Quarterly report pursuant to Section 13 or 15(d)

Summary of Significant Accounting Policies - Additional Information (Detail)

v2.4.1.9
Summary of Significant Accounting Policies - Additional Information (Detail) (USD $)
 3 Months Ended 1 Months Ended
Mar. 31, 2015
Segment
Mar. 31, 2014
Oct. 31, 2014
State
Project
Dec. 31, 2014
Summary Of Significant Accounting Policies [Line Items]        
Financing receivable, past due 90 days      
Cash and cash equivalents original maturity period 3 months      
Impairment of equity method investment $ 0us-gaap_EquityMethodInvestmentOtherThanTemporaryImpairment      
Real estate investment description To qualify as a REIT, we must meet a number of organizational and operational requirements, including a requirement that we currently distribute at least 90% of our net taxable income, excluding capital gains, to our shareholders.      
Income tax examination, description We have no examinations in progress, none are expected at this time, and years 2010 through 2014 are open.      
Uncertain tax positions 0hasi_UncertainTaxPositions     0hasi_UncertainTaxPositions
Accrued interest and penalties 0us-gaap_IncomeTaxExaminationPenaltiesAndInterestAccrued     0us-gaap_IncomeTaxExaminationPenaltiesAndInterestAccrued
Interest and penalties recognized during the period 0us-gaap_IncomeTaxExaminationPenaltiesAndInterestExpense 0us-gaap_IncomeTaxExaminationPenaltiesAndInterestExpense    
Number of segment reported 1us-gaap_NumberOfReportableSegments      
2013 Plan [Member] | Performance Based Restricted Stock Award [Member]        
Summary Of Significant Accounting Policies [Line Items]        
Stock-based award vesting minimum percentage 0.00%hasi_ShareBasedCompensationAwardMinimumVestingPercentage
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockUnitsRSUMember
/ us-gaap_PlanNameAxis
= hasi_TwoThousandAndThirteenStockCompensationPlanMember 		     
Stock-based award vesting maximum percentage 150.00%hasi_ShareBasedCompensationAwardMaximumVestingPercentage
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockUnitsRSUMember
/ us-gaap_PlanNameAxis
= hasi_TwoThousandAndThirteenStockCompensationPlanMember 		     
Stock-based award, range of vesting percentage description The award earned is generally between 0% and 150% of the initial target, depending on the extent to which the performance target are met.      
Strong Upwind Holdings LLC [Member]        
Summary Of Significant Accounting Policies [Line Items]        
Project investment amount     $ 144,000,000us-gaap_InvestmentOwnedAtCost
/ dei_LegalEntityAxis
= hasi_StrongUpwindHoldingsLlcMember 		 
Ownership percentage     50.00%us-gaap_EquityMethodInvestmentOwnershipPercentage
/ dei_LegalEntityAxis
= hasi_StrongUpwindHoldingsLlcMember 		 
Number of limited liability companies     4hasi_NumberOfLimitedLiabilityCompanies
/ dei_LegalEntityAxis
= hasi_StrongUpwindHoldingsLlcMember 		 
Number of States     5hasi_NumberOfStates
/ dei_LegalEntityAxis
= hasi_StrongUpwindHoldingsLlcMember 		 
Strong Upwind Holdings LLC [Member] | Wind Project Investment [Member]        
Summary Of Significant Accounting Policies [Line Items]        
Number of operating projects     10hasi_NumberOfOperatingProjects
/ us-gaap_FinancialInstrumentAxis
= hasi_WindProjectInvestmentMember
/ dei_LegalEntityAxis
= hasi_StrongUpwindHoldingsLlcMember 		 
Minimum [Member]        
Summary Of Significant Accounting Policies [Line Items]        
Percentage of taxable income distributed to stockholders 90.00%hasi_PercentageOfTaxableIncomeOfRealEstateInvestmentTrustDistributedToStockholders
/ us-gaap_RangeAxis
= us-gaap_MinimumMember 		     
Minimum [Member] | Strong Upwind Holdings LLC [Member]        
Summary Of Significant Accounting Policies [Line Items]        
Ownership interest based on voting percentage     4.00%hasi_OwnershipInterestPercentageBasedOnVotingInterest
/ dei_LegalEntityAxis
= hasi_StrongUpwindHoldingsLlcMember
/ us-gaap_RangeAxis
= us-gaap_MinimumMember 		 
Maximum [Member] | Strong Upwind Holdings LLC [Member]        
Summary Of Significant Accounting Policies [Line Items]        
Ownership interest based on voting percentage     17.50%hasi_OwnershipInterestPercentageBasedOnVotingInterest
/ dei_LegalEntityAxis
= hasi_StrongUpwindHoldingsLlcMember
/ us-gaap_RangeAxis
= us-gaap_MaximumMember