Related Part Debt (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Related Party Transaction [Line Items]
Related party debt	$ 4,150	$ 6,850
Riverside Renewable Energy Investments
Related Party Transaction [Line Items]
Related party debt	4,150	4,150
Gaiam Incorporated
Related Party Transaction [Line Items]
Related party debt		$ 2,700