Description of Business and Summary of Significant Accounting Policies - Schedule of Impact of Topic 606 (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	Jul. 31, 2019	Apr. 30, 2019	Jan. 31, 2019	Oct. 31, 2018	Jul. 31, 2018	Apr. 30, 2018	Jan. 31, 2018	Oct. 31, 2017	Jul. 31, 2019	Jul. 31, 2018	Jul. 31, 2017	Jul. 31, 2016	[1]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Prepaid expenses and other current assets	$ 266				$ 202				$ 266	$ 202
Long-term deferred income tax liabilities	1				2				1	2
Other assets					213					213
Deferred revenue	619				581				619	581
Other current liabilities	202				198				202	198
Long-term deferred revenue	4				3				4	3
Other long-term obligations					184					184
Stockholders’ equity	3,749				2,816				3,749	2,816	$ 1,699	$ 1,492
Net revenue	994	$ 3,272	$ 1,502	$ 1,016	864	$ 2,912	$ 1,339	$ 910	6,784	6,025	5,196
Cost of revenue										978	810
Selling and marketing									1,927	1,631	1,415
Operating income	$ (153)	$ 1,784	$ 233	$ (10)	$ (200)	$ 1,601	$ 194	$ (35)	1,854	1,560	1,418
Income tax provision									$ 324	237	405
Net income										$ 1,329	$ 985
Diluted net income per share (in dollars per share)	$ (0.17)	$ 5.22	$ 0.72	$ 0.13	$ (0.15)	$ 4.53	$ 0.70	$ (0.01)	$ 5.89	$ 5.09	$ 3.78
As Reported
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Prepaid expenses and other current assets					$ 184					$ 184
Long-term deferred income tax liabilities					87					87
Other assets					190					190
Deferred revenue					961					961
Other current liabilities					191					191
Long-term deferred revenue					197					197
Other long-term obligations					123					123
Stockholders’ equity					2,354					2,354
Net revenue										5,964	$ 5,177
Cost of revenue										977	809
Selling and marketing										1,634	1,420
Operating income										1,497	1,395
Income tax provision										292	396
Net income										$ 1,211	$ 971
Diluted net income per share (in dollars per share)										$ 4.64	$ 3.72
Accounting Standards Update 2014-09 | Topic 606 Adjustment
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Prepaid expenses and other current assets					18					$ 18
Long-term deferred income tax liabilities					(85)					(85)
Other assets					23					23
Deferred revenue					(380)					(380)
Other current liabilities					7					7
Long-term deferred revenue					(194)					(194)
Other long-term obligations					61					61
Stockholders’ equity					$ 462					462
Net revenue										61	$ 19
Cost of revenue										1	1
Selling and marketing										(3)	(5)
Operating income										63	23
Income tax provision										(55)	9
Net income										$ 118	$ 14
Diluted net income per share (in dollars per share)										$ 0.45	$ 0.06

[1] The cumulative effect adjustment to retained earnings related to the adoption of ASU 2014-09, “Revenue from Contracts with Customers (Topic 606)” as of July 31, 2016 was $331 million.