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Income Taxes Narrative (Details) (USD $) In Millions, unless otherwise specified | 9 Months Ended
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Sep. 30, 2014
Income Tax Narrative [Abstract] |
IRS Proposed R&D Tax Adjustment | $ 4.6

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- Details
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Namespace Prefix: | sm_
Data Type: | xbrli:stringItemType
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- Definition IRS Proposed R&D Tax Adjustment + References No definition available. + Details
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Namespace Prefix: | sm_
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