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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

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- Definition Number of reporting units tested for impairment of goodwill. A reporting unit is an operating segment or one level below an operating segment. + References No definition available. + Details
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