Ameresco, Inc. Annual report pursuant to Section 13 and 15(d)

Fair Value Measurement - Fair Value of Assets and Liabilities Measured on a Recurring Basis (Details) - Recurring - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Liabilities:
Total liabilities	$ 6,027	$ 3,529
Fair Value, Inputs, Level 2
Assets:
Asset derivatives	766	233
Fair Value, Inputs, Level 2 \| Interest Rate Swap
Assets:
Asset derivatives	733	233
Liabilities:
Liability derivatives	3,187	3,529
Fair Value, Inputs, Level 2 \| Commodity swap
Assets:
Asset derivatives	33	0
Liabilities:
Liability derivatives	70	0
Fair Value, Inputs, Level 2 \| Hybrid Instrument
Liabilities:
Liability derivatives	1,808	0
Fair Value, Inputs, Level 3
Liabilities:
Contingent consideration liabilities	$ 962	$ 0