Quarterly report pursuant to Section 13 or 15(d)

Document and Entity Information

v2.4.0.6
Document and Entity Information
9 Months Ended
Sep. 30, 2012
Nov. 02, 2012
Class A Common Stock
Nov. 02, 2012
Class B Common Stock
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, 2012    
Document Fiscal Year Focus 2012    
Document Fiscal Period Focus Q3    
Amendment Flag false    
Entity Common Stock, Shares Outstanding   27,081,880 18,000,000