Represents the consolidated interest coverage ratio.

No definition available.

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- Definition

Percentage points added to the reference rate to compute the variable rate on the debt instrument.

+ References

No definition available.

+ Details

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- Definition

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

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 1B
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=123466505&loc=SL123495323-112611

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(1))
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

+ Details

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- Definition

Face (par) amount of the original debt instrument that was repurchased.

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- References

No definition available.

+ Details

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Data Type:	xbrli:stringItemType
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Period Type:	duration

- Definition

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

+ References

No definition available.

+ Details

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

- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.19(b),22(b))
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

+ Details

Name:	us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity
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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

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

+ References

+ Details

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

- Definition

The cash inflow during the period from additional borrowings in aggregate debt. Includes proceeds from short-term and long-term debt.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 14
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=123570139&loc=d3e3255-108585

+ Details

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

- Definition

Indebtedness divided by net capital.

+ References

No definition available.

+ Details

Name:	us-gaap_RatioOfIndebtednessToNetCapital1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	instant

- Details

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- Details

Name:	us-gaap_VariableRateAxis=us-gaap_BaseRateMember
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- Details

Name:	us-gaap_VariableRateAxis=us-gaap_LondonInterbankOfferedRateLIBORMember
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- Details

Name:	us-gaap_CreditFacilityAxis=acm_TermLoanFacilityMember
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Name:	us-gaap_CreditFacilityAxis=acm_TermBFacilityMember
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Name:	us-gaap_DebtInstrumentAxis=acm_CreditAgreementMember
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Name:	us-gaap_DebtInstrumentAxis=acm_SeniorNotes2024Member
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Debt - Credit Agreement (Details)			3 Months Ended
Debt - Credit Agreement (Details)	Apr. 13, 2021 USD ($)	Feb. 08, 2021 USD ($)	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)	Sep. 30, 2021 USD ($)	Jun. 25, 2021 USD ($)
Debt agreements
Current borrowing capacity			$ 466,500,000
Proceeds from secured delayed draw term loan facility			441,013,000	$ 409,710,000
2014 Credit Agreement \| Base Rate
Debt agreements
Interest rate, basis spread (as a percent)		0.225%
2014 Credit Agreement \| LIBOR
Debt agreements
Interest rate, basis spread (as a percent)		1.225%
2014 Credit Agreement \| Term loan A
Debt agreements
Maximum borrowing capacity						$ 215,000,000
2014 Credit Agreement \| Term B facility
Debt agreements
Maximum borrowing capacity	$ 700,000,000
2014 Credit Agreement \| Term B facility \| Base Rate
Debt agreements
Interest rate, basis spread (as a percent)	0.75%
2014 Credit Agreement \| Term B facility \| Euro currency rate
Debt agreements
Interest rate, basis spread (as a percent)	1.75%
2014 Credit Agreement \| Revolving credit facility
Debt agreements
Current borrowing capacity			1,144,800,000		$ 1,144,800,000
Outstanding letters of credit			$ 5,200,000		$ 5,200,000
Credit Agreement
Debt agreements
Consolidated leverage ratio		4.00	2.40
Consolidated interest coverage ratio		3.00
Credit Agreement \| Term loan A
Debt agreements
Maximum borrowing capacity		$ 246,968,737.50
Credit Agreement \| Revolving credit facility
Debt agreements
Maximum borrowing capacity		$ 1,150,000,000
2024 Senior Notes
Debt agreements
Cash tender	$ 700,000,000
Interest rate (as a percent)	5.875%					5.875%