Name:	rbkb_EmployeeBenefitPlanEmployerDiscretionaryContributionMinimumServicePeriodForEligibility
Namespace Prefix:	rbkb_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

Percentage of a participant's eligible compensation that the employer contributes as a discretionary contribution in employee stock purchase, saving, or similar plan (employee benefit plan (EBP)).

No definition available.

Name:	rbkb_EmployeeBenefitPlanEmployerDiscretionaryContributionRate
Namespace Prefix:	rbkb_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

Percentage vested in eligible matching compensation contributed for participant in employee stock purchase, saving, or similar plan (employee benefit plan (EBP)) after vesting period has been completed.

No definition available.

Name:	rbkb_EmployeeBenefitPlanEmployerMatchingContributionVestingPercent
Namespace Prefix:	rbkb_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

Percentage vested in eligible matching compensation contributed for participant in employee stock purchase, saving, or similar plan (employee benefit plan (EBP)) for each period of service.

No definition available.

Name:	rbkb_EmployeeBenefitPlanEmployerMatchingContributionVestingPercentForEachPeriodOfService
Namespace Prefix:	rbkb_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

The period of service a participant must complete before becoming eligible to receive matching employer contributions under the (employee benefit plan (EBP)).

No definition available.

Name:	rbkb_EmployeeBenefitPlanEmployerMatchingContributionVestingPeriod
Namespace Prefix:	rbkb_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

Represents the minimum age criteria for plan eligibility under (employee benefit plan (EBP)).

No definition available.

Name:	rbkb_EmployeeBenefitPlanMinimumAgeForPlanEligibility
Namespace Prefix:	rbkb_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

Represents the minimum service period for plan eligibility under (employee benefit plan (EBP)).

No definition available.

Name:	rbkb_EmployeeBenefitPlanMinimumServicePeriodForPlanEligibility
Namespace Prefix:	rbkb_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

Number of notes outstanding a participant may borrow at any time in employee stock purchase, saving, or similar plan (employee benefit plan (EBP)).

No definition available.

Name:	rbkb_EmployeeBenefitPlanNoteReceivableFromParticipantAccountMaximumBorrowingNumberOfLoans
Namespace Prefix:	rbkb_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

Represents the percentage points added to the prime rate to compute the interest rate on participant loans.

No definition available.

Name:	rbkb_EmployeeBenefitPlanNoteReceivableFromParticipantBasisSpreadOnPrimeRate
Namespace Prefix:	rbkb_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

Term of participant loan of employee stock purchase, saving, or similar plan (employee benefit plan (EBP)).

No definition available.

Name:	rbkb_EmployeeBenefitPlanNoteReceivableFromParticipantTerm
Namespace Prefix:	rbkb_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

Percentage by which a participant's contribution is automatically increased each year under the plan's escalation feature.

No definition available.

Name:	rbkb_EmployeeBenefitPlanParticipantContributionAutomaticDeferralRateAnnualIncrease
Namespace Prefix:	rbkb_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

The maximum percentage by which a participant's contribution is automatically increased each year under the plan's escalation feature.

No definition available.

Name:	rbkb_EmployeeBenefitPlanParticipantContributionAutomaticMaximumDeferralRateAnnualIncrease
Namespace Prefix:	rbkb_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

The percentage of eligible compensation that the employer contributes to all eligible participants as a non-elective safe harbor contribution under the (employee benefit plan (EBP)).

No definition available.

Name:	rbkb_EmployeeBenefitPlanSafeHarborContributionRate
Namespace Prefix:	rbkb_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

Indicates (true false) whether description of employee stock purchase, saving, or similar plan (employee benefit plan (EBP)) is published and made available.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 962
-SubTopic 205
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478416/962-205-50-1

Name:	us-gaap-ebp_EmployeeBenefitPlanDescriptionAvailable
Namespace Prefix:	us-gaap-ebp_
Data Type:	xbrli:booleanItemType
Balance Type:	na
Period Type:	duration

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.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 962
-SubTopic 205
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478416/962-205-50-1

Name:	us-gaap-ebp_EmployeeBenefitPlanDescriptionOfPlanLineItems
Namespace Prefix:	us-gaap-ebp_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Percentage of employer matching contribution on eligible participant contribution to employee stock purchase, saving, or similar plan (employee benefit plan (EBP)).

Name:	us-gaap-ebp_EmployeeBenefitPlanEmployerContributionMatchingPercentage
Namespace Prefix:	us-gaap-ebp_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

Percentage of participant compensation eligible for employer matching contribution for participant in employee stock purchase, saving, or similar plan (employee benefit plan (EBP)).

Name:	us-gaap-ebp_EmployeeBenefitPlanEmployerContributionParticipantCompensationMatchedPercentage
Namespace Prefix:	us-gaap-ebp_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

Amount of plan asset, in forfeited nonvested account, no longer allocated to participant in employee stock purchase, saving, or similar plan (employee benefit plan (EBP)).

Name:	us-gaap-ebp_EmployeeBenefitPlanForfeitedNonvestedAccount
Namespace Prefix:	us-gaap-ebp_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Amount of decrease in forfeited nonvested account of employee stock purchase, saving, or similar plan (employee benefit plan (EBP)) from employer contribution.

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 962
-SubTopic 325
-Name Accounting Standards Codification
-Section 55
-Paragraph 17
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478873/962-325-55-17

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 962
-SubTopic 205
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (j)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478416/962-205-50-1

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 962
-SubTopic 205
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.6A-04(5)(c))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477804/962-205-S99-1

Name:	us-gaap-ebp_EmployeeBenefitPlanForfeitedNonvestedAccountDecreaseForEmployerContribution
Namespace Prefix:	us-gaap-ebp_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Amount of maximum account balance that participant in employee stock purchase, saving, or similar plan (employee benefit plan (EBP)) can borrow.

Name:	us-gaap-ebp_EmployeeBenefitPlanNoteReceivableFromParticipantAccountMaximumBorrowingAmount
Namespace Prefix:	us-gaap-ebp_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Percentage of maximum account balance that participant in employee stock purchase, saving, or similar plan (employee benefit plan (EBP)) can borrow to total participant account balance.

Name:	us-gaap-ebp_EmployeeBenefitPlanNoteReceivableFromParticipantAccountMaximumBorrowingToTotalAccountPercentage
Namespace Prefix:	us-gaap-ebp_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

Amount of minimum account balance that participant in employee stock purchase, saving, or similar plan (employee benefit plan (EBP)) can borrow.

Name:	us-gaap-ebp_EmployeeBenefitPlanNoteReceivableFromParticipantAccountMinimumBorrowingAmount
Namespace Prefix:	us-gaap-ebp_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Percentage of eligible compensation contributed for participant automatically enrolled in employee stock purchase, saving, or similar plan (employee benefit plan (EBP)).

Name:	us-gaap-ebp_EmployeeBenefitPlanParticipantContributionAutomaticDeferralRate
Namespace Prefix:	us-gaap-ebp_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

Interest rate on participant loan in schedule of asset held for investment of employee stock purchase, saving, or similar plan (employee benefit plan (EBP)).

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Name Employee Retirement Income Security Act of 1974
-Number 2520
-Section 103
-Subsection 10
-Paragraph b
-Subparagraph (1)(i)(D)
-Publisher DOL-EBSA

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 962
-SubTopic 205
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.6A-05(a)(Schedule I))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477804/962-205-S99-1