Note 13 - Stock-based Compensation - Nonvested Option Awards Activity (Details) - $ / shares	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Options granted, shares (in shares)	85,000	195,200
Options granted, weighted average exercise price (in dollars per share)	$ 2.11	$ 28.15
Options forfeited, weighted average exercise price (in dollars per share)	$ 30.11	$ 13
Options expired, shares (in shares)	(59,750)	(500)
Options expired, weighted average exercise price (in dollars per share)	$ 23.53	$ 3.5
Share-Based Payment Arrangement, Option [Member]
Nonvested, shares (in shares)	235,575	95,250
Nonvest, weighted average exercise price (in dollars per share)	$ 31.1	$ 40.7
Nonvested, weighted average grant date fair value (in dollars per share)	$ 14	$ 15.1
Options granted, shares (in shares)	85,000	195,200
Options granted, weighted average exercise price (in dollars per share)	$ 2.11	$ 28.15
Granted, weighted average grant date fair value (in dollars per share)	$ 0.65	$ 13.65
Vested, shares (in shares)	(58,145)	(51,375)
Vested, weighted average exercise price (in dollars per share)	$ 33.47	$ 39
Vested, weighted average grant date fair value (in dollars per share)	$ 13.82	$ 14.7
Forfeited, shares (in shares)	(87,500)	(3,500)
Options forfeited, weighted average exercise price (in dollars per share)	$ 30.11	$ 13
Forfeited, weighted average grant date fair value (in dollars per share)	$ 12.68	$ 13
Options expired, shares (in shares)	(8,500)
Options expired, weighted average exercise price (in dollars per share)	$ 49.82
Expired, weighted average grant date fair value (in dollars per share)	$ 21.45
Nonvested, shares (in shares)	166,430	235,575
Nonvest, weighted average exercise price (in dollars per share)	$ 15.04	$ 31.1
Nonvested, weighted average grant date fair value (in dollars per share)	$ 6.6	$ 14