Annual report pursuant to Section 13 and 15(d)

Summary of Significant Accounting Policies - Accounts Receivable (Details)

v2.4.1.9
Summary of Significant Accounting Policies - Accounts Receivable (Details) (USD $)
In Thousands, unless otherwise specified
 12 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Allowance for Doubtful Accounts Receivable [Roll Forward]      
Allowance for doubtful accounts, beginning of period $ 1,519us-gaap_AllowanceForDoubtfulAccountsReceivable $ 1,174us-gaap_AllowanceForDoubtfulAccountsReceivable $ 1,135us-gaap_AllowanceForDoubtfulAccountsReceivable
Charges to costs and expenses 1,988us-gaap_ProvisionForDoubtfulAccounts 502us-gaap_ProvisionForDoubtfulAccounts 149us-gaap_ProvisionForDoubtfulAccounts
Account write-offs and other (656)amrc_AllowanceForDoubtfulAccountsReceivableChargeOffsAndOther (157)amrc_AllowanceForDoubtfulAccountsReceivableChargeOffsAndOther (110)amrc_AllowanceForDoubtfulAccountsReceivableChargeOffsAndOther
Allowance for doubtful accounts, end of period $ 2,851us-gaap_AllowanceForDoubtfulAccountsReceivable $ 1,519us-gaap_AllowanceForDoubtfulAccountsReceivable $ 1,174us-gaap_AllowanceForDoubtfulAccountsReceivable
Minimum      
Allowance for Doubtful Accounts Receivable [Roll Forward]      
Accounts receivable retainage 5.00%amrc_AccountsReceivableRetainage
/ us-gaap_RangeAxis
= us-gaap_MinimumMember 		   
Maximum      
Allowance for Doubtful Accounts Receivable [Roll Forward]      
Accounts receivable retainage 10.00%amrc_AccountsReceivableRetainage
/ us-gaap_RangeAxis
= us-gaap_MaximumMember