Loans and Allowance for Loan Losses (Details 4) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Summary of loan portfolio aging analysis
30-59 Days Past Due	$ 3,863	$ 446
60-89 Days Past Due	100	412
Greater Than 90 Days	3,111	2,609
Total Past Due	7,074	3,467
Current	509,418	474,110
Total Loans Receivable	516,492	477,577
Commercial & Industrial [Member]
Summary of loan portfolio aging analysis
30-59 Days Past Due
60-89 Days Past Due
Greater Than 90 Days	987	1,890
Total Past Due	987	1,890
Current	87,498	83,752
Total Loans Receivable	88,485	85,642
Commercial Real Estate [Member]
Summary of loan portfolio aging analysis
30-59 Days Past Due	3,660	424
60-89 Days Past Due		364
Greater Than 90 Days	1,747	168
Total Past Due	5,407	956
Current	211,623	204,345
Total Loans Receivable	217,030	205,301
Agricultural & Farmland [Member]
Summary of loan portfolio aging analysis
30-59 Days Past Due
60-89 Days Past Due
Greater Than 90 Days
Total Past Due
Current	46,217	39,210
Total Loans Receivable	46,217	39,210
Residential Real Estate [Member]
Summary of loan portfolio aging analysis
30-59 Days Past Due	164
60-89 Days Past Due	19	14
Greater Than 90 Days	377	453
Total Past Due	560	467
Current	112,654	99,153
Total Loans Receivable	113,214	99,620
Consumer & Other [Member]
Summary of loan portfolio aging analysis
30-59 Days Past Due	39	22
60-89 Days Past Due	81	34
Greater Than 90 Days		98
Total Past Due	120	154
Current	51,426	47,650
Total Loans Receivable	$ 51,546	$ 47,804

Financing receivables that are less than 60 days past due but more than 29 days past due.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 50

-Paragraph 7A

-URI http://asc.fasb.org/extlink&oid=35738203&loc=SL6953401-111524

+ Details

Name:	us-gaap_FinancingReceivableRecordedInvestment30To59DaysPastDue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Financing receivables that are less than 90 days past due but more than 59 days past due.

+ References

+ Details

Name:	us-gaap_FinancingReceivableRecordedInvestment60To89DaysPastDue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Financing receivables that are current.

+ References

+ Details

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

- Definition

Financing receivables that are equal to or greater than 90 days past due.

+ References

+ Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentEqualToGreaterThan90DaysPastDue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Recorded Investment in financing receivables that are past due at the balance sheet date.

+ References

+ Details

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

- Details

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

- Definition

Amount before allowance of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Includes deferred interest and fees, undisbursed portion of loan balance, unamortized costs and premiums and discounts from face amounts. Excludes loans and leases covered under loss sharing agreements.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 45

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=28367877&loc=d3e4428-111522

+ Details

Name:	us-gaap_LoansAndLeasesReceivableGrossCarryingAmount
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_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: