Gain on Sale of Business (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Oct. 31, 2020	Oct. 31, 2019	Oct. 31, 2020	Oct. 31, 2019	Jul. 31, 2020
Gain on Sale of Business [Abstract]
Proceeds from Divestiture of Businesses			$ 177	$ 0
Disposal Group, Including Discontinued Operation, Assets					$ 50
Disposal Group, Not Discontinued Operation, Gain (Loss) on Disposal	$ 0	$ 0	$ 127	$ 0