LOANS AND ACL - Analysis of loans by aging category (Details) - USD ($) $ in Thousands	Jun. 30, 2025	Mar. 31, 2025
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual	$ 143	$ 155
Total Past Due and Non-accrual	3,805	4,237
Total loans	1,068,080	1,062,460
30-89 Days Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	3,662	4,082
Current
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	1,064,275	1,058,223
Commercial and Construction \| Commercial Business
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual	32	37
Total Past Due and Non-accrual	3,694	3,830
Total loans	231,826	232,935
Commercial and Construction \| Commercial Business \| 30-89 Days Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	3,662	3,793
Commercial and Construction \| Commercial Business \| Current
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	228,132	229,105
Commercial Real Estate Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	945,841	950,363
Commercial Real Estate Portfolio Segment \| Commercial Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual	82	88
Total Past Due and Non-accrual	82	330
Total loans	599,617	592,185
Commercial Real Estate Portfolio Segment \| Commercial Real Estate \| 30-89 Days Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans		242
Commercial Real Estate Portfolio Segment \| Commercial Real Estate \| Current
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	599,535	591,855
Commercial Real Estate Portfolio Segment \| Land
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	3,659	4,610
Commercial Real Estate Portfolio Segment \| Land \| Current
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	3,659	4,610
Commercial Real Estate Portfolio Segment \| Multi-Family
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	90,606	91,451
Commercial Real Estate Portfolio Segment \| Multi-Family \| Current
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	90,606	91,451
Commercial Real Estate Portfolio Segment \| Real Estate Construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	20,133	29,182
Commercial Real Estate Portfolio Segment \| Real Estate Construction \| Current
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	20,133	29,182
Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual	29	30
Total Past Due and Non-accrual	29	77
Total loans	122,239	112,097
Consumer \| 30-89 Days Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans		47
Consumer \| Current
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	$ 122,210	$ 112,020

Represents the monetary amount of Financing Receivable Recorded Investment (Past Due and Non-accrual), as of the indicated date.

No definition available.

+ Details

Name:	rvsb_FinancingReceivableRecordedInvestmentPastDueAndNonAccrual
Namespace Prefix:	rvsb_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

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.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 310
-SubTopic 20
-Name Accounting Standards Codification
-Section 40
-Paragraph 7
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481628/310-20-40-7

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 310
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 2
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481990/310-10-45-2

+ Details

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

- Definition

Amortized cost excluding accrued interest, before allowance for credit loss, of financing receivable. Excludes net investment in lease.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 45
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479344/326-20-45-1

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 3B
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-3B

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 5
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-5

+ Details

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

- Definition

Amortized cost of financing receivable on nonaccrual status. Excludes net investment in lease.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/otherTransitionRef
-Topic 310
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 7
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481962/310-10-50-7

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Name Regulation S-K (SK)
-Number 229
-Section 1405
-Paragraph a
-Subparagraph (3)
-Publisher SEC

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Name Regulation S-K (SK)
-Number 229
-Section 1405
-Paragraph a
-Subparagraph (2)
-Publisher SEC

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 16
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-16

+ Details

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

- Details

Name:	us-gaap_FinancingReceivablesPeriodPastDueAxis=rvsb_FinancingReceivables30To89DaysPastDueMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

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

- Details

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

- Details

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

- Details

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

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=us-gaap_ConstructionLoansMember
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: