Note 9 - Stock-based Compensation Expense - Restricted Stock and Restricted Stock Units Activity (Details)	9 Months Ended
	Sep. 30, 2022 $ / shares shares
Granted (in shares)	0
Restricted Stock [Member]
Unvested outstanding at beginning of period (in shares)	5,500
Unvested outstanding at beginning of period, weighted average grant date fair value (in dollars per share) | $ / shares	$ 4.82
Granted (in shares)	0
Granted, weighted average grant date fair value (in dollars per share) | $ / shares	$ 0
Vested (in shares)	(5,500)
Vested, weighted average grant date fair value (in dollars per share) | $ / shares	$ 4.82
Forfeited or cancelled (in shares)	0
Unvested outstanding at end of period (in shares)	0
Unvested outstanding at beginning of period, weighted average grant date fair value (in dollars per share) | $ / shares	$ 0