Amount equal to the present value (the principal) at the beginning of the lease term of minimum lease payments during the lease term (excluding that portion of the payments representing executory costs such as insurance, maintenance, and taxes to be paid by the lessor, together with any profit thereon) net of payments or other amounts applied to the principal through the balance sheet date.

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Long-Term Debt (Details) (USD $)	Jun. 30, 2013	Jun. 14, 2013	Dec. 31, 2012
Debt Instrument [Line Items]
Senior Notes	$ 300,000,000	$ 300,000,000	$ 0
Line of Credit Facility [Abstract]
Capital leases	75,000		86,000
Total long-term debt	470,898,000		206,086,000
less: current portion of long-term debt	4,349,000		24,000
Noncurrent portion of long-term debt	466,549,000		206,062,000
SemGroup Corporate Revolving Credit Facility [Member]
Line of Credit Facility [Abstract]
Borrowings	0		201,500,000
Rose Rock Credit Facility [Member]
Line of Credit Facility [Abstract]
Borrowings	166,500,000		4,500,000
SemMexico Credit Facility [Member]
Line of Credit Facility [Abstract]
Borrowings	4,323,000		0
Revolving Credit Facility [Member] \| Corporate [Member]
Line of Credit Facility [Abstract]
Borrowings	$ 0