Earnings per share - Earnings per common share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Earnings Per Share [Abstract]
Weighted average common shares outstanding during the period - shares used for basic earnings per common share	3,351	3,328
Common shares issuable under share based payment plans which are potentially dilutive	0	3
Common shares used for diluted earnings per common share	3,351	3,331
Net income (loss)	$ (464)	$ 884
Earnings (loss) per common share:
Earnings (loss) per share-basic	$ (0.14)	$ .27
Earnings (loss) per share-diluted	$ (0.14)	$ 0.27