cash Flow Hedging [Member] | Commodity contracts [Member] | Cost of Products Sold [Member]
Cash flow hedging derivative instruments gain loss
Gains (losses) reclassified from accumulated other comprehensive loss to earnings (effective portion)	0.0	9.6	0.0	28.4
Cash Flow Hedging [Member] | Interest rate contract [Member] | Interest Expense [Member]
Cash flow hedging derivative instruments gain loss
Gains (losses) reclassified from accumulated other comprehensive loss to earnings (effective portion)	$ (0.1)	$ (0.1)	$ (0.4)	$ (0.4)