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

Leases - Additional Information (Details) $ in Thousands	3 Months Ended		6 Months Ended
Leases - Additional Information (Details) $ in Thousands	Jun. 30, 2022 USD ($)	Jun. 30, 2021 USD ($)	Jun. 30, 2022 USD ($) project	Jun. 30, 2021 USD ($)
Lessee, Lease, Description [Line Items]
Net amortization expense	$ 57	$ 57	$ 114	$ 114
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			3
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		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		$ 11,515