XML 123 R104.htm IDEA: XBRL DOCUMENT
v3.21.2

Commitments and Contingencies (Details) - USD ($) $ in Millions |  |  | 1 Months Ended | 12 Months Ended |  |
--- | --- | --- | --- | --- | --- | ---
Jan. 31, 2020 | Apr. 30, 2019 | Dec. 31, 2019 | Apr. 30, 2019 | Mar. 31, 2019 | Sep. 30, 2021 | Dec. 06, 2019 | Dec. 31, 2014
New York |  |  |  |  |  |  |  |
Commitments and Contingencies |  |  |  |  |  |  |  |
Contingency liability |  |  |  |  |  | $ 146.0 |  |
Percentage of claim recoveries due to seller | 10.00% |  |  |  |  |  |  |
Percentage of claim recoveries due to purchaser | 90.00% |  |  |  |  |  |  |
Montana |  |  |  |  |  |  |  |
Commitments and Contingencies |  |  |  |  |  |  |  |
Damages sought |  | $ 132.0 |  | $ 132.0 | $ 79.0 |  |  |
Damages sought, counter party |  |  | $ 93.0 |  |  |  |  |
Department of Energy | New York | Minimum |  |  |  |  |  |  |  |
Commitments and Contingencies |  |  |  |  |  |  |  |
Contingency liability |  |  |  |  |  | 106.0 |  |
Department of Energy | New York | Maximum |  |  |  |  |  |  |  |
Commitments and Contingencies |  |  |  |  |  |  |  |
Contingency liability |  |  |  |  |  | 146.0 |  |
Fund investment capital commitments |  |  |  |  |  |  |  |
Commitments and Contingencies |  |  |  |  |  |  |  |
Commitment |  |  |  |  |  | $ 19.3 |  |
Commitment period |  |  |  |  |  | 7 years |  |
Standby letters of credit |  |  |  |  |  |  |  |
Commitments and Contingencies |  |  |  |  |  |  |  |
Contingency liability |  |  |  |  |  | $ 483.0 |  |
Surety Bond |  |  |  |  |  |  |  |
Commitments and Contingencies |  |  |  |  |  |  |  |
Contingency liability |  |  |  |  |  | 4,300.0 |  |
Collectibility of Receivables |  |  |  |  |  |  |  |
Commitments and Contingencies |  |  |  |  |  |  |  |
Unapproved change orders |  |  |  |  |  |  |  | $ 103.0
Collectibility of Receivables | New York |  |  |  |  |  |  |  |
Commitments and Contingencies |  |  |  |  |  |  |  |
Unapproved change orders |  |  |  |  |  |  | $ 60.4 |
Collectibility of Receivables | New York | Minimum |  |  |  |  |  |  |  |
Commitments and Contingencies |  |  |  |  |  |  |  |
Damages sought |  |  |  |  |  | 148.5 |  |
Collectibility of Receivables | New York | Maximum |  |  |  |  |  |  |  |
Commitments and Contingencies |  |  |  |  |  |  |  |
Damages sought |  |  |  |  |  | 329.4 |  |
Collectibility of Receivables | Montana |  |  |  |  |  |  |  |
Commitments and Contingencies |  |  |  |  |  |  |  |
Unapproved change orders |  |  |  |  |  | 90.0 |  |
Damages sought |  |  |  |  |  | $ 144.0 |  |

X
- Definition The value of the award the counter party seeks in the legal matter. + References No definition available. + Details
Name: | acm_LossContingencyDamagesSoughtValueCounterParty
Namespace Prefix: | acm_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Percentage of claim recoveries and costs due to purchaser. + References No definition available. + Details
Name: | acm_PercentageOfClaimRecoveriesAndCostsDueToPurchaser
Namespace Prefix: | acm_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Percentage of claim recoveries and costs due to seller. + References No definition available. + Details
Name: | acm_PercentageOfClaimRecoveriesAndCostsDueToSeller
Namespace Prefix: | acm_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition The minimum amount the entity agreed to spend under the long-term purchase commitment. + References No definition available. + Details
Name: | us-gaap_LongTermPurchaseCommitmentAmount
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Period covered by the long-term purchase commitment, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. + References No definition available. + Details
Name: | us-gaap_LongtermPurchaseCommitmentPeriod
Namespace Prefix: | us-gaap_
Data Type: | xbrli:durationItemType
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_LossContingenciesLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition The value (monetary amount) of the award the plaintiff seeks in the legal matter. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 450 -SubTopic 20 -Section 50 -Paragraph 9 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=121557415&loc=d3e14557-108349 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 450 -SubTopic 20 -Section 50 -Paragraph 4 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=121557415&loc=d3e14435-108349 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 450 -SubTopic 20 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=121557415&loc=d3e14326-108349 + Details
Name: | us-gaap_LossContingencyDamagesSoughtValue
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Reflects the estimated amount of loss from the specified contingency as of the balance sheet date. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 450 -SubTopic 20 -Section 50 -Paragraph 4 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=121557415&loc=d3e14435-108349 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 450 -SubTopic 20 -Section 50 -Paragraph 9 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=121557415&loc=d3e14557-108349 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 460 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=121555522&loc=d3e12021-110248 + Details
Name: | us-gaap_LossContingencyEstimateOfPossibleLoss
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

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 -Publisher FASB -Name Accounting Standards Codification -Topic 910 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=6471471&loc=d3e48698-109348 + Details
Name: | us-gaap_UnapprovedChangeOrdersAmount
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Details
Name: | srt_StatementGeographicalAxis=stpr_NY
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_StatementGeographicalAxis=stpr_MT
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_AccountsNotesLoansAndFinancingReceivablesByLegalEntityOfCounterpartyTypeAxis=us-gaap_GovernmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_RangeAxis=srt_MinimumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_RangeAxis=srt_MaximumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_LongTermPurchaseCommitmentByCategoryOfItemPurchasedAxis=us-gaap_CapitalAdditionsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_LossContingenciesByNatureOfContingencyAxis=us-gaap_FinancialStandbyLetterOfCreditMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_LossContingenciesByNatureOfContingencyAxis=us-gaap_SuretyBondMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_LossContingenciesByNatureOfContingencyAxis=us-gaap_CollectibilityOfReceivablesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |