Note 3 - Loans and Allowance for Loan Losses - Acquired Impaired Loans Accretable Yield (Details) - USD ($)		3 Months Ended
		Mar. 31, 2018	Mar. 31, 2017
Balance at beginning of period		$ 1,404,000	$ 1,726,000
Additions		0	1,000
Accretion income		(131,000)	(147,000)
Net reclassification from nonaccretable to accretable		86,000	63,000
Reductions (1)	[1]	(40,000)	(179,000)
Balance at end of period		$ 1,319,000	$ 1,464,000

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