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Namespace Prefix:	smbc_
Data Type:	xbrli:monetaryItemType
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Period Type:	instant

Represents the monetary amount of Impaired Financing Receivable With and Without Related Allowance Recorded Investment, as of the indicated date.

No definition available.

Name:	smbc_ImpairedFinancingReceivableWithAndWithoutRelatedAllowanceRecordedInvestment
Namespace Prefix:	smbc_
Data Type:	xbrli:monetaryItemType
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Amount at par value of financing receivable purchased with credit deterioration.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 50
-Paragraph 19
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=121599337&loc=SL82919265-210447

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
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Period Type:	duration

Amount of investment in impaired financing receivables for which there is no related allowance for credit losses.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 14A
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=121611835&loc=SL6953550-111524

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
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Amount of unpaid principal balance of impaired financing receivables for which there is no related allowance for credit losses.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 15
-Subparagraph (a)(4)
-URI http://asc.fasb.org/extlink&oid=121611835&loc=d3e5212-111524

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