Investment Securities: Schedule of Contractual maturities of debt securities (Details) - USD ($) $ in Thousands	Sep. 30, 2025	Sep. 30, 2024
Held-to-maturity Securities, Amortized Cost:
Due within one year	$ 24,152
Due after one year to five years	56,882
Due after five years to ten years	134
Due after ten years	55,693
Total	136,861	$ 172,097
Held-to-maturity Securities, Estimated Fair Value:
Due within one year	23,898
Due after one year to five years	54,352
Due after five years to ten years	233
Due after ten years	53,851
Total	132,334	166,007
Available-for-sale Securities, Amortized Cost:
Due within one year	7,091
Due after one year to five years	3,780
Due after five years to ten years	194
Due after ten years	67,552
Total	78,617	$ 72,231
Available-for-sale Securities, Estimated Fair Value:
Due within one year	7,092
Due after one year to five years	3,772
Due after five years to ten years	193
Due after ten years	67,183
Total	$ 78,240