Goodwill and Other Intangible Assets (Details 2) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, net	$ 173,065	$ 174,838	$ 7,585	$ 8,950
Crude [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, net	16,640	5,775
SemGas [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, net	152,383	163,144
SemMexico [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, net	4,016	5,888
Corporate and other [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, net	$ 26	$ 31