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

Financing Receivables and Investments - Summary of Anticipated Maturity Dates of Financing Receivables and Investments (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Receivables [Abstract]
Financing Receivables, payment due total	$ 395,562
Financing Receivables, payment due in less than 1 year	1,253
Financing Receivables, payment due in 1-5 years	96,065
Financing Receivables, payment due in 5-10 years	16,348
Financing Receivables, payment due in more than 10 years	281,896
Investments, payment due total	91,277	91,964
Investments, payment due in less than 1 year
Investments, payment due in 1-5 years	15,101
Investments, payment due in 5-10 years
Investments, payment due in more than 10 years	$ 76,176