Stockholders' Equity - Share-Based Compensation Expense (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Apr. 30, 2018	Apr. 30, 2017	Apr. 30, 2018	Apr. 30, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated share-based compensation expense	$ 92	$ 71	$ 283	$ 241
Software and Software Development Costs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Capitalized computer software, gross			2	6
Cost of revenue
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated share-based compensation expense	14	2	30	6
Selling and marketing
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated share-based compensation expense	25	19	75	66
Research and development
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated share-based compensation expense	30	24	99	89
General and administrative
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated share-based compensation expense	$ 23	$ 26	$ 79	$ 80