Note 6 - Stock-based Compensation - Restricted Stock Activity (Details) - shares	3 Months Ended		6 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Mar. 31, 2023	Mar. 31, 2022
Vested (in shares)		(625)
Restricted Stock [Member]
Non Vested at December 31, 2022 and 2021 (in shares)		1,875
The 2013 Plan [Member]
Non Vested at December 31, 2022 and 2021 (in shares)	250		250	2,250
Vested (in shares)	(250)		(250)	(1,000)
Non Vested at March 31, 2023 and 2022 (in shares)	0	1,250	0	1,250