Segment Information - Net Sales by Major Product and Services (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue	$ 16,200	$ 3,613
Engineering, Procurement and Construction (EPC) [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue	13,035	3,185
Power Purchase Agreements (PPA) [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue	2,999	302
Operating and Maintenance (O&M) [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue		$ 126
Residential PhotoVoltaic Systems [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue	161
Other Services [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue	$ 5