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

Leases - Additional Information (Details) $ in Thousands	3 Months Ended		9 Months Ended
Leases - Additional Information (Details) $ in Thousands	Sep. 30, 2023 USD ($)	Sep. 30, 2022 USD ($)	Sep. 30, 2023 USD ($) project lease_liability	Sep. 30, 2022 USD ($)	Aug. 31, 2023	Jan. 31, 2023
Lessee, Lease, Description [Line Items]
Number of lease liabilities \| lease_liability			2
Lease agreement period					30 years	37 years
Net amortization expense	$ 57	$ 57	$ 171	$ 171
Ground Lease
Lessee, Lease, Description [Line Items]
Commitment for future lease payments for leases that do not yet meet the criteria of a ROU asset or liability	$ 10,500		$ 10,500
Lease term	20 years		20 years
Office Lease
Lessee, Lease, Description [Line Items]
Commitment for future lease payments for leases that do not yet meet the criteria of a ROU asset or liability	$ 1,354		$ 1,354
Lease term	5 years		5 years
August 2018 Long Term Finance Liability \| Solar Photovoltaic Projects
Lessee, Lease, Description [Line Items]
Solar PV projects sold \| project			5
Investment fund call option exercise			$ 91,137
August 2018 Long Term Finance Liability \| Solar Photovoltaic Projects \| Revolving Credit Facility \| Line of Credit
Lessee, Lease, Description [Line Items]
Available funding under lending commitment	$ 350,000		$ 350,000
December 2020 Long Term Finance Liability \| Solar Photovoltaic Projects
Lessee, Lease, Description [Line Items]
Solar PV projects sold \| project			3
Investment fund call option exercise			$ 9,201