Discontinued Operations and Disposal Groups (Details) - USD ($) $ in Millions	3 Months Ended			9 Months Ended
	Jan. 31, 2021	Jul. 31, 2020	Jan. 31, 2020	Jan. 31, 2021	Jan. 31, 2020
Discontinued Operations and Disposal Groups [Abstract]
Disposal Group, Including Discontinued Operation, Assets		$ 50
Proceeds from Divestiture of Businesses				$ 177	$ 0
Disposal Group, Not Discontinued Operation, Gain (Loss) on Disposal	$ 0	$ 127	$ 0	$ 127	$ 0