Quarterly report pursuant to Section 13 or 15(d)

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

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Nonrecourse Debt - Schedule of Outstanding Amounts under Each Nonrecourse Asset-Backed Debt Agreements and Bank Loans and Value of Assets Pledged as Security (Detail) - USD ($)
$ in Millions
3 Months Ended 12 Months Ended
Mar. 31, 2016
Dec. 31, 2015
Financial Instruments Owned and Pledged as Collateral [Line Items]    
Debt issuance costs $ (13)  
Value of Assets Pledged, Financing receivables 91 $ 97
Nonrecourse Asset-Backed Debt Agreement [Member]    
Financial Instruments Owned and Pledged as Collateral [Line Items]    
Debt issuance costs (15) (16)
Outstanding Balance 552 563
Nonrecourse Asset-Backed Debt Agreement [Member] | HASI Sustainable Yield Bond 2013-1 [Member]    
Financial Instruments Owned and Pledged as Collateral [Line Items]    
Outstanding Balance 82 83
Value of Assets Pledged, Financing receivables $ 98 99
Description of Assets Pledged Financing receivables  
Nonrecourse Asset-Backed Debt Agreement [Member] | ABS Loan Agreement [Member]    
Financial Instruments Owned and Pledged as Collateral [Line Items]    
Outstanding Balance $ 99 102
Value of Assets Pledged, Equity interest $ 110 117
Description of Assets Pledged Equity interest in Strong Upwind Holdings I, LLC  
Nonrecourse Asset-Backed Debt Agreement [Member] | HASI Sustainable Yield Bond 2015-1 [Member]    
Financial Instruments Owned and Pledged as Collateral [Line Items]    
Outstanding Balance $ 99 100
Description of Assets Pledged Financing receivables, real estate and real estate intangibles  
Value of Assets Pledged, Financing receivables, real estate and real estate intangibles $ 139 139
Nonrecourse Asset-Backed Debt Agreement [Member] | HASI SYB Loan Agreement 2015-1 [Member]    
Financial Instruments Owned and Pledged as Collateral [Line Items]    
Outstanding Balance 84 90
Value of Assets Pledged, Equity interest $ 110 117
Description of Assets Pledged Equity interest in Strong Upwind Holdings II and III, LLC, related interest rate swap  
Nonrecourse Asset-Backed Debt Agreement [Member] | HASI SYB Loan Agreement 2015-2 [Member]    
Financial Instruments Owned and Pledged as Collateral [Line Items]    
Outstanding Balance $ 42 42
Value of Assets Pledged, Equity interest $ 70 71
Description of Assets Pledged Equity interest in Buckeye Wind Energy Class B Holdings LLC, related interest rate swap  
Nonrecourse Asset-Backed Debt Agreement [Member] | HASI SYB Loan Agreement 2015-3 [Member]    
Financial Instruments Owned and Pledged as Collateral [Line Items]    
Outstanding Balance $ 161 162
Value of Assets Pledged, Financing receivables $ 174 $ 175
Description of Assets Pledged Residential Solar Financing receivables