Income Taxes (Components of Income Tax Expense) (Details) - USD ($) $ in Millions	12 Months Ended
	Apr. 30, 2021	Apr. 30, 2020	Apr. 30, 2019
Current:
U.S. federal	$ 146	$ 95	$ 107
Foreign	50	29	34
State and local	35	19	28
Current income tax expense	231	143	169
Deferred:
U.S. federal	(4)	34	37
Foreign	(47)	7	4
State and local	(2)	(2)	(3)
Deferred income taxes expense	(53)	39	38
Total income tax expense	$ 178	$ 182	$ 207