Stockholders' Equity - Share-Based Compensation Expense (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
Jul. 31, 2019	Jul. 31, 2018	Jul. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense	$ 401	$ 382	$ 326
Income tax benefit	(200)	(199)	(179)
Decrease in net income	201	183	147
Software and Software Development Costs
Decrease in net income per share:
Share-based compensation expense	$ 4	$ 3	$ 7
Share Based Compensation Expense
Decrease in net income per share:
Basic (in dollars per share)	$ 0.77	$ 0.71	$ 0.57
Diluted (in dollars per share)	$ 0.76	$ 0.70	$ 0.56
Cost of product revenue
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense	$ 1	$ 3	$ 0
Cost of service and other revenue
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense	57	40	8
Selling and marketing
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense	103	101	88
Research and development
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense	136	133	122
General and administrative
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense	104	105	108
Total share-based compensation expense
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense	$ 401	$ 382	$ 326

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