Derivative Financial Instruments (Details 1) - Cash Flow Hedging [Member] - Interest rate contract [Member] - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Oct. 31, 2018	Oct. 31, 2017	Oct. 31, 2018	Oct. 31, 2017
Derivative Instruments, Gain (Loss) [Line Items]
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, before Tax	$ 7.9	$ 1.0	$ 10.5	$ 3.5
Change in accumulated other comprehensive income (loss)	8.0	1.2	10.7	3.8
Interest Expense [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) reclassified from accumulated other comprehensive income (loss) to interest expense	$ (0.1)	$ (0.2)	$ (0.2)	$ (0.3)