Stockholders' Equity - Share-Based Compensation Expense (Details) - USD ($)	3 Months Ended		9 Months Ended
	Apr. 30, 2019	Apr. 30, 2018	Apr. 30, 2019	Apr. 30, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation	$ 98,000,000	$ 92,000,000	$ 303,000,000	$ 283,000,000
Software and Software Development Costs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Capitalized computer software, gross	1,000,000	0	3,000,000	2,000,000
Cost of revenue
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation	15,000,000	14,000,000	44,000,000	30,000,000
Selling and marketing
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation	23,000,000	25,000,000	78,000,000	75,000,000
Research and development
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation	32,000,000	30,000,000	101,000,000	99,000,000
General and administrative
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation	$ 28,000,000	$ 23,000,000	$ 80,000,000	$ 79,000,000