Name:	smbc_AccumulatedOtherComprehensiveIncomeLossGross
Namespace Prefix:	smbc_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Represents the monetary amount of Accumulated Other Comprehensive Income (Loss) Tax Effect, during the indicated time period.

No definition available.

Name:	smbc_AccumulatedOtherComprehensiveIncomeLossTaxEffect
Namespace Prefix:	smbc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Represents the monetary amount of Net unrealized gain (loss) on securities available for sale for which a portion of an other than temporary impairment has been recognized in income, during the indicated time period.

No definition available.

Name:	smbc_NetUnrealizedGainLossOnSecuritiesAvailableForSaleForWhichPortionOfOtherThanTemporaryImpairmentHasBeenRecognizedInIncome
Namespace Prefix:	smbc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Represents the monetary amount of Other comprehensive income defined benefit pension plan unrealized gain, during the indicated time period.

No definition available.

Name:	smbc_OtherComprehensiveIncomeDefinedBenefitPensionPlanUnrealizedGain
Namespace Prefix:	smbc_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Represents the monetary amount of Other comprehensive income unrealized gain (loss) securities available for sale, net, during the indicated time period.

No definition available.

Name:	smbc_OtherComprehensiveIncomeUnrealizedGainLossSecuritiesAvailableForSaleNet
Namespace Prefix:	smbc_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Accumulated change in equity from transactions and other events and circumstances from non-owner sources, net of tax effect, at period end. Excludes Net Income (Loss), and accumulated changes in equity from transactions resulting from investments by owners and distributions to owners. Includes foreign currency translation items, certain pension adjustments, unrealized gains and losses on certain investments in debt and equity securities, other than temporary impairment (OTTI) losses related to factors other than credit losses on available-for-sale and held-to-maturity debt securities that an entity does not intend to sell and it is not more likely than not that the entity will be required to sell before recovery of the amortized cost basis, as well as changes in the fair value of derivatives related to the effective portion of a designated cash flow hedge.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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Data Type:	xbrli:monetaryItemType
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Period Type:	instant

- References

No definition available.