Annual report pursuant to Section 13 and 15(d)

Cover Page

v3.22.0.1
Cover Page - USD ($)
 12 Months Ended
Dec. 31, 2021
Feb. 25, 2022
Jun. 30, 2021
Entity Information [Line Items]      
Document Type 10-K    
Document Annual Report true    
Document Period End Date Dec. 31, 2021    
Current Fiscal Year End Date --12-31    
Document Transition Report false    
Entity File Number 001-34811    
Entity Registrant Name Ameresco, Inc.    
Entity Incorporation, State or Country Code DE    
Entity Tax Identification Number 04-3512838    
Entity Address, Address Line One 111 Speen Street    
Entity Address, Address Line Two Suite 410    
Entity Address, City or Town Framingham    
Entity Address, State or Province MA    
Entity Address, Postal Zip Code 01701    
City Area Code 508    
Local Phone Number 661-2200    
Title of 12(b) Security Class A Common Stock, par value $0.0001 per share    
Trading Symbol AMRC    
Security Exchange Name NYSE    
Entity Well-known Seasoned Issuer Yes    
Entity Voluntary Filers No    
Entity Current Reporting Status Yes    
Entity Interactive Data Current Yes    
Entity Filer Category Large Accelerated Filer    
Entity Small Business false    
Entity Emerging Growth Company false    
Entity Shell Company false    
ICFR Auditor Attestation Flag true    
Entity Public Float     $ 1,929,538,589
Documents Incorporated by Reference Portions of the definitive proxy statement for our 2022 annual meeting of stockholders are incorporated by reference into Part III.    
Entity Central Index Key 0001488139    
Document Fiscal Year Focus 2021    
Document Fiscal Period Focus FY    
Amendment Flag false    
Class A Common Stock      
Entity Information [Line Items]      
Entity Common Stock, Shares Outstanding (in shares)   33,724,309  
Class B Common Stock      
Entity Information [Line Items]      
Entity Common Stock, Shares Outstanding (in shares)   18,000,000