Description of Business and Summary of Significant Accounting Policies - Additional Information (Details) - USD ($)	12 Months Ended
	Jul. 31, 2020	Jul. 31, 2019	Jul. 31, 2018	Aug. 01, 2019
Property, Plant and Equipment [Line Items]
Net change in customer fund deposits	$ (19,000,000)	$ (69,000,000)	$ 5,000,000
Deferred revenue, revenue recognized	$ 619,000,000	581,000,000
Revenue, performance obligation, description of timing	P12M
Long-term deferred revenue	$ 13,000,000	4,000,000
Advertising expense	778,000,000	800,000,000	615,000,000
Notes receivable	$ 40,000,000	95,000,000
Business combination measurement period	1 year
Goodwill impairment charges	$ 0	$ 0	0
Acquired intangible assets, useful life	4 years	4 years
Acquired intangible asset impairment	$ 0	$ 0	0
Operating lease right-of-use assets	226,000,000
Lease liabilities	267,000,000
Elimination of deferred rent liabilities	$ 0	(47,000,000)
Accounting Standards Update 2016-02
Property, Plant and Equipment [Line Items]
Operating lease right-of-use assets				$ 319,000,000
Lease liabilities				361,000,000
Elimination of deferred rent liabilities				47,000,000
Elimination of prepaid rent				$ 5,000,000
Minimum
Property, Plant and Equipment [Line Items]
Capitalized contract cost, amortization period	3 years
Property and equipment, useful life	2 years
Acquired intangible assets, useful life	3 years
Maximum
Property, Plant and Equipment [Line Items]
Capitalized contract cost, amortization period	4 years
Property and equipment, useful life	30 years
Acquired intangible assets, useful life	7 years
Software Development | Minimum
Property, Plant and Equipment [Line Items]
Property and equipment, useful life	3 years
Software Development | Maximum
Property, Plant and Equipment [Line Items]
Property and equipment, useful life	6 years
Restatement Adjustment
Property, Plant and Equipment [Line Items]
Net change in customer fund deposits		$ 69,000,000	$ (5,000,000)
Small Business Administration (SBA), CARES Act, Paycheck Protection Program
Property, Plant and Equipment [Line Items]
Loans held for sale	$ 98,000,000