Investment Securities: Schedule of Contractual maturities of debt securities (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Sep. 30, 2023
Held-to-maturity Securities, Amortized Cost:
Due within one year	$ 27,472
Due after one year to five years	81,840
Due after five years to ten years	1,250
Due after ten years	61,535
Total	172,097
Held-to-maturity Securities, Estimated Fair Value:
Due within one year	27,262
Due after one year to five years	77,870
Due after five years to ten years	1,277
Due after ten years	59,598
Total	166,007	$ 253,766
Available-for-sale Securities, Amortized Cost:
Due within one year	3,934
Due after one year to five years	2,131
Due after five years to ten years	5,160
Due after ten years	61,006
Total	72,231	$ 43,132
Available-for-sale Securities, Estimated Fair Value:
Due within one year	3,939
Due after one year to five years	2,130
Due after five years to ten years	5,144
Due after ten years	61,044
Total	$ 72,257