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		6 Months Ended
	Jan. 31, 2019	Jan. 31, 2018	Jan. 31, 2019	Jan. 31, 2018	Oct. 31, 2018	Jul. 31, 2018	Oct. 31, 2017	Jul. 31, 2017
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating activities			$ 198	$ 174
Investing activities			(41)	(436)
Financing activities			(477)	258
Effect of exchange rates on cash, cash equivalents, restricted cash, and restricted cash equivalents			(2)	3
Net decrease in cash, cash equivalents, restricted cash, and restricted cash equivalents			(322)	(1)
Prepaid expenses and other current assets	$ 253		253			$ 202
Long-term deferred income taxes						2
Other assets						213
Deferred revenue	639		639			581
Other current liabilities	257		257			198
Long-term deferred revenue	3		3			3
Other long-term obligations						184
Stockholders’ equity	2,796	$ 1,721	2,796	1,721	$ 2,782	2,816	$ 1,562	$ 1,699
Net revenue	1,502	1,339	2,518	2,249
Selling and marketing	548	469	894	777
Operating income	233	194	223	159
Income tax provision (benefit)	46	10	(2)	(25)
Net income (loss)	$ 189	$ 183	$ 223	$ 181
Diluted net loss per share (in dollars per share)	$ 0.72	$ 0.70	$ 0.84	$ 0.70
Previously Reported
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating activities				$ 174
Investing activities				(486)
Financing activities				258
Effect of exchange rates on cash, cash equivalents, restricted cash, and restricted cash equivalents				3
Net decrease in cash, cash equivalents, restricted cash, and restricted cash equivalents				(51)
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		$ 1,165		2,051
Selling and marketing		469		777
Operating income		20		(37)
Income tax provision (benefit)		40		(2)
Net income (loss)		$ (21)		$ (38)
Diluted net loss per share (in dollars per share)		$ (0.08)		$ (0.15)
Restatement Adjustment | Accounting Standards Update 2016-18
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating activities				$ 0
Investing activities				50
Financing activities				0
Effect of exchange rates on cash, cash equivalents, restricted cash, and restricted cash equivalents				0
Net decrease in cash, cash equivalents, restricted cash, and restricted cash equivalents				50
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		$ 174		198
Selling and marketing		0		0
Operating income		174		196
Income tax provision (benefit)		(30)		(23)
Net income (loss)		$ 204		$ 219
Diluted net loss per share (in dollars per share)		$ 0.78		$ 0.85