Note 22 - Parent Company Financial Information - Condensed Statements of Income (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Other operating expense									$ 11,929	$ 12,727	$ 11,841
Income tax expense	$ 2,833	$ 2,580	$ 2,951	$ 2,630	$ 2,596	$ 1,118	$ 2,500	$ 2,568	10,994	8,782	20,628
Net income	$ 9,564	$ 9,156	$ 10,451	$ 9,631	$ 9,306	$ 9,100	$ 9,066	$ 8,868	38,802	36,340	21,485
Parent Company [Member]
Cash dividends received from subsidiary bank									38,500	48,000	22,720
Other income									444	306	352
Other operating expense									1,420	2,293	2,044
Income before income taxes and equity in undistributed net income of subsidiaries									37,524	46,013	21,028
Income tax expense									(276)	(595)	(678)
Income before equity in undistributed net income of subsidiaries									37,800	46,608	21,706
Equity in (dividends in excess) of undistributed net income of subsidiaries									1,002	(10,268)	(221)
Net income									$ 38,802	$ 36,340	$ 21,485