Derivative Financial Instruments (Details 1) - Cash Flow Hedging [Member] - Interest rate contracts - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Oct. 31, 2019	Oct. 31, 2018	Oct. 31, 2019	Oct. 31, 2018
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) recognized in other comprehensive income (loss)	$ (44.1)	$ 7.9	$ (97.1)	$ 10.5
Change in accumulated other comprehensive income (loss)	(44.0)	8.0	(96.9)	10.7
Interest Expense [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) reclassified from accumulated other comprehensive income (loss) to interest expense	$ (0.1)	$ (0.1)	$ (0.2)	$ (0.2)