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

Basis of Presentation	9 Months Ended
Basis of Presentation	Sep. 30, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	BASIS OF PRESENTATION The accompanying condensed consolidated financial statements of Ameresco, Inc. (including its subsidiaries, the “Company”) are unaudited, pursuant to certain rules and regulations of the Securities and Exchange Commission, and include, in the opinion of the Company, normal recurring adjustments necessary for a fair presentation in conformity with accounting principles generally accepted in the United States (“GAAP”) of the results for the periods indicated. The results of operations for the three and nine months ended September 30, 2019 are not necessarily indicative of results which may be expected for the full year. The December 31, 2018 consolidated balance sheet data was derived from audited financial statements, but certain information and footnote disclosures normally included in financial statements prepared in accordance with GAAP have been condensed or omitted. The interim condensed consolidated financial statements, and notes thereto, should be read in conjunction with the audited consolidated financial statements for the year ended December 31, 2018, and notes thereto, included in the Company’s annual report on Form 10-K for the year ended December 31, 2018 filed with the Securities and Exchange Commission on March 8, 2019.