Quarterly report pursuant to Section 13 or 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
 3 Months Ended
Mar. 31, 2015
Mar. 31, 2014
Changes in the Allowance for Doubtful Accounts [Roll Forward]    
Allowance for doubtful accounts, beginning of period $ 2,851us-gaap_AllowanceForDoubtfulAccountsReceivable $ 1,519us-gaap_AllowanceForDoubtfulAccountsReceivable
Charges to costs and expenses 33us-gaap_ProvisionForDoubtfulAccounts 244us-gaap_ProvisionForDoubtfulAccounts
Account write-offs and other (91)amrc_AllowanceForDoubtfulAccountsReceivableChargeOffsAndOther (136)amrc_AllowanceForDoubtfulAccountsReceivableChargeOffsAndOther
Allowance for doubtful accounts, end of period $ 2,793us-gaap_AllowanceForDoubtfulAccountsReceivable $ 1,627us-gaap_AllowanceForDoubtfulAccountsReceivable
Minimum    
Accounts, Notes, Loans and Financing Receivable [Line Items]    
Accounts Receivable Retainage 5.00%amrc_AccountsReceivableRetainage
/ us-gaap_RangeAxis
= us-gaap_MinimumMember 		 
Maximum    
Accounts, Notes, Loans and Financing Receivable [Line Items]    
Accounts Receivable Retainage 10.00%amrc_AccountsReceivableRetainage
/ us-gaap_RangeAxis
= us-gaap_MaximumMember