Loans and Asset Quality - Schedule of Current, Past Due, and Nonaccrual TDR Loans (Details) $ in Thousands	12 Months Ended
Dec. 31, 2021 USD ($) loan	Dec. 31, 2020 USD ($) loan
TDR
Current	$ 3,944	$ 1,454
Nonaccrual	0	1,217
Total TDRs	$ 3,944	$ 2,671
Number of TDR loans
Current \| loan	11	8
Nonaccrual \| loan	1	4
Total TDRs \| loan	12	12
30-89 Days Past Due
TDR
Past Due	$ 0	$ 0
Number of TDR loans
Past Due \| loan	0	0
90 Days or More Past Due
TDR
Past Due	$ 0	$ 0
Number of TDR loans
Past Due \| loan	0	0
Real estate \| Commercial real estate
TDR
Current	$ 3,634	$ 1,151
Nonaccrual	0	1,212
Total TDRs	3,634	2,363
Real estate \| Commercial real estate \| 30-89 Days Past Due
TDR
Past Due	0	0
Real estate \| Commercial real estate \| 90 Days or More Past Due
TDR
Past Due	0	0
Real estate \| One-to-four family residential
TDR
Current	289	303
Nonaccrual	0	0
Total TDRs	289	303
Real estate \| One-to-four family residential \| 30-89 Days Past Due
TDR
Past Due	0	0
Real estate \| One-to-four family residential \| 90 Days or More Past Due
TDR
Past Due	0	0
Real estate \| Construction and development
TDR
Current	0	0
Nonaccrual	0	0
Total TDRs	0	0
Real estate \| Construction and development \| 30-89 Days Past Due
TDR
Past Due	0	0
Real estate \| Construction and development \| 90 Days or More Past Due
TDR
Past Due	0	0
Commercial and industrial
TDR
Current	0	0
Nonaccrual	0	5
Total TDRs	0	5
Commercial and industrial \| 30-89 Days Past Due
TDR
Past Due	0	0
Commercial and industrial \| 90 Days or More Past Due
TDR
Past Due	0	0
SBA PPP, net of deferred income
TDR
Current	0	0
Nonaccrual	0	0
Total TDRs	0	0
SBA PPP, net of deferred income \| 30-89 Days Past Due
TDR
Past Due	0	0
SBA PPP, net of deferred income \| 90 Days or More Past Due
TDR
Past Due	0	0
Tax-exempt
TDR
Current	0	0
Nonaccrual	0	0
Total TDRs	0	0
Tax-exempt \| 30-89 Days Past Due
TDR
Past Due	0	0
Tax-exempt \| 90 Days or More Past Due
TDR
Past Due	0	0
Consumer
TDR
Current	21	0
Nonaccrual	0	0
Total TDRs	21	0
Consumer \| 30-89 Days Past Due
TDR
Past Due	0	0
Consumer \| 90 Days or More Past Due
TDR
Past Due	$ 0	$ 0

Financing Receivable, Modifications, Number of Contracts, Current

No definition available.

Name:	rrbi_FinancingReceivableModificationsNumberOfContractsCurrent
Namespace Prefix:	rrbi_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Financing Receivable, Modifications, Number of Contracts, Nonaccrual

+ References

No definition available.

+ Details

Name:	rrbi_FinancingReceivableModificationsNumberOfContractsNonaccrual
Namespace Prefix:	rrbi_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Financing Receivable, Modifications, Number of Contracts, Past Due

+ References

No definition available.

+ Details

Name:	rrbi_FinancingReceivableModificationsNumberOfContractsPastDue
Namespace Prefix:	rrbi_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Financing Receivable, Troubled Debt Restructuring, Current

+ References

No definition available.

+ Details

Name:	rrbi_FinancingReceivableTroubledDebtRestructuringCurrent
Namespace Prefix:	rrbi_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Financing Receivable, Troubled Debt Restructuring, Nonaccrual

+ References

No definition available.

+ Details

Name:	rrbi_FinancingReceivableTroubledDebtRestructuringNonaccrual
Namespace Prefix:	rrbi_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Financing Receivable, Troubled Debt Restructuring, Past Due

+ References

No definition available.

+ Details

Name:	rrbi_FinancingReceivableTroubledDebtRestructuringPastDue
Namespace Prefix:	rrbi_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Number Of Loans [Abstract]

+ References

No definition available.

+ Details

Name:	rrbi_NumberOfLoansAbstract
Namespace Prefix:	rrbi_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

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

+ References

+ Details

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

- Definition

Amount of financing receivable modified as troubled debt restructuring.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 33
-URI http://asc.fasb.org/extlink&oid=123577603&loc=SL6953676-111524

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 40
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=121585226&loc=d3e18845-111554

+ Details

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

- References

No definition available.

+ Details

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

- Details

Name:	us-gaap_FinancingReceivablesPeriodPastDueAxis=rrbi_FinancialAsset30to89DaysPastDueMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablesPeriodPastDueAxis=us-gaap_FinancingReceivablesEqualToGreaterThan90DaysPastDueMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=rrbi_RealEstatePortfolioSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

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

- Details

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

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=rrbi_CommercialAndIndustrialSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=rrbi_SmallBusinessAdministrationPaycheckProtectionProgramMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=rrbi_TaxExemptPortfolioSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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