Premises and Equipment: Property, Plant and Equipment (Details) - USD ($) $ in Thousands	Sep. 30, 2025	Sep. 30, 2024
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	$ 44,197	$ 42,650
Less accumulated depreciation	22,513	21,164
Premises and equipment, net	21,684	21,486
Land
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	5,404	5,404
Buildings and improvements
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	26,131	25,592
Furniture and equipment
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	12,199	11,316
Property held for future expansion
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	116	116
Construction and purchases in progress
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	$ 347	$ 222