Income Taxes - Unrecognized Tax Benefits (Details) - USD ($) $ in Millions	12 Months Ended
	Jul. 31, 2020	Jul. 31, 2019	Jul. 31, 2018
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Gross unrecognized tax benefits, beginning balance	$ 120	$ 90	$ 61
Increases related to tax positions from prior fiscal years, including acquisitions	2	13	10
Decreases related to tax positions from prior fiscal years	(35)	0	(3)
Increases related to tax positions taken during current fiscal year	21	23	23
Settlements with tax authorities	(1)	(1)	(1)
Lapse of statute of limitations	(6)	(5)	0
Gross unrecognized tax benefits, ending balance	$ 101	$ 120	$ 90