Stockholders' Equity - Share-Based Compensation Expense (Details) - USD ($) $ in Millions	3 Months Ended
	Oct. 31, 2018	Oct. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation	$ 105	$ 97
Software and Software Development Costs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Capitalized computer software, gross	1	1
Cost of revenue
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation	14	3
Selling and marketing
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation	30	25
Research and development
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation	35	39
General and administrative
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation	$ 26	$ 30