Income Taxes - Provision for income taxes from continuing operations (Details) - USD ($) $ in Millions	12 Months Ended
	Jul. 31, 2019	Jul. 31, 2018	Jul. 31, 2017
Current:
Federal	$ 271	$ 197	$ 345
State	67	38	36
Foreign	14	14	8
Total current	352	249	389
Deferred:
Federal	(23)	(14)	12
State	(4)	2	2
Foreign	(1)	0	2
Total deferred	(28)	(12)	16
Total provision for income taxes	$ 324	$ 237	$ 405