Long-Term Debt (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Debt Instrument [Line Items]
Senior notes	$ 300,000
Capital leases	83	$ 132
Total long-term debt	1,074,628	767,132
less: current portion of long-term debt	31	40
Noncurrent portion of long-term debt	1,074,597	767,092
Corporate Segment [Member]
Debt Instrument [Line Items]
Senior notes	300,000	300,000
Revolving Credit Facility [Member] \| Corporate Segment [Member]
Debt Instrument [Line Items]
Borrowings	30,000	35,000
Revolving Credit Facility [Member] \| SemMexico [Member]
Debt Instrument [Line Items]
Borrowings	0	0
Rose Rock Midstream L P [Member]
Debt Instrument [Line Items]
Noncurrent portion of long-term debt	744,597	432,092
Rose Rock Midstream L P [Member] \| Rose Rock Notes due 2022 [Member]
Debt Instrument [Line Items]
Senior notes	400,000	400,000
Rose Rock Midstream L P [Member] \| Rose Rock Notes due 2023 [Member]
Debt Instrument [Line Items]
Senior notes	344,545	0
Rose Rock Midstream L P [Member] \| Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Borrowings	$ 0	$ 32,000

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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Sum of the carrying values as of the balance sheet date of all debt, including all short-term borrowings, long-term debt, and capital lease obligations.

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The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

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Including the current and noncurrent portions, carrying value as of the balance sheet date of Notes with the highest claim on the assets of the issuer in case of bankruptcy or liquidation (with maturities initially due after one year or beyond the operating cycle if longer). Senior note holders are paid off in full before any payments are made to junior note holders.

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