RIVERVIEW BANCORP, INC. (PARENT COMPANY ONLY) - STATEMENTS OF INCOME (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Mar. 31, 2023	Dec. 31, 2022	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Dec. 31, 2021	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2023	Mar. 31, 2022	Mar. 31, 2021
EXPENSE:
Total expense	$ 9,950	$ 9,848	$ 9,804	$ 9,769	$ 10,115	$ 9,279	$ 8,187	$ 9,137	$ 39,371	$ 36,718	$ 36,254
LOSS BEFORE INCOME TAXES AND EQUITY IN UNDISTRIBUTED INCOME OF THE BANK	4,085	6,815	6,761	6,018	5,407	7,171	8,363	7,335	23,679	28,276	13,453
BENEFIT FOR INCOME TAXES	1,102	1,575	1,567	1,366	1,282	1,661	1,933	1,580	5,610	6,456	2,981
NET INCOME	2,983	$ 5,240	$ 5,194	$ 4,652	4,125	$ 5,510	$ 6,430	$ 5,755	18,069	21,820	10,472
RIVERVIEW BANCORP, INC. (PARENT COMPANY ONLY)
INCOME:
Interest on investment securities and other short-term investments									129	16	17
Total income									129	16	17
EXPENSE:
Management service fees paid to the Bank									143	143	143
Other expenses									1,424	670	731
Total expense									1,567	813	874
LOSS BEFORE INCOME TAXES AND EQUITY IN UNDISTRIBUTED INCOME OF THE BANK									(1,438)	(797)	(857)
BENEFIT FOR INCOME TAXES									(303)	(167)	(180)
LOSS OF PARENT COMPANY									(1,135)	(630)	(677)
EQUITY IN UNDISTRIBUTED INCOME OF THE BANK	$ 19,204				$ 22,450				19,204	22,450	11,149
NET INCOME									$ 18,069	$ 21,820	$ 10,472