Goodwill and Other Intangible Assets (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Sep. 02, 2013	Aug. 01, 2013
Goodwill [Line Items]
Goodwill	$ 58,326	$ 62,021	$ 9,884	$ 9,453
Crude [Member]
Goodwill [Line Items]
Goodwill	36,116	28,322
SemGas [Member]
Goodwill [Line Items]
Goodwill	13,052	23,839
SemMexico [Member]
Goodwill [Line Items]
Goodwill	9,158	9,860
Barcas Field Services, LLC [Member] | Crude [Member]
Goodwill [Line Items]
Goodwill					28,234
Mid-America Midstream Gas Services, LLC [Member] | SemGas [Member]
Goodwill [Line Items]
Goodwill						$ 13,052