Note 4 - Loans and Related Allowance for Loan Loss - Loans by Aging Categories (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Loans current	$ 698,375	$ 671,212
Past due	2,064	6,296
Non-accrual	3,435	4,389
Loans	703,874	681,897
Financing Receivables, 30 to 59 Days Past Due [Member]
Past due	1,296	5,247
Financing Receivables, 60 to 89 Days Past Due [Member]
Past due	145	698
Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Past due	623	351
Originated Loans [Member]
Loans current	562,866	518,478
Past due	1,939	4,397
Non-accrual	2,299	2,477
Loans	567,104	525,352
Originated Loans [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Past due	1,246	3,901
Originated Loans [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Past due	145	368
Originated Loans [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Past due	548	128
Acquired Loans [Member]
Loans current	135,509	152,734
Past due	125	1,899
Non-accrual	1,136	1,912
Loans	136,770	156,545
Acquired Loans [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Past due	50	1,346
Acquired Loans [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Past due		330
Acquired Loans [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Past due	75	223
Residential Portfolio Segment [Member] | Real Estate Sector [Member]
Loans current	266,746	266,462
Past due	253	3,253
Non-accrual	1,432	1,873
Loans	268,431	271,588
Residential Portfolio Segment [Member] | Real Estate Sector [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Past due	136	2,531
Residential Portfolio Segment [Member] | Real Estate Sector [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Past due	42	379
Residential Portfolio Segment [Member] | Real Estate Sector [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Past due	75	343
Residential Portfolio Segment [Member] | Real Estate Sector [Member] | Originated Loans [Member]
Loans current	192,769	183,939
Past due	133	1,830
Non-accrual	312	308
Loans	193,214	186,077
Residential Portfolio Segment [Member] | Real Estate Sector [Member] | Originated Loans [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Past due	91	1,638
Residential Portfolio Segment [Member] | Real Estate Sector [Member] | Originated Loans [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Past due	42	72
Residential Portfolio Segment [Member] | Real Estate Sector [Member] | Originated Loans [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Past due		120
Residential Portfolio Segment [Member] | Real Estate Sector [Member] | Acquired Loans [Member]
Loans current	73,977	82,523
Past due	120	1,423
Non-accrual	1,120	1,565
Loans	75,217	85,511
Residential Portfolio Segment [Member] | Real Estate Sector [Member] | Acquired Loans [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Past due	45	893
Residential Portfolio Segment [Member] | Real Estate Sector [Member] | Acquired Loans [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Past due		307
Residential Portfolio Segment [Member] | Real Estate Sector [Member] | Acquired Loans [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Past due	75	223
Commercial Portfolio Segment [Member] | Originated Loans [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Past due	52	8
Commercial Portfolio Segment [Member] | Real Estate Sector [Member]
Loans current	202,980	200,258
Past due		332
Non-accrual	288	420
Loans	203,268	201,010
Commercial Portfolio Segment [Member] | Real Estate Sector [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Past due		332
Commercial Portfolio Segment [Member] | Real Estate Sector [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Past due
Commercial Portfolio Segment [Member] | Real Estate Sector [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Past due
Commercial Portfolio Segment [Member] | Real Estate Sector [Member] | Originated Loans [Member]
Loans current	150,154	139,821
Past due
Non-accrual	288	73
Loans	150,442	139,894
Commercial Portfolio Segment [Member] | Real Estate Sector [Member] | Originated Loans [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Past due
Commercial Portfolio Segment [Member] | Real Estate Sector [Member] | Originated Loans [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Past due
Commercial Portfolio Segment [Member] | Real Estate Sector [Member] | Originated Loans [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Past due
Commercial Portfolio Segment [Member] | Real Estate Sector [Member] | Acquired Loans [Member]
Loans current	52,826	60,437
Past due		332
Non-accrual		347
Loans	52,826	61,116
Commercial Portfolio Segment [Member] | Real Estate Sector [Member] | Acquired Loans [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Past due		332
Commercial Portfolio Segment [Member] | Real Estate Sector [Member] | Acquired Loans [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Past due
Commercial Portfolio Segment [Member] | Real Estate Sector [Member] | Acquired Loans [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Past due
Commercial Portfolio Segment [Member] | Commercial and Industrial Sector [Member]
Loans current	83,624	77,887
Past due	496	1,096
Non-accrual	1,629	1,829
Loans	85,749	80,812
Commercial Portfolio Segment [Member] | Commercial and Industrial Sector [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Past due		1,073
Commercial Portfolio Segment [Member] | Commercial and Industrial Sector [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Past due		23
Commercial Portfolio Segment [Member] | Commercial and Industrial Sector [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Past due	496
Commercial Portfolio Segment [Member] | Commercial and Industrial Sector [Member] | Originated Loans [Member]
Loans current	75,108	68,310
Past due	496	952
Non-accrual	1,613	1,829
Loans	77,217	71,091
Commercial Portfolio Segment [Member] | Commercial and Industrial Sector [Member] | Originated Loans [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Past due		952
Commercial Portfolio Segment [Member] | Commercial and Industrial Sector [Member] | Originated Loans [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Past due
Commercial Portfolio Segment [Member] | Commercial and Industrial Sector [Member] | Originated Loans [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Past due	496
Commercial Portfolio Segment [Member] | Commercial and Industrial Sector [Member] | Acquired Loans [Member]
Loans current	8,516	9,577
Past due		144
Non-accrual	16
Loans	8,532	9,721
Commercial Portfolio Segment [Member] | Commercial and Industrial Sector [Member] | Acquired Loans [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Past due		121
Commercial Portfolio Segment [Member] | Commercial and Industrial Sector [Member] | Acquired Loans [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Past due		23
Commercial Portfolio Segment [Member] | Commercial and Industrial Sector [Member] | Acquired Loans [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Past due
Construction Portfolio Segment [Member] | Real Estate Sector [Member]
Loans current	28,906	10,539
Past due
Non-accrual	59	107
Loans	28,965	10,646
Construction Portfolio Segment [Member] | Real Estate Sector [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Past due
Construction Portfolio Segment [Member] | Real Estate Sector [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Past due
Construction Portfolio Segment [Member] | Real Estate Sector [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Past due
Construction Portfolio Segment [Member] | Real Estate Sector [Member] | Originated Loans [Member]
Loans current	28,906	10,539
Past due
Non-accrual	59	107
Loans	28,965	10,646
Construction Portfolio Segment [Member] | Real Estate Sector [Member] | Originated Loans [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Past due
Construction Portfolio Segment [Member] | Real Estate Sector [Member] | Originated Loans [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Past due
Construction Portfolio Segment [Member] | Real Estate Sector [Member] | Originated Loans [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Past due
Construction Portfolio Segment [Member] | Real Estate Sector [Member] | Acquired Loans [Member]
Loans
Consumer Portfolio Segment [Member]
Loans current	112,675	112,429
Past due	1,315	1,615
Non-accrual	27	160
Loans	114,017	114,204
Consumer Portfolio Segment [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Past due	1,160	1,311
Consumer Portfolio Segment [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Past due	103	296
Consumer Portfolio Segment [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Past due	52	8
Consumer Portfolio Segment [Member] | Originated Loans [Member]
Loans current	112,485	112,232
Past due	1,310	1,615
Non-accrual	27	160
Loans	113,822	114,007
Consumer Portfolio Segment [Member] | Originated Loans [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Past due	1,155	1,311
Consumer Portfolio Segment [Member] | Originated Loans [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Past due	103	296
Consumer Portfolio Segment [Member] | Acquired Loans [Member]
Loans current	190	197
Past due	5
Non-accrual
Loans	195	197
Consumer Portfolio Segment [Member] | Acquired Loans [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Past due	5
Consumer Portfolio Segment [Member] | Acquired Loans [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Past due
Consumer Portfolio Segment [Member] | Acquired Loans [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Past due
Other Portfolio Segment [Member]
Loans current	3,444	3,637
Past due
Non-accrual
Loans	3,444	3,637
Other Portfolio Segment [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Past due
Other Portfolio Segment [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Past due
Other Portfolio Segment [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Past due
Other Portfolio Segment [Member] | Originated Loans [Member]
Loans current	3,444	3,637
Past due
Non-accrual
Loans	3,444	3,637
Other Portfolio Segment [Member] | Originated Loans [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Past due
Other Portfolio Segment [Member] | Originated Loans [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Past due
Other Portfolio Segment [Member] | Originated Loans [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Past due
Other Portfolio Segment [Member] | Acquired Loans [Member]
Loans