Commitments and Contingencies (Details Textual) (USD $)	3 Months Ended
	Mar. 31, 2013 sites	Aug. 18, 2011 bbl
Commitments and Contingencies (Textual) [Abstract]
Site contingency number of sites checked	6
Number of sites requiring remediation and water contamination as per phase two investigations	4
Accrued liability, estimated fines and environmental contributions	400,000
Asset retirement obligation liability	40,500,000
Estimated cost to retire facilities	105,500,000
SemCrude Pipeline [Member]
Commitments and Contingencies (Textual) [Abstract]
Loss contingency claims, number of barrels of crude oil owed		141,000
Site contingency number of sites checked	5
SemGas [Member]
Commitments and Contingencies (Textual) [Abstract]
Site contingency number of sites checked	1
Due under the contract	26,000
Future obligations	2,500,000
Processing Capacity	125
Future obligations related to processing facility	1,700,000
Minimum [Member]
Commitments and Contingencies (Textual) [Abstract]
Notice required to cancel purchase agreements, days	30 days
Maximum [Member]
Commitments and Contingencies (Textual) [Abstract]
Notice required to cancel purchase agreements, days	120 days