Annual report pursuant to Section 13 and 15(d)

Long-term Debt - Schedule of Outstanding Non-Recourse Asset-Backed Debt and Bank Loans (Detail)

v3.8.0.1
Long-term Debt - Schedule of Outstanding Non-Recourse Asset-Backed Debt and Bank Loans (Detail) - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2017
Jan. 31, 2017
Dec. 31, 2016
Financial Instruments Owned and Pledged as Collateral [Line Items]      
Debt issuance costs $ (27)    
Value of Assets Pledged, Equity interest $ 29   $ 41
Minimum [Member]      
Financial Instruments Owned and Pledged as Collateral [Line Items]      
Non-recourse Asset-Backed Debt, Interest Rate 2.26%    
Non-recourse Asset-Backed Debt, Maturity Date 2018-12    
Non-recourse Asset-Backed Debt, Anticipated Balance at Maturity $ 5    
Maximum [Member]      
Financial Instruments Owned and Pledged as Collateral [Line Items]      
Non-recourse Asset-Backed Debt, Interest Rate 7.45%    
Non-recourse Asset-Backed Debt, Maturity Date 2046-12    
HASI Sustainable Yield Bond 2013-1 [Member]      
Financial Instruments Owned and Pledged as Collateral [Line Items]      
Non-recourse Asset-Backed Debt, Interest Rate 2.79%    
Non-recourse Asset-Backed Debt, Maturity Date 2019-12    
Non-recourse Asset-Backed Debt, Anticipated Balance at Maturity $ 57    
ABS Loan Agreement [Member]      
Financial Instruments Owned and Pledged as Collateral [Line Items]      
Non-recourse Asset-Backed Debt, Interest Rate 5.74%    
Non-recourse Asset-Backed Debt, Maturity Date 2021-09    
Non-recourse Asset-Backed Debt, Anticipated Balance at Maturity $ 17    
HASI Sustainable Yield Bond 2015-1A [Member]      
Financial Instruments Owned and Pledged as Collateral [Line Items]      
Non-recourse Asset-Backed Debt, Interest Rate 4.28%    
Non-recourse Asset-Backed Debt, Maturity Date 2034-10    
HASI Sustainable Yield Bond 2015-1B [Member]      
Financial Instruments Owned and Pledged as Collateral [Line Items]      
Non-recourse Asset-Backed Debt, Interest Rate 5.41%    
Non-recourse Asset-Backed Debt, Maturity Date 2034-10    
2017 Credit Agreement [Member]      
Financial Instruments Owned and Pledged as Collateral [Line Items]      
Non-recourse Asset-Backed Debt, Interest Rate 4.12%    
Non-recourse Asset-Backed Debt, Maturity Date 2023-01    
HASI SYB Loan Agreement 2015-2 [Member]      
Financial Instruments Owned and Pledged as Collateral [Line Items]      
Non-recourse Asset-Backed Debt, Interest Rate 5.78%    
Non-recourse Asset-Backed Debt, Maturity Date 2023-12    
HASI SYB Loan Agreement 2015-3 [Member]      
Financial Instruments Owned and Pledged as Collateral [Line Items]      
Non-recourse Asset-Backed Debt, Interest Rate 4.92%    
Non-recourse Asset-Backed Debt, Maturity Date 2020-12    
Non-recourse Asset-Backed Debt, Anticipated Balance at Maturity $ 127    
HASI SYB Loan Agreement 2016-1 [Member]      
Financial Instruments Owned and Pledged as Collateral [Line Items]      
Non-recourse Asset-Backed Debt, Interest Rate 4.44%    
Non-recourse Asset-Backed Debt, Maturity Date 2021-11    
Non-recourse Asset-Backed Debt, Anticipated Balance at Maturity $ 104    
HASI SYB Trust 2016-2 [Member]      
Financial Instruments Owned and Pledged as Collateral [Line Items]      
Non-recourse Asset-Backed Debt, Interest Rate 4.35%    
Non-recourse Asset-Backed Debt, Maturity Date 2037-04    
2017 Master Repurchase Agreement [Member]      
Financial Instruments Owned and Pledged as Collateral [Line Items]      
Non-recourse Asset-Backed Debt, Interest Rate 3.98%    
Non-recourse Asset-Backed Debt, Maturity Date 2019-07    
Non-recourse Asset-Backed Debt, Anticipated Balance at Maturity $ 31    
HASI ECON 101 Trust [Member]      
Financial Instruments Owned and Pledged as Collateral [Line Items]      
Non-recourse Asset-Backed Debt, Interest Rate 3.57%    
Non-recourse Asset-Backed Debt, Maturity Date 2041-05    
HASI SYB Trust 2017-1 [Member]      
Financial Instruments Owned and Pledged as Collateral [Line Items]      
Non-recourse Asset-Backed Debt, Interest Rate 3.86%    
Non-recourse Asset-Backed Debt, Maturity Date 2042-03    
Asset-Backed Nonrecourse Debt Agreement [Member]      
Financial Instruments Owned and Pledged as Collateral [Line Items]      
Other non-recourse debt $ 90   84
Debt issuance costs (27)   (17)
Outstanding Balance 1,211   692
Value of Assets Pledged, Equity interest $ 162   81
Description of Assets Pledged Receivables    
Asset-Backed Nonrecourse Debt Agreement [Member] | HASI Sustainable Yield Bond 2013-1 [Member]      
Financial Instruments Owned and Pledged as Collateral [Line Items]      
Outstanding Balance $ 67   75
Value of Assets Pledged, Equity interest $ 86   93
Description of Assets Pledged Receivables    
Asset-Backed Nonrecourse Debt Agreement [Member] | ABS Loan Agreement [Member]      
Financial Instruments Owned and Pledged as Collateral [Line Items]      
Outstanding Balance $ 81   90
Value of Assets Pledged, Equity interest $ 79   97
Description of Assets Pledged Equity interest in Strong Upwind Holdings I, LLC    
Asset-Backed Nonrecourse Debt Agreement [Member] | HASI Sustainable Yield Bond 2015-1A [Member]      
Financial Instruments Owned and Pledged as Collateral [Line Items]      
Outstanding Balance $ 94   97
Non-recourse Asset-Backed Debt, Interest Rate 4.28%    
Non-recourse Asset-Backed Debt, Maturity Date 2034-10    
Value of Assets Pledged, Equity interest $ 137   138
Description of Assets Pledged Receivables, real estate and real estate intangibles    
Asset-Backed Nonrecourse Debt Agreement [Member] | HASI Sustainable Yield Bond 2015-1B [Member]      
Financial Instruments Owned and Pledged as Collateral [Line Items]      
Outstanding Balance $ 14 $ 14  
Non-recourse Asset-Backed Debt, Interest Rate 5.00%    
Non-recourse Asset-Backed Debt, Maturity Date 2034-10    
Value of Assets Pledged, Equity interest $ 137    
Description of Assets Pledged Class B Bond of HASI Sustainable Yield Bond 2015-1    
Asset-Backed Nonrecourse Debt Agreement [Member] | HASI SYB Loan Agreement 2015-1 [Member]      
Financial Instruments Owned and Pledged as Collateral [Line Items]      
Outstanding Balance     74
Value of Assets Pledged, Equity interest     96
Description of Assets Pledged Equity interest in Strong Upwind Holdings II and III, LLC, related interest rate swap    
Asset-Backed Nonrecourse Debt Agreement [Member] | 2017 Credit Agreement [Member]      
Financial Instruments Owned and Pledged as Collateral [Line Items]      
Outstanding Balance $ 180    
Value of Assets Pledged, Equity interest $ 226    
Description of Assets Pledged Equity interests in Strong Upwind Holdings I, II, III, and IV LLC, and Northern Frontier, LLC    
Asset-Backed Nonrecourse Debt Agreement [Member] | HASI SYB Loan Agreement 2015-2 [Member]      
Financial Instruments Owned and Pledged as Collateral [Line Items]      
Outstanding Balance $ 36   41
Value of Assets Pledged, Equity interest $ 68   70
Description of Assets Pledged Equity interest in Buckeye Wind Energy Class B Holdings LLC, related interest rate swap    
Asset-Backed Nonrecourse Debt Agreement [Member] | HASI SYB Loan Agreement 2015-3 [Member]      
Financial Instruments Owned and Pledged as Collateral [Line Items]      
Outstanding Balance $ 143   150
Value of Assets Pledged, Equity interest $ 171   175
Description of Assets Pledged Residential solar receivables, related interest rate swaps    
Asset-Backed Nonrecourse Debt Agreement [Member] | HASI SYB Loan Agreement 2016-1 [Member]      
Financial Instruments Owned and Pledged as Collateral [Line Items]      
Outstanding Balance $ 121   98
Value of Assets Pledged, Equity interest $ 143   $ 114
Description of Assets Pledged Residential solar receivables, related interest rate swaps    
Asset-Backed Nonrecourse Debt Agreement [Member] | HASI SYB Trust 2016-2 [Member]      
Financial Instruments Owned and Pledged as Collateral [Line Items]      
Outstanding Balance $ 81    
Value of Assets Pledged, Equity interest $ 86    
Description of Assets Pledged Receivables    
Asset-Backed Nonrecourse Debt Agreement [Member] | 2017 Master Repurchase Agreement [Member]      
Financial Instruments Owned and Pledged as Collateral [Line Items]      
Outstanding Balance $ 35    
Value of Assets Pledged, Equity interest $ 38    
Description of Assets Pledged Receivables and investments    
Asset-Backed Nonrecourse Debt Agreement [Member] | HASI ECON 101 Trust [Member]      
Financial Instruments Owned and Pledged as Collateral [Line Items]      
Outstanding Balance $ 134    
Value of Assets Pledged, Equity interest $ 140    
Description of Assets Pledged Receivables and investments    
Asset-Backed Nonrecourse Debt Agreement [Member] | HASI SYB Trust 2017-1 [Member]      
Financial Instruments Owned and Pledged as Collateral [Line Items]      
Outstanding Balance $ 162    
Value of Assets Pledged, Equity interest $ 209    
Description of Assets Pledged Receivables, real estate and real estate intangibles