Income Taxes (Details 1) - USD ($) $ in Millions	12 Months Ended
	Apr. 30, 2020	Apr. 30, 2019	Apr. 30, 2018
Current:
Federal	$ 188.7	$ 227.9	$ 277.9
Foreign	8.5	16.0	7.9
State and local	42.4	36.8	40.0
Deferred:
Federal	7.1	(73.6)	(802.3)
Foreign	0.6	(0.1)	0.5
State and local	(0.1)	(19.8)	(1.6)
Total income tax expense (benefit)	$ 247.2	$ 187.2	$ (477.6)