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Commitments and Contingencies - Refinery Turnaround Project (Details) - Refinery Turnaround Project - USD ($) $ in Millions	1 Months Ended
	Dec. 31, 2019	Apr. 30, 2019	Mar. 31, 2019	Sep. 30, 2023
Commitments and Contingencies
Amount of work outside original contract				$ 90.0
Payment entitled to				$ 144.0
Construction lien against the refinery for unpaid labor and materials costs		$ 132.0
A Refinery in Montana
Commitments and Contingencies
Damages sought, counter party	$ 93.0		$ 79.0

X

- Definition

The value of construction lien filed against a counter-party related to contract agreement.

+ References

No definition available.

+ Details

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Namespace Prefix:	acm_
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Balance Type:	debit
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X

- Definition

Amount of payment from counter party the entity is entitled to..

+ References

No definition available.

+ Details

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Namespace Prefix:	acm_
Data Type:	xbrli:monetaryItemType
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X

- Definition

The value of the award the counter party seeks in the legal matter.

+ References

No definition available.

+ Details

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- Definition

N/A

+ References

No definition available.

+ Details

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X

- Definition

Amount of cost incurred on construction contract for unapproved change order, claim, or similar item subject to uncertainty.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 910
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482332/910-20-50-1

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- Details

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X

- Details

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