SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Additional Information (Details) - USD ($)		1 Months Ended		12 Months Ended
	May 21, 2020	Oct. 31, 2020	Dec. 31, 2019	Mar. 31, 2023	Jul. 31, 2022	Mar. 31, 2022
Summary Of Significant Accounting Policies [Line Items]
Number of shares additional issued		500
Additional Shares exercised	500
Assets Held-in-trust				$ 890,600,000,000		$ 1,300,000,000
Operating lease right-of-use assets				6,705,000		7,907,000
Operating lease liabilities				$ 7,064,000		8,306,000
Loans and Leases Receivable, Gross, Total						990,408,000
Core Deposit Intangibles | Merchants Bancorp
Summary Of Significant Accounting Policies [Line Items]
Estimated amortized period of Core Deposit Intangibles				10 years
Core Deposit Intangibles, gross				$ 1,400,000		1,400,000
Accumulated amortization				984,000		$ 868,000
Estimated amortization expense of Core Deposit Intangibles for fiscal years ended March 31, 2024				108,000
Estimated amortization expense of Core Deposit Intangibles for fiscal years ended March 31, 2025				100,000
Estimated amortization expense of Core Deposit Intangibles for fiscal years ended March 31, 2026				93,000
Estimated amortization expense of Core Deposit Intangibles for fiscal years ended March 31, 2027				$ 78,000
Building and improvements | Maximum
Summary Of Significant Accounting Policies [Line Items]
Estimated useful life				45 years
Furniture and equipment | Minimum
Summary Of Significant Accounting Policies [Line Items]
Estimated useful life				3 years
Furniture and equipment | Maximum
Summary Of Significant Accounting Policies [Line Items]
Estimated useful life				20 years
Leasehold improvements | Minimum
Summary Of Significant Accounting Policies [Line Items]
Estimated useful life				15 years
Leasehold improvements | Maximum
Summary Of Significant Accounting Policies [Line Items]
Estimated useful life				25 years
Riverview Bank
Summary Of Significant Accounting Policies [Line Items]
Non controlling Interest					$ 234,000
Trust Company
Summary Of Significant Accounting Policies [Line Items]
Number of shares issued			1,500
Number of stock options exercised			1,500
Trust Company | Riverview Bank
Summary Of Significant Accounting Policies [Line Items]
Ownership percentage				100.00%	97.30%