XML 89 R56.htm IDEA: XBRL DOCUMENT
v3.10.0.1

Business Acquisitions, Goodwill and Intangible Assets - Goodwill (Details) - USD ($) $ in Thousands | 12 Months Ended
--- | ---
Sep. 30, 2018 | Sep. 30, 2017
Changes in the carrying value of goodwill by reporting segment |  |
Goodwill at the beginning of the period | $ 5,992,881 | $ 5,823,800
Measurement period adjustments | 91,000 |
Impairment | (125,400) |
Acquisitions |  | 127,100
Disposed |  | (1,800)
Foreign Exchange Impact | (37,400) | 43,800
Goodwill at the end of the period | 5,921,116 | 5,992,881
Design and Consulting Services |  |
Changes in the carrying value of goodwill by reporting segment |  |
Goodwill at the beginning of the period | 3,218,900 | 3,198,200
Acquisitions |  | 3,800
Disposed |  | (1,800)
Foreign Exchange Impact | (29,700) | 18,700
Goodwill at the end of the period | 3,189,200 | 3,218,900
Construction Services |  |
Changes in the carrying value of goodwill by reporting segment |  |
Goodwill at the beginning of the period | 1,049,900 | 915,200
Measurement period adjustments | 91,000 |
Impairment | (125,400) |
Acquisitions |  | 123,300
Foreign Exchange Impact | (6,600) | 11,400
Goodwill at the end of the period | 1,008,900 | 1,049,900
Management Services |  |
Changes in the carrying value of goodwill by reporting segment |  |
Goodwill at the beginning of the period | 1,724,100 | 1,710,400
Foreign Exchange Impact | (1,100) | 13,700
Goodwill at the end of the period | $ 1,723,000 | $ 1,724,100

X
- Definition Represents the amount of goodwill, disposed during period. + References No definition available. + Details
Name: | acm_GoodwillDisposedDuringPeriod
Namespace Prefix: | acm_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=35741047&loc=d3e13816-109267 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 20 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6388280&loc=d3e13770-109266 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 20 -Section 45 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=77989000&loc=SL49117168-202975 + Details
Name: | us-gaap_Goodwill
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of increase in asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized resulting from a business combination. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=35741047&loc=d3e13816-109267 + Details
Name: | us-gaap_GoodwillAcquiredDuringPeriod
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of foreign currency translation gain (loss) which increases (decreases) an asset representing future economic benefits from other assets acquired in a business combination that are not individually identified and separately recognized. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (f) -URI http://asc.fasb.org/extlink&oid=35741047&loc=d3e13816-109267 + Details
Name: | us-gaap_GoodwillForeignCurrencyTranslationGainLoss
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition The amount of an adjustment to a previously reported goodwill impairment charge, which will be recognized in the subsequent reporting period. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 20 -Section 50 -Paragraph 2 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=35741047&loc=d3e13854-109267 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 20 -Section 35 -Paragraph 19 -URI http://asc.fasb.org/extlink&oid=77993916&loc=d3e12323-109265 + Details
Name: | us-gaap_GoodwillImpairedAdjustmentToInitialEstimateAmount
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of loss from the write-down of an asset representing the future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 20 -Section 50 -Paragraph 2 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=35741047&loc=d3e13854-109267 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 20 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6388280&loc=d3e13777-109266 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3602-108585 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (e) -URI http://asc.fasb.org/extlink&oid=35741047&loc=d3e13816-109267 + Details
Name: | us-gaap_GoodwillImpairmentLoss
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_GoodwillRollForward
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_StatementBusinessSegmentsAxis=acm_DesignConsultingServicesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementBusinessSegmentsAxis=acm_ConstructionServicesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementBusinessSegmentsAxis=acm_ManagementSupportServicesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |