Supplemental Cash Flow Information Supplemental Cash Flow Information (Details Textual) (USD $)	6 Months Ended
	Jun. 30, 2013		Jun. 30, 2012
Sale of interest in equity investment to related party	$ 33,716,000	[1]
Tax effect of adjustment to APIC from sale of equity investment to less than wholly owned subsidiary	33,700,000
Warrants exercised during period	762,807
Proceeds from Warrant Exercises	224,000		0
Interest Paid	4,100,000		4,200,000
Income Taxes Paid, Net	2,000,000		6,100,000
Capital Expenditures Incurred but Not yet Paid	3,700,000		8,500,000
Noncontrolling Interest [Member]
Sale of interest in equity investment to related party	90,516,000	[1]
Additional Paid-in Capital [Member]
Sale of interest in equity investment to related party	(56,800,000)	[1]
Semcrude Pipeline [Member]
Equity Method Investment, Ownership Percentage	33.00%
Warrant [Member]
Stock Issued During Period, Shares, Conversion of Convertible Securities	420,067
Adjustments to Additional Paid in Capital, Other	$ 23,300,000

[1] * On January 13, 2013, we contributed a 33% interest in SemCrude Pipeline, L.L.C. to our consolidated subsidiary, Rose Rock. As this transaction was between entities under common control, the interest in SemCrude Pipeline, L.L.C. was recorded by Rose Rock based on SemGroup's book value. This amount represents the purchase price in excess of book value which was attributed to the noncontrolling interest owners of Rose Rock. The entry to additional paid-in capital has been recorded net of tax.