Annual report pursuant to Section 13 and 15(d)

Document and Entity Information

v2.4.1.9
Document and Entity Information (USD $)
12 Months Ended
Dec. 31, 2014
Jun. 30, 2014
Mar. 02, 2015
Entity Information [Line Items]      
Entity Registrant Name Ameresco, Inc.    
Entity Central Index Key 0001488139    
Current Fiscal Year End Date --12-31    
Entity Filer Category Accelerated Filer    
Document Type 10-K    
Document Period End Date Dec. 31, 2014    
Document Fiscal Year Focus 2014    
Document Fiscal Period Focus FY    
Amendment Flag false    
Entity Well-known Seasoned Issuer No    
Entity Voluntary Filers No    
Entity Current Reporting Status Yes    
Entity Public Float   $ 149,918,286dei_EntityPublicFloat  
Class A Common Stock      
Entity Information [Line Items]      
Common Stock     28,415,292dei_EntityCommonStockSharesOutstanding
/ us-gaap_StatementClassOfStockAxis
= us-gaap_CommonClassAMember
Class B Common Stock      
Entity Information [Line Items]      
Common Stock     18,000,000dei_EntityCommonStockSharesOutstanding
/ us-gaap_StatementClassOfStockAxis
= us-gaap_CommonClassBMember