Note 10 - Stockholders' Equity - Stock Option Plan (Details) - $ / shares	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Beginning balance, number outstanding (in shares)	417,000
Ending balance, number outstanding (in shares)	618,500	417,000
Number of shares exercisable (in shares)	265,000	377,000
Ending balance, weighted average exercise price (in dollars per share)	$ 15.00
Number of options exercisable, weighted average exercise price (in dollars per share)	$ 15.00
Granted during period (in shares)	333,500
The 2007 Share Incentive Plan [Member]
Beginning balance, number outstanding (in shares)	345,000	345,000
Canceled during period (in shares)	(125,000)
Ending balance, number outstanding (in shares)	220,000	345,000
Number of shares exercisable (in shares)	200,000	305,000
Beginning balance, weighted average exercise price (in dollars per share)	$ 12.33	$ 12.33
Canceled during period, weighted average exercise price (in dollars per share)	11.94
Ending balance, weighted average exercise price (in dollars per share)	12.56	12.33
Number of options exercisable, weighted average exercise price (in dollars per share)	$ 12.78	$ 12.60
The 2001 Non-qualified Stock Option Plan [Member]
Beginning balance, number outstanding (in shares)	7,000	22,930
Canceled during period (in shares)	(7,000)	(15,930)
Ending balance, number outstanding (in shares)	0	7,000
Number of shares exercisable (in shares)		7,000
Beginning balance, weighted average exercise price (in dollars per share)	$ 7.90	$ 5.36
Canceled during period, weighted average exercise price (in dollars per share)	$ 7.90	4.25
Ending balance, weighted average exercise price (in dollars per share)		7.90
Number of options exercisable, weighted average exercise price (in dollars per share)		$ 7.90
The 2016 Share Incentive Plan [Member]
Beginning balance, number outstanding (in shares)	65,000	65,000
Ending balance, number outstanding (in shares)	398,500	65,000
Number of shares exercisable (in shares)	65,000
Beginning balance, weighted average exercise price (in dollars per share)	$ 5.94	$ 5.94
Ending balance, weighted average exercise price (in dollars per share)	4.43	$ 5.94
Number of options exercisable, weighted average exercise price (in dollars per share)	$ 5.94
Granted during period (in shares)	333,500
Granted during period, weighted average exercise price (in dollars per share)	$ 4.13