Note 15 - Share-based Compensation - Restricted Shares (Details) - Restricted Stock [Member] - $ / shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Unvested at beginning of year (in shares)	21,470	31,790	25,870
Unvested at beginning of year, weighted average grant date fair value (in dollars per share)	$ 12.91	$ 14.06	$ 12.15
Granted (in shares)	12,484	9,675	18,323
Granted, weighted average grant date fair value (in dollars per share)	$ 6.12	$ 15.52	$ 18.07
Vested (in shares)	(12,903)	(19,995)	(10,999)
Vested, weighted average grant date fair value (in dollars per share)	$ 13.82	$ 15.99	$ 16.21
Forfeited (in shares)	(2,553)		(1,404)
Forfeited, weighted average grant date fair value (in dollars per share)	$ 15.86		$ 14.44
Unvested at end of year (in shares)	18,498	21,470	31,790
Unvested at end of year, weighted average grant date fair value (in dollars per share)	$ 7.29	$ 12.91	$ 14.06