Note 15 - Stock Plans - Summary of Stock Option Activity (Details) - Incentive and Non-Qualified Stock Options [Member] - $ / shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Stock options outstanding (in shares)	40,000	50,000
Outstanding, weighted average grant date fair value (in dollars per share)	$ 16.97	$ 16.97
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross (in shares)	64,500
Granted, weighted average grant date fair value (in dollars per share)	$ 9.22
Stock options vested (in shares)	(10,000)	(10,000)
Vested, weighted average grant date fair value (in dollars per share)	$ 16.97	$ 16.97
Stock options forfeited or cancelled (in shares)	(250)
Forfeited or cancelled, weighted average grant date fair value (in dollars per share)	$ 9.22
Stock options outstanding (in shares)	94,250	40,000
Outstanding, weighted average grant date fair value (in dollars per share)	$ 11.69	$ 16.97