Income Taxes - Provision for income taxes from continuing operations (Details) - USD ($) $ in Millions	12 Months Ended
	Jul. 31, 2020	Jul. 31, 2019	Jul. 31, 2018
Current:
Federal	$ 372	$ 271	$ 197
State	79	67	38
Foreign	21	14	14
Total current	472	352	249
Deferred:
Federal	(47)	(23)	(14)
State	(47)	(4)	2
Foreign	(6)	(1)	0
Total deferred	(100)	(28)	(12)
Total provision for income taxes	$ 372	$ 324	$ 237