Note 3 - Loans and Allowance for Loan Losses - Acquired Impaired Loans Accretable Yield (Details) - USD ($)		3 Months Ended		9 Months Ended
		Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Balance at beginning of period		$ 1,247,000	$ 1,658,000	$ 1,404,000	$ 1,726,000
Additions		0	2,000	0	223,000
Accretion income		(118,000)	(141,000)	(372,000)	(429,000)
Net reclassification from nonaccretable to accretable		118,000	83,000	289,000	330,000
Reductions (1)	[1]	(2,000)	(23,000)	(76,000)	(271,000)
Balance at end of period		$ 1,245,000	$ 1,579,000	$ 1,245,000	$ 1,579,000

[1] Reductions primarily reflect the result of exit events, including loan payoffs and charge-offs.