Note 18 - Parent Company Financial Information (Details) - Condensed Statement of Income - 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
Condensed Income Statements, Captions [Line Items]
Provision for income taxes	$ 2,993	$ 940	$ 845	$ 1,122	$ 743	$ 821	$ 702	$ 788	$ 5,900	$ 3,054	$ 2,570
Net income	$ 489	$ 2,554	$ 2,386	$ 2,860	$ 2,269	$ 2,292	$ 2,098	$ 2,265	8,289	8,924	8,233
Parent Company [Member]
Condensed Income Statements, Captions [Line Items]
Dividends from subsidiary									3,382	3,093	3,228
Interest, dividend and other income									183	171	180
Securities gains									1,477	566	636
Total income									5,042	3,830	4,044
Expenses									301	295	298
Income before applicable income taxes and equity in undistributed income of subsidiary									4,741	3,535	3,746
Provision for income taxes									554	159	163
Income before equity in undistributed income of subsidiary									4,187	3,376	3,583
Equity in undistributed income of subsidiary									4,102	5,548	4,650
Net income									$ 8,289	$ 8,924	$ 8,233