OREO and Other Repossessed Assets: Narrative (Details) $ in Thousands	12 Months Ended
	Sep. 30, 2021 USD ($) property loan	Sep. 30, 2020 USD ($) property	Sep. 30, 2019 USD ($)
Other Real Estate, Foreclosed Assets, and Repossessed Assets [Abstract]
(Gain) loss on sales of OREO and other repossessed assets, net	$ 92	$ 35	$ 89
OREO, number of repossessed assets | loan	0
Number of other repossessed assets | property	1	0
Recorded amount of foreclosed residential real estate properties held in OREO	$ 30