ALLOWANCE FOR LOAN LOSSES - Additional information (Details)	3 Months Ended	6 Months Ended
Sep. 30, 2021 item	Sep. 30, 2020 item	Sep. 30, 2021 USD ($) item	Sep. 30, 2020 USD ($) item
ALLOWANCE FOR LOAN LOSSES
Interest income foregone on non-accrual loans			$ 14,000	$ 35,000
Post-modification outstanding recorded investment amount				$ 129,000
Percentage Of Delinquent Loan Amount			75.00%
Number of TDR loans default \| item	0	1	0	1

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.

No definition available.

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