Investment Securities: Unrealized Gain (Loss) on Investments (Details) $ in Thousands	Sep. 30, 2025 USD ($) security	Sep. 30, 2024 USD ($) security
Held-to-maturity Securities, Fair Value:
Estimated Fair Value - Less Than 12 Months	$ 843	$ 805
Estimated Fair Value - 12 Months or Longer	99,382	127,905
Total Estimated Fair Value	100,225	128,710
Held-to-maturity Securities, Gross Unrealized Losses
Gross Unrealized Losses - Less Than 12 Months	(6)	(6)
Gross Unrealized Losses - 12 Months or Longer	(4,937)	(6,567)
Total Gross Unrealized Losses	$ (4,943)	$ (6,573)
Held-to-maturity, Qty, Less Than 12 Months | security	5	2
Held-to-maturity, Qty, 12 Months or Longer | security	70	81
Estimated Fair Value - Less Than 12 Months	$ 15,899	$ 13,330
Estimated Fair Value - 12 Months or Longer	28,947	25,751
Total Estimated Fair Value	44,846	39,081
Available-for-sale Securities, Gross Unrealized Losses:
Available-for-sale Securities, Continuous Unrealized Loss Position, Less Than 12 Months, Accumulated Loss	(67)	(118)
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(692)	(407)
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	$ (759)	$ (525)
Available-for-sale, Qty, Less than 12 Months | security	4,000	5
Available-for-sale, Qty, 12 Months or Longer | security	24	23
U.S. Treasury and U.S. government agency securities
Held-to-maturity Securities, Fair Value:
Estimated Fair Value - Less Than 12 Months	$ 0	$ 0
Estimated Fair Value - 12 Months or Longer	56,960	78,363
Total Estimated Fair Value	56,960	78,363
Held-to-maturity Securities, Gross Unrealized Losses
Gross Unrealized Losses - Less Than 12 Months	0	0
Gross Unrealized Losses - 12 Months or Longer	(2,760)	(4,197)
Total Gross Unrealized Losses	$ (2,760)	$ (4,197)
Held-to-maturity, Qty, Less Than 12 Months | security	0	0
Held-to-maturity, Qty, 12 Months or Longer | security	14	17
Estimated Fair Value - Less Than 12 Months	$ 3,977	$ 1,962
Estimated Fair Value - 12 Months or Longer	0	0
Total Estimated Fair Value	3,977	1,962
Available-for-sale Securities, Gross Unrealized Losses:
Available-for-sale Securities, Continuous Unrealized Loss Position, Less Than 12 Months, Accumulated Loss	0	(1)
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	0	0
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	$ 0	$ (1)
Available-for-sale, Qty, Less than 12 Months | security	1	1
Available-for-sale, Qty, 12 Months or Longer | security	0	0
MBS: U.S. government agencies
Held-to-maturity Securities, Fair Value:
Estimated Fair Value - Less Than 12 Months	$ 7	$ 1
Estimated Fair Value - 12 Months or Longer	27,776	28,618
Total Estimated Fair Value	27,783	28,619
Held-to-maturity Securities, Gross Unrealized Losses
Gross Unrealized Losses - Less Than 12 Months	0	0
Gross Unrealized Losses - 12 Months or Longer	(1,357)	(1,378)
Total Gross Unrealized Losses	$ (1,357)	$ (1,378)
Held-to-maturity, Qty, Less Than 12 Months | security	1	1
Held-to-maturity, Qty, 12 Months or Longer | security	42	44
Estimated Fair Value - Less Than 12 Months	$ 11,922	$ 11,368
Estimated Fair Value - 12 Months or Longer	28,947	25,751
Total Estimated Fair Value	40,869	37,119
Available-for-sale Securities, Gross Unrealized Losses:
Available-for-sale Securities, Continuous Unrealized Loss Position, Less Than 12 Months, Accumulated Loss	(67)	(117)
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(692)	(407)
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	$ (759)	$ (524)
Available-for-sale, Qty, Less than 12 Months | security	3,000	4
Available-for-sale, Qty, 12 Months or Longer | security	24	23
Private label residential
Held-to-maturity Securities, Fair Value:
Estimated Fair Value - Less Than 12 Months	$ 341	$ 804
Estimated Fair Value - 12 Months or Longer	14,646	20,447
Total Estimated Fair Value	14,987	21,251
Held-to-maturity Securities, Gross Unrealized Losses
Gross Unrealized Losses - Less Than 12 Months	(2)	(6)
Gross Unrealized Losses - 12 Months or Longer	(820)	(974)
Total Gross Unrealized Losses	$ (822)	$ (980)
Held-to-maturity, Qty, Less Than 12 Months | security	3	1
Held-to-maturity, Qty, 12 Months or Longer | security	14	19
Bank issued trust preferred securities
Held-to-maturity Securities, Fair Value:
Estimated Fair Value - Less Than 12 Months	$ 495	$ 0
Estimated Fair Value - 12 Months or Longer	0	477
Total Estimated Fair Value	495	477
Held-to-maturity Securities, Gross Unrealized Losses
Gross Unrealized Losses - Less Than 12 Months	(4)	0
Gross Unrealized Losses - 12 Months or Longer	0	(18)
Total Gross Unrealized Losses	$ (4)	$ (18)
Held-to-maturity, Qty, Less Than 12 Months | security	1	0
Held-to-maturity, Qty, 12 Months or Longer | security	0	1