Quarterly report pursuant to Section 13 or 15(d)

Document and Entity Information

v3.8.0.1
Document and Entity Information - shares
9 Months Ended
Sep. 30, 2017
Nov. 01, 2017
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, 2017  
Document Fiscal Year Focus 2017  
Document Fiscal Period Focus Q3  
Amendment Flag false  
Common Class A    
Entity Information [Line Items]    
Common Stock (in shares)   27,503,502
Common Class B    
Entity Information [Line Items]    
Common Stock (in shares)   18,000,000