Ameresco, Inc. Annual report pursuant to Section 13 and 15(d)

Annual report pursuant to Section 13 and 15(d)

Goodwill and Intangible Assets - Goodwill (Details)

Goodwill and Intangible Assets - Goodwill (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Goodwill [Roll Forward]
Beginning Balance	$ 53,074us-gaap_Goodwill	$ 48,969us-gaap_Goodwill
Goodwill acquired during the year	7,590us-gaap_GoodwillAcquiredDuringPeriod	3,682us-gaap_GoodwillAcquiredDuringPeriod
Goodwill, Purchase Accounting Adjustments	641
Currency effects	(826)	423
Ending Balance	60,479us-gaap_Goodwill	53,074us-gaap_Goodwill	48,969us-gaap_Goodwill
Goodwill, Impaired, Accumulated Impairment Loss	(1,016)	(1,016)
Finite-Lived Intangible Assets, Purchase Accounting Adjustments	801
Deferred Tax Liabilities, Goodwill and Intangible Assets	160
Percent of goodwill fair value that exceeds carrying value	15.00%
Impairment of goodwill	0us-gaap_GoodwillImpairmentLoss	0us-gaap_GoodwillImpairmentLoss	1,016us-gaap_GoodwillImpairmentLoss
Minimum
Goodwill [Roll Forward]
Intangible assets amortization period	1 year
Minimum \| Customer contracts
Goodwill [Roll Forward]
Intangible assets amortization period	1 year
Minimum \| Customer Relationships, Noncompete Agreements, Technology and Trade Names
Goodwill [Roll Forward]
Intangible assets amortization period	4 years
Maximum
Goodwill [Roll Forward]
Intangible assets amortization period	15 years
Maximum \| Customer contracts
Goodwill [Roll Forward]
Intangible assets amortization period	5 years
Maximum \| Customer Relationships, Noncompete Agreements, Technology and Trade Names
Goodwill [Roll Forward]
Intangible assets amortization period	15 years
U.S. Regions
Goodwill [Roll Forward]
Beginning Balance	24,759	23,709
Goodwill acquired during the year	0	1,050
Goodwill, Purchase Accounting Adjustments	0
Currency effects	0	0
Ending Balance	24,759	24,759
Goodwill, Impaired, Accumulated Impairment Loss	0	0
U.S. Federal
Goodwill [Roll Forward]
Beginning Balance	3,375	3,375
Goodwill acquired during the year	0	0
Goodwill, Purchase Accounting Adjustments	0
Currency effects	0	0
Ending Balance	3,375	3,375
Goodwill, Impaired, Accumulated Impairment Loss	0	0
Canada
Goodwill [Roll Forward]
Beginning Balance	4,124	3,827
Goodwill acquired during the year	0
Goodwill, Purchase Accounting Adjustments	0
Currency effects	(343)	297
Ending Balance	3,781	4,124
Goodwill, Impaired, Accumulated Impairment Loss	(1,016)	(1,016)
Small-Scale Infrastructure
Goodwill [Roll Forward]
Beginning Balance	0	0
Goodwill acquired during the year	0	0
Goodwill, Purchase Accounting Adjustments	0
Currency effects	0	0
Ending Balance	0	0
Goodwill, Impaired, Accumulated Impairment Loss	0	0
Other
Goodwill [Roll Forward]
Beginning Balance	20,816	18,058
Goodwill acquired during the year	7,590	2,632
Goodwill, Purchase Accounting Adjustments	641
Currency effects	(483)	126
Ending Balance	28,564	20,816
Goodwill, Impaired, Accumulated Impairment Loss	$ 0	$ 0