Quarterly report pursuant to Section 13 or 15(d)

Document and Entity Information

Document and Entity Information - shares
9 Months Ended
Sep. 30, 2016
Oct. 28, 2016
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-Q  
Document Period End Date Sep. 30, 2016  
Document Fiscal Year Focus 2016  
Document Fiscal Period Focus Q3  
Amendment Flag false  
Common Class A    
Entity Information [Line Items]    
Common Stock   27,849,019
Common Class B    
Entity Information [Line Items]    
Common Stock   18,000,000