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Fair Value of Financial Instruments - Non-Financial Assets Measured at Fair Value on a Non-Recurring Basis (Details) - USD ($) | 3 Months Ended | 9 Months Ended
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Jul. 31, 2020 | Jul. 31, 2020
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Goodwill, impairment loss | $ 0 | $ 163,800,000
Impairment of intangible assets | $ 0 |
Education |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Goodwill, impairment loss |  | 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 |  | 9,000,000.0
Impairment of intangible assets |  | 3,400,000
Impairment of intangible assets, gross |  | (8,700,000)
Impairment of intangible assets, accumulated amortization |  | $ 5,300,000

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- Definition 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. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 20 -Section 50 -Paragraph 2 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=108376223&loc=d3e13854-109267 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=118932676&loc=d3e3602-108585 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (e) -URI http://asc.fasb.org/extlink&oid=108376223&loc=d3e13816-109267 Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 20 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=99380562&loc=d3e13777-109266 + Details
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