Note 9 - Allowance for Loan Losses and Credit Quality Information - Allowance for Loan Losses (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Dec. 31, 2016
Balance	$ 9,590	$ 9,363	$ 9,903	$ 9,709
Provision for losses	269	381	(1)	(351)
Charge-offs	(17)	(52)	(218)	(59)
Recoveries	203	633	361	1,026
Balance	10,045	10,325	10,045	10,325
Specific reserves					$ 741	$ 988
General reserves					9,304	8,915
Balance	10,045	9,363	10,045	10,325	10,045	9,903
Individually reviewed for impairment					4,828	4,570
Collectively reviewed for impairment					594,994	556,224
Ending balance					599,822	560,794
Residential Portfolio Segment [Member]
Balance	1,110	1,050	1,186	990
Provision for losses	(106)	220	(182)	280
Charge-offs	0	0	0	0
Recoveries	0	0	0	0
Balance	1,004	1,270	1,004	1,270
Specific reserves					194	235
General reserves					810	951
Balance	1,110	1,050	1,004	1,270	1,004	1,186
Individually reviewed for impairment					1,393	1,107
Collectively reviewed for impairment					106,919	102,148
Ending balance					108,312	103,255
Commercial Real Estate Portfolio Segment [Member]
Balance	4,958	5,437	4,953	6,078
Provision for losses	452	(37)	363	(859)
Charge-offs	0	0	0	0
Recoveries	80	427	174	608
Balance	5,490	5,827	5,490	5,827
Specific reserves					275	248
General reserves					5,215	4,705
Balance	4,958	5,437	5,490	5,827	5,490	4,953
Individually reviewed for impairment					2,163	1,880
Collectively reviewed for impairment					322,437	297,200
Ending balance					324,600	299,080
Consumer Portfolio Segment [Member]
Balance	1,332	1,395	1,613	1,200
Provision for losses	224	132	116	315
Charge-offs	(17)	(8)	(218)	(15)
Recoveries	5	12	33	31
Balance	1,544	1,531	1,544	1,531
Specific reserves					199	434
General reserves					1,345	1,179
Balance	1,332	1,395	1,544	1,531	1,544	1,613
Individually reviewed for impairment					825	940
Collectively reviewed for impairment					73,735	72,343
Ending balance					74,560	73,283
Commercial Portfolio Segment [Member]
Balance	2,190	1,481	2,151	1,441
Provision for losses	(301)	66	(298)	(87)
Charge-offs	0	(44)	0	(44)
Recoveries	118	194	154	387
Balance	2,007	1,697	2,007	1,697
Specific reserves					73	71
General reserves					1,934	2,080
Balance	$ 2,190	$ 1,481	$ 2,007	$ 1,697	2,007	2,151
Individually reviewed for impairment					447	643
Collectively reviewed for impairment					91,903	84,533
Ending balance					$ 92,350	$ 85,176