RIVERVIEW BANCORP, INC. (PARENT COMPANY ONLY) - STATEMENTS OF CASH FLOWS (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
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 2,983	$ 5,240	$ 5,194	$ 4,652	$ 4,125	$ 5,510	$ 6,430	$ 5,755	$ 18,069	$ 21,820	$ 10,472
Adjustments to reconcile net income to net cash used in operating activities:
Stock-based compensation expense									390	319	396
Changes in assets and liabilities:
Net cash used in operating activities									13,575	16,463	24,167
CASH FLOWS FROM INVESTING ACTIVITIES:
Net cash provided by investing activities									(76,245)	(221,659)	(150,247)
CASH FLOWS FROM FINANCING ACTIVITIES:
Dividends paid									(5,117)	(4,670)	(4,478)
Proceeds from exercise of stock options									4	16	50
Repurchase of common stock									(6,706)	(1,940)	(1,447)
Net cash used in financing activities									(156,710)	181,212	349,520
NET INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS									(219,380)	(23,984)	223,440
CASH AND CASH EQUIVALENTS, BEGINNING OF YEAR				241,424				265,408	241,424	265,408	41,968
CASH AND CASH EQUIVALENTS, END OF YEAR	22,044				241,424				22,044	241,424	265,408
RIVERVIEW BANCORP, INC. (PARENT COMPANY ONLY)
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income									18,069	21,820	10,472
Adjustments to reconcile net income to net cash used in operating activities:
Equity in undistributed income of the Bank									(19,204)	(22,450)	(11,149)
Amortization expense									85	85	86
Provision (benefit) for deferred income taxes									(1)	2
Stock-based compensation expense									390	319	396
Changes in assets and liabilities:
Other assets									(1,019)	131	224
Accrued expenses and other liabilities									112	48	(417)
Net cash used in operating activities									(1,568)	(45)	(388)
CASH FLOWS FROM INVESTING ACTIVITIES:
Dividend from the Bank									8,000	7,500	6,000
Net cash provided by investing activities									8,000	7,500	6,000
CASH FLOWS FROM FINANCING ACTIVITIES:
Dividends paid									(5,117)	(4,670)	(4,478)
Proceeds from exercise of stock options									4	16	50
Repurchase of common stock									(6,706)	(1,940)	(1,447)
Net cash used in financing activities									(11,819)	(6,594)	(5,875)
NET INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS									(5,387)	861	(263)
CASH AND CASH EQUIVALENTS, BEGINNING OF YEAR				$ 10,867				$ 10,006	10,867	10,006	10,269
CASH AND CASH EQUIVALENTS, END OF YEAR	$ 5,480				$ 10,867				$ 5,480	$ 10,867	$ 10,006