Note 9 - Allowance for Loan Losses and Credit Quality Information - Allowance for Loan Losses (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2019	Dec. 31, 2018
Balance	$ 8,686	$ 9,311
Provision for losses	27	(125)
Charge-offs	(82)	(92)
Recoveries	42	35
Balance	8,673	9,129
Specific reserves			$ 819	$ 794
General reserves			7,854	7,892
Balance	8,673	9,311	8,673	8,686
Individually reviewed for impairment			3,490	3,696
Collectively reviewed for impairment			604,154	591,160
Ending balance			607,644	594,856
Residential Portfolio Segment [Member]
Balance	833	900
Provision for losses	100	(68)
Charge-offs	0	(23)
Recoveries	0	0
Balance	933	809
Specific reserves			123	98
General reserves			810	735
Balance	833	900	933	833
Individually reviewed for impairment			1,247	1,226
Collectively reviewed for impairment			107,963	109,472
Ending balance			109,210	110,698
Commercial Real Estate Portfolio Segment [Member]
Balance	4,869	5,073
Provision for losses	13	118
Charge-offs	0	0
Recoveries	10	7
Balance	4,892	5,198
Specific reserves			453	451
General reserves			4,439	4,418
Balance	4,869	5,073	4,892	4,869
Individually reviewed for impairment			1,276	1,311
Collectively reviewed for impairment			348,588	334,819
Ending balance			349,864	336,130
Consumer Portfolio Segment [Member]
Balance	1,622	1,630
Provision for losses	3	(145)
Charge-offs	(39)	(69)
Recoveries	2	7
Balance	1,588	1,423
Specific reserves			153	172
General reserves			1,435	1,450
Balance	1,622	1,630	1,588	1,622
Individually reviewed for impairment			620	856
Collectively reviewed for impairment			72,465	71,676
Ending balance			73,085	72,532
Commercial Portfolio Segment [Member]
Balance	1,362	1,708
Provision for losses	(89)	(30)
Charge-offs	(43)	0
Recoveries	30	21
Balance	1,260	1,699
Specific reserves			90	73
General reserves			1,170	1,289
Balance	$ 1,362	$ 1,708	1,260	1,362
Individually reviewed for impairment			347	303
Collectively reviewed for impairment			75,138	75,193
Ending balance			$ 75,485	$ 75,496