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Business Acquisitions and Related Transactions (Narrative) (Details) (USD $)
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3 Months Ended | 9 Months Ended | 1 Months Ended | 9 Months Ended | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
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Sep. 30, 2012
entity
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Sep. 30, 2012
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Sep. 30, 2011
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Sep. 30, 2012
Minimum [Member]
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Sep. 30, 2012
Maximum [Member]
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Apr. 30, 2011
Quantum [Member]
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Aug. 31, 2010
Quantum [Member]
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Sep. 30, 2012
Quantum [Member]
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Sep. 30, 2012
AEG [Member]
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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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Sep. 30, 2012
FAME [Member]
entity
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Jul. 31, 2012
FAME [Member]
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| Business Acquisition [Line Items] | ||||||||||||||
| Number of businesses acquired | 1 | 1 | ||||||||||||
| Initial cash payment | $ 6,150,000 | |||||||||||||
| Additional payment | 0 | 1,956,366 | 1,956,366 | |||||||||||
| Cash paid | 11,993,236 | 50,057,113 | 4,497,141 | 4,486,950 | ||||||||||
| Security deposit with third-party escrow agent | 1,000,000 | 900,000 | 900,000 | |||||||||||
| Maximum additional consideration for former stockholders of acquiree | 1,150,000 | 5,000,000 | 5,000,000 | 865,000 | ||||||||||
| Fair value of additional consideration for former stockholders of acquiree | $ 1,652,000 | |||||||||||||
| Intangible assets amortization period | 1 year | 14 years | ||||||||||||
| X | ||||||||||
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- Definition
Business Acquisition, Cost of Acquired Entity, Security Deposit in Escrow No definition available.
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| X | ||||||||||
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- Definition
Fair value, as of the acquisition date, of potential payments under the contingent consideration arrangement including cash and shares. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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| X | ||||||||||
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- Definition
Amount of cash paid to acquire the entity. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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| X | ||||||||||
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- Details
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| X | ||||||||||
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- Definition
For contingent consideration arrangements recognized in connection with a business combination, this element represents an estimate of the high-end of the potential range (undiscounted) of the consideration which may be paid. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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| X | ||||||||||
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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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| X | ||||||||||
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- Definition
The number of businesses acquired by the entity during the period. No definition available.
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| X | ||||||||||
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- Definition
Cash outflow representing an adjustment to the purchase price of a previous acquisition. No definition available.
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| X | ||||||||||
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- Definition
The cash outflow associated with the acquisition of business during the period. The cash portion only of the acquisition price. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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