Note 22 - Parent Company Financial Information - Condensed Statements of Cash Flows (Details) - USD ($) $ in Thousands	3 Months Ended										12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018		Dec. 31, 2017		Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018		Dec. 31, 2017		Dec. 31, 2016
Operating activities
Net income	$ 9,306	$ 9,100	$ 9,066	$ 8,868		$ 1,213		$ 7,652	$ 6,418	$ 6,202	$ 36,340		$ 21,485		$ 25,126
Adjustments to reconcile net income to net cash provided by operating activities
Gain on sale of securities		$ 618				4			$ 657		618		661		(335)
Decrease in other operating activities											4,981		6,570		6,957
Net cash provided by operating activities											49,499		36,370		43,088
Investing activities
Proceeds from sale of securities available for sale											8,937		13,664		104,928
Net cash provided by investing activities											49,398		67,796		110,210
Financing activities
Payments for repurchase of treasury stock											(34,412)		(1,263)		(23,762)
Payments of common dividends											(21,090)		(11,563)		(10,396)
Net cash used in financing activities											(179,975)		(22,522)		(128,778)
Net (decrease) increase in cash and cash equivalents											(81,078)		81,644		24,520
Cash and cash equivalents at beginning of period				157,951	[1]					76,307	157,951	[1]	76,307		51,787
Cash and cash equivalents at end of period	76,873					157,951	[1]				76,873		157,951	[1]	76,307
Parent Company [Member]
Operating activities
Net income											36,340		21,485		25,126
Adjustments to reconcile net income to net cash provided by operating activities
Gain on sale of securities															(65)
Decrease in other operating activities											1,509		656		397
Net cash provided by operating activities											37,849		22,141		25,458
Investing activities
Proceeds from sale of securities available for sale															8,660
Proceeds from divestitures															4,900
Return of capital from subsidiaries															3,654
Dividends in excess of undistributed net income of subsidiaries											10,268		221		4,943
Net change in other investing activities															(98)
Net cash provided by investing activities											10,268		221		22,059
Financing activities
Repayments of long-term debt													(15,464)
Proceeds from issuance of common stock											832		738		1,243
Payments for repurchase of treasury stock											(34,412)		(1,263)		(23,762)
Payments of common dividends											(21,090)		(11,563)		(10,396)
Net change in other financing activities											1,063		845		592
Net cash used in financing activities											(53,607)		(26,707)		(32,323)
Net (decrease) increase in cash and cash equivalents											(5,490)		(4,345)		15,194
Cash and cash equivalents at beginning of period				$ 19,216						$ 23,561	19,216		23,561		8,367
Cash and cash equivalents at end of period	$ 13,726					$ 19,216					$ 13,726		$ 19,216		$ 23,561

[1] Derived from audited financial statements