XML 81 R60.htm IDEA: XBRL DOCUMENT v3.3.0.814

Pension Benefit Obligations (Details 3) - Pension Plan, Defined Benefit - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2015	Sep. 30, 2014
Post-retirement plan
Fair values of plan assets	$ 672.3	$ 672.3
Changes in the fair value of Level 3 assets
Fair value of plan assets at beginning of year	672.3
Fair value of plan assets at end of year	1,384.8	672.3
Cash and Cash Equivalents
Post-retirement plan
Fair values of plan assets	7.9	7.9
Changes in the fair value of Level 3 assets
Fair value of plan assets at beginning of year	7.9
Fair value of plan assets at end of year	44.4	7.9
Global equity securities
Post-retirement plan
Fair values of plan assets	52.8
Changes in the fair value of Level 3 assets
Fair value of plan assets at end of year	52.8
Domestic equity securities
Post-retirement plan
Fair values of plan assets	60.0
Changes in the fair value of Level 3 assets
Fair value of plan assets at end of year	60.0
Diversified Funds
Post-retirement plan
Fair values of plan assets	159.3	159.3
Changes in the fair value of Level 3 assets
Fair value of plan assets at beginning of year	159.3
Fair value of plan assets at end of year	287.4	159.3
Equity Funds
Post-retirement plan
Fair values of plan assets	220.3	220.3
Changes in the fair value of Level 3 assets
Fair value of plan assets at beginning of year	220.3
Fair value of plan assets at end of year	309.6	220.3
Fixed Income Funds
Post-retirement plan
Fair values of plan assets	219.3	219.3
Changes in the fair value of Level 3 assets
Fair value of plan assets at beginning of year	219.3
Fair value of plan assets at end of year	542.5	219.3
Hedge Funds
Post-retirement plan
Fair values of plan assets	27.9	27.9
Changes in the fair value of Level 3 assets
Fair value of plan assets at beginning of year	27.9
Fair value of plan assets at end of year	53.0	27.9
Assets Held by Insurance Company
Post-retirement plan
Fair values of plan assets	37.6	37.6
Changes in the fair value of Level 3 assets
Fair value of plan assets at beginning of year	37.6
Fair value of plan assets at end of year	35.1	37.6
Level 1
Post-retirement plan
Fair values of plan assets	3.4	3.4
Changes in the fair value of Level 3 assets
Fair value of plan assets at beginning of year	3.4
Fair value of plan assets at end of year	11.0	3.4
Level 1 | Cash and Cash Equivalents
Post-retirement plan
Fair values of plan assets	3.4	3.4
Changes in the fair value of Level 3 assets
Fair value of plan assets at beginning of year	3.4
Fair value of plan assets at end of year	11.0	3.4
Level 2
Post-retirement plan
Fair values of plan assets	655.2	655.2
Changes in the fair value of Level 3 assets
Fair value of plan assets at beginning of year	655.2
Fair value of plan assets at end of year	1,360.2	655.2
Level 2 | Cash and Cash Equivalents
Post-retirement plan
Fair values of plan assets	4.5	4.5
Changes in the fair value of Level 3 assets
Fair value of plan assets at beginning of year	4.5
Fair value of plan assets at end of year	33.4	4.5
Level 2 | Global equity securities
Post-retirement plan
Fair values of plan assets	52.8
Changes in the fair value of Level 3 assets
Fair value of plan assets at end of year	52.8
Level 2 | Domestic equity securities
Post-retirement plan
Fair values of plan assets	60.0
Changes in the fair value of Level 3 assets
Fair value of plan assets at end of year	60.0
Level 2 | Diversified Funds
Post-retirement plan
Fair values of plan assets	159.3	159.3
Changes in the fair value of Level 3 assets
Fair value of plan assets at beginning of year	159.3
Fair value of plan assets at end of year	287.4	159.3
Level 2 | Equity Funds
Post-retirement plan
Fair values of plan assets	220.3	220.3
Changes in the fair value of Level 3 assets
Fair value of plan assets at beginning of year	220.3
Fair value of plan assets at end of year	309.6	220.3
Level 2 | Fixed Income Funds
Post-retirement plan
Fair values of plan assets	219.3	219.3
Changes in the fair value of Level 3 assets
Fair value of plan assets at beginning of year	219.3
Fair value of plan assets at end of year	542.5	219.3
Level 2 | Hedge Funds
Post-retirement plan
Fair values of plan assets	14.2	14.2
Changes in the fair value of Level 3 assets
Fair value of plan assets at beginning of year	14.2
Fair value of plan assets at end of year	39.4	14.2
Level 2 | Assets Held by Insurance Company
Post-retirement plan
Fair values of plan assets	37.6	37.6
Changes in the fair value of Level 3 assets
Fair value of plan assets at beginning of year	37.6
Fair value of plan assets at end of year	35.1	37.6
Level 3
Post-retirement plan
Fair values of plan assets	13.7	13.7
Changes in the fair value of Level 3 assets
Fair value of plan assets at beginning of year	13.7
Fair value of plan assets at end of year	13.6	13.7
Level 3 | Hedge Funds
Post-retirement plan
Fair values of plan assets	13.7	12.6
Changes in the fair value of Level 3 assets
Fair value of plan assets at beginning of year	13.7	12.6
Defined Benefit Plan, Actual Return on Plan Assets Still Held	(0.1)	1.1
Fair value of plan assets at end of year	$ 13.6	$ 13.7

X

- Definition

Actual return on plan assets, separately identifying the amount related to assets still held at the reporting date.

+ References

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



-Publisher FASB



-Name Accounting Standards Codification



-Topic 715



-SubTopic 20



-Section 50



-Paragraph 1



-Subparagraph (d)(iv)(02)(A)



-URI http://asc.fasb.org/extlink&oid=35743120&loc=d3e1928-114920



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



-Publisher FASB



-Name Accounting Standards Codification



-Topic 715



-SubTopic 20



-Section 50



-Paragraph 5



-Subparagraph (c)(iv)(02)(A)



-URI http://asc.fasb.org/extlink&oid=35743120&loc=d3e2446-114920

+ Details

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

X

- Definition

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

+ References

No definition available.

+ Details

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

X

- Definition

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.

+ References

No definition available.

+ Details

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

X

- Definition

Assets, usually stocks, bonds, and other investments, that have been segregated and restricted (usually in a trust) to provide benefits, at their fair value as of the measurement date. Plan assets include amounts contributed by the employer (and by employees for a contributory plan) and amounts earned from investing the contributions, less benefits paid. If a plan has liabilities other than for benefits, those non-benefit obligations may be considered as reductions of plan assets.

+ References

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



-Publisher FASB



-Name Accounting Standards Codification



-Topic 715



-SubTopic 30



-Section 35



-Paragraph 50



-URI http://asc.fasb.org/extlink&oid=29635418&loc=d3e12355-114930



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



-Publisher FASB



-Name Accounting Standards Codification



-Topic 715



-SubTopic 20



-Section 50



-Paragraph 1



-Subparagraph (b)



-URI http://asc.fasb.org/extlink&oid=35743120&loc=d3e1928-114920

+ Details

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

X

- Details

Name:	us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis=us-gaap_PensionPlansDefinedBenefitMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=us-gaap_CashAndCashEquivalentsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=acm_ForeignCorporateEquitySecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=acm_DomesticCorporateEquitySecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=acm_DiversifiedFundsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=us-gaap_EquityFundsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=us-gaap_FixedIncomeFundsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=us-gaap_HedgeFundsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=acm_AssetsHeldByInsuranceCompanyMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel1Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel2Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel3Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: