Quarterly report pursuant to Section 13 or 15(d)

Long-term Debt - Schedule of Interest Rate Swaps which are Designated as Cash Flow Hedges (Detail)

v3.8.0.1
Long-term Debt - Schedule of Interest Rate Swaps which are Designated as Cash Flow Hedges (Detail) - Cash Flow Hedging [Member] - Interest Rate Swap [Member] - USD ($)
 9 Months Ended
Sep. 30, 2017
Dec. 31, 2016
Derivatives, Fair Value [Line Items]    
Notional Value $ 410,000,000 $ 431,000,000
Fair Value $ (1,300,000) 1,000,000
HASI SYB Loan Agreement 2015-1 [Member]    
Derivatives, Fair Value [Line Items]    
Hedged Rate 1.55%  
Notional Value   67,000,000
HASI SYB Loan Agreement 2015-1 [Member] | Minimum [Member]    
Derivatives, Fair Value [Line Items]    
Maturity 2015-12  
HASI SYB Loan Agreement 2015-1 [Member] | Maximum [Member]    
Derivatives, Fair Value [Line Items]    
Maturity 2021-09  
HASI SYB Loan Agreement 2015-1 [Member] | Base Rate [Member]    
Derivatives, Fair Value [Line Items]    
Base Rate 3 month Libor  
HASI SYB Loan Agreement 2015-2 A [Member]    
Derivatives, Fair Value [Line Items]    
Hedged Rate 1.52%  
Notional Value $ 36,000,000 37,000,000
HASI SYB Loan Agreement 2015-2 A [Member] | Minimum [Member]    
Derivatives, Fair Value [Line Items]    
Maturity 2015-12  
HASI SYB Loan Agreement 2015-2 A [Member] | Maximum [Member]    
Derivatives, Fair Value [Line Items]    
Maturity 2018-12  
HASI SYB Loan Agreement 2015-2 A [Member] | Base Rate [Member]    
Derivatives, Fair Value [Line Items]    
Base Rate 3 month Libor  
HASI SYB Loan Agreement 2015-2 B [Member]    
Derivatives, Fair Value [Line Items]    
Hedged Rate 2.55%  
Notional Value $ 29,000,000 29,000,000
Fair Value $ (300,000) (200,000)
HASI SYB Loan Agreement 2015-2 B [Member] | Minimum [Member]    
Derivatives, Fair Value [Line Items]    
Maturity 2018-12  
HASI SYB Loan Agreement 2015-2 B [Member] | Maximum [Member]    
Derivatives, Fair Value [Line Items]    
Maturity 2024-12  
HASI SYB Loan Agreement 2015-2 B [Member] | Base Rate [Member]    
Derivatives, Fair Value [Line Items]    
Base Rate 3 month Libor  
HASI SYB Loan Agreement 2015-3 [Member]    
Derivatives, Fair Value [Line Items]    
Hedged Rate 2.34%  
Notional Value $ 119,000,000 119,000,000
Fair Value $ (100,000) 1,000,000
HASI SYB Loan Agreement 2015-3 [Member] | Minimum [Member]    
Derivatives, Fair Value [Line Items]    
Maturity 2020-11  
HASI SYB Loan Agreement 2015-3 [Member] | Maximum [Member]    
Derivatives, Fair Value [Line Items]    
Maturity 2028-08  
HASI SYB Loan Agreement 2015-3 [Member] | Base Rate [Member]    
Derivatives, Fair Value [Line Items]    
Base Rate 1 month Libor  
HASI SYB Loan Agreement 2016-1 A [Member]    
Derivatives, Fair Value [Line Items]    
Hedged Rate 1.88%  
Notional Value $ 119,000,000 72,000,000
Fair Value $ 100,000 200,000
HASI SYB Loan Agreement 2016-1 A [Member] | Minimum [Member]    
Derivatives, Fair Value [Line Items]    
Maturity 2016-11  
HASI SYB Loan Agreement 2016-1 A [Member] | Maximum [Member]    
Derivatives, Fair Value [Line Items]    
Maturity 2021-11  
HASI SYB Loan Agreement 2016-1 A [Member] | Base Rate [Member]    
Derivatives, Fair Value [Line Items]    
Base Rate 3 month Libor  
HASI SYB Loan Agreement 2016-1 B [Member]    
Derivatives, Fair Value [Line Items]    
Hedged Rate 2.73%  
Notional Value $ 107,000,000 $ 107,000,000
Fair Value $ (1,000,000)  
HASI SYB Loan Agreement 2016-1 B [Member] | Minimum [Member]    
Derivatives, Fair Value [Line Items]    
Maturity 2021-11  
HASI SYB Loan Agreement 2016-1 B [Member] | Maximum [Member]    
Derivatives, Fair Value [Line Items]    
Maturity 2032-10  
HASI SYB Loan Agreement 2016-1 B [Member] | Base Rate [Member]    
Derivatives, Fair Value [Line Items]    
Base Rate 3 month Libor