Goodwill and Other Intangible Assets (Details Textual) - USD ($) $ in Thousands		3 Months Ended		12 Months Ended
	Jul. 17, 2017	Dec. 31, 2017	Sep. 30, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Goodwill [Line Items]
Goodwill, Amortization Period for Income Taxes	15 years			15 years
SemGas [Member]
Goodwill [Line Items]
Goodwill, Impairment Loss					$ 13,052
Crude Transportation [Member]
Goodwill [Line Items]
Goodwill, Impairment Loss			$ 26,600	$ 26,628		$ 9,488
Impairment of Intangible Assets, Finite-lived		$ 12,100		$ 12,087