Stockholders' Equity - Share-Based Compensation Expense (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jan. 31, 2020	Jan. 31, 2019	Jan. 31, 2020	Jan. 31, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation	$ 107	$ 100	$ 218	$ 205
Software and Software Development Costs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Capitalized computer software, gross	1	1	2	2
Cost of revenue
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation	14	15	29	29
Selling and marketing
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation	29	25	59	55
Research and development
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation	37	34	75	69
General and administrative
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation	$ 27	$ 26	$ 55	$ 52