Note 10 - Stock Based Compensation - Nonvested Restricted Stock Activity (Details) - Restricted Stock [Member]	3 Months Ended
	Mar. 31, 2021 $ / shares shares
Nonvested, shares (in shares) | shares	58,539
Nonvested, weighted average grant date value per share (in dollars per share) | $ / shares	$ 34.81
Granted, shares (in shares) | shares	23,638
Granted, weighted average grant date value per share (in dollars per share) | $ / shares	$ 28.01
Vested, shares (in shares) | shares	(16,144)
Vested, weighted average grant date value per share (in dollars per share) | $ / shares	$ 38.74
Forfeited, shares (in shares) | shares	(158)
Forfeited, weighted average grant date value per share (in dollars per share) | $ / shares	$ 27.74
Nonvested, shares (in shares) | shares	65,875
Nonvested, weighted average grant date value per share (in dollars per share) | $ / shares	$ 31.43