REAL ESTATE OWNED: Activity in REO (Real Estate Owned) (Details) - USD ($) $ in Thousands	12 Months Ended
Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2016
Real Estate Owned
Balance at beginning of year, net	$ 298	$ 595	$ 1,603
Additions	0	0	298
Dispositions	0	(267)	(937)
Writedowns	0	(30)	(369)
Balance at end of year, net	$ 298	$ 298	$ 595

Represents additions to Real Estate Owned (REO) during the indicated time period.

No definition available.

Name:	rvsb_RealEstateOwnedAdditions
Namespace Prefix:	rvsb_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Represents the balance of Real Estate Owned (REO) as of the indicated date.

No definition available.

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

Represents dispositions of Real Estate Owned (REO) during the indicated time period.

No definition available.

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

Represents writedowns of Real Estate Owned (REO) during the indicated time period.

No definition available.

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

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

No definition available.

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