Annual report pursuant to Section 13 and 15(d)

Summary of Significant Accounting Policies - Earnings Per Share (Details)

v3.6.0.2
Summary of Significant Accounting Policies - Earnings Per Share (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
Accounting Policies [Abstract]                      
Net income attributable to Ameresco, Inc.                 $ 12,032 $ 844 $ 10,383
Basic weighted-average shares outstanding (in shares) 45,811,358 46,360,575 46,719,122 46,742,488 46,556,977 46,517,638 46,493,162 46,408,123 46,409,192 46,494,448 46,161,846
Effect of dilutive securities:                      
Stock options (in shares)                 84,285 1,170,447 865,909
Diluted weighted-average shares outstanding (in shares) 45,907,120 46,430,163 46,793,350 46,860,344 46,566,977 48,056,359 47,385,412 46,408,123 46,493,477 47,664,895 47,027,755
Stock options excluded from calculation of dilutive shares as the effect would be anti-dilutive (in shares)                 3,530,220 1,767,778 1,737,261