Loans and Allowance for Credit Losses for Loans - Past Due, Non-Accrual and Current Loans by Loan Portfolio Class. (Details) - USD ($) $ in Thousands	Mar. 31, 2025	Mar. 31, 2024
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	$ 359,554	$ 183,570
Current Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	359,413	170,198
30-89 Days Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	0	6,276
90 Days or More Past Due Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	141	7,096
Commercial and industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	113,632	84,718
Commercial and industrial | Current Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	113,632	73,859
Commercial and industrial | 30-89 Days Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	0	5,916
Commercial and industrial | 90 Days or More Past Due Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	0	4,943
Commercial Real Estate | Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	243,735	98,370
Commercial Real Estate | Current Loans | Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	243,689	96,217
Commercial Real Estate | 30-89 Days Past Due | Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	0	0
Commercial Real Estate | 90 Days or More Past Due Loans | Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	46	2,153
Residential mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	2,146	360
Residential mortgage | Current Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	2,051	0
Residential mortgage | 30-89 Days Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	0	360
Residential mortgage | 90 Days or More Past Due Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	95	0
Home equity
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	41	122
Home equity | Current Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	41	122
Home equity | 30-89 Days Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	0	0
Home equity | 90 Days or More Past Due Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	$ 0	$ 0