Note 22 - Parent Company Financial Information - Condensed Statements of Cash Flows (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
Net income	$ 9,564	$ 9,156	$ 10,451	$ 9,631	$ 9,306	$ 9,100	$ 9,066	$ 8,868	$ 38,802	$ 36,340	$ 21,485
Decrease in other operating activities									7,003	3,974	5,893
Net cash provided by operating activities									56,655	49,499	36,370
Investing activities
Net cash provided by investing activities									171,377	49,398	67,796
Payments for repurchase of common stock									16,362	34,412	1,263
Payments of common stock dividends									(15,060)	(21,090)	(11,563)
Net cash used in financing activities									(87,896)	(179,975)	(22,522)
Net increase (decrease) in cash and cash equivalents									140,136	(81,078)	81,644
Cash and cash equivalents at beginning of period				76,873				157,951	76,873	157,951	76,307
Cash and cash equivalents at end of period	217,009				76,873				217,009	76,873	157,951
Parent Company [Member]
Net income									38,802	36,340	21,485
Decrease in other operating activities									1,865	1,509	656
Net cash provided by operating activities									40,667	37,849	22,141
Investing activities
Dividends in excess of undistributed net income of subsidiaries									(1,002)	10,268	221
Net cash provided by investing activities									(1,002)	10,268	221
Repayments of long-term debt											(15,464)
Proceeds from issuance of common stock									136	832	738
Payments for repurchase of common stock									(16,362)	(34,412)	(1,263)
Payments of common stock dividends									(15,060)	(21,090)	(11,563)
Net change in other financing activities									1,893	1,063	845
Net cash used in financing activities									(29,393)	(53,607)	(26,707)
Net increase (decrease) in cash and cash equivalents									10,272	(5,490)	(4,345)
Cash and cash equivalents at beginning of period				$ 13,726				$ 19,216	13,726	19,216	23,561
Cash and cash equivalents at end of period	$ 23,998				$ 13,726				$ 23,998	$ 13,726	$ 19,216