Acquisitions Purchase Consideration (Details) - USD ($) $ in Thousands			12 Months Ended
	Aug. 31, 2017	Apr. 01, 2015	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Business Acquisition [Line Items]
Business Acquisition, Equity Interest Issued or Issuable, Number of Shares		592,970
Business Acquisition, Equity Interest Issued or Issuable, Value Assigned			$ 0	$ 0	$ 30,164
Payments to Acquire Businesses, Gross			$ 11,945	$ 0	20,930
Gatherco [Member]
Business Acquisition [Line Items]
Business Acquisition, Equity Interest Issued or Issuable, Value Assigned		$ 30,200			30,164
Payments to Acquire Businesses, Gross		27,500			27,494
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities, Long-term Debt		1,696			1,696
Business Combination, Consideration Transferred					57,658
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Cash and Equivalents		$ (6,800)			$ (6,806)
Unregulated Energy
Business Acquisition [Line Items]
Goodwill, Acquired During Period	$ 1,900
Unregulated Energy | ARM [Member]
Business Acquisition [Line Items]
Goodwill, Acquired During Period	$ 6,800