Net Income Per Common Share: Schedule of Earnings per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Mar. 31, 2023	Mar. 31, 2022
Earnings Per Share, Basic [Abstract]
Numerator – net income	$ 6,663	$ 5,327	$ 14,169	$ 10,812
Denominator – weighted average common shares outstanding (in shares)	8,220,532	8,337,407	8,226,467	8,346,839
Basic net income per common share (in dollars per share)	$ 0.81	$ 0.64	$ 1.72	$ 1.30
Earnings Per Share, Diluted [Abstract]
Effect of dilutive stock options (in shares)	83,838	84,468	85,163	88,697
Weighted average common shares and common stock equivalents (in shares)	8,304,370	8,421,875	8,311,630	8,435,536
Diluted net income per common share (in dollars per share)	$ 0.80	$ 0.63	$ 1.70	$ 1.28
Stock Options
Earnings Per Share, Diluted [Abstract]
Antidilutive securities excluded from computation of earnings per share (in shares)	176,867	204,398	177,484	207,256