Note 11 - Stock Options - Transactions Involving the Directors Plans (Details) - Employee Plans [Member] - $ / shares	3 Months Ended	12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2015
Outstanding (in shares)	5,000	5,000	6,000	22,000
Outstanding (in dollars per share)	$ 3.54	$ 3.54	$ 3.44	$ 5.30
Granted (in shares)
Granted (in dollars per share)
Canceled/expired (in shares)			(1,000)	(16,000)
Canceled/expired (in dollars per share)			$ 2.925	$ 6
Exercised (in shares)
Exercised (in dollars per share)
Outstanding (in shares)	5,000	5,000	5,000	6,000
Outstanding (in dollars per share)	$ 3.54	$ 3.54	$ 3.54	$ 3.44
Exercisable end of the period (in shares)	5,000	5,000	5,000	6,000
Exercisable end of the period (in dollars per share)	$ 3.54	$ 3.54	$ 3.54	$ 3.44