Note 16 - Stock-Based Compensation - Options Outstanding (Details)	12 Months Ended
	Dec. 31, 2019 $ / shares shares
Number outstanding (in shares) | shares	426,913
Number exercisable (in shares) | shares	365,084
$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	18,405
Weighted average remaining contractual life (Year)	1 year 1 month 10 days
Weighted average exercise price options outstanding (in dollars per share)	$ 8.10
Number exercisable (in shares) | shares	18,405
Weighted average exercise price options exercisable (in dollars per share)	$ 8.10
$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	88,490
Weighted average remaining contractual life (Year)	1 year 5 months 19 days
Weighted average exercise price options outstanding (in dollars per share)	$ 9.21
Number exercisable (in shares) | shares	88,490
Weighted average exercise price options exercisable (in dollars per share)	$ 9.21
$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	67,541
Weighted average remaining contractual life (Year)	3 years 2 months 27 days
Weighted average exercise price options outstanding (in dollars per share)	$ 15.64
Number exercisable (in shares) | shares	66,741
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	115,645
Weighted average remaining contractual life (Year)	4 years 6 months 22 days
Weighted average exercise price options outstanding (in dollars per share)	$ 17.31
Number exercisable (in shares) | shares	114,633
Weighted average exercise price options exercisable (in dollars per share)	$ 17.30
$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	59,905
Weighted average remaining contractual life (Year)	6 years 29 days
Weighted average exercise price options outstanding (in dollars per share)	$ 22.63
Number exercisable (in shares) | shares	46,309
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	76,927
Weighted average remaining contractual life (Year)	7 years 10 months 28 days
Weighted average exercise price options outstanding (in dollars per share)	$ 41.84
Number exercisable (in shares) | shares	30,506
Weighted average exercise price options exercisable (in dollars per share)	$ 43.73