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

Business Segment Information - Revenue (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Revenue from External Customer [Line Items]
Revenues	$ 174,225	$ 180,598	$ 162,628	$ 133,776	$ 173,768	$ 189,142	$ 152,489	$ 115,433	$ 651,227	$ 630,832	$ 593,241
Project
Revenue from External Customer [Line Items]
Revenues									454,200	434,380	386,816
Operating Assets
Revenue from External Customer [Line Items]
Revenues									64,882	55,130	51,756
Operations and Maintenance
Revenue from External Customer [Line Items]
Revenues									63,082	59,117	59,424
Integrated-PV
Revenue from External Customer [Line Items]
Revenues									29,325	40,070	51,200
Other services
Revenue from External Customer [Line Items]
Revenues									$ 39,738	$ 42,135	$ 44,045