Annual report pursuant to Section 13 and 15(d)

Long-term Debt - Additional Information (Detail)

v3.8.0.1
Long-term Debt - Additional Information (Detail) - USD ($)
$ / shares in Units, shares in Millions
 1 Months Ended 12 Months Ended
Aug. 31, 2017
Dec. 31, 2017
Jan. 31, 2017
Dec. 31, 2016
Debt Instrument [Line Items]        
Non-recourse Asset-Backed Debt, Aggregate Principal Amount   $ 1,210,861,000   $ 692,091,000
SunPower Corporation [Member] | Residential Solar Loan [Member]        
Debt Instrument [Line Items]        
Payment of principal and interest on loan   $ 1,000,000    
HASI Sustainable Yield Bond 2015-1A [Member]        
Debt Instrument [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]        
Debt Instrument [Line Items]        
Non-recourse Asset-Backed Debt, Interest Rate   5.41%    
Non-recourse Asset-Backed Debt, Maturity Date   2034-10    
4.125% Convertible Senior Notes Due September 1, 2022 [Member]        
Debt Instrument [Line Items]        
Non-recourse Asset-Backed Debt, Interest Rate 4.125%      
Debt instrument issued $ 145,000,000 $ 148,000,000    
Principal 150,000,000 $ 150,000,000    
Maturity date   Sep. 01, 2022    
Conversion of debt $ 1,000      
Conversion price per share $ 36.7107      
Conversion price per share 27.24      
Adjustment for dividends declared $ 0.33      
Conversion of debt equals shares 5.5      
Redemption price, percentage   100.00%    
Redemption description   We have a redemption option to call the convertible notes prior to maturity (i) on or after March 1, 2022 and (ii) at any time if such a redemption is deemed reasonably necessary to preserve our qualification as a REIT. The redemption price will be equal to the principal of the notes being redeemed, plus accrued and unpaid interest. In the event of redemption after March 1, 2022, there will be an additional make-whole premium paid to the holder of the redeemed notes unless the redemption is deemed reasonably necessary to preserve our qualification as a REIT.    
Asset-Backed Nonrecourse Debt Agreement [Member]        
Debt Instrument [Line Items]        
Debt instrument issued   $ 1,211,000,000   692,000,000
Asset-Backed Nonrecourse Debt Agreement [Member] | HASI Sustainable Yield Bond 2015-1A [Member]        
Debt Instrument [Line Items]        
Non-recourse Asset-Backed Debt, Aggregate Principal Amount   $ 101,000,000    
Non-recourse Asset-Backed Debt, Interest Rate   4.28%    
Non-recourse Asset-Backed Debt, Maturity Date   2034-10    
Debt instrument issued   $ 94,000,000   $ 97,000,000
Asset-Backed Nonrecourse Debt Agreement [Member] | HASI Sustainable Yield Bond 2015-1B [Member]        
Debt Instrument [Line Items]        
Non-recourse Asset-Backed Debt, Aggregate Principal Amount   $ 18,000,000    
Non-recourse Asset-Backed Debt, Interest Rate   5.00%    
Non-recourse Asset-Backed Debt, Maturity Date   2034-10    
Debt instrument issued   $ 14,000,000 $ 14,000,000