Description of Business and Summary of Significant Accounting Policies - Schedule of Impact of ASU 2016-18 and ASU 2014-09 (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		9 Months Ended
	Apr. 30, 2019	Apr. 30, 2018	Apr. 30, 2019	Apr. 30, 2018	Jan. 31, 2019	Jul. 31, 2018	Jan. 31, 2018	Jul. 31, 2017
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating activities			$ 2,446	$ 2,149
Investing activities			(301)	(541)
Financing activities			(641)	(469)
Effect of exchange rates on cash, cash equivalents, restricted cash, and restricted cash equivalents			(6)	(7)
Net increase in cash, cash equivalents, restricted cash, and restricted cash equivalents			1,498	1,132
Prepaid expenses and other current assets	$ 255		255			$ 202
Long-term deferred income taxes						2
Other assets						213
Deferred revenue	572		572			581
Other current liabilities						198
Long-term deferred revenue	5		5			3
Other long-term obligations						184
Stockholders’ equity	4,070	$ 2,912	4,070	2,912	$ 2,796	2,816	$ 1,721	$ 1,699
Net revenue	3,272	2,912	5,790	5,161
Selling and marketing	652	549	1,546	1,326
Operating income	1,784	1,601	2,007	1,760
Income tax provision	419	417	417	392
Net income	$ 1,378	$ 1,186	$ 1,601	$ 1,367
Diluted net loss per share (in dollars per share)	$ 5.22	$ 4.53	$ 6.06	$ 5.25
Previously Reported
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating activities				$ 2,149
Investing activities				(588)
Financing activities				(469)
Effect of exchange rates on cash, cash equivalents, restricted cash, and restricted cash equivalents				(7)
Net increase in cash, cash equivalents, restricted cash, and restricted cash equivalents				1,085
Prepaid expenses and other current assets						184
Long-term deferred income taxes						87
Other assets						190
Deferred revenue						961
Other current liabilities						191
Long-term deferred revenue						197
Other long-term obligations						123
Stockholders’ equity						2,354
Net revenue		$ 2,925		4,976
Selling and marketing		549		1,326
Operating income		1,615		1,578
Income tax provision		417		415
Net income		$ 1,200		$ 1,162
Diluted net loss per share (in dollars per share)		$ 4.59		$ 4.47
Restatement Adjustment | Accounting Standards Update 2016-18
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating activities				$ 0
Investing activities				47
Financing activities				0
Effect of exchange rates on cash, cash equivalents, restricted cash, and restricted cash equivalents				0
Net increase in cash, cash equivalents, restricted cash, and restricted cash equivalents				47
Restatement Adjustment | Accounting Standards Update 2014-09
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Prepaid expenses and other current assets						18
Long-term deferred income taxes						(85)
Other assets						23
Deferred revenue						(380)
Other current liabilities						7
Long-term deferred revenue						(194)
Other long-term obligations						61
Stockholders’ equity						$ 462
Net revenue		$ (13)		185
Selling and marketing		0		0
Operating income		(14)		182
Income tax provision		0		(23)
Net income		$ (14)		$ 205
Diluted net loss per share (in dollars per share)		$ (0.06)		$ 0.78