Goodwill and Intangible Assets, Net - Carrying Value of Goodwill (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Goodwill [Line Items]
Beginning balance	$ 51,786
Ending balance	87,543	$ 51,786
Mainstream Energy Corporation
Goodwill [Line Items]
Acquisition		$ 51,786
Ending balance	51,786
Clean Energy Experts, LLC
Goodwill [Line Items]
Acquisition	35,757
Ending balance	$ 35,757