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Summary of Significant Accounting Policies - Goodwill and Intangible Assets (Details) (USD $)
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9 Months Ended | |||||
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Jul. 31, 2011
AEG [Member]
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Aug. 31, 2011
Ameresco Southwest [Member]
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Dec. 31, 2011
AIS [Member]
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Jul. 31, 2012
FAME [Member]
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Sep. 30, 2012
Minimum [Member]
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Sep. 30, 2012
Maximum [Member]
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| Goodwill [Line Items] | ||||||
| Goodwill recorded for acquisitions | $ 8,728,169 | $ 16,545,434 | $ 1,549,467 | $ 2,291,163 | ||
| Intangible assets amortization period | 1 year | 14 years | ||||
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- Definition
Amount of goodwill arising from a business combination, which is the excess of the cost of the acquired entity over the amounts assigned to assets acquired and liabilities assumed. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
Useful life of finite-lived intangible assets, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. No definition available.
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- Details
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