Amount of loss from the write-down of an asset representing the future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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Name:	us-gaap_GoodwillImpairmentLoss
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Summary of Significant Accounting Policies - Goodwill and Intangible Assets (Details) - USD ($) $ in Millions	12 Months Ended
	Jul. 31, 2020	Jul. 31, 2019	Jul. 31, 2018
Finite-Lived Intangible Assets [Line Items]
Goodwill impairment	$ 0	$ 0	$ 0
Minimum
Finite-Lived Intangible Assets [Line Items]
Estimated useful lives	8 years
Maximum
Finite-Lived Intangible Assets [Line Items]
Estimated useful lives	20 years