Acquisitions - Acquisition of Perigee - Narrative (Details) - USD ($) $ in Thousands		6 Months Ended
	Apr. 01, 2017	Jun. 30, 2017
Business Acquisition [Line Items]
Net contribution by NG&E		$ 210
National Gas & Electric, LLC
Business Acquisition [Line Items]
Net contribution by NG&E		1,400
National Gas & Electric, LLC | Perigee Energy, LLC
Business Acquisition [Line Items]
Purchase price	$ 4,400
Base price	2,000
Additional customer option payment	200
Initial working capital estimate	2,200	2,600
Working capital	$ 2,200
Net contribution by NG&E		$ 1,300