JUNIOR SUBORDINATED DEBENTURES: Terms of the current Debentures (Details) - USD ($) $ in Thousands		12 Months Ended
		Mar. 31, 2018	Mar. 31, 2017
Debt Instrument [Line Items]
Amount Outstanding		$ 27,836
Fair value adjustment	[1]	(1,352)
Junior subordinated debentures		$ 26,484	$ 26,390
Riverview Bancorp Statutory Trust I
Debt Instrument [Line Items]
Issuance Date		12/2005
Amount Outstanding		$ 7,217
Rate Type	[2]	Variable
Initial Rate		5.88%
Current Rate		3.48%
Maturity Date		3/2036
Riverview Bancorp Statutory Trust II
Debt Instrument [Line Items]
Issuance Date		06/2007
Amount Outstanding		$ 15,464
Rate Type	[3]	Variable
Initial Rate		7.03%
Current Rate		3.47%
Maturity Date		9/2037
Merchants Bancorp Statutory Trust I
Debt Instrument [Line Items]
Issuance Date		06/2003
Amount Outstanding		$ 5,155
Rate Type	[4]	Variable
Initial Rate		4.16%
Current Rate		5.39%
Maturity Date		6/2033

[1] Amount, net of accretion, is attributable to the MBank transaction. See Note 3.

[2] The trust preferred securities reprice quarterly based on the three-month LIBOR plus 1.36%.

[3] The trust preferred securities reprice quarterly based on the three-month LIBOR plus 1.35%.

[4] The trust preferred securities reprice quarterly based on the three-month LIBOR plus 3.10%.