Equity Method Investments (Details Textual) $ / shares in Units, bbl in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016 USD ($)	Jun. 30, 2015 USD ($)	Jun. 30, 2016 USD ($) bbl	Jun. 30, 2015 USD ($) 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	$ 5,897	$ (41)	$ 5,897
General and administrative	20,775	22,917	41,835	55,227
Loss (gain) on sale or impairment of equity method investment	(9,120)	(6,623)	30,644	(14,517)
Net proceeds from sale of common units of equity method investee			60,483	56,318
White Cliffs Pipeline, L.L.C. [Member]
Schedule of Equity Method Investments [Line Items]
General and administrative	400	400	900	700
NGL Energy Partners LP [Member]
Schedule of Equity Method Investments [Line Items]
Gain (loss) on issuance of common units by equity method investee	$ 0	5,900	(41)	$ 5,900
Units of equity investee divested | shares				1,999,533
Closing price per common unit | $ / shares					$ 13.00	$ 11.04
Loss (gain) on sale or impairment of equity method investment			$ 9,100
Net proceeds from sale of common units of equity method investee				$ 56,300
Transaction related costs				500
Gain on sale of common units of equity method investee		$ 6,600		$ 14,500
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
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
Incremental capacity expected to be added | bbl			65