FEDERAL HOME LOAN BANK ADVANCES (Details) - USD ($) $ in Millions	9 Months Ended
Dec. 31, 2020	Mar. 31, 2020
FEDERAL HOME LOAN BANK ADVANCES
Weighted average interest rate on FHLB advances	0.31%	2.54%
Percentages of federal home loan banks credit line facility	45.00%
Additional borrowing from FHlB	$ 224.9
Loans Pledged As Collateral To Fhib	$ 382.6

Represents percentages related to credit line facility is equal to 45% of total assets.

No definition available.

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- Definition

Represents amount related to loans pledged as collateral to FHIB.

+ References

No definition available.

+ Details

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

- Definition

Weighted average interest rate on advances made and reported by Federal Home Loan Bank (FHLBank).

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- References

No definition available.

+ Details

Name:	us-gaap_FederalHomeLoanBanksAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
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Period Type:	duration

- Definition

Amount of cash inflow from Federal Home Loan Bank (FHLBank) borrowing, classified as financing activity.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 14
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3255-108585

+ Details

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Balance Type:	debit
Period Type:	duration