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

Our Portfolio - Analysis of Portfolio by Type of Obligor and Credit Quality (Parenthetical) (Detail) $ in Thousands	9 Months Ended
	Sep. 30, 2017 USD ($) Transactions	Dec. 31, 2016 USD ($)
Financing Receivable, Recorded Investment [Line Items]
Total financing receivable	$ 1,062,051	$ 1,042,237
Number of transactions \| Transactions	130
Financial receivable outstanding, Average Remaining Balance	$ 12,000
Total aggregate remaining balance	51,000
Maximum [Member]
Financing Receivable, Recorded Investment [Line Items]
Financial receivable outstanding, Average Remaining Balance	1,000
Investment Grade By Independent Rating Agency [Member]
Financing Receivable, Recorded Investment [Line Items]
Total financing receivable	10,000
U.S. Federal Government [Member]
Financing Receivable, Recorded Investment [Line Items]
Total financing receivable	474,000
State, Local, Institutions [Member]
Financing Receivable, Recorded Investment [Line Items]
Total financing receivable	205,000
Commercial Investment Grade [Member]
Financing Receivable, Recorded Investment [Line Items]
Financial receivable outstanding, Average Remaining Balance	9,000
Commercial Investment Grade [Member] \| Residential Solar Loan [Member] \| Subsidiaries Of SunPower Corporation [Member]
Financing Receivable, Recorded Investment [Line Items]
Total financing receivable	$ 310,000