Note 22 - Parent Company Financial Information - Condensed Balance Sheets (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Assets
Cash and due from banks	$ 37,115	$ 36,645
Securities available for sale	165,580	165,579
Investment in subsidiaries	0	0
Other assets	76,363	86,197
Total assets	2,388,460	2,386,398
Liabilities
Total liabilities	2,037,746	2,047,341
Stockholders' equity
Preferred stock
Common stock	21,382	21,382
Additional paid-in capital	228,750	228,142
Retained earnings	180,543	170,377
Treasury stock	(79,121)	(78,833)
Accumulated other comprehensive loss	(840)	(2,011)
Total stockholders' equity	350,714	339,057	$ 343,017	$ 351,374
Total liabilities and stockholders' equity	2,388,460	2,386,398
Parent Company [Member]
Assets
Cash and due from banks	19,216	23,561
Securities available for sale		17
Loans to affiliates	184	228
Investment in subsidiaries	322,595	321,389
Other assets	9,010	9,560
Total assets	351,005	354,755
Liabilities
Subordinated debt		15,464
Other liabilities	291	234
Total liabilities	291	15,698
Stockholders' equity
Preferred stock
Common stock	21,382	21,382
Additional paid-in capital	228,750	228,142
Retained earnings	180,543	170,377
Treasury stock	(79,121)	(78,833)
Accumulated other comprehensive loss	(840)	(2,011)
Total stockholders' equity	350,714	339,057
Total liabilities and stockholders' equity	$ 351,005	$ 354,755