Note 9 - Shareholders' Equity - Stock Option Activity (Details) - USD ($)	12 Months Ended
	Dec. 31, 2021	Feb. 01, 2011
Options balance, number of shares (in shares)	403,790
Options balance, weighted average exercise price per share (in dollars per share)	$ 3.81
Granted, number of shares (in shares)	22,300
Granted, weighted average exercise price per share (in dollars per share)	$ 2.19
Cancelled/Expired, number of shares (in shares)	(23,090)
Cancelled/Expired, weighted average exercise price per share (in dollars per share)	$ 18.06
Exercised, number of shares (in shares)	0
Exercised, weighted average exercise price per share (in dollars per share)	$ 0
Options balance, , number of shares (in shares)	403,000
Option balance, weighted average exercise price per share (in dollars per share)	$ 2.90
Options outstanding and expected to vest, weighted average remaining contractual term (Year)	6 years 9 months 21 days
Options outstanding and expected to vest, aggregate intrinsic value	$ 94,003
Options exercisable, number of shares (in shares)	324,800
Options exercisable, weighted average exercise price per share (in dollars per share)	$ 2.94
Options exercisable, weighted average remaining contractual term (Year)	6 years 3 months 29 days
Options exercisable, aggregate intrinsic value	$ 87,469
The 2018 Non-qualified Stock Option Plan [Member]
Options balance, number of shares (in shares)	308,790
Options balance, weighted average exercise price per share (in dollars per share)	$ 3.24
Granted, number of shares (in shares)	22,300
Granted, weighted average exercise price per share (in dollars per share)	$ 2.19
Cancelled/Expired, number of shares (in shares)	(17,090)
Cancelled/Expired, weighted average exercise price per share (in dollars per share)	$ 3.13
Exercised, number of shares (in shares)	0
Exercised, weighted average exercise price per share (in dollars per share)	$ 0
Options balance, , number of shares (in shares)	314,000
Option balance, weighted average exercise price per share (in dollars per share)	$ 3.17
The 2012 Non-qualified Stock Option Plan [Member]
Options balance, number of shares (in shares)	36,000
Options balance, weighted average exercise price per share (in dollars per share)	$ 0.98
Granted, number of shares (in shares)	0
Granted, weighted average exercise price per share (in dollars per share)	$ 0
Exercised, number of shares (in shares)	0
Exercised, weighted average exercise price per share (in dollars per share)	$ 0
Options balance, , number of shares (in shares)	36,000
Option balance, weighted average exercise price per share (in dollars per share)	$ 0.98
Cancelled, number of shares (in shares)	0
Cancelled, weighted average exercise price per share (in dollars per share)	$ 0
The 2011 Non-qualified Stock Option [Member]
Options balance, number of shares (in shares)	43,000
Options balance, weighted average exercise price per share (in dollars per share)	$ 3.00
Granted, number of shares (in shares)	0
Granted, weighted average exercise price per share (in dollars per share)	$ 0
Exercised, number of shares (in shares)	0
Exercised, weighted average exercise price per share (in dollars per share)	$ 0
Options balance, , number of shares (in shares)	43,000
Option balance, weighted average exercise price per share (in dollars per share)	$ 3.00
Cancelled, number of shares (in shares)	0
Cancelled, weighted average exercise price per share (in dollars per share)	$ 0
Options exercisable, weighted average exercise price per share (in dollars per share)		$ 0.98
The 2002 Stock Option Plan [Member]
Options balance, number of shares (in shares)	16,000
Options balance, weighted average exercise price per share (in dollars per share)	$ 23.33
Granted, number of shares (in shares)	0
Granted, weighted average exercise price per share (in dollars per share)	$ 0
Cancelled/Expired, number of shares (in shares)	(6,000)
Cancelled/Expired, weighted average exercise price per share (in dollars per share)	$ 60.58
Exercised, number of shares (in shares)	0
Exercised, weighted average exercise price per share (in dollars per share)	$ 0
Options balance, , number of shares (in shares)	10,000
Option balance, weighted average exercise price per share (in dollars per share)	$ 0.98