Note 8 - Stock Options and Restricted Stock - Summary of the Status of Non-vested Shares (Details) - $ / shares	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Balance, non-vested (in shares)	0	3,533
Balance, non-vested, weighted average grant date fair value (in dollars per share)	$ 0	$ 3.30
Vested, non-vested (in shares)	0	(1,755)
Vested, weighted average grant date fair value (in dollars per share)	$ 0	$ 3.36
Forfeited, non-vested (in shares)	0	(1,778)
Forfeited, weighted average grant date fair value (in dollars per share)	$ 0	$ 19.29
Balance, non-vested (in shares)	0	0
Balance, non-vested, weighted average grant date fair value (in dollars per share)	$ 0	$ 0