This element represents loss contingency amount estimated recovery from third party

No definition available.

Name:	acm_LossContingencyAmountEstimatedRecoveryFromThirdParty
Namespace Prefix:	acm_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

This element represents the amount paid to the federal government for completed and fully operational projects as well as damages and civil penalties (including doubling and trebling of damages) for violation of the statutes.

+ References

No definition available.

+ Details

Name:	acm_LossContingencyPaymentsIncludingDamagesAndCivilPenalties
Namespace Prefix:	acm_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Represents the minimum information about estimated cost to complete the project and promised amenities

+ References

No definition available.

+ Details

Name:	acm_MinimumEstimatedCostToCompleteProjectAndPromisedAmenities
Namespace Prefix:	acm_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Represents the information pertaining to number of initial public offering investors.

+ References

No definition available.

+ Details

Name:	acm_NumberOfInitialPublicOfferingInvestors
Namespace Prefix:	acm_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

This element represents the number of the projects failure to comply with U.S. Agency for International Development (USAID) source, origin, and nationality regulations.

+ References

No definition available.

+ Details

Name:	acm_NumberOfProjectsFailedToComplyRegulations
Namespace Prefix:	acm_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the amount of securities acquired by investors

+ References

No definition available.

+ Details

Name:	acm_SecuritiesAcquiredByInvestors
Namespace Prefix:	acm_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of long-term debt before deduction of unamortized discount or premium. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt, with initial maturities beyond one year or the normal operating cycle, if longer.

+ References

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 20

-Article 5

Reference 2: 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)

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 22

-Article 5

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 16

-Article 9

+ Details

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

- Details

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

- Definition

Amount of damages paid to the plaintiff in the legal matter.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 450

-SubTopic 20

-Section 50

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=25496072&loc=d3e14326-108349

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 450

-SubTopic 20

-Section 50

-Paragraph 4

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=25496072&loc=d3e14435-108349

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 450

-SubTopic 20

-Section 50

-Paragraph 9

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=25496072&loc=d3e14557-108349

+ Details

Name:	us-gaap_LossContingencyDamagesPaidValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The value (monetary amount) of the award the plaintiff seeks in the legal matter.

+ References

+ Details

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

- Definition

Reflects the estimated amount of loss from the specified contingency as of the balance sheet date.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 450

-SubTopic 20

-Section 50

-Paragraph 4

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=25496072&loc=d3e14435-108349

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 450

-SubTopic 20

-Section 50

-Paragraph 9

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=25496072&loc=d3e14557-108349

+ Details

Name:	us-gaap_LossContingencyEstimateOfPossibleLoss
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Number of defendants named in a legal action.

+ References

No definition available.

+ Details

Name:	us-gaap_LossContingencyNumberOfDefendants
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

The estimated maximum amount of possible loss from the contingency.

+ References

+ Details

Name:	us-gaap_LossContingencyRangeOfPossibleLossMaximum
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The estimated minimum amount of possible loss from the contingency.

+ References

+ Details

Name:	us-gaap_LossContingencyRangeOfPossibleLossMinimum
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The difference between the maximum amount of estimated loss and the amount recorded as of the balance sheet date.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 450

-SubTopic 20

-Section 05

-Paragraph 5

-URI http://asc.fasb.org/extlink&oid=6395354&loc=d3e12631-108344

+ Details

Name:	us-gaap_LossContingencyRangeOfPossibleLossPortionNotAccrued
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The cash inflow associated with the amount received from entity's first offering of stock to the public.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Financing Activities

-URI http://asc.fasb.org/extlink&oid=6513228

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 14

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3255-108585

+ Details

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

Commitments and Contingencies (Details)	0 Months Ended		0 Months Ended			1 Months Ended		1 Months Ended	0 Months Ended	6 Months Ended	12 Months Ended	6 Months Ended	0 Months Ended
Commitments and Contingencies (Details)	Jun. 17, 2014 AUD	Mar. 31, 2015 Standby Letters of Credit USD ($)	Oct. 17, 2014 USAID Egyptian Projects URS Corporation Washington Group International USD ($) item project	Mar. 31, 2015 DOE Deactivation Demolition And Removal Project Member URS Corporation Washington Group International USD ($)	Mar. 31, 2015 DOE Deactivation Demolition And Removal Project Member Department of Energy Member USD ($)	Dec. 31, 2014 DOE Deactivation Demolition And Removal Project Member Department of Energy Member URS Corporation Washington Group International USD ($)	Mar. 31, 2015 DOE Deactivation Demolition And Removal Project Member Department of Energy Member URS Corporation Washington Group International USD ($)	Jan. 31, 2010 Canadian Pipeline Contract Member URS Corporation Flint Energy Services Ltd Member CAD	Dec. 06, 2014 Waste Isolation Pilot Plant Environmental Incidents Member URS Corporation Nuclear Waste Partnership LLC Member USD ($)	Mar. 31, 2015 AECOM Australia item	Sep. 30, 2006 AECOM Australia AUD	Mar. 31, 2014 RCM applicants AUD	Jun. 17, 2014 Portigon AG AUD
Commitments and Contingencies
Contingency liability of general and professional liability insurance programs and for payment and performance guarantees		$ 439,000,000
Number of subcontractors			2
Number of projects failed to comply USAID regulations			5
Amount paid to federal government for the five completed and operational projects ( including damages and civil penalties)			373,000,000
Projects costs, minimum				146,000,000	106,000,000		106,000,000
Projects costs, maximum							146,000,000
Total project costs				300,000,000
Amount recovery ( including additional Fees)						103,000,000
Minimum cost to complete the project						100,000,000
Civil penalty Amount									17,700,000
Proceeds from initial public offering (IPO)											700,000,000
Bank loan											1,400,000,000
Number of initial public offering investors										770
Damages claimed by applicants								85,000,000				1,680,000,000	76,000,000
Securities acquired by investors	155,000,000acm_SecuritiesAcquiredByInvestors