Quarterly report pursuant to Section 13 or 15(d)

Nonrecourse Debt - Schedule of Outstanding Amounts under Each Nonrecourse Asset-Backed Debt Agreement and Value of Assets Pledged as Security (Detail)

v3.3.0.814
Nonrecourse Debt - Schedule of Outstanding Amounts under Each Nonrecourse Asset-Backed Debt Agreement and Value of Assets Pledged as Security (Detail) - Nonrecourse Asset-Backed Debt Agreement [Member] - USD ($)
$ in Millions
9 Months Ended
Sep. 30, 2015
Dec. 31, 2014
HASI Sustainable Yield Bond 2013-1 [Member]    
Financial Instruments Owned and Pledged as Collateral [Line Items]    
Outstanding Balance $ 84 $ 92
Value of Assets Pledged, Financing receivables $ 100 104
Description of Assets Pledged Financing receivables  
ABS Loan Agreement [Member]    
Financial Instruments Owned and Pledged as Collateral [Line Items]    
Outstanding Balance $ 103 116
Value of Assets Pledged, Equity interest in Strong Upwind JV $ 121 $ 144
Description of Assets Pledged Equity interest in Strong Upwind Holdings I, LLC  
HASI Sustainable Yield Bond 2015-1 [Member]    
Financial Instruments Owned and Pledged as Collateral [Line Items]    
Outstanding Balance $ 101  
Value of Assets Pledged, Real estate and real estate intangibles $ 140  
Description of Assets Pledged Financing receivables, real estate and real estate intangibles