Allowance for Credit Losses - Summary of Amortized Cost Basis of Nonaccrual Loans and Loans Past due 90 Days or Greater and Still Accruing (Detail) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023	Sep. 30, 2023
Financing Receivable, Nonaccrual [Line Items]
Nonaccrual with No Allowance for Credit Loss	$ 5,898	$ 6,304
Nonaccrual with a related Allowance for Credit Loss		733	$ 0
Total Nonaccrual	5,898	7,037
Loans 90 days or greater past due still accruing	776	213
Agriculture and Farmland [Member]
Financing Receivable, Nonaccrual [Line Items]
Nonaccrual with No Allowance for Credit Loss	0	0
Nonaccrual with a related Allowance for Credit Loss		0	0
Total Nonaccrual	0	0
Loans 90 days or greater past due still accruing	0	0
Construction [Member]
Financing Receivable, Nonaccrual [Line Items]
Nonaccrual with No Allowance for Credit Loss	0	191
Nonaccrual with a related Allowance for Credit Loss		0	0
Total Nonaccrual	0	191
Loans 90 days or greater past due still accruing	91	0
Commercial and Industrial [Member]
Financing Receivable, Nonaccrual [Line Items]
Nonaccrual with No Allowance for Credit Loss	6	53
Nonaccrual with a related Allowance for Credit Loss		8	0
Total Nonaccrual	6	61
Loans 90 days or greater past due still accruing	80	58
Multifamily [Member]
Financing Receivable, Nonaccrual [Line Items]
Nonaccrual with No Allowance for Credit Loss	0	0
Nonaccrual with a related Allowance for Credit Loss		0	0
Total Nonaccrual	0	0
Loans 90 days or greater past due still accruing	0	0
Owner Occupied [Member]
Financing Receivable, Nonaccrual [Line Items]
Nonaccrual with No Allowance for Credit Loss	2,631	2,465
Nonaccrual with a related Allowance for Credit Loss		83	0
Total Nonaccrual	2,631	2,548
Loans 90 days or greater past due still accruing	0	6
Non-owner Occupied [Member]
Financing Receivable, Nonaccrual [Line Items]
Nonaccrual with No Allowance for Credit Loss	352	948
Nonaccrual with a related Allowance for Credit Loss		281	0
Total Nonaccrual	352	1,229
Loans 90 days or greater past due still accruing	0	0
First Liens [Member]
Financing Receivable, Nonaccrual [Line Items]
Nonaccrual with No Allowance for Credit Loss	2,620	2,346
Nonaccrual with a related Allowance for Credit Loss		361	0
Total Nonaccrual	2,620	2,707
Loans 90 days or greater past due still accruing	605	149
Second Liens and Lines of Credit [Member]
Financing Receivable, Nonaccrual [Line Items]
Nonaccrual with No Allowance for Credit Loss	289	294
Nonaccrual with a related Allowance for Credit Loss		0	0
Total Nonaccrual	289	294
Loans 90 days or greater past due still accruing	0	0
Municipal [Member]
Financing Receivable, Nonaccrual [Line Items]
Nonaccrual with No Allowance for Credit Loss	0
Nonaccrual with a related Allowance for Credit Loss		0	0
Total Nonaccrual	0	0
Loans 90 days or greater past due still accruing	0	0
Consumer [Member]
Financing Receivable, Nonaccrual [Line Items]
Nonaccrual with No Allowance for Credit Loss	0	7
Nonaccrual with a related Allowance for Credit Loss		0	$ 0
Total Nonaccrual	0	7
Loans 90 days or greater past due still accruing	$ 0	$ 0