Insurance - Insurance Related Balances and Activity (Details) - USD ($) $ in Millions	Apr. 30, 2017	Oct. 31, 2016
Liability for Claims and Claims Adjustment Expense [Line Items]
Insurance recoverables	$ 69.8	$ 69.7
Claim Types Excluding Medical and Dental
Liability for Claims and Claims Adjustment Expense [Line Items]
Insurance claim reserves	432.7	417.9
Medical and Dental Self Insurance Program [Member]
Liability for Claims and Claims Adjustment Expense [Line Items]
Insurance claim reserves	$ 6.8	$ 5.9

Carrying amount as of the balance sheet date of amounts expected to be recovered under the terms of insurance contracts.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.17)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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Balance Type:	debit
Period Type:	instant

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
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- Definition

Carrying amount (including both current and noncurrent portions) of accrued known and estimated losses incurred as of the balance sheet date for which no insurance coverage exists, and for which a claim has been made or is probable of being asserted, typically arising from workmen's compensation-type of incidents and personal injury to nonemployees from accidents on the entity's property.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.24)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Details

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Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	abm_InsurancePoliciesAxis=abm_MedicalAndDentalSelfInsuranceProgramMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: