Quarterly report pursuant to Section 13 or 15(d)

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

v3.10.0.1
Long-term Debt - Schedule of Interest Rate Swaps which are Designated as Cash Flow Hedges (Details) - Cash Flow Hedging [Member] - Interest Rate Swap [Member] - USD ($)
$ in Millions
Jun. 30, 2018
Dec. 31, 2017
Derivatives, Fair Value [Line Items]    
Notional Value $ 429.0 $ 438.0
Fair Value $ 7.6 (0.1)
HASI SYB Loan Agreement 2015-2 [Member]    
Derivatives, Fair Value [Line Items]    
Derivative, Fixed Interest Rate 1.52%  
Notional Value $ 30.0 31.0
Fair Value $ 0.1 0.1
HASI SYB Loan Agreement 2015-2 [Member]    
Derivatives, Fair Value [Line Items]    
Derivative, Fixed Interest Rate 2.55%  
Notional Value $ 29.0 29.0
Fair Value $ 0.3 (0.2)
HASI SYB Loan Agreement 2015-3 [Member]    
Derivatives, Fair Value [Line Items]    
Derivative, Fixed Interest Rate 2.34%  
Notional Value $ 119.0 119.0
Fair Value $ 2.3 0.0
HASI SYB Loan Agreement 2016-1 [Member]    
Derivatives, Fair Value [Line Items]    
Derivative, Fixed Interest Rate 1.88%  
Notional Value $ 112.0 120.0
Fair Value $ 3.3 1.1
HASI SYB Loan Agreement 2016-1 [Member]    
Derivatives, Fair Value [Line Items]    
Derivative, Fixed Interest Rate 2.73%  
Notional Value $ 107.0 107.0
Fair Value $ 0.9 (1.1)
2017 Master Repurchase Agreement [Member]    
Derivatives, Fair Value [Line Items]    
Derivative, Fixed Interest Rate 2.42%  
Notional Value $ 32.0 32.0
Fair Value $ 0.7 $ 0.0