Ameresco, Inc. Quarterly report pursuant to Section 13 or 15(d)

Quarterly report pursuant to Section 13 or 15(d)

Summary of Significant Accounting Policies - Accounts Receivable (Details)

Summary of Significant Accounting Policies - Accounts Receivable (Details) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2012 customer	Jun. 30, 2011 customer	Jun. 30, 2012 customer	Jun. 30, 2011 customer	Dec. 31, 2011 customer
Changes in the Allowance for Doubtful Accounts [Roll Forward]
Allowance for doubtful accounts, beginning of period			$ 1,135,391	$ 1,677,278
Charges to costs and expenses	24,107	34	77,743	24,220
Account write-offs and other			(111,721)	(195,296)
Allowance for doubtful accounts, end of period	$ 1,101,413	$ 1,506,202	$ 1,101,413	$ 1,506,202
Accounts Receivable Additional Disclosures [Abstract]
Number of major customer accounting for more than 10% of Company's total accounts receivable	0		0		0
Number of major customer accounting for more than 10% of Company's total revenue	0	0	0	1
Percentage of revenue accounted for by major customer				10.50%

- Definition

Amount of the current period expense charged against operations, the offset which is generally to the allowance for doubtful accounts for the purpose of reducing receivables, including notes receivable, to an amount that approximates their net realizable value (the amount expected to be collected).

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