Ameresco, Inc. Quarterly report [Sections 13 or 15(d)]

Quarterly report [Sections 13 or 15(d)]

DEBT AND FINANCING LEASE LIABILITIES - Additional Information (Details)

DEBT AND FINANCING LEASE LIABILITIES - Additional Information (Details) $ in Thousands						3 Months Ended	9 Months Ended
	May 12, 2026 USD ($)	Mar. 30, 2026 USD ($)	Feb. 03, 2026 USD ($) project	Sep. 26, 2025 USD ($)	Jan. 23, 2025 USD ($)	Jun. 30, 2025 USD ($)	Sep. 30, 2026 USD ($) facility energy_asset	Sep. 30, 2025 USD ($)	Aug. 06, 2026 USD ($)	Jun. 30, 2026 USD ($)	Jun. 29, 2026 USD ($)	Dec. 31, 2025 USD ($)
Debt Instrument [Line Items]
Repayments of secured debt							$ 4,875	$ 16,750
Proceeds from long-term corporate debt financings							45,000	$ 100,000
Surety Bond
Debt Instrument [Line Items]
Letters of credit outstanding							16,124
Senior secured corporate term loans \| Secured Debt
Debt Instrument [Line Items]
Repayments of secured debt					$ 13,000
Long-term debt, gross							$ 135,125					$ 95,000
Term Loan A \| Secured Debt
Debt Instrument [Line Items]
Fixed interest rate, percentage							6.43%
Senior Secured Credit Facility \| Secured Debt
Debt Instrument [Line Items]
Debt issuance costs							$ 2,345
Senior Secured Credit Facility, Term Loan Maturing December 2028 \| Line of Credit
Debt Instrument [Line Items]
Credit facility, periodic payment					$ 1,250
Senior Secured Credit Facility, Term Loan Maturing December 2028 \| Secured Debt
Debt Instrument [Line Items]
Debt issuance costs		$ 131
Interest expense		1,085
Proceeds from long-term corporate debt financings		2,784
Senior Secured Credit Facility, Maturing December 2028 \| Line of Credit
Debt Instrument [Line Items]
Minimum debt service coverage ratio					1.5
Total funded debt to EBITDA covenant ratio					3.5
August 2018 Long Term Finance Liability \| Solar Photovoltaic Projects
Debt Instrument [Line Items]
Line of credit, number of facilities \| facility							2
Solar PV projects sold \| energy_asset							3
Cash proceeds from sale-leaseback of energy assets							$ 9,314
Financing Facility, Due December 31, 2046 \| Secured Debt
Debt Instrument [Line Items]
Fixed interest rate, percentage									6.72%
Original principal amount									$ 30,640
Debt instrument, fee amount									$ 546
Fair value of the embedded derivative							$ 679
Revolving Credit Facility \| Line of Credit
Debt Instrument [Line Items]
Fixed interest rate, percentage							6.33%
Proceeds used to repay revolving credit facility					$ 180,000
Revolving Credit Facility \| Senior Secured Credit Facility, Revolver, Maturing December 2028 \| Line of Credit
Debt Instrument [Line Items]
Maximum borrowing capacity					225,000
Line of credit facility, accordion feature, increase limit		100,000
Repayments of loan		41,000
Revolving Credit Facility \| Financing Facility, Due September 2040 \| Line of Credit
Debt Instrument [Line Items]
Fixed interest rate, percentage				8.75%
Proceeds used to repay revolving credit facility			$ 97,759
Number of projects \| project			2
Long-term debt, gross			$ 99,900
Long-term debt							$ 434,395
Revolving Credit Facility \| Construction Credit Facility, Due March 2026 \| Line of Credit
Debt Instrument [Line Items]
Fixed interest rate, percentage							5.36%
Funds available for borrowing							$ 83,391
Long-term debt, gross							$ 16,609
Revolving Credit Facility \| Variable Rate Construction Facility, Due December 2027 \| Line of Credit
Debt Instrument [Line Items]
Fixed interest rate, percentage							8.66%
Maximum borrowing capacity											$ 400,000
Line of credit facility, accordion feature, increase limit											100,000
Long-term debt							$ 282,366
Line of credit facility, decreased limit										$ 50,000
Line of credit facility, maximum borrowing capacity, including according feature										$ 450,000	$ 500,000
Contributions to joint venture	$ 57,942
Secured Debt \| Senior Secured Credit Facility, Term Loan Maturing December 2028 \| Line of Credit
Debt Instrument [Line Items]
Original principal amount					$ 100,000
Credit facility, periodic payment		1,812
Increase in term loan		45,000
Funds available for borrowing		$ 55,000
Financing Facility \| Financing Facility, Due September 2040 \| Line of Credit
Debt Instrument [Line Items]
Repayments of loan						$ 7,000
Proceeds to pay off the construction credit facility				$ 25,500
Aggregate true-up payment amount				$ 15,653
Minimum \| Revolving Credit Facility \| Senior secured corporate term loans \| Line of Credit
Debt Instrument [Line Items]
Unused capacity, commitment fee percentage					0.25%
Minimum \| Revolving Credit Facility \| Senior secured corporate term loans \| Line of Credit \| Base Rate
Debt Instrument [Line Items]
Interest rate					0.75%
Minimum \| Revolving Credit Facility \| Senior secured corporate term loans \| Line of Credit \| Secured Overnight Financing Rate (SOFR)
Debt Instrument [Line Items]
Interest rate					1.75%
Maximum \| Revolving Credit Facility \| Senior secured corporate term loans \| Line of Credit
Debt Instrument [Line Items]
Unused capacity, commitment fee percentage					0.375%
Maximum \| Revolving Credit Facility \| Senior secured corporate term loans \| Line of Credit \| Base Rate
Debt Instrument [Line Items]
Interest rate					1.75%
Maximum \| Revolving Credit Facility \| Senior secured corporate term loans \| Line of Credit \| Secured Overnight Financing Rate (SOFR)
Debt Instrument [Line Items]
Interest rate					2.75%