Note 16 - Stock-Based Compensation - Options Outstanding (Details)	12 Months Ended
	Dec. 31, 2020 $ / shares shares
Number outstanding (in shares) | shares	407,763
Number exercisable (in shares) | shares	354,899
$7.99 to $8.93
Exercise price range, lower range (in dollars per share)	$ 7.99
Exercise price range, upper range (in dollars per share)	$ 8.93
Number outstanding (in shares) | shares	11,325
Weighted average remaining contractual life (Year)	1 month 20 days
Weighted average exercise price options outstanding (in dollars per share)	$ 8.15
Number exercisable (in shares) | shares	11,325
Weighted average exercise price options exercisable (in dollars per share)	$ 8.15
$9.00 to $9.30
Exercise price range, lower range (in dollars per share)	9.00
Exercise price range, upper range (in dollars per share)	$ 9.30
Number outstanding (in shares) | shares	60,328
Weighted average remaining contractual life (Year)	1 year 29 days
Weighted average exercise price options outstanding (in dollars per share)	$ 9.30
Number exercisable (in shares) | shares	60,328
Weighted average exercise price options exercisable (in dollars per share)	$ 9.30
$15.50 to $15.65
Exercise price range, lower range (in dollars per share)	15.50
Exercise price range, upper range (in dollars per share)	$ 15.65
Number outstanding (in shares) | shares	66,491
Weighted average remaining contractual life (Year)	2 years 2 months 26 days
Weighted average exercise price options outstanding (in dollars per share)	$ 15.64
Number exercisable (in shares) | shares	66,491
Weighted average exercise price options exercisable (in dollars per share)	$ 15.64
$17.10 to $18.00
Exercise price range, lower range (in dollars per share)	17.10
Exercise price range, upper range (in dollars per share)	$ 18.00
Number outstanding (in shares) | shares	113,527
Weighted average remaining contractual life (Year)	3 years 6 months 21 days
Weighted average exercise price options outstanding (in dollars per share)	$ 17.31
Number exercisable (in shares) | shares	113,527
Weighted average exercise price options exercisable (in dollars per share)	$ 17.31
$21.71 to $22.64
Exercise price range, lower range (in dollars per share)	21.71
Exercise price range, upper range (in dollars per share)	$ 22.64
Number outstanding (in shares) | shares	58,115
Weighted average remaining contractual life (Year)	5 years 2 months 19 days
Weighted average exercise price options outstanding (in dollars per share)	$ 22.88
Number exercisable (in shares) | shares	56,115
Weighted average exercise price options exercisable (in dollars per share)	$ 22.63
$36.00 to $48.50
Exercise price range, lower range (in dollars per share)	36.00
Exercise price range, upper range (in dollars per share)	$ 48.50
Number outstanding (in shares) | shares	97,977
Weighted average remaining contractual life (Year)	7 years 4 months 20 days
Weighted average exercise price options outstanding (in dollars per share)	$ 41.45
Number exercisable (in shares) | shares	47,113
Weighted average exercise price options exercisable (in dollars per share)	$ 42.98