Loans and Allowance for Loan Losses (Details 1) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2015
Summary of balance of the allowance for loan losses and the recorded investment in loans
Beginning balance	$ 6,990	$ 6,771
Charge Offs	(94)	(302)
Recoveries	59	11
Provision	250	350
Ending Balance	7,205	6,830
Allowance: Ending balance: individually evaluated for impairment	1,961		$ 1,963
Allowance: Ending balance: collectively evaluated for impairment	5,244		5,027
Loans: Ending balance individually evaluated for impairment	7,678		8,057
Loans: Ending balance collectively evaluated for impairment	569,328		549,558
Residential Real Estate [Member]
Summary of balance of the allowance for loan losses and the recorded investment in loans
Beginning balance	$ 1,312	1,308
Charge Offs		(13)
Recoveries		2
Provision	$ 30	21
Ending Balance	1,342	1,318
Allowance: Ending balance: individually evaluated for impairment	165		167
Allowance: Ending balance: collectively evaluated for impairment	1,177		1,145
Loans: Ending balance individually evaluated for impairment	1,931		1,713
Loans: Ending balance collectively evaluated for impairment	130,696		129,093
Consumer & Other [Member]
Summary of balance of the allowance for loan losses and the recorded investment in loans
Beginning balance	674	768
Charge Offs	(2)	(31)
Recoveries	24	3
Provision	(66)	94
Ending Balance	630	834
Allowance: Ending balance: individually evaluated for impairment	37		37
Allowance: Ending balance: collectively evaluated for impairment	593		637
Loans: Ending balance individually evaluated for impairment	446		464
Loans: Ending balance collectively evaluated for impairment	53,047		$ 53,760
Commercial & Industrial [Member]
Summary of balance of the allowance for loan losses and the recorded investment in loans
Beginning balance	914	1,630
Charge Offs	(92)	(8)
Recoveries	35	5
Provision	68	(53)
Ending Balance	$ 925	1,574
Allowance: Ending balance: individually evaluated for impairment
Allowance: Ending balance: collectively evaluated for impairment	$ 925		$ 914
Loans: Ending balance individually evaluated for impairment			126
Loans: Ending balance collectively evaluated for impairment	$ 91,958		86,416
Commercial RE & Construction [Member]
Summary of balance of the allowance for loan losses and the recorded investment in loans
Beginning balance	$ 3,886	2,857
Charge Offs		$ (250)
Recoveries
Provision	$ 234	$ 285
Ending Balance	4,120	2,892
Allowance: Ending balance: individually evaluated for impairment	1,759		1,759
Allowance: Ending balance: collectively evaluated for impairment	2,361		2,127
Loans: Ending balance individually evaluated for impairment	5,301		5,754
Loans: Ending balance collectively evaluated for impairment	251,160		$ 236,454
Agricultural & Farmland [Member]
Summary of balance of the allowance for loan losses and the recorded investment in loans
Beginning balance	$ 204	$ 208
Charge Offs
Recoveries		$ 1
Provision	$ (16)	3
Ending Balance	$ 188	$ 212
Allowance: Ending balance: individually evaluated for impairment
Allowance: Ending balance: collectively evaluated for impairment	$ 188		$ 204
Loans: Ending balance individually evaluated for impairment
Loans: Ending balance collectively evaluated for impairment	$ 42,467		$ 43,835

A valuation allowance for financing receivables that are expected to be uncollectible.

Name:	us-gaap_FinancingReceivableAllowanceForCreditLosses
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The valuation allowance for financing receivables that are expected to be uncollectible that were collectively evaluated for impairment.

+ References

+ Details

Name:	us-gaap_FinancingReceivableAllowanceForCreditLossesCollectivelyEvaluatedForImpairment
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of valuation allowance for financing receivables that are expected to be uncollectible that were individually evaluated for impairment.

+ References

+ Details

Name:	us-gaap_FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of recovery of financing receivables doubtful of collection that were previously charged off.

+ References

+ Details

Name:	us-gaap_FinancingReceivableAllowanceForCreditLossesRecovery
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

+ References

No definition available.

+ Details

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

- Definition

Amount of direct write-downs of financing receivables charged against the allowance.

+ References

+ Details

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

- Definition

The balance of financing receivables that were collectively evaluated for impairment.

+ References

+ Details

Name:	us-gaap_FinancingReceivableCollectivelyEvaluatedForImpairment
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The balance of financing receivables that were individually evaluated for impairment.

+ References

+ Details

Name:	us-gaap_FinancingReceivableIndividuallyEvaluatedForImpairment
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of expense related loan transactions, lease transactions, credit loss from transactions other than loan and lease transactions, and other loss based on assessment of uncollectability from the counterparty to reduce the account to their net realizable value.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 11B
-Subparagraph (c)(2)
-URI http://asc.fasb.org/extlink&oid=66008989&loc=SL6953423-111524

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 225
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04.11)
-URI http://asc.fasb.org/extlink&oid=6879574&loc=d3e536633-122882

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=66902209&loc=d3e3602-108585

+ Details

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

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=us-gaap_ResidentialRealEstateMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=us-gaap_ConsumerPortfolioSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=sbfg_CommercialAndIndustrialPortfolioSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=sbfg_CommercialReConstructionPortfolioSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=sbfg_AgriculturalFarmlandPortfolioSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: