Net Income Per Common Share: Schedule of Earnings per Share (Details) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended		9 Months Ended
		Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Earnings Per Share, Basic [Abstract]
Numerator – net income		$ 6,211	$ 5,956	$ 17,912	$ 17,685
Denominator – weighted average common shares outstanding (in shares)		8,309,947	8,338,637	8,331,908	8,313,913
Basic net income per common share (in dollars per share)		$ 0.75	$ 0.71	$ 2.15	$ 2.13
Earnings Per Share, Diluted [Abstract]
Effect of dilutive stock options (in shares)	[1]	69,036	143,723	105,122	154,299
Weighted average common shares and common stock equivalents (in shares)		8,378,983	8,482,360	8,437,030	8,468,212
Diluted net income per common share (in dollars per share)		$ 0.74	$ 0.70	$ 2.12	$ 2.09
Stock Options
Earnings Per Share, Diluted [Abstract]
Antidilutive securities excluded from computation of earnings per share (in shares)		135,212	102,050	126,052	102,353

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