Represents an extended maturity period of loans receivable.

No definition available.

Name:	rvsb_ExtendedMaturityPeriodOfLoansReceivable
Namespace Prefix:	rvsb_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Interest income foregone on loans not accruing. In general, when a loan is 90 days delinquent or when collection of principal or interest appears doubtful, it is placed on non-accrual status, at which time the accrual of interest ceases and a reserve for unrecoverable accrued interest is established and charged against operations. Payments received on non-accrual loans are applied to reduce the outstanding principal balance on a cash-basis method. As a general practice, a loan is not removed from non-accrual status until all delinquent principal, interest and late fees have been brought current and the borrower has demonstrated a history of performance based upon the contractual terms of the note.

+ References

No definition available.

+ Details

Name:	rvsb_InterestIncomeForegoneOnNonAccrualLoans
Namespace Prefix:	rvsb_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- 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

No definition available.

+ Details

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

- Definition

Amount, after troubled debt restructuring, of modified financing receivable.

+ 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=121611835&loc=SL6953676-111524

+ Details

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

- Definition

Number of financing receivable contracts modified as troubled debt restructuring within previous 12 months, with subsequent payment default.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 34
-URI http://asc.fasb.org/extlink&oid=121611835&loc=SL6953682-111524

+ Details

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

- Details

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

- Details

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

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=rvsb_RealEstateOneToFourFamilyMember
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:

ALLOWANCE FOR LOAN LOSSES - Additional information (Details)	12 Months Ended
	Mar. 31, 2021 USD ($) item	Mar. 31, 2020 USD ($)	Mar. 31, 2019 USD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Interest income foregone on non-accrual loans	$ 49,000	$ 75,000	$ 94,000
Commercial Real Estate Portfolio Segment \| Commercial and Constructions
Accounts, Notes, Loans and Financing Receivable [Line Items]
Post-modification outstanding recorded investment amount	27,000	$ 25,000
Commercial Real Estate Portfolio Segment \| Real estate one-to-four family
Accounts, Notes, Loans and Financing Receivable [Line Items]
Post-modification outstanding recorded investment amount	$ 129,000
Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of TDR loans default \| item	1
Consumer \| Real estate one-to-four family
Accounts, Notes, Loans and Financing Receivable [Line Items]
Extended maturity period of loans receivable	10 years