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)							2 Months Ended	9 Months Ended
	Oct. 31, 2025 USD ($)	Sep. 26, 2025 USD ($)	Jun. 27, 2025 USD ($)	May 27, 2025 USD ($)	Apr. 30, 2025 USD ($)	Jan. 23, 2025 USD ($)	Jun. 27, 2025 USD ($)	Sep. 30, 2025 USD ($) project	Sep. 30, 2024 USD ($)	Dec. 31, 2024 USD ($)	Sep. 28, 2023
Debt Instrument [Line Items]
Repayments of secured debt								$ 16,750,000	$ 68,750,000
Make-whole Provision April 2045 \| Other liabilities \| Not Designated
Debt Instrument [Line Items]
Liability derivatives, fair value					$ 3,040,000
Make-whole Provisions May 2038 \| Other liabilities \| Not Designated
Debt Instrument [Line Items]
Liability derivatives, fair value				$ 347,000
Senior secured corporate term loans \| Secured Debt
Debt Instrument [Line Items]
Repayments of secured debt						$ 13,000,000
Long-term debt, gross								$ 96,250,000		$ 13,000,000
Term Loan A \| Secured Debt
Debt Instrument [Line Items]
Fixed interest rate, percentage								7.06%
Senior Secured Credit Facility \| Secured Debt
Debt Instrument [Line Items]
Debt issuance costs								$ 2,345,000
Senior Secured Notes, Due September 2045 \| Senior Notes
Debt Instrument [Line Items]
Fixed interest rate, percentage					6.72%
Debt issuance costs					$ 3,126,000
Proceeds from issuance of senior long-term debt			$ 10,291,000		$ 67,708,000		$ 78,000,000
Debt instrument, term					20 years
Original principal amount					$ 300,000,000
Investment tax credit, prepayment amount								$ 30,000,000
Term Loan Due May 27,2028 \| Line of Credit
Debt Instrument [Line Items]
Repayments of debt				8,273,000
Term Loan Due June 2025 \| Line of Credit
Debt Instrument [Line Items]
Repayments of debt				$ 31,086,000
August 2018 Long Term Finance Liability \| Solar Photovoltaic Projects
Debt Instrument [Line Items]
Solar PV projects sold \| project								8
Cash proceeds from sale-leaseback of energy assets								$ 28,554,000
Senior Secured First Lien Term Notes, 5.71% Due December 31, 2043 \| Senior Notes \| Subsequent Event
Debt Instrument [Line Items]
Fixed interest rate, percentage	5.71%
Proceeds from issuance of senior long-term debt	$ 34,356,000
Second Lien Term Notes, 7.4% Due September 2040 \| Senior Notes \| Subsequent Event
Debt Instrument [Line Items]
Fixed interest rate, percentage	7.40%
Proceeds from issuance of senior long-term debt	$ 15,129,000
Senior Secured First Lien Term Notes, 5.71% Due December 2043 And Second Lien Term Notes, 7.40% Due September 2040Due September 2030 \| Senior Notes \| Subsequent Event
Debt Instrument [Line Items]
Debt issuance costs	$ 763,000
Debt instrument, term	20 years
Original principal amount	$ 80,000,000
Revolving Credit Facility
Debt Instrument [Line Items]
Credit facility, periodic payment						$ 1,250,000
Minimum debt service coverage ratio						1.5
Revolving Credit Facility \| Line of Credit
Debt Instrument [Line Items]
Fixed interest rate, percentage								7.71%
Proceeds used to repay revolving credit facility						$ 180,000,000
Maximum borrowing capacity						$ 100,000,000
Revolving Credit Facility \| Senior Secured Credit Facility \| Line of Credit \| Debt Covenant, Period Five
Debt Instrument [Line Items]
Total funded debt to EBITDA covenant ratio						3.5
Revolving Credit Facility \| Term Loan Due December 28, 2028 \| Secured Debt
Debt Instrument [Line Items]
Repayments of secured debt						$ 225,000,000
Revolving Credit Facility \| Construction Credit Facility, Due December 2027 \| Line of Credit
Debt Instrument [Line Items]
Fixed interest rate, percentage								8.31%
Maximum borrowing capacity								$ 415,000,000
Repayments of debt								75,272,000
Long-term debt								408,483,000
Proceeds to pay off the construction credit facility								171,448,000
Increase in maximum commitment								$ 400,000,000
Revolving Credit Facility \| Construction Credit Facility, Due March 2026 \| Line of Credit
Debt Instrument [Line Items]
Fixed interest rate, percentage								5.92%
Long-term debt, gross								$ 19,505,000
Funds available for borrowing								80,495,000
Revolving Credit Facility \| Fixed Rate Note, Due August, 2039 \| Line of Credit
Debt Instrument [Line Items]
Fixed interest rate, percentage											6.70%
Internal rate of return, percentage											8.51%
Revolving Credit Facility \| Minimum \| Senior secured corporate term loans \| Line of Credit
Debt Instrument [Line Items]
Unused capacity, commitment fee percentage						0.25%
Revolving Credit Facility \| Minimum \| Base Rate \| Senior secured corporate term loans \| Line of Credit
Debt Instrument [Line Items]
Interest rate						0.75%
Revolving Credit Facility \| Minimum \| Secured Overnight Financing Rate (SOFR) \| Senior secured corporate term loans \| Line of Credit
Debt Instrument [Line Items]
Interest rate						1.75%
Revolving Credit Facility \| Maximum \| Senior secured corporate term loans \| Line of Credit
Debt Instrument [Line Items]
Unused capacity, commitment fee percentage						0.375%
Revolving Credit Facility \| Maximum \| Base Rate \| Senior secured corporate term loans \| Line of Credit
Debt Instrument [Line Items]
Interest rate						1.75%
Revolving Credit Facility \| Maximum \| Secured Overnight Financing Rate (SOFR) \| Senior secured corporate term loans \| Line of Credit
Debt Instrument [Line Items]
Interest rate						2.75%
Line of Credit \| Term Loan Due May 27,2028 \| Line of Credit
Debt Instrument [Line Items]
Fixed interest rate, percentage				6.62%
Debt issuance costs				$ 402,000
Proceeds used to repay revolving credit facility				8,273,000
Original principal amount				$ 12,221,000
Line of Credit \| Term Loan Due June 2025 \| Line of Credit
Debt Instrument [Line Items]
Fixed interest rate, percentage				6.87%
Term Loan \| Term Loan Due December 28, 2028 \| Secured Debt
Debt Instrument [Line Items]
Repayments of secured debt						$ 100,000,000
Financing Facility \| Financing Facility, Due September 2040
Debt Instrument [Line Items]
Fixed interest rate, percentage				8.75%
Financing Facility \| Financing Facility, Due September 2040 \| Line of Credit
Debt Instrument [Line Items]
Repayments of loan								7,000,000
Aggregate true-up payment amount		$ 15,653,000
Long-term debt								$ 348,182,000
Proceeds to pay off the construction credit facility		$ 25,500,000