Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jan. 31, 2021	Jan. 31, 2020	Jan. 31, 2021	Jan. 31, 2020
Income Tax Disclosure [Abstract]
Income tax expense	$ 0.2	$ 0.1	$ 0.5	$ 0.3