XML 82 R61.htm IDEA: XBRL DOCUMENT
v3.6.0.2

Acquisition and Development Agreement and Carry and Earning Agreement (Details) - Mitsui E&P Texas LP $ in Millions | Jun. 30, 2011 USD ($)
--- | ---
Acquisition and Development Agreement [Abstract] |
Percentage of Working Interests Transferred to Acquirer Entity | 12.50%
Acreage of Working Interests Transferred to Acquirer Entity | 39,000
Percentage of the entity's costs and expenses during the first three years following the closing of the transaction, borne by the acquirer entity (as a percent) | 90.00%
Costs and expenses incurred by acquiree entity on behalf of entity that the acquirer entity has agreed to pay | $ 680.0
Portion of Drilling and Completion Costs Not Carried by Acquirer | 10.00%

X
- Definition Acquisition and Development Agreement [Abstract] + References No definition available. + Details
Name: | sm_AcquisitionAndDevelopmentAgreementAbstract
Namespace Prefix: | sm_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Represents the acreage of working interests transferred to acquirer entity. + References No definition available. + Details
Name: | sm_AcreageofWorkingInterestsTransferredtoAcquirerEntity
Namespace Prefix: | sm_
Data Type: | xbrli:decimalItemType
Balance Type: | na
Period Type: | instant

X
- Definition Represents the costs and expenses incurred by acquiree entity on behalf of entity which the acquirer entity would repay on a proportionate basis. + References No definition available. + Details
Name: | sm_CostsandExpensesIncurredbyAcquireeEntityonBehalfofEntityThatAcquirerEntityAgreedtoPay
Namespace Prefix: | sm_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Represents the percentage of working interests transferred to acquirer entity. + References No definition available. + Details
Name: | sm_PercentageofWorkingInterestsTransferredtoAcquirerEntity
Namespace Prefix: | sm_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Represents the percentage of costs incurred by the entity, which the acquirer entity has agreed to bear for first three years following the closing of transaction. + References No definition available. + Details
Name: | sm_PortionOfDrillingAndCompletionCostsCarriedByAcquirer
Namespace Prefix: | sm_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Portion of Drilling and Completion Costs Not Carried by Acquirer + References No definition available. + Details
Name: | sm_PortionOfDrillingAndCompletionCostsNotCarriedByAcquirer
Namespace Prefix: | sm_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Details
Name: | us-gaap_BusinessAcquisitionAxis=sm_MitsuiEAndPTexasLpMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |