Property Held For Sale (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013
Activity of Property Held for Sale [Roll Forward]
Beginning balance	$ 53,392	$ 56,172
Acquisitions	2,673	11,805
Capitalized improvements	87	276
Dispositions	(14,852)	(11,139)
Valuation adjustments	(3,771)	(3,722)
Reclassification of covered loans	0smmf_ReclassificationOfCoveredLoans	0smmf_ReclassificationOfCoveredLoans
Balance at year end	$ 37,529	$ 53,392

Disposition Amount Of Property Held For Sale

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- Definition

Other Real Estate And Foreclosed Assets, Valuation Adjustments

+ References

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- Definition

Reclassification Of Covered Loans

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- Definition

Carrying amount as of the balance sheet date of other real estate and foreclosed assets. Other real estate may include real estate investments, real estate loans that qualify as investments in real estate, and premises that are no longer used in operations may also be included in real estate owned. Foreclosed assets include all assets obtained in full or partial satisfaction of a debt arrangement through foreclosure proceedings.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.9-03.10(4))

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- Definition

Carrying amount as of the balance sheet date of land and buildings obtained through foreclosure proceedings or defeasance in full or partial satisfaction of a debt arrangement.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 45

-Paragraph 3

-URI http://asc.fasb.org/extlink&oid=28367877&loc=d3e4437-111522

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-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 28

-Article 12

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

-Paragraph c

-Subparagraph Schedule III

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Amount of land and buildings and improvements made to real estate investments and capitalized after acquisition for entities with a substantial portion of business acquiring and holding investment real estate.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 970

-SubTopic 360

-Section S99

-Paragraph 1

-Subparagraph (SX 210.12-28)

-URI http://asc.fasb.org/extlink&oid=6590653&loc=d3e638233-123024

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 205

-SubTopic 10

-Section S99

-Paragraph 6

-Subparagraph (SX 210.5-04.(c) Schedule III)

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-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

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-Name Regulation S-X (SX)

-Number 210

-Section 04

-Paragraph c

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-Article 5

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