Credit Facilities and Long-Term Debt (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
Debt Instrument [Line Items]
Revolving credit facilities	$ 56,558,000us-gaap_LineOfCredit	$ 21,406,000us-gaap_LineOfCredit
Other	258,000us-gaap_CapitalLeaseObligations	75,000us-gaap_CapitalLeaseObligations
Total debt	56,816,000us-gaap_DebtAndCapitalLeaseObligations	21,481,000us-gaap_DebtAndCapitalLeaseObligations
Current maturities of long-term debt	56,733,000us-gaap_DebtCurrent	21,465,000us-gaap_DebtCurrent
Long-term debt	83,000	16,000
Maturities of long term debt in 2015	200,000
Amortization of financing cost for future years [Abstract]
Amortization of financing costs in 2015	697,000
Amortization of financing costs in 2016	697,000smp_AmortizationOfFinancingCostsYearTwo
Amortization of financing costs in 2017	697,000
Amortization of financing costs in 2018	176,000
Total amortization	2,267,000us-gaap_DeferredFinanceCostsNet	2,975,000us-gaap_DeferredFinanceCostsNet
Amount capitalized in relation to amendment of revolving credit facility		$ 1,300,000

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Amount of amortization expense expected to be recognized during the next fiscal year following the latest fiscal year for financing costs.

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Amount of amortization expense expected to be recognized during the fourth fiscal year following the latest fiscal year for financing costs.

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Amount of amortization expense expected to be recognized during the third fiscal year following the latest fiscal year for financing costs.

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Amount of amortization expense expected to be recognized during the second fiscal year following the latest fiscal year for financing costs.

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Represents the amount capitalized in relation to amendment of revolving credit facility for costs related to bank, legal and other professional fees.

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No definition available.

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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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Amount of short-term debt and current maturity of long-term debt and capital lease obligations due within one year or the normal operating cycle, if longer.

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For an unclassified balance sheet, the carrying amount (net of accumulated amortization) as of the balance sheet date of capitalized costs associated with the issuance of debt instruments (for example, legal, accounting, underwriting, printing, and registration costs) that will be charged against earnings over the life of the debt instruments to which such costs pertain.

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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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Amount of long-term debt payable, sinking fund requirements, and other securities issued that are redeemable by holder at fixed or determinable prices and dates maturing in the next fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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