Note 10 - Share-based Compensation - Stock Option Activity (Details) - $ / shares	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Outstanding as of end of year (in dollars per share)	$ 2.13
Share-based Payment Arrangement, Option [Member]
Outstanding (in shares)	844,455	1,570,455
Outstanding, weighted average exercise price (in dollars per share)	$ 2.00	$ 1.96
Exercised (in shares)	(183,064)	0
Exercised, weighted average exercise price (in dollars per share)	$ 1.61	$ 0
Forfeited (in shares)	(1,146)	(726,000)
Forfeited, weighted average exercise price (in dollars per share)	$ 5.69	$ 1.91
Expired (in shares)	(35,714)	0
Expired, weighted average exercise price (in dollars per share)	$ 1.73	$ 0
Outstanding as of end of year (in shares)	624,531	844,455
Outstanding as of end of year (in dollars per share)	$ 2.13	$ 2.00
Stock options exercisable at year end (in shares)	624,531	832,478
Options exercisable, weighted average exercise price (in dollars per share)	$ 2.13	$ 1.98
Performance Shares [Member]
Outstanding (in shares)	686,001	737,497
Outstanding, weighted average exercise price (in dollars per share)	$ 1.64	$ 1.64
Exercised (in shares)	(686,001)	(51,496)
Exercised, weighted average exercise price (in dollars per share)	$ 1.64	$ 1.64
Outstanding as of end of year (in shares)	0	686,001
Outstanding as of end of year (in dollars per share)	$ 0	$ 1.64
Stock options exercisable at year end (in shares)	0	686,001
Options exercisable, weighted average exercise price (in dollars per share)	$ 0	$ 1.64