Note 9 - Allowance for Loan Losses and Credit Quality Information - Allowance for Loan Losses (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Dec. 31, 2016
Balance	$ 10,045	$ 10,325	$ 9,903	$ 9,709
Provision for loan losses	(581)	80	(582)	(271)
Charge-offs	(351)	(203)	(569)	(262)
Recoveries	164	104	525	1,130
Balance	9,277	10,306	9,277	10,306
Specific reserves					$ 1,138	$ 988
General reserves					8,139	8,915
Balance	9,277	10,325	9,277	10,306	9,277	9,903
Individually reviewed for impairment					4,665	4,570
Collectively reviewed for impairment					587,190	556,224
Ending balance					591,855	560,794
Residential Portfolio Segment [Member]
Balance	1,004	1,270	1,186	990
Provision for loan losses	(63)	31	(245)	311
Charge-offs	(6)	(66)	(6)	(66)
Recoveries	0	0	0	0
Balance	935	1,235	935	1,235
Specific reserves					130	235
General reserves					805	951
Balance	1,004	1,270	935	1,235	935	1,186
Individually reviewed for impairment					1,041	1,107
Collectively reviewed for impairment					106,271	102,148
Ending balance					107,312	103,255
Commercial Real Estate Portfolio Segment [Member]
Balance	5,490	5,827	4,953	6,078
Provision for loan losses	(509)	(288)	(147)	(1,148)
Charge-offs	0	(67)	0	(67)
Recoveries	32	48	207	657
Balance	5,013	5,520	5,013	5,520
Specific reserves					544	248
General reserves					4,469	4,705
Balance	5,490	5,827	5,013	5,520	5,013	4,953
Individually reviewed for impairment					2,155	1,880
Collectively reviewed for impairment					327,096	297,200
Ending balance					329,251	299,080
Consumer Portfolio Segment [Member]
Balance	1,544	1,531	1,613	1,200
Provision for loan losses	141	116	257	432
Charge-offs	(45)	(14)	(263)	(29)
Recoveries	6	4	39	34
Balance	1,646	1,637	1,646	1,637
Specific reserves					266	434
General reserves					1,380	1,179
Balance	1,544	1,531	1,646	1,637	1,646	1,613
Individually reviewed for impairment					925	940
Collectively reviewed for impairment					74,059	72,343
Ending balance					74,984	73,283
Commercial Portfolio Segment [Member]
Balance	2,007	1,697	2,151	1,441
Provision for loan losses	(150)	221	(447)	134
Charge-offs	(300)	(56)	(300)	(100)
Recoveries	126	52	279	439
Balance	1,683	1,914	1,683	1,914
Specific reserves					198	71
General reserves					1,485	2,080
Balance	$ 2,007	$ 1,697	$ 1,683	$ 1,914	1,683	2,151
Individually reviewed for impairment					544	643
Collectively reviewed for impairment					79,764	84,533
Ending balance					$ 80,308	$ 85,176