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	Mar. 31, 2021	Dec. 31, 2020
Liabilities:
Total liabilities	$ 8,992	$ 11,163
Level 2
Assets:
Total assets	1,405	365
Level 2 \| Interest rate swap instruments
Assets:
Total assets	1,290	2
Liabilities:
Liability derivatives	7,202	10,073
Level 2 \| Commodity swap instruments
Assets:
Total assets	115	363
Level 2 \| Make-whole provisions
Liabilities:
Liability derivatives	1,112	412
Level 3
Liabilities:
Contingent consideration	$ 678	$ 678