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

Fair Value Measurement - Fair Value of Assets and Liabilities Measured on a Recurring Basis (Details) - Recurring - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Liabilities:
Total liabilities	$ 13,202	$ 7,832
Level 2
Assets:
Total assets	0	213
Level 2 \| Interest rate swap instruments
Assets:
Total assets	0	15
Liabilities:
Liability derivatives	11,128	6,236
Level 2 \| Commodity swap instruments
Assets:
Total assets	0	198
Liabilities:
Liability derivatives	44	0
Level 2 \| Make-whole provisions
Liabilities:
Liability derivatives	1,352	918
Level 3
Liabilities:
Contingent consideration	$ 678	$ 678