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Namespace Prefix:	acm_
Data Type:	num:percentItemType
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Period Type:	duration

Represents the average effective interest rate during the period, net of the impact of the interest rate swaps.

No definition available.

Name:	acm_LineOfCreditFacilityInterestRateDuringPeriodNetOfInterestRateSwap
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Data Type:	num:percentItemType
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Period Type:	duration

Sum of the carrying values as of the balance sheet date of all debt, including all short-term borrowings, long-term debt, and capital lease obligations.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
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-Subparagraph (SX 210.9-03.13,16)
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-Paragraph 1
-Subparagraph (SX 210.7-03.16)
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Name:	us-gaap_DebtAndCapitalLeaseObligations
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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Face (par) amount of debt instrument at time of issuance.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
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Name:	us-gaap_DebtInstrumentFaceAmount
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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Fair value portion of debt instrument payable, including, but not limited to, notes payable and loans payable.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
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Name:	us-gaap_DebtInstrumentFairValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Contractual interest rate for funds borrowed, under the debt agreement.

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 210.5-02.22(a)(1))
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Name:	us-gaap_DebtInstrumentInterestRateStatedPercentage
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Data Type:	num:percentItemType
Balance Type:	na
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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.

Name:	us-gaap_DebtInstrumentLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

End date of debt instrument redemption period, in CCYY-MM-DD format.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
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Name:	us-gaap_DebtInstrumentRedemptionPeriodEndDate
Namespace Prefix:	us-gaap_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

Start date of debt instrument redemption period, in CCYY-MM-DD format.

Name:	us-gaap_DebtInstrumentRedemptionPeriodStartDate
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Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

Percentage price of original principal amount of debt at which debt can be redeemed by the issuer.

Name:	us-gaap_DebtInstrumentRedemptionPricePercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

Percentage of principal amount of debt redeemed.

No definition available.

Name:	us-gaap_DebtInstrumentRedemptionPricePercentageOfPrincipalAmountRedeemed
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

The total amount of the contingent obligation under letters of credit outstanding as of the reporting date.

No definition available.

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

Amount of borrowing capacity currently available under the credit facility (current borrowing capacity less the amount of borrowings outstanding).

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
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-Paragraph 1
-Subparagraph (SX 210.5-02.19(b),22(b))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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

The fair value amount of long-term debt whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission.

No definition available.

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

Name:	us-gaap_DebtInstrumentAxis=acm_OtherDebtMember
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Data Type:	na
Balance Type:
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Name:	us-gaap_DebtInstrumentAxis=acm_UnsecuredCreditFacilitiesMember
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Data Type:	na
Balance Type:
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Name:	us-gaap_DebtInstrumentAxis=acm_SeniorNotes5.75Due2022AndSeniorNotes5.875Due2024Member
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Name:	us-gaap_DebtInstrumentAxis=acm_SeniorNotes5.75Due2022Member
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Name:	us-gaap_DebtInstrumentRedemptionPeriodAxis=us-gaap_DebtInstrumentRedemptionPeriodOneMember
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Name:	us-gaap_DebtInstrumentAxis=acm_SeniorNotes5.875Due2024Member
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Name:	us-gaap_DebtInstrumentRedemptionPeriodAxis=us-gaap_DebtInstrumentRedemptionPeriodTwoMember
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Name:	us-gaap_DebtInstrumentRedemptionPeriodAxis=us-gaap_DebtInstrumentRedemptionPeriodThreeMember
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Name:	us-gaap_DebtInstrumentAxis=us-gaap_SeniorNotesMember
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Data Type:	na
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Name:	us-gaap_BusinessAcquisitionAxis=acm_UrsCorporationMember
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Data Type:	na
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Name:	us-gaap_DebtInstrumentAxis=acm_SeniorNotes3.85PercentDue2017Member
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Name:	us-gaap_DebtInstrumentAxis=acm_SeniorNotes5.00PercentDue2022Member
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