Hannon Armstrong Sustainable Infrastructure Capital, Inc. Quarterly report pursuant to Section 13 or 15(d)

Quarterly report pursuant to Section 13 or 15(d)

Credit Facility - Additional Information (Detail)

Credit Facility - Additional Information (Detail) (USD $)	1 Months Ended	3 Months Ended	1 Months Ended
	Dec. 31, 2014	Mar. 31, 2015	Apr. 30, 2015	May 31, 2014	Jul. 31, 2013
Line of Credit Facility [Line Items]
Credit facility outstanding	$ 315,748,000us-gaap_LineOfCredit	$ 321,184,000us-gaap_LineOfCredit
Termination of credit facility	Jul. 19, 2019
Issuance costs		11,000,000us-gaap_DebtIssuanceCosts
Pledge of investments in financing receivables	422,000,000	463,000,000
Weighted average short-term borrowing rate	2.40%	2.40%
Fees for loan agreement description		Fees for each Loan Agreement equal to 0.50%, divided by 360, multiplied by the excess of the available borrowing capacity under each Loan Agreement over the actual amount borrowed under such Loan Agreement.
Default underlying financings		50.00%hasi_DefaultUnderlyingFinancing
Senior Secured Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Credit facility outstanding					350,000,000
Maximum advances on credit facilities		1,350,000,000
Qualifying Government and Institutional Loans (G&I Facility) [Member]
Line of Credit Facility [Line Items]
Line of credit facility, increase (decrease) in overall capacity	(25,000,000)
Termination of credit facility		Jul. 19, 2019
Maximum advances on credit facilities	375,000,000
Maximum borrowings allowed at any point in time	125,000,000
Line of credit facility, decrease in maximum borrowing capacity	75,000,000
London Interbank Offered Rate		("LIBOR") plus 1.50%
Floating interest rate		1.50%
Issuance costs	20,000
Qualifying Government and Institutional Loans (G&I Facility) [Member] \| Federal Funds [Member]
Line of Credit Facility [Line Items]
London Interbank Offered Rate		Federal Funds Rate plus 1.50%
Floating interest rate		1.50%
Qualifying Government and Institutional Loans (G&I Facility) [Member] \| Credit Default Option [Member]
Line of Credit Facility [Line Items]
London Interbank Offered Rate		LIBOR plus 2.50%
Floating interest rate		2.50%
Qualifying Government and Institutional Loans (G&I Facility) [Member] \| U.S. Federal Government [Member]
Line of Credit Facility [Line Items]
Applicable valuation percentages		80.00%
Qualifying Government and Institutional Loans (G&I Facility) [Member] \| Institutional [Member]
Line of Credit Facility [Line Items]
Applicable valuation percentages		75.00%
Qualifying Government and Institutional Loans (G&I Facility) [Member] \| Senior Secured Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Credit facility outstanding		100,000,000
Maximum advances on credit facilities		300,000,000
Qualifying Government and Institutional Loans (G&I Facility) [Member] \| Subsequent Event [Member]
Line of Credit Facility [Line Items]
Line of credit facility, increase (decrease) in overall capacity			(75,000,000)
Maximum advances on credit facilities			300,000,000
Maximum borrowings allowed at any point in time			100,000,000
Line of credit facility, decrease in maximum borrowing capacity			25,000,000
Qualifying Project Finance Loans (PF Facility) [Member]
Line of Credit Facility [Line Items]
Line of credit facility, increase (decrease) in overall capacity	475,000,000
Line of credit facility, increase in maximum borrowing capacity	75,000,000
Termination of credit facility		Jul. 19, 2019
Maximum advances on credit facilities	975,000,000
Maximum borrowings allowed at any point in time	325,000,000
London Interbank Offered Rate		LIBOR plus 2.50%
Floating interest rate		2.50%
Issuance costs	20,000
Applicable valuation percentages		67.00%
Qualifying Project Finance Loans (PF Facility) [Member] \| Federal Funds [Member]
Line of Credit Facility [Line Items]
London Interbank Offered Rate		Federal Funds Rate plus 2.50%
Floating interest rate		2.50%
Qualifying Project Finance Loans (PF Facility) [Member] \| Credit Default Option [Member]
Line of Credit Facility [Line Items]
London Interbank Offered Rate		LIBOR plus 5.00%
Floating interest rate		5.00%
Qualifying Project Finance Loans (PF Facility) [Member] \| Senior Secured Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Credit facility outstanding		400,000,000
Maximum advances on credit facilities		1,050,000,000
Qualifying Project Finance Loans (PF Facility) [Member] \| Subsequent Event [Member]
Line of Credit Facility [Line Items]
Line of credit facility, increase (decrease) in overall capacity			75,000,000
Line of credit facility, increase in maximum borrowing capacity			75,000,000
Maximum advances on credit facilities			1,050,000,000
Maximum borrowings allowed at any point in time			400,000,000
Line of credit facility, decrease in maximum borrowing capacity			350,000,000
Qualifying Project Finance Loans (PF Facility) [Member] \| Minimum [Member]
Line of Credit Facility [Line Items]
Line of credit facility, increase (decrease) in overall capacity				200,000,000
Line of credit facility, increase in maximum borrowing capacity				100,000,000
Qualifying Project Finance Loans (PF Facility) [Member] \| Maximum [Member]
Line of Credit Facility [Line Items]
Line of credit facility, increase (decrease) in overall capacity				500,000,000
Line of credit facility, increase in maximum borrowing capacity				$ 250,000,000