Annual report pursuant to Section 13 and 15(d)

Summary of Significant Accounting Policies - Revision to Previously Issued Financial Statements (Details)

v3.6.0.2
Summary of Significant Accounting Policies - Revision to Previously Issued Financial Statements (Details) - USD ($)
 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
Error Corrections and Prior Period Adjustments Restatement [Line Items]                      
Long-term debt and capital lease liabilities, less current portions and net of deferred financing fees $ 100,490,000               $ 140,593,000 $ 100,490,000  
Income tax provision (benefit)                 4,370,000 4,976,000 $ (4,091,000)
Net income (loss) 3,269,000 $ 5,715,000 $ 1,994,000 $ 1,054,000 $ (1,137,000) $ 4,178,000 $ 1,991,000 $ (4,188,000) 11,997,000 (4,684,000) 10,383,000
Net income attributable to Ameresco, Inc.                 (12,032,000) $ (844,000) (10,383,000)
Earnings per share, basic and diluted (in dollars per share)                   $ 0.02  
Comprehensive income (loss)                 10,634,000 $ (7,292,000) 4,651,000
Comprehensive income (loss) attributable to common shareholders                 10,669,000 (1,764,000) 4,651,000
Deferred income taxes                 2,867,000 4,086,000 (2,749,000)
Cash flows from operating activities                 $ (58,073,000) (49,538,000) $ 1,308,000
Revision To Deferred Tax Liability And Related Income Tax Provision | Restatement Adjustment                      
Error Corrections and Prior Period Adjustments Restatement [Line Items]                      
Long-term debt and capital lease liabilities, less current portions and net of deferred financing fees $ 2,133,000                 2,133,000  
Income tax provision (benefit)                   2,133,000  
Net income (loss)                   (2,133,000)  
Net income attributable to Ameresco, Inc.                   2,133,000  
Comprehensive income (loss)                   (2,133,000)  
Comprehensive income (loss) attributable to common shareholders                   (2,133,000)  
Deferred income taxes                   (2,133,000)  
Cash flows from operating activities                   $ 0  
Revision To Deferred Tax Liability And Related Income Tax Provision | Scenario, Previously Reported                      
Error Corrections and Prior Period Adjustments Restatement [Line Items]                      
Earnings per share, basic and diluted (in dollars per share)                   $ 0.06