Loans and Allowance for loan Losses (Details 7) $ in Thousands	12 Months Ended
Dec. 31, 2014 USD ($) Numbers
Commercial Real Estate Mortgage [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Pre-Modifications, Number of Contracts \| Numbers	1
Financing Receivable, Modifications, Pre-Modification Outstanding Recorded Investment	$ 1,757
Financing Receivable, Modifications, Post-Modification Outstanding Recorded Investment	$ 1,757
Consumer Real Estate Mortgage [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Pre-Modifications, Number of Contracts \| Numbers	3
Financing Receivable, Modifications, Pre-Modification Outstanding Recorded Investment	$ 3,169
Financing Receivable, Modifications, Post-Modification Outstanding Recorded Investment	$ 3,169
Commercial and Industrial Loans [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Pre-Modifications, Number of Contracts \| Numbers	1
Financing Receivable, Modifications, Pre-Modification Outstanding Recorded Investment	$ 52
Financing Receivable, Modifications, Post-Modification Outstanding Recorded Investment	$ 52

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

No definition available.

+ Details

Name:	us-gaap_FinancingReceivableModificationsLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Number of financing receivables that have been modified by troubled debt restructurings.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 33
-URI http://asc.fasb.org/extlink&oid=49124121&loc=SL6953676-111524

+ Details

Name:	us-gaap_FinancingReceivableModificationsNumberOfContracts2
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Post-modification amount of investment in financing receivables modified by troubled debt restructurings.

+ References

+ Details

Name:	us-gaap_FinancingReceivableModificationsPostModificationRecordedInvestment2
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Pre-modification amount of investment in financing receivables modified by troubled debt restructurings.

+ References

+ Details

Name:	us-gaap_FinancingReceivableModificationsPreModificationRecordedInvestment2
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Details

Name:	us-gaap_FinancialInstrumentAxis=smbk_CommercialRealEstateMortgageMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=smbk_ConsumerRealEstateMortgageMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=smbk_CommercialAndIndustrialLoansMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: