Description of Business and Summary of Significant Accounting Policies - Narrative (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Apr. 30, 2020	Apr. 30, 2019	Apr. 30, 2020	Apr. 30, 2019	Aug. 01, 2019	Jul. 31, 2019
Capitalized Contract Cost [Line Items]
Net change in customer fund deposits			$ (47)	$ 16
Deferred revenue recognized	$ 89	$ 83	$ 598	559
Timing of performance obligation			12 months
Long-term deferred revenue	6		$ 6			$ 4
Notes receivable	89		89			95
Operating lease right-of-use assets	220		220
Present value of lease liabilities	265		265
Deferred rent liability	$ 0		$ 0			$ (47)
Accounting Standards Update 2016-02
Capitalized Contract Cost [Line Items]
Operating lease right-of-use assets					$ 319
Present value of lease liabilities					361
Deferred rent liability					47
Prepaid rent					$ 5
Restatement adjustment
Capitalized Contract Cost [Line Items]
Net change in customer fund deposits				$ 16