Loans and Allowance for Loan Losses (Details 5) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013
Commercial & Industrial [Member]
Summary of Impaired loan activity
With no related allowance recorded, Recorded Investment	$ 316	$ 316
With no related allowance recorded, Unpaid Principal Balance	316	316
With no related allowance recorded, Related Allowance
With no related allowance recorded, Average Recorded Investment	316	335
With no related allowance recorded, Interest Income Recognized		13
With a specific allowance recorded, Recorded Investment	952	1,800
With a specific allowance recorded, Unpaid Principal Balance	1,552	1,800
With a specific allowance recorded, Related Allowance	510	1,079
With a specific allowance recorded, Average Recorded Investment	1,605	1,780
With a specific allowance recorded, Interest Income Recognized		44
Total Recorded Investment	1,268	2,116
Total Unpaid Principal Balance	1,868	2,116
Total Related Allowance	510	1,079
Total Average Recorded Investment	1,921	2,115
Total Interest Income Recognized		57
Commercial RE & Construction [Member]
Summary of Impaired loan activity
With no related allowance recorded, Recorded Investment	530	389
With no related allowance recorded, Unpaid Principal Balance	530	442
With no related allowance recorded, Related Allowance
With no related allowance recorded, Average Recorded Investment	571	579
With no related allowance recorded, Interest Income Recognized	20	16
With a specific allowance recorded, Recorded Investment	1,505	260
With a specific allowance recorded, Unpaid Principal Balance	1,505	260
With a specific allowance recorded, Related Allowance	1,018	56
With a specific allowance recorded, Average Recorded Investment	1,521	318
With a specific allowance recorded, Interest Income Recognized	60	14
Total Recorded Investment	2,035	649
Total Unpaid Principal Balance	2,035	702
Total Related Allowance	1,018	56
Total Average Recorded Investment	2,092	897
Total Interest Income Recognized	80	30
Agricultural & Farmland [Member]
Summary of Impaired loan activity
With no related allowance recorded, Recorded Investment
With no related allowance recorded, Unpaid Principal Balance
With no related allowance recorded, Related Allowance
With no related allowance recorded, Average Recorded Investment
With no related allowance recorded, Interest Income Recognized
With a specific allowance recorded, Recorded Investment
With a specific allowance recorded, Unpaid Principal Balance
With a specific allowance recorded, Related Allowance
With a specific allowance recorded, Average Recorded Investment
With a specific allowance recorded, Interest Income Recognized
Total Recorded Investment
Total Unpaid Principal Balance
Total Related Allowance
Total Average Recorded Investment
Total Interest Income Recognized
Residential Real Estate [Member]
Summary of Impaired loan activity
With no related allowance recorded, Recorded Investment	567	1,131
With no related allowance recorded, Unpaid Principal Balance	611	1,131
With no related allowance recorded, Related Allowance
With no related allowance recorded, Average Recorded Investment	734	1,315
With no related allowance recorded, Interest Income Recognized	49	65
With a specific allowance recorded, Recorded Investment	1,080	854
With a specific allowance recorded, Unpaid Principal Balance	1,080	854
With a specific allowance recorded, Related Allowance	242	192
With a specific allowance recorded, Average Recorded Investment	1,146	921
With a specific allowance recorded, Interest Income Recognized	47	41
Total Recorded Investment	1,647	1,985
Total Unpaid Principal Balance	1,691	1,985
Total Related Allowance	242	192
Total Average Recorded Investment	1,880	2,236
Total Interest Income Recognized	96	106
Consumer & Other [Member]
Summary of Impaired loan activity
With no related allowance recorded, Recorded Investment	110	252
With no related allowance recorded, Unpaid Principal Balance	110	252
With no related allowance recorded, Related Allowance
With no related allowance recorded, Average Recorded Investment	124	268
With no related allowance recorded, Interest Income Recognized	10	14
With a specific allowance recorded, Recorded Investment	371	338
With a specific allowance recorded, Unpaid Principal Balance	371	338
With a specific allowance recorded, Related Allowance	41	168
With a specific allowance recorded, Average Recorded Investment	402	371
With a specific allowance recorded, Interest Income Recognized	20	25
Total Recorded Investment	481	590
Total Unpaid Principal Balance	481	590
Total Related Allowance	41	168
Total Average Recorded Investment	526	639
Total Interest Income Recognized	30	39
All Impaired Loans less than $100,000 [Member]
Summary of Impaired loan activity
With no related allowance recorded, Recorded Investment	565	1,242
With no related allowance recorded, Unpaid Principal Balance	565	1,242
With no related allowance recorded, Related Allowance
With no related allowance recorded, Average Recorded Investment	565	1,242
With no related allowance recorded, Interest Income Recognized
With a specific allowance recorded, Recorded Investment	371
With a specific allowance recorded, Unpaid Principal Balance	371
With a specific allowance recorded, Related Allowance	41
With a specific allowance recorded, Average Recorded Investment	402
With a specific allowance recorded, Interest Income Recognized	20
Total Recorded Investment	565	1,242
Total Unpaid Principal Balance	565	1,242
Total Related Allowance
Total Average Recorded Investment	565	1,242
Total Interest Income Recognized

Amount of related allowance for which there is no related allowance for credit losses.

No definition available.

Name:	rbnf_ImpairedFinancingReceivableWithNoRelatedAllowanceRecordedRecordedInvestment
Namespace Prefix:	rbnf_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Impaired Financing Receivable with specific allowance recorded Related Allowance.

+ References

No definition available.

+ Details

Name:	rbnf_ImpairedFinancingReceivableWithSpecificAllowanceRecordedRelatedAllowance
Namespace Prefix:	rbnf_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Details

Name:	rbnf_ImpairedLoanActivityAbstract
Namespace Prefix:	rbnf_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Average amount of investment of impaired financing receivables with related allowance for credit losses and without a related allowance for credit losses.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 50

-Paragraph 15

-Subparagraph (c)(1)

-URI http://asc.fasb.org/extlink&oid=35738203&loc=d3e5212-111524

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 50

-Paragraph 17

-URI http://asc.fasb.org/extlink&oid=35738203&loc=d3e5258-111524

+ Details

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

- Definition

Amount of interest income recognized that the financing receivables (with related allowance for credit losses and without a related allowance for credit losses) were impaired.

+ References

+ Details

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

- Definition

Amount of investment of impaired financing receivables with related allowance for credit losses and without a related allowance for credit losses.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 50

-Paragraph 14A

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=35738203&loc=SL6953550-111524

+ Details

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

- Definition

Amount of allowance for credit losses related to recorded investment.

+ References

+ Details

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

- Definition

Amount of unpaid principal balance of impaired financing receivables with related allowance for credit losses and without related allowance for credit losses.

+ References

+ Details

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

- Definition

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

+ References

+ Details

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

- Definition

Amount of interest income, recognized on accrual basis, on financing receivables that are recognized as impaired, for which there is no related allowance for credit losses.

+ References

+ Details

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

- Definition

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

+ References

+ Details

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

- Definition

Amount of unpaid principal balance of impaired financing receivables for which there is no related allowance for credit losses.

+ References

+ Details

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

- Definition

Amount of average investment of impaired financing receivables for which there is a related allowance for credit losses.

+ References

+ Details

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

- Definition

Amount of interest income, recognized on accrual basis, on financing receivables, for which there is a related allowance for credit losses and are recognized as impaired.

+ References

+ Details

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

- Definition

Amount of investment in impaired financing receivables for which there is a related allowance for credit losses.

+ References

+ Details

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

- Definition

Unpaid principal balance of impaired financing receivables for which there is a related allowance for credit losses.

+ References

+ Details

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

- Details

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

- Details

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

- Details

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

- Details

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

- Details

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

- Details

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