Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	3 Months Ended		9 Months Ended
	Jan. 31, 2022	Jan. 31, 2021	Jan. 31, 2022	Jan. 31, 2021
Basic and diluted earnings per share
Net income available to common stockholders	$ 259	$ 219	$ 687	$ 783
Share data (in thousands):
Basic average common shares outstanding	478,887	478,599	478,844	478,471
Dilutive effect of stock-based awards	1,680	2,237	1,755	2,194
Diluted average common shares outstanding	480,567	480,836	480,599	480,665
Basic earnings per share (dollars per share)	$ 0.54	$ 0.46	$ 1.43	$ 1.64
Diluted earnings per share (dollars per share)	$ 0.54	$ 0.45	$ 1.43	$ 1.63