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

Goodwill and Other Intangible Assets - Narrative (Details)	3 Months Ended		12 Months Ended
	Apr. 30, 2021 reportingUnit	Apr. 30, 2020 USD ($)	Oct. 31, 2021 USD ($)	Oct. 31, 2020 USD ($)
Goodwill [Line Items]
Goodwill, impairment loss		$ 163,800,000	$ 0	$ 163,800,000
Number of reporting units evaluated for impairment \| reportingUnit	3
Education
Goodwill [Line Items]
Goodwill, impairment loss		99,300,000		99,300,000
Aviation
Goodwill [Line Items]
Goodwill, impairment loss		55,500,000		55,500,000
Technical Solutions
Goodwill [Line Items]
Goodwill, impairment loss		$ 9,000,000		$ 9,000,000.0