Description of Business and Summary of Significant Accounting Policies - Additional Information (Details) - USD ($)	12 Months Ended
	Jul. 31, 2019	Jul. 31, 2018	Jul. 31, 2017
Property, Plant and Equipment [Line Items]
Deferred revenue, revenue recognized	$ 581,000,000	$ 574,000,000
Revenue, performance obligation, description of timing	P12M
Long-term deferred revenue	$ 4,000,000	3,000,000
Advertising expense	800,000,000	615,000,000	$ 480,000,000
Notes receivable	$ 95,000,000	55,000,000
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	4 years
Minimum
Property, Plant and Equipment [Line Items]
Capitalized contract cost, amortization period	3 years
Property and Equipment, Useful Life (in years)	2 years
Acquired Intangible Assets, Useful Life (in years)	3 years
Minimum | Accounting Standards Update 2016-02 | Pro Forma
Property, Plant and Equipment [Line Items]
Right-of-use assets	$ 320,000,000
Lease liabilities	$ 320,000,000
Maximum
Property, Plant and Equipment [Line Items]
Capitalized contract cost, amortization period	4 years
Property and Equipment, Useful Life (in years)	30 years
Acquired Intangible Assets, Useful Life (in years)	7 years
Maximum | Accounting Standards Update 2016-02 | Pro Forma
Property, Plant and Equipment [Line Items]
Right-of-use assets	$ 370,000,000
Lease liabilities	$ 370,000,000
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)	6 years
Restatement Adjustment | Accounting Standards Update 2014-09
Property, Plant and Equipment [Line Items]
Long-term deferred revenue		$ (194,000,000)