Ameresco, Inc. Quarterly report pursuant to Section 13 or 15(d)

Leases - Additional Information (Details) $ in Thousands	3 Months Ended
Leases - Additional Information (Details) $ in Thousands	Mar. 31, 2022 USD ($) project	Mar. 31, 2021 USD ($)
Lessee, Lease, Description [Line Items]
Net amortization expense	$ 57	$ 57
Solar Photovoltaic Projects \| August 2018 Long Term Finance Liability
Lessee, Lease, Description [Line Items]
Solar PV projects sold \| project	2
Investment fund call option exercise	$ 8,201
Solar Photovoltaic Projects \| December 2020 Long Term Finance Liability
Lessee, Lease, Description [Line Items]
Solar PV projects sold \| project	1
Investment fund call option exercise	$ 4,423
Solar Photovoltaic Projects \| Revolving Credit Facility \| Line of Credit \| August 2018 Long Term Finance Liability
Lessee, Lease, Description [Line Items]
Available funding under lending commitment	220,367
Solar Photovoltaic Projects \| Revolving Credit Facility \| Line of Credit \| December 2020 Long Term Finance Liability
Lessee, Lease, Description [Line Items]
Available funding under lending commitment	$ 11,515