Derivative Financial Instruments (Details 2) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Oct. 31, 2018	Oct. 31, 2017	Oct. 31, 2018	Oct. 31, 2017
Gains and losses recognized in cost of products sold on derivatives not designated as qualified hedging instruments
Total gains (losses) recognized in cost of products sold	$ (2.4)	$ (9.6)	$ (28.6)	$ (2.7)
Commodity contracts
Gains and losses recognized in cost of products sold on derivatives not designated as qualified hedging instruments
Total gains (losses) recognized in cost of products sold	(3.2)	(13.9)	(30.1)	2.5
Foreign currency exchange contracts
Gains and losses recognized in cost of products sold on derivatives not designated as qualified hedging instruments
Total gains (losses) recognized in cost of products sold	$ 0.8	$ 4.3	$ 1.5	$ (5.2)