Description of Business and Summary of Significant Accounting Policies - Additional Information (Details) - USD ($)	12 Months Ended
	Jul. 31, 2018	Jul. 31, 2017	Jul. 31, 2016
Property, Plant and Equipment [Line Items]
Product revenue recognition period (in years)	3 years
Advertising expense	$ 615,000,000	$ 480,000,000	$ 394,000,000
Notes receivable	55,000,000	0
Allowance for loan losses	$ 0
Business Combination Measurement Period (in years)	1 year
Goodwill impairment charges	$ 0	0	0
Acquired intangible asset impairment	$ 0	$ 0	0
Acquired Intangible Assets, Useful Life (in years)	4 years	6 years
Income tax provision	$ 292,000,000	$ 396,000,000	$ 397,000,000
Tax cuts and jobs act of 2017, incremental tax benefit	$ 73,000,000
Minimum
Property, Plant and Equipment [Line Items]
Property and Equipment, Useful Life (in years)	2 years
Acquired Intangible Assets, Useful Life (in years)	1 year
Maximum
Property, Plant and Equipment [Line Items]
Property and Equipment, Useful Life (in years)	30 years
Acquired Intangible Assets, Useful Life (in years)	7 years
Software Development | Minimum
Property, Plant and Equipment [Line Items]
Property and Equipment, Useful Life (in years)	3 years
Software Development | Maximum
Property, Plant and Equipment [Line Items]
Property and Equipment, Useful Life (in years)	5 years
Restatement Adjustment | Accounting Standards Update 2014-09
Property, Plant and Equipment [Line Items]
Tax cuts and jobs act of 2017, incremental tax benefit, change in rate	$ 18,000,000
Pro Forma
Property, Plant and Equipment [Line Items]
Income tax provision	237,000,000	405,000,000
Pro Forma | Restatement Adjustment | Accounting Standards Update 2014-09
Property, Plant and Equipment [Line Items]
Decrease in deferred revenue	574,000,000	514,000,000
Increase in deferred tax liabilities	146,000,000	201,000,000
Income tax provision	$ (55,000,000)	$ 9,000,000