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

Securitization of Receivables - Summary of Certain Transactions with Securitization Trusts (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Fair Value Assumption, Date of Securitization or Asset-backed Financing Arrangement, Transferor's Continuing Involvement, Servicing Assets or Liabilities [Line Items]
Gains on securitizations	$ 7,256	$ 4,223
Securitization Trust [Member]
Fair Value Assumption, Date of Securitization or Asset-backed Financing Arrangement, Transferor's Continuing Involvement, Servicing Assets or Liabilities [Line Items]
Gains on securitizations	6,000	4,000
Purchase of receivables securitized	129,000	87,000
Proceeds from securitizations	135,000	91,000
Cash received from residual and servicing assets	1,000	2,000
Securitization Trust [Member] \| Residual Assets [Member]
Fair Value Assumption, Date of Securitization or Asset-backed Financing Arrangement, Transferor's Continuing Involvement, Servicing Assets or Liabilities [Line Items]
Residual and servicing assets included in other assets	$ 53,000	$ 22,000