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Fair Value of Financial Instruments - Narrative (Details) $ in Millions | 3 Months Ended | 6 Months Ended |
--- | --- | --- | ---
Apr. 30, 2020 USD ($) | Apr. 30, 2020 USD ($) | Apr. 30, 2021 reportingUnit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Goodwill reporting units | reportingUnit |  |  | 3
Goodwill, impairment loss | $ 163.8 |  |
Education |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Goodwill, impairment loss | 99.3 | $ 99.3 |
Aviation |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Goodwill, impairment loss | 55.5 |  |
Impairment of intangible assets | 5.6 |  |
Impairment of intangible assets, gross | 13.8 |  |
Impairment of intangible assets, accumulated amortization | 8.2 |  |
Technical Solutions |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Goodwill, impairment loss | 9.0 |  |
Impairment of intangible assets | 3.4 |  |
Impairment of intangible assets, gross | 8.7 |  |
Impairment of intangible assets, accumulated amortization | $ 5.3 |  |

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