| Cover | Aug. 01, 2021 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Document Period End Date | Aug. 01, 2022 |
| Entity Registrant Name | Ameresco, Inc. |
| Entity Incorporation, State or Country Code | DE |
| Entity File Number | 001-34811 |
| Entity Tax Identification Number | 04-3512838 |
| Entity Address, Address Line One | 111 Speen Street, |
| Entity Address, City or Town | Framingham, |
| Entity Address, State or Province | MA |
| Entity Address, Postal Zip Code | 1701 |
| City Area Code | 508 |
| Local Phone Number | 661-2200 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Entity Emerging Growth Company | false |
| Amendment Flag | false |
| Entity Central Index Key | 0001488139 |
| Entity Address, Address Line Two | Suite 410, |
