Note 18 - Earnings per Share - Basic and Diluted (Details) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended								12 Months Ended
		Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Earnings per Share
Net income		$ 18,271	$ 17,344	$ 13,739	$ 11,228	$ 15,891	$ 15,095	$ 13,504	$ 12,918	$ 60,582	$ 57,408	$ 43,120
Basic EPS		$ 1.16	$ 1.10	$ 0.87	$ 0.71	$ 1.01	$ 0.96	$ 0.86	$ 0.82	$ 3.84	$ 3.65	$ 2.92
Diluted EPS		$ 1.14	$ 1.09	$ 0.86	$ 0.70	$ 0.99	$ 0.94	$ 0.85	$ 0.81	$ 3.80	$ 3.60	$ 2.86
Weighted average common shares outstanding (in shares)	[1]									15,771,650	15,730,016	14,768,687
Weighted average common shares issuable upon exercise of stock options and under the employee stock purchase plan (in shares)										180,987	237,759	296,043
Weighted average common and common equivalent shares outstanding (in shares)	[2]									15,952,637	15,967,775	15,064,730

[1] The increase in weighted average common shares outstanding from 2018 to 2019 was primarily due to the common stock

[2] Excludes anti-dilutive shares of 104,636, 80,437 and 91,954 at December 31, 2020, 2019 and 2018, respectively.