Note 2 - Sales/Mergers/Acquisitions - FHLB Advances (Details) - USD ($) $ in Thousands		3 Months Ended		12 Months Ended
	Jul. 02, 2018	Dec. 31, 2018	Sep. 30, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2019	Jul. 01, 2018
Business Acquisition [Line Items]
Common stock, issued (in shares)		15,718,208		15,718,208		15,828,098
Common stock, outstanding (in shares)		15,718,208		15,718,208		15,828,098
Acquisition costs				$ 1,795	$ 1,069
Springfield Bancshares
Business Acquisition [Line Items]
Overnight FHLB advances assumed							$ 40,000
FHLB term advances assumed							34,500
Subordinated debentures							4,700
Bank stock loan							4,800
Fair value of FHLB and other borrowings assumed							$ 84,100
Revenue of acquiree since acquisition date		$ 15,200	$ 15,200
Earnings of acquiree since acquisition date		4,800	4,800
Payment of bank stock loan	$ 4,800
Acquisition costs		$ 391	$ 391	$ 1,400