Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Oct. 31, 2021	Oct. 31, 2020	Oct. 31, 2021	Oct. 31, 2020
Income Tax Disclosure [Abstract]
Income tax expense	$ 0.0	$ 0.2	$ 0.4	$ 0.3