Income Taxes - Unrecognized tax benefits (Details) - USD ($) $ in Millions	12 Months Ended
	Jul. 31, 2021	Jul. 31, 2020	Jul. 31, 2019
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Gross unrecognized tax benefits, beginning balance	$ 101	$ 120	$ 90
Increases related to tax positions from prior fiscal years, including acquisitions	69	2	13
Decreases related to tax positions from prior fiscal years	0	(35)	0
Increases related to tax positions taken during current fiscal year	31	21	23
Settlements with tax authorities	0	(1)	(1)
Lapse of statute of limitations	(11)	(6)	(5)
Gross unrecognized tax benefits, ending balance	$ 190	$ 101	$ 120