Equity Method Investments (Details Textual) $ / shares in Units, bbl in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016 USD ($)	Sep. 30, 2015 USD ($)	Sep. 30, 2016 USD ($) bbl	Sep. 30, 2015 USD ($) shares	Apr. 27, 2016 $ / shares	Dec. 31, 2015 $ / shares
Schedule of Equity Method Investments [Line Items]
Gain (loss) on issuance of common units by equity method investee	$ 0	$ 136,000	$ (41,000)	$ 6,033,000
General and administrative	20,583,000	23,045,000	62,419,000	78,272,000
Net proceeds from sale of common units of equity method investee			60,483,000	56,318,000
White Cliffs Pipeline, L.L.C. [Member]
Schedule of Equity Method Investments [Line Items]
General and administrative	$ 300,000	400,000	1,200,000	1,100,000
NGL Energy Partners LP [Member]
Schedule of Equity Method Investments [Line Items]
Gain (loss) on issuance of common units by equity method investee		$ 100,000	(41,000)	$ 6,000,000
Units of equity investee divested | shares				1,999,533
Closing price per common unit | $ / shares					$ 13.00	$ 11.04
Net proceeds from sale of common units of equity method investee				$ 56,300,000
Transaction related costs				500,000
Gain on sale of common units of equity method investee			$ 9,100,000	$ 14,500,000
NGL Energy Partners LP [Member] | General Partner [Member]
Schedule of Equity Method Investments [Line Items]
General partner ownership interest			11.78%
White Cliffs Pipeline, L.L.C. [Member]
Schedule of Equity Method Investments [Line Items]
Percentage of limited partner ownership interest	51.00%		51.00%
Glass Mountain Pipeline LLC [Member]
Schedule of Equity Method Investments [Line Items]
Project funding contributions			$ 300,000
Percentage of limited partner ownership interest	50.00%		50.00%
Pipeline expansion [Member] | White Cliffs Pipeline, L.L.C. [Member]
Schedule of Equity Method Investments [Line Items]
Project funding contributions			$ 2,200,000
Incremental capacity expected to be added | bbl			65