Note 20 - Parent Company Financial Statements - Condensed Statements of Cash Flows (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Net income	$ (1,435)	$ 5,312	$ 4,482	$ 3,329	$ 2,545	$ 4,324	$ 3,556	$ 6,180	$ 11,688	$ 16,605	$ 14,992
Deferred income tax expense (benefit)									270	885	1,631
Gain on extinguishment of subordinated notes payable to unconsolidated trusts									0	(4,050)	0
Net cash provided by operating activities									28,042	20,740	25,930
Net cash provided by investing activities									(11,053)	87,151	15,875
Cash paid to extinguish subordinated notes payable to unconsolidated trusts										(10,950)
Dividends paid, common stock									(3,005)	(1,575)
Redemption of preferred stock											(10,000)
Dividends paid, preferred stock											(508)
Shares issued under employee stock purchase plan									179	155	130
Net cash used in financing activities									(10,115)	(114,850)	(22,226)
Net increase in cash and cash equivalents									6,874	(6,959)	19,579
Cash and cash equivalents at beginning of year				113,534				120,493	113,534	120,493	100,914
Cash and cash equivalents at end of year	120,408				113,534				120,408	113,534	120,493
Employee Stock Purchase Plan Expense [Member]
Noncash compensation expense									33	32	31
Director Fee Compensation [Member]
Noncash compensation expense									105	92	104
Parent Company [Member]
Net income									11,688	16,605	14,992
Equity in undistributed loss (income) of subsidiaries									10,018	8,700	(2,727)
Change in other assets and liabilities, net									(2,408)	(1,116)	582
Deferred income tax expense (benefit)									740	(46)	(54)
Gain on extinguishment of subordinated notes payable to unconsolidated trusts										(4,050)
Net cash provided by operating activities									20,144	20,192	12,901
Return of equity from nonbank subsidiary										500	1,355
Net cash provided by investing activities										500	1,355
Cash paid to extinguish subordinated notes payable to unconsolidated trusts										(10,950)
Dividends paid, common stock									(3,005)	(1,575)
Redemption of preferred stock											(10,000)
Dividends paid, preferred stock											(508)
Shares issued under employee stock purchase plan									179	155	130
Net cash used in financing activities									(2,826)	(12,370)	(10,378)
Net increase in cash and cash equivalents									17,318	8,322	3,878
Cash and cash equivalents at beginning of year				$ 44,286				$ 35,964	44,286	35,964	32,086
Cash and cash equivalents at end of year	$ 61,604				$ 44,286				61,604	44,286	35,964
Parent Company [Member] | Employee Stock Purchase Plan Expense [Member]
Noncash compensation expense									1	7	4
Parent Company [Member] | Director Fee Compensation [Member]
Noncash compensation expense									$ 105	$ 92	$ 104