Note 9 - Share-based Compensation - Shares Authorized, Available for Future Grant and Outstanding Under Each Plan (Details)	Sep. 30, 2022 shares
Authorized (in shares)	1,950,000
Available (in shares)	1,103,081
Outstanding (in shares)	324,896
The 2016 Plan [Member]
Authorized (in shares)	1,300,000
Available (in shares)	879,875
Outstanding (in shares)	306,896
2014 Directors Plan [Member]
Authorized (in shares)	650,000
Available (in shares)	223,206
Outstanding (in shares)	12,000
The 2004 Directors Plan [Member]
Available (in shares)	0
Outstanding (in shares)	6,000