Note 3 - Loans and Allowance for Loan Losses - Acquired Impaired Loans Accretable Yield (Details) - USD ($)		3 Months Ended		6 Months Ended
		Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Balance at beginning of period		$ 1,319,000	$ 1,464,000	$ 1,404,000	$ 1,726,000
Additions		0	220,000	0	221,000
Accretion income		(123,000)	(140,000)	(254,000)	(287,000)
Net reclassification from nonaccretable to accretable		86,000	184,000	172,000	247,000
Reductions (1)	[1]	(35,000)	(70,000)	(75,000)	(249,000)
Balance at end of period		$ 1,247,000	$ 1,658,000	$ 1,247,000	$ 1,658,000

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