XML 72 R18.htm IDEA: XBRL DOCUMENT
v3.3.0.814

Concentration of Credit Risk | 12 Months Ended
--- | ---
Sep. 30, 2015
Concentration of Credit Risk |
Concentration of Credit Risk | 11. Concentration of Credit Risk Financial instruments which potentially subject the Company to concentrations of credit risk consist principally of cash investments and trade receivables. The Company's cash balances and short-term investments are maintained in accounts held by major banks and financial institutions located primarily in the U.S., Canada, Europe, Australia, Middle East and Hong Kong. If the Company extends significant credit to clients in a specific geographic area or industry, the Company may experience disproportionately high levels of default if those clients are adversely affected by factors particular to their geographic area or industry. Concentrations of credit risk with respect to trade receivables are limited due to the large number of customers comprising the Company's customer base, including, in large part, governments, government agencies and quasi-government organizations, and their dispersion across many different industries and geographies. See Note 20 regarding the Company's foreign revenues. In order to mitigate credit risk, the Company continually reviews the credit worthiness of its major private clients.

X
- Definition The entire disclosure for concentrations of credit risk related to financial instruments. + References No definition available. + Details
Name: | acm_ConcentrationOfInvestmentCreditRiskTextBlock
Namespace Prefix: | acm_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- References No definition available. + Details
Name: | us-gaap_RisksAndUncertaintiesAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration