Ameresco, Inc. Quarterly report pursuant to Section 13 or 15(d)

Quarterly report pursuant to Section 13 or 15(d)

Goodwill and Intangible Assets - Goodwill (Details)

Goodwill and Intangible Assets - Goodwill (Details) (USD $)	3 Months Ended	9 Months Ended
	Sep. 30, 2012 entity	Sep. 30, 2012
Goodwill [Line Items]
Number of businesses acquired	1
Goodwill [Roll Forward]
December 31, 2011		$ 47,881,346
Foreign Currency Translation and Other Adjustments		144,796
September 30, 2012	50,317,305	50,317,305
U.S Federal [Member]
Goodwill [Roll Forward]
December 31, 2011		3,374,967
Foreign Currency Translation and Other Adjustments		0
September 30, 2012	3,374,967	3,374,967
Central U.S Region [Member]
Goodwill [Roll Forward]
December 31, 2011		1,972,415
Foreign Currency Translation and Other Adjustments		0
September 30, 2012	1,972,415	1,972,415
Other U.S Regions [Member]
Goodwill [Roll Forward]
December 31, 2011		21,736,140
Foreign Currency Translation and Other Adjustments		0
September 30, 2012	21,736,140	21,736,140
Canada [Member]
Goodwill [Roll Forward]
December 31, 2011		2,874,383
Foreign Currency Translation and Other Adjustments		144,796
September 30, 2012	5,310,342	5,310,342
All Other [Member]
Goodwill [Roll Forward]
December 31, 2011		17,923,441
Foreign Currency Translation and Other Adjustments		0
September 30, 2012	17,923,441	17,923,441
FAME [Member]
Goodwill [Line Items]
Number of businesses acquired		1
Goodwill [Roll Forward]
Acquisitions		2,291,163
FAME [Member] \| Canada [Member]
Goodwill [Roll Forward]
Acquisitions		$ 2,291,163

- Definition

Carrying amount as of the balance sheet date, which is the cumulative amount paid and (if applicable) the fair value of any noncontrolling interest in the acquiree, adjusted for any amortization recognized prior to the adoption of any changes in generally accepted accounting principles (as applicable) and for any impairment charges, in excess of the fair value of net assets acquired in one or more business combination transactions.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 142

-Paragraph 45

-Subparagraph e

-Clause 1

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 20

-Section 50

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=14024403&loc=d3e13816-109267

Reference 3: 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 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 141R

-Paragraph 68

-Subparagraph l

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 5: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 141R

-Paragraph 34

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 6: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 142

-Paragraph 43

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 7: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 142

-Paragraph 45

-Subparagraph e

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 8: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 141R

-Paragraph 72

-Subparagraph d

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

- Definition

The aggregate amount of goodwill acquired in the period and allocated to the reportable segment. The value is stated at fair value based on the purchase price allocation.

+ References + Details