Note 8 - Allowance for Loan Losses (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance for loan losses, beginning of period	$ 7,550	$ 7,655	$ 7,554	$ 8,001
Provision for (credit to) loan losses	0	0	125	60
Charge-offs	(29)	(21)	(274)	(502)
Recoveries	72	35	188	110
Allowance for loan losses, end of period	7,593	7,669	7,593	7,669
Commercial Portfolio Segment [Member] | Commercial and Industrial [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance for loan losses, beginning of period	1,350	1,603	1,521	1,892
Provision for (credit to) loan losses	(55)	(79)	(105)	(357)
Charge-offs	0	0	(140)	(30)
Recoveries	9	11	28	30
Allowance for loan losses, end of period	1,304	1,535	1,304	1,535
Commercial Portfolio Segment [Member] | Construction Loans [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance for loan losses, beginning of period	429	149	286	297
Provision for (credit to) loan losses	(79)	118	64	(30)
Charge-offs	0	0		0
Recoveries	0	0		0
Allowance for loan losses, end of period	350	267	350	267
Commercial Portfolio Segment [Member] | Secured by Commercial Real Estate [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance for loan losses, beginning of period	2,231	2,655	2,411	2,700
Provision for (credit to) loan losses	233	(494)	49	(458)
Charge-offs	0	0		(85)
Recoveries	2	3	6	7
Allowance for loan losses, end of period	2,466	2,164	2,466	2,164
Commercial Portfolio Segment [Member] | Secured by Residential Real Estate [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance for loan losses, beginning of period	1,550	1,635	1,812	1,630
Provision for (credit to) loan losses	(57)	(53)	(359)	251
Charge-offs	0	(4)	(20)	(321)
Recoveries	50	2	110	20
Allowance for loan losses, end of period	1,543	1,580	1,543	1,580
State and Political Subdivisions Portfolio Segment [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance for loan losses, beginning of period	204	232	222	221
Provision for (credit to) loan losses	(64)	(4)	(82)	7
Charge-offs	0	0		0
Recoveries	0	0		0
Allowance for loan losses, end of period	140	228	140	228
Finance Leases Portfolio Segment [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance for loan losses, beginning of period	226	121	164	93
Provision for (credit to) loan losses	(6)	(4)	99	22
Charge-offs	0	0	(52)	(8)
Recoveries	0	5	9	15
Allowance for loan losses, end of period	220	122	220	122
Retail Portfolio Segment [Member] | Consumer Loans [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance for loan losses, beginning of period	73	71	76	85
Provision for (credit to) loan losses	33	18	49	33
Charge-offs	(29)	(17)	(62)	(58)
Recoveries	7	10	21	22
Allowance for loan losses, end of period	84	82	84	82
Retail Portfolio Segment [Member] | Family Residential Mortgages [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance for loan losses, beginning of period	298	313	350	312
Provision for (credit to) loan losses	(20)	(7)	(72)	(6)
Charge-offs	0	0		0
Recoveries	0	0		0
Allowance for loan losses, end of period	278	306	278	306
Retail Portfolio Segment [Member] | Home Equity Loan [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance for loan losses, beginning of period	343	474	428	453
Provision for (credit to) loan losses	(7)	(28)	(102)	(19)
Charge-offs	0	0		0
Recoveries	4	4	14	16
Allowance for loan losses, end of period	340	450	340	450
Unallocated Financing Receivables [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance for loan losses, beginning of period	846	402	284	318
Provision for (credit to) loan losses	22	533	584	617
Charge-offs	0	0	0	0
Recoveries	0	0	0	0
Allowance for loan losses, end of period	$ 868	$ 935	$ 868	$ 935