|
Business Acquisitions and Related Transactions - Results of Acquired Companies (Details) (USD $)
|
3 Months Ended | 9 Months Ended | ||
|---|---|---|---|---|
|
Sep. 30, 2012
|
Sep. 30, 2011
|
Sep. 30, 2012
|
Sep. 30, 2011
|
|
| Business Acquisition [Line Items] | ||||
| Revenue | $ 163,906,205 | $ 227,803,568 | $ 474,579,479 | $ 539,705,280 |
| Pre-tax income (loss) | 9,455,118 | 15,048,776 | 18,737,801 | 34,820,723 |
|
AEG [Member]
|
||||
| Business Acquisition [Line Items] | ||||
| Revenue | 4,016,327 | 12,716,577 | ||
| Pre-tax income (loss) | 169,900 | 817,837 | ||
|
Ameresco Southwest [Member]
|
||||
| Business Acquisition [Line Items] | ||||
| Revenue | 14,595,348 | 37,986,302 | ||
| Pre-tax income (loss) | 1,504,066 | 2,775,583 | ||
|
AIS [Member]
|
||||
| Business Acquisition [Line Items] | ||||
| Revenue | 1,998,577 | 8,015,249 | ||
| Pre-tax income (loss) | $ (281,288) | $ (241,073) | ||