Net Income Per Common Share: Schedule of Earnings per Share (Details) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended
		Dec. 31, 2019	Dec. 31, 2018
Earnings Per Share, Basic [Abstract]
Numerator – net income		$ 6,652	$ 5,615
Denominator – weighted average common shares outstanding (in shares)		8,341,470	8,293,212
Basic net income per common share (in dollars per share)		$ 0.80	$ 0.68
Earnings Per Share, Diluted [Abstract]
Effect of dilutive stock options (in shares)	[1]	133,559	164,491
Weighted average common shares and common stock equivalents (in shares)		8,475,029	8,457,703
Diluted net income per common share (in dollars per share)		$ 0.78	$ 0.66
Stock Options
Earnings Per Share, Diluted [Abstract]
Antidilutive securities excluded from computation of earnings per share (in shares)		104,816	102,850

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