Annual report pursuant to Section 13 and 15(d)

Our Portfolio - Financing Receivables, Investments, Real Estate and Equity Method Investments - Additional Information (Detail)

v2.4.1.9
Our Portfolio - Financing Receivables, Investments, Real Estate and Equity Method Investments - Additional Information (Detail) (USD $)
 3 Months Ended 9 Months Ended 12 Months Ended
Jun. 30, 2014
Dec. 31, 2012
Dec. 31, 2014
Investment
Dec. 31, 2014
Investment
Dec. 31, 2013
Investment
Sep. 30, 2012
Mar. 31, 2014
May 31, 2013
Financing Receivable, Recorded Investment [Line Items]                
Financing receivables and investments     $ 900,000,000us-gaap_LoansAndLeasesReceivableNetReportedAmount $ 900,000,000us-gaap_LoansAndLeasesReceivableNetReportedAmount        
Deferred funding obligations     88,288,000us-gaap_ContractualObligation 88,288,000us-gaap_ContractualObligation 74,675,000us-gaap_ContractualObligation      
Restricted cash     3,000,000hasi_RestrictedCashAndCashEquivalent 3,000,000hasi_RestrictedCashAndCashEquivalent 49,900,000hasi_RestrictedCashAndCashEquivalent      
Available-for-sale debt securities at fair value     59,600,000us-gaap_AvailableForSaleSecuritiesDebtSecurities 59,600,000us-gaap_AvailableForSaleSecuritiesDebtSecurities     3,200,000us-gaap_AvailableForSaleSecuritiesDebtSecurities  
Investments classified as held-to-maturity carrying value 14,700,000us-gaap_HeldToMaturitySecuritiesSoldSecurityAtCarryingValue              
Sale of investments classified as held-to-maturity 15,500,000us-gaap_ProceedsFromSaleOfHeldToMaturitySecurities              
Realized gain on sale of investments classified as held-to-maturity 800,000us-gaap_HeldToMaturitySecuritiesSoldSecurityRealizedGainLoss              
Available-for-sale debt securities sold at fair value     59,600,000hasi_AvailableForSaleSecuritiesSoldFairValue          
Available-for-sale debt securities at cost     56,300,000hasi_AvailableForSaleSecuritiesCost 56,300,000hasi_AvailableForSaleSecuritiesCost        
Realized gain on sale of investments     3,300,000us-gaap_AvailableForSaleSecuritiesGrossRealizedGains 3,300,000us-gaap_AvailableForSaleSecuritiesGrossRealizedGains        
Investments in unrealized loss position     0hasi_NumberOfInvestmentPositionsCarriedAtUnrealizedLoss 0hasi_NumberOfInvestmentPositionsCarriedAtUnrealizedLoss 0hasi_NumberOfInvestmentPositionsCarriedAtUnrealizedLoss      
Financing receivable allowance     1,200,000us-gaap_AllowanceForNotesAndLoansReceivableCurrent 1,200,000us-gaap_AllowanceForNotesAndLoansReceivableCurrent        
Charged off of receivable against allowance       9,800,000us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs        
Allowance for credit losses     1,200,000us-gaap_FinancingReceivableAllowanceForCreditLosses 1,200,000us-gaap_FinancingReceivableAllowanceForCreditLosses 11,000,000us-gaap_FinancingReceivableAllowanceForCreditLosses 0us-gaap_FinancingReceivableAllowanceForCreditLosses    
Maximum exposure loss for variable interest entity       800,000hasi_VariableInterestEntityMaximumExposureToLoss        
Accrued interest income       0us-gaap_InterestExpenseRelatedParty 2,400,000us-gaap_InterestExpenseRelatedParty      
Other financing receivables on non accrual status     0us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus 0us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus 0us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus      
Provision for credit losses   0hasi_ProvisionForCreditLosses       0hasi_ProvisionForCreditLosses    
Loan modifications that qualify as trouble debt restructurings   0us-gaap_FinancingReceivablesImpairedTroubledDebtRestructuringWriteDown   0us-gaap_FinancingReceivablesImpairedTroubledDebtRestructuringWriteDown 0us-gaap_FinancingReceivablesImpairedTroubledDebtRestructuringWriteDown 0us-gaap_FinancingReceivablesImpairedTroubledDebtRestructuringWriteDown    
Debt and Real Estate Portfolio [Member]                
Financing Receivable, Recorded Investment [Line Items]                
% of Debt and Real Estate Portfolio       98.00%us-gaap_ConcentrationRiskPercentage1
/ us-gaap_ConcentrationRiskByBenchmarkAxis
= hasi_PortfolioMember 		       
Minimum [Member]                
Financing Receivable, Recorded Investment [Line Items]                
Lease agreement expected expirations, term       2047        
Long term land lease agreements expiration dates range       2033        
Long term land lease agreements extended expiration dates range       2052        
Maximum [Member]                
Financing Receivable, Recorded Investment [Line Items]                
Lease agreement expected expirations, term       2061        
Long term land lease agreements expiration dates range       2044        
Long term land lease agreements extended expiration dates range       2047        
November Two Thousand Fourteen [Member]                
Financing Receivable, Recorded Investment [Line Items]                
Loan expected recovery       800,000hasi_LoanAndLeaseLossExpectedRecovery
/ us-gaap_StatementScenarioAxis
= hasi_NovemberTwoThousandFourteenMember 		       
Maximum agreed recovery amount       2,000,000hasi_LoanAndLeaseLossAgreedMaximumRecovery
/ us-gaap_StatementScenarioAxis
= hasi_NovemberTwoThousandFourteenMember 		       
Energy Source LLC [Member]                
Financing Receivable, Recorded Investment [Line Items]                
Financing receivable allowance         11,000,000us-gaap_AllowanceForNotesAndLoansReceivableCurrent
/ dei_LegalEntityAxis
= hasi_EnergySourceMember 		     
Financing receivable allowance, face amount               24,000,000hasi_LoansReceivableFaceAmount
/ dei_LegalEntityAxis
= hasi_EnergySourceMember
Financial receivable average outstanding balance     $ 11,800,000us-gaap_NotesAndLoansReceivableGrossCurrent
/ dei_LegalEntityAxis
= hasi_EnergySourceMember 		$ 11,800,000us-gaap_NotesAndLoansReceivableGrossCurrent
/ dei_LegalEntityAxis
= hasi_EnergySourceMember 		$ 24,700,000us-gaap_NotesAndLoansReceivableGrossCurrent
/ dei_LegalEntityAxis
= hasi_EnergySourceMember