Annual report pursuant to Section 13 and 15(d)

Summary of Significant Accounting Policies - Derivative Financial Instruments (Details)

v2.4.1.9
Summary of Significant Accounting Policies - Derivative Financial Instruments (Details) (USD $)
3 Months Ended 1 Months Ended 12 Months Ended
Jun. 30, 2014
Mar. 31, 2010
swap
Jul. 31, 2011
swap
Oct. 31, 2012
swap
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Dec. 31, 2007
contract
Sep. 30, 2013
Derivative [Line Items]                  
Interest Expense Reclassified from Accumulated Other Comprehensive (Loss) Income, Net into Other Expenses, Net $ 566,000us-gaap_DerivativeInstrumentsLossReclassifiedFromAccumulatedOCIIntoIncomeEffectivePortion                
Interest Rate Swap                  
Derivative [Line Items]                  
Number of instruments               2us-gaap_DerivativeNumberOfInstrumentsHeld
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_InterestRateSwapMember
 
Interest Rate Swap | Interest Rate Swap Contract 1                  
Derivative [Line Items]                  
Notional amount               13,081,000invest_DerivativeNotionalAmount
/ amrc_DerivativeInstrumentByContractAxis
= amrc_InterestRateSwapContract1Member
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_InterestRateSwapMember
 
Interest rate swaps, variable to fixed interest rates               5.40%us-gaap_DerivativeVariableInterestRate
/ amrc_DerivativeInstrumentByContractAxis
= amrc_InterestRateSwapContract1Member
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_InterestRateSwapMember
 
Interest Rate Swap | Interest Rate Swap Contract 2                  
Derivative [Line Items]                  
Notional amount               3,256,000invest_DerivativeNotionalAmount
/ amrc_DerivativeInstrumentByContractAxis
= amrc_InterestRateSwapContract2Member
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_InterestRateSwapMember
 
Interest rate swaps, variable to fixed interest rates               5.30%us-gaap_DerivativeVariableInterestRate
/ amrc_DerivativeInstrumentByContractAxis
= amrc_InterestRateSwapContract2Member
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_InterestRateSwapMember
 
Interest Rate Swap | Interest Rate Swap Contract 3                  
Derivative [Line Items]                  
Number of instruments   1us-gaap_DerivativeNumberOfInstrumentsHeld
/ amrc_DerivativeInstrumentByContractAxis
= amrc_InterestRateSwapContract3Member
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_InterestRateSwapMember
             
Term of interest rate swap contract   14 years              
Notional amount   27,900,000invest_DerivativeNotionalAmount
/ amrc_DerivativeInstrumentByContractAxis
= amrc_InterestRateSwapContract3Member
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_InterestRateSwapMember
             
Interest rate swaps, variable to fixed interest rates   6.99%us-gaap_DerivativeVariableInterestRate
/ amrc_DerivativeInstrumentByContractAxis
= amrc_InterestRateSwapContract3Member
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_InterestRateSwapMember
             
Interest Rate Swap | Interest Rate Swap Contract 4                  
Derivative [Line Items]                  
Number of instruments     1us-gaap_DerivativeNumberOfInstrumentsHeld
/ amrc_DerivativeInstrumentByContractAxis
= amrc_InterestRateSwapContract4Member
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_InterestRateSwapMember
           
Term of interest rate swap contract     5 years            
Notional amount     38,571,000invest_DerivativeNotionalAmount
/ amrc_DerivativeInstrumentByContractAxis
= amrc_InterestRateSwapContract4Member
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_InterestRateSwapMember
           
Interest rate swaps, variable to fixed interest rates     1.965%us-gaap_DerivativeVariableInterestRate
/ amrc_DerivativeInstrumentByContractAxis
= amrc_InterestRateSwapContract4Member
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_InterestRateSwapMember
           
Interest Rate Swap | Interest Rate Swap Contract 5                  
Derivative [Line Items]                  
Number of instruments       2us-gaap_DerivativeNumberOfInstrumentsHeld
/ amrc_DerivativeInstrumentByContractAxis
= amrc_InterestRateSwapContract5Member
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_InterestRateSwapMember
         
Term of interest rate swap contract       8 years          
Notional amount       16,750,000invest_DerivativeNotionalAmount
/ amrc_DerivativeInstrumentByContractAxis
= amrc_InterestRateSwapContract5Member
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_InterestRateSwapMember
         
Interest rate swaps, variable to fixed interest rates       1.71%us-gaap_DerivativeVariableInterestRate
/ amrc_DerivativeInstrumentByContractAxis
= amrc_InterestRateSwapContract5Member
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_InterestRateSwapMember
         
Future Increase in Notional Amount                 42,247,000amrc_FutureIncreaseInNotionalAmount
/ amrc_DerivativeInstrumentByContractAxis
= amrc_InterestRateSwapContract5Member
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_InterestRateSwapMember
Interest Rate Swap | Interest Rate Swap Contract 6                  
Derivative [Line Items]                  
Number of instruments       2us-gaap_DerivativeNumberOfInstrumentsHeld
/ amrc_DerivativeInstrumentByContractAxis
= amrc_InterestRateSwapContract6Member
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_InterestRateSwapMember
         
Term of interest rate swap contract       8 years          
Notional amount       25,377,000invest_DerivativeNotionalAmount
/ amrc_DerivativeInstrumentByContractAxis
= amrc_InterestRateSwapContract6Member
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_InterestRateSwapMember
         
Interest rate swaps, variable to fixed interest rates       3.70%us-gaap_DerivativeVariableInterestRate
/ amrc_DerivativeInstrumentByContractAxis
= amrc_InterestRateSwapContract6Member
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_InterestRateSwapMember
         
Not Designated as Hedging Instrument | Interest Rate Swap                  
Derivative [Line Items]                  
Amount of Gain (Loss) Recognized in Income on Derivative         $ 0us-gaap_DerivativeGainLossOnDerivativeNet
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_InterestRateSwapMember
/ us-gaap_HedgingDesignationAxis
= us-gaap_NondesignatedMember
$ (266,000)us-gaap_DerivativeGainLossOnDerivativeNet
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_InterestRateSwapMember
/ us-gaap_HedgingDesignationAxis
= us-gaap_NondesignatedMember
$ 98,000us-gaap_DerivativeGainLossOnDerivativeNet
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_InterestRateSwapMember
/ us-gaap_HedgingDesignationAxis
= us-gaap_NondesignatedMember