Name:	abm_AvailableforsaleDebtSecuritiesOriginalPrincipalAmount
Namespace Prefix:	abm_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

The number of different issuers of the auction rate securities held by the Company.

No definition available.

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Namespace Prefix:	abm_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

Amount before tax of unrealized gain in accumulated other comprehensive income (AOCI) on investments in debt securities classified as available-for-sale.

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

This item represents the cost of debt securities, which are categorized neither as held-to-maturity nor trading, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments recognized, as defined), and fair value hedge accounting adjustments, if any.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
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-Section 50
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-Name Accounting Standards Codification
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Amount of debt securities categorized neither as held-to-maturity nor trading.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
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Period Type:	instant

The cumulative amount of credit losses recognized in earnings related to debt securities held for which a portion of an other than temporary impairment (OTTI) was recognized in other comprehensive income (a component of shareholders' equity).

Reference 1: http://www.xbrl.org/2003/role/presentationRef
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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

The cash inflow associated with the sale of debt securities classified as available-for-sale securities.

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

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.

No definition available.