Fair Value of Financial Instruments - Narrative (Details)	3 Months Ended		9 Months Ended
	Jul. 31, 2021 USD ($)	Apr. 30, 2020 USD ($) reportingUnit	Jul. 31, 2021 USD ($)	Jul. 31, 2020 USD ($)	Oct. 31, 2020 USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impairment loss on fixed assets			$ 9,100,000	$ 0
Carrying value of fixed assets	$ 111,800,000		111,800,000		$ 133,700,000
Goodwill reporting units | reportingUnit		3
Goodwill, impairment loss		$ 163,800,000
Education
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Goodwill, impairment loss		99,300,000		$ 99,300,000
Aviation
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Goodwill, impairment loss		55,500,000
Impairment of intangible assets		5,600,000
Impairment of intangible assets, gross		13,800,000
Impairment of intangible assets, accumulated amortization		8,200,000
Technical Solutions
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Goodwill, impairment loss		9,000,000
Impairment of intangible assets		3,400,000
Impairment of intangible assets, gross		8,700,000
Impairment of intangible assets, accumulated amortization		$ 5,300,000
Corporate | Internal Use Software
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impairment loss on fixed assets	9,100,000		9,100,000
Carrying value of fixed assets	$ 0		$ 0