XML 36 R50.htm IDEA: XBRL DOCUMENT
v2.4.0.8

Significant Accounting Policies (Details) (USD $) In Billions, unless otherwise specified | 12 Months Ended
--- | ---
Sep. 30, 2014 item | Sep. 30, 2013 | Sep. 30, 2012 | Sep. 30, 2011
Fiscal Year |  |  |  |
Fiscal year period |  | 364 days | 364 days | 364 days
Revenue Recognition |  |  |  |
Other direct costs | $ 3.5 | $ 3.2 | $ 3.0 |
Cost-Plus Contracts |  |  |  |
Number of major types of cost-plus contracts the Company enters into | 2 |  |  |
Fixed Price Contracts |  |  |  |
Number of types of fixed price contracts | 2 |  |  |
Pension Plans |  |  |  |
Amortization period of the difference between actual return and expected return | 5 years |  |  |
Specified percentage to be exceeded for amortization of cumulative, net unrecognized gains or losses (as a percent) | 10.00% |  |  |

X
- Details
Name: | acm_CostPlusContractsAbstract
Namespace Prefix: | acm_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Represents the percentage of the greater of the projected benefit obligation or the market related value of plan assets that has to be exceeded for amortization of cumulative net unrecognized gains or losses. + References No definition available. + Details
Name: | acm_DefinedBenefitPensionPlanAmortizationOfGainsLossesSpecifiedPercentageToBeExceeded
Namespace Prefix: | acm_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Represents the amortization period of the difference between the actual return (including capital, dividends, and interest) and the expected return in PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. + References No definition available. + Details
Name: | acm_DefinedBenefitPensionPlanAmortizationPeriodOfDifferenceBetweenActualReturnAndExpectedReturn
Namespace Prefix: | acm_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | acm_FiscalYearAbstract
Namespace Prefix: | acm_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Represents the entity's fiscal year period in PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. + References No definition available. + Details
Name: | acm_FiscalYearPeriod
Namespace Prefix: | acm_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | acm_FixedPriceContractsAbstract
Namespace Prefix: | acm_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Represents the number of major types of cost-plus contracts that the entity enters into. + References No definition available. + Details
Name: | acm_NumberOfMajorTypesOfCostPlusContracts
Namespace Prefix: | acm_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition Represents the number of types of fixed price contracts. + References No definition available. + Details
Name: | acm_NumberOfTypesOfFixedPriceContracts
Namespace Prefix: | acm_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | acm_PensionPlansAbstract
Namespace Prefix: | acm_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Other costs incurred and are directly related to services rendered by an entity during the reporting period. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 225 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03.2(d)) -URI http://asc.fasb.org/extlink&oid=26872669&loc=d3e20235-122688 + Details
Name: | us-gaap_OtherCostOfServices
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Details
Name: | us-gaap_RevenueRecognitionAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration