Note 3 - Loans Receivable and Allowance for Loan Losses - Delinquency Status of Performing and Non-performing Loans (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Loans receivable, gross	$ 710,118	$ 581,657
Non-accruing loans	2,051	1,821
Commercial Real Estate Portfolio Segment [Member]
Loans receivable, gross	296,625	271,229
Non-accruing loans
Residential Portfolio Segment [Member]
Loans receivable, gross	150,664	86,514
Non-accruing loans	1,590	1,590
Commercial Portfolio Segment [Member]
Loans receivable, gross	117,673	60,977
Non-accruing loans	286	231
Consumer Portfolio Segment [Member]
Loans receivable, gross	90,973	101,449
Non-accruing loans	175
Construction Portfolio Segment [Member]
Loans receivable, gross	48,328	53,895
Construction to Permanent Portfolio Segment [Member]
Loans receivable, gross	5,855	7,593
Pass [Member]
Loans receivable, gross	688,180	573,850
Non-accruing loans
Pass [Member] | Commercial Real Estate Portfolio Segment [Member]
Loans receivable, gross	278,775	265,246
Non-accruing loans
Pass [Member] | Residential Portfolio Segment [Member]
Loans receivable, gross	147,537	84,924
Non-accruing loans
Pass [Member] | Commercial Portfolio Segment [Member]
Loans receivable, gross	116,887	60,743
Non-accruing loans
Pass [Member] | Consumer Portfolio Segment [Member]
Loans receivable, gross	90,798	101,449
Non-accruing loans
Pass [Member] | Construction Portfolio Segment [Member]
Loans receivable, gross	48,328	53,895
Non-accruing loans
Pass [Member] | Construction to Permanent Portfolio Segment [Member]
Loans receivable, gross	5,855	7,593
Non-accruing loans
Special Mention [Member]
Loans receivable, gross	14,699	4,531
Non-accruing loans
Special Mention [Member] | Commercial Real Estate Portfolio Segment [Member]
Loans receivable, gross	13,162	4,531
Non-accruing loans
Special Mention [Member] | Residential Portfolio Segment [Member]
Loans receivable, gross	1,537
Non-accruing loans
Substandard [Member]
Loans receivable, gross	7,239	3,276
Non-accruing loans	2,051	1,821
Substandard [Member] | Commercial Real Estate Portfolio Segment [Member]
Loans receivable, gross	4,688	1,452
Non-accruing loans
Substandard [Member] | Residential Portfolio Segment [Member]
Loans receivable, gross	1,590	1,590
Non-accruing loans	1,590	1,590
Substandard [Member] | Commercial Portfolio Segment [Member]
Loans receivable, gross	786	234
Non-accruing loans	286	231
Substandard [Member] | Consumer Portfolio Segment [Member]
Loans receivable, gross	175
Non-accruing loans	175
Performing Financial Instruments [Member]
Performing (accruing) loans, past due	11,442	1,718
Performing (accruing) loans, current	696,625	578,118
Loans receivable, gross	708,067	579,836
Performing Financial Instruments [Member] | Commercial Real Estate Portfolio Segment [Member]
Performing (accruing) loans, past due	3,651
Performing (accruing) loans, current	292,974	271,229
Loans receivable, gross	296,625	271,229
Performing Financial Instruments [Member] | Residential Portfolio Segment [Member]
Performing (accruing) loans, past due	2,367	1,589
Performing (accruing) loans, current	146,707	83,335
Loans receivable, gross	149,074	84,924
Performing Financial Instruments [Member] | Commercial Portfolio Segment [Member]
Performing (accruing) loans, past due	5,299	51
Performing (accruing) loans, current	112,088	60,695
Loans receivable, gross	117,387	60,746
Performing Financial Instruments [Member] | Consumer Portfolio Segment [Member]
Performing (accruing) loans, past due	125
Performing (accruing) loans, current	90,673
Loans receivable, gross	90,798
Performing Financial Instruments [Member] | Pass [Member]
Performing (accruing) loans, past due	8,591	1,718
Performing (accruing) loans, current	679,589	572,132
Loans receivable, gross	688,180	573,850
Performing Financial Instruments [Member] | Pass [Member] | Commercial Real Estate Portfolio Segment [Member]
Performing (accruing) loans, past due	1,300
Performing (accruing) loans, current	277,475	265,246
Loans receivable, gross	278,775	265,246
Performing Financial Instruments [Member] | Pass [Member] | Residential Portfolio Segment [Member]
Performing (accruing) loans, past due	2,367	1,589
Performing (accruing) loans, current	145,170	83,335
Loans receivable, gross	147,537	84,924
Performing Financial Instruments [Member] | Pass [Member] | Commercial Portfolio Segment [Member]
Performing (accruing) loans, past due	4,799	51
Performing (accruing) loans, current	112,088	60,692
Loans receivable, gross	116,887	60,743
Performing Financial Instruments [Member] | Pass [Member] | Consumer Portfolio Segment [Member]
Performing (accruing) loans, past due	125	78
Performing (accruing) loans, current	90,673	101,371
Loans receivable, gross	90,798	101,449
Performing Financial Instruments [Member] | Pass [Member] | Construction Portfolio Segment [Member]
Performing (accruing) loans, past due
Performing (accruing) loans, current	48,328	53,895
Loans receivable, gross	48,328	53,895
Performing Financial Instruments [Member] | Pass [Member] | Construction to Permanent Portfolio Segment [Member]
Performing (accruing) loans, past due
Performing (accruing) loans, current	5,855	7,593
Loans receivable, gross	5,855	7,593
Performing Financial Instruments [Member] | Special Mention [Member]
Performing (accruing) loans, past due	652
Performing (accruing) loans, current	14,047	4,531
Loans receivable, gross	14,699	4,531
Performing Financial Instruments [Member] | Special Mention [Member] | Commercial Real Estate Portfolio Segment [Member]
Performing (accruing) loans, past due	652
Performing (accruing) loans, current	12,510	4,531
Loans receivable, gross	13,162	4,531
Performing Financial Instruments [Member] | Special Mention [Member] | Residential Portfolio Segment [Member]
Performing (accruing) loans, past due
Performing (accruing) loans, current	1,537
Loans receivable, gross	1,537
Performing Financial Instruments [Member] | Substandard [Member]
Performing (accruing) loans, past due	2,199
Performing (accruing) loans, current	2,989	1,455
Loans receivable, gross	5,188	1,455
Performing Financial Instruments [Member] | Substandard [Member] | Commercial Real Estate Portfolio Segment [Member]
Performing (accruing) loans, past due	1,699
Performing (accruing) loans, current	2,989	1,452
Loans receivable, gross	4,688	1,452
Performing Financial Instruments [Member] | Substandard [Member] | Residential Portfolio Segment [Member]
Performing (accruing) loans, past due
Performing (accruing) loans, current
Loans receivable, gross
Performing Financial Instruments [Member] | Substandard [Member] | Commercial Portfolio Segment [Member]
Performing (accruing) loans, past due	500
Performing (accruing) loans, current		3
Loans receivable, gross	500	3
Performing Financial Instruments [Member] | Substandard [Member] | Consumer Portfolio Segment [Member]
Performing (accruing) loans, past due
Performing (accruing) loans, current
Loans receivable, gross
Financing Receivables, 30 to 59 Days Past Due [Member] | Performing Financial Instruments [Member]
Performing (accruing) loans, past due	4,307	253
Financing Receivables, 30 to 59 Days Past Due [Member] | Performing Financial Instruments [Member] | Commercial Real Estate Portfolio Segment [Member]
Performing (accruing) loans, past due	1,952
Financing Receivables, 30 to 59 Days Past Due [Member] | Performing Financial Instruments [Member] | Residential Portfolio Segment [Member]
Performing (accruing) loans, past due	556	131
Financing Receivables, 30 to 59 Days Past Due [Member] | Performing Financial Instruments [Member] | Commercial Portfolio Segment [Member]
Performing (accruing) loans, past due	1,799	47
Financing Receivables, 30 to 59 Days Past Due [Member] | Performing Financial Instruments [Member] | Consumer Portfolio Segment [Member]
Performing (accruing) loans, past due
Financing Receivables, 30 to 59 Days Past Due [Member] | Performing Financial Instruments [Member] | Pass [Member]
Performing (accruing) loans, past due	3,655	253
Financing Receivables, 30 to 59 Days Past Due [Member] | Performing Financial Instruments [Member] | Pass [Member] | Commercial Real Estate Portfolio Segment [Member]
Performing (accruing) loans, past due	1,300
Financing Receivables, 30 to 59 Days Past Due [Member] | Performing Financial Instruments [Member] | Pass [Member] | Residential Portfolio Segment [Member]
Performing (accruing) loans, past due	556	131
Financing Receivables, 30 to 59 Days Past Due [Member] | Performing Financial Instruments [Member] | Pass [Member] | Commercial Portfolio Segment [Member]
Performing (accruing) loans, past due	1,799	47
Financing Receivables, 30 to 59 Days Past Due [Member] | Performing Financial Instruments [Member] | Pass [Member] | Consumer Portfolio Segment [Member]
Performing (accruing) loans, past due		75
Financing Receivables, 30 to 59 Days Past Due [Member] | Performing Financial Instruments [Member] | Pass [Member] | Construction Portfolio Segment [Member]
Performing (accruing) loans, past due
Financing Receivables, 30 to 59 Days Past Due [Member] | Performing Financial Instruments [Member] | Pass [Member] | Construction to Permanent Portfolio Segment [Member]
Performing (accruing) loans, past due
Financing Receivables, 30 to 59 Days Past Due [Member] | Performing Financial Instruments [Member] | Special Mention [Member]
Performing (accruing) loans, past due	652
Financing Receivables, 30 to 59 Days Past Due [Member] | Performing Financial Instruments [Member] | Special Mention [Member] | Commercial Real Estate Portfolio Segment [Member]
Performing (accruing) loans, past due	652
Financing Receivables, 30 to 59 Days Past Due [Member] | Performing Financial Instruments [Member] | Special Mention [Member] | Residential Portfolio Segment [Member]
Performing (accruing) loans, past due
Financing Receivables, 30 to 59 Days Past Due [Member] | Performing Financial Instruments [Member] | Substandard [Member]
Performing (accruing) loans, past due
Financing Receivables, 30 to 59 Days Past Due [Member] | Performing Financial Instruments [Member] | Substandard [Member] | Commercial Real Estate Portfolio Segment [Member]
Performing (accruing) loans, past due
Financing Receivables, 30 to 59 Days Past Due [Member] | Performing Financial Instruments [Member] | Substandard [Member] | Residential Portfolio Segment [Member]
Performing (accruing) loans, past due
Financing Receivables, 30 to 59 Days Past Due [Member] | Performing Financial Instruments [Member] | Substandard [Member] | Commercial Portfolio Segment [Member]
Performing (accruing) loans, past due
Financing Receivables, 30 to 59 Days Past Due [Member] | Performing Financial Instruments [Member] | Substandard [Member] | Consumer Portfolio Segment [Member]
Performing (accruing) loans, past due
Financing Receivables, 60 to 89 Days Past Due [Member] | Performing Financial Instruments [Member]
Performing (accruing) loans, past due	2,688	13
Financing Receivables, 60 to 89 Days Past Due [Member] | Performing Financial Instruments [Member] | Commercial Real Estate Portfolio Segment [Member]
Performing (accruing) loans, past due	1,699
Financing Receivables, 60 to 89 Days Past Due [Member] | Performing Financial Instruments [Member] | Residential Portfolio Segment [Member]
Performing (accruing) loans, past due	364	9
Financing Receivables, 60 to 89 Days Past Due [Member] | Performing Financial Instruments [Member] | Commercial Portfolio Segment [Member]
Performing (accruing) loans, past due	500	4
Financing Receivables, 60 to 89 Days Past Due [Member] | Performing Financial Instruments [Member] | Consumer Portfolio Segment [Member]
Performing (accruing) loans, past due	125
Financing Receivables, 60 to 89 Days Past Due [Member] | Performing Financial Instruments [Member] | Pass [Member]
Performing (accruing) loans, past due	989	13
Financing Receivables, 60 to 89 Days Past Due [Member] | Performing Financial Instruments [Member] | Pass [Member] | Commercial Real Estate Portfolio Segment [Member]
Performing (accruing) loans, past due
Financing Receivables, 60 to 89 Days Past Due [Member] | Performing Financial Instruments [Member] | Pass [Member] | Residential Portfolio Segment [Member]
Performing (accruing) loans, past due	364	9
Financing Receivables, 60 to 89 Days Past Due [Member] | Performing Financial Instruments [Member] | Pass [Member] | Commercial Portfolio Segment [Member]
Performing (accruing) loans, past due	500	4
Financing Receivables, 60 to 89 Days Past Due [Member] | Performing Financial Instruments [Member] | Pass [Member] | Consumer Portfolio Segment [Member]
Performing (accruing) loans, past due	125
Financing Receivables, 60 to 89 Days Past Due [Member] | Performing Financial Instruments [Member] | Pass [Member] | Construction Portfolio Segment [Member]
Performing (accruing) loans, past due
Financing Receivables, 60 to 89 Days Past Due [Member] | Performing Financial Instruments [Member] | Pass [Member] | Construction to Permanent Portfolio Segment [Member]
Performing (accruing) loans, past due
Financing Receivables, 60 to 89 Days Past Due [Member] | Performing Financial Instruments [Member] | Special Mention [Member]
Performing (accruing) loans, past due
Financing Receivables, 60 to 89 Days Past Due [Member] | Performing Financial Instruments [Member] | Special Mention [Member] | Commercial Real Estate Portfolio Segment [Member]
Performing (accruing) loans, past due
Financing Receivables, 60 to 89 Days Past Due [Member] | Performing Financial Instruments [Member] | Special Mention [Member] | Residential Portfolio Segment [Member]
Performing (accruing) loans, past due
Financing Receivables, 60 to 89 Days Past Due [Member] | Performing Financial Instruments [Member] | Substandard [Member]
Performing (accruing) loans, past due	1,699
Financing Receivables, 60 to 89 Days Past Due [Member] | Performing Financial Instruments [Member] | Substandard [Member] | Commercial Real Estate Portfolio Segment [Member]
Performing (accruing) loans, past due	1,699
Financing Receivables, 60 to 89 Days Past Due [Member] | Performing Financial Instruments [Member] | Substandard [Member] | Residential Portfolio Segment [Member]
Performing (accruing) loans, past due
Financing Receivables, 60 to 89 Days Past Due [Member] | Performing Financial Instruments [Member] | Substandard [Member] | Commercial Portfolio Segment [Member]
Performing (accruing) loans, past due
Financing Receivables, 60 to 89 Days Past Due [Member] | Performing Financial Instruments [Member] | Substandard [Member] | Consumer Portfolio Segment [Member]
Performing (accruing) loans, past due
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Performing Financial Instruments [Member]
Performing (accruing) loans, past due	4,447	1,452
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Performing Financial Instruments [Member] | Commercial Real Estate Portfolio Segment [Member]
Performing (accruing) loans, past due
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Performing Financial Instruments [Member] | Residential Portfolio Segment [Member]
Performing (accruing) loans, past due	1,447	1,449
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Performing Financial Instruments [Member] | Commercial Portfolio Segment [Member]
Performing (accruing) loans, past due	3,000
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Performing Financial Instruments [Member] | Consumer Portfolio Segment [Member]
Performing (accruing) loans, past due
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Performing Financial Instruments [Member] | Pass [Member]
Performing (accruing) loans, past due	3,947	1,452
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Performing Financial Instruments [Member] | Pass [Member] | Commercial Real Estate Portfolio Segment [Member]
Performing (accruing) loans, past due
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Performing Financial Instruments [Member] | Pass [Member] | Residential Portfolio Segment [Member]
Performing (accruing) loans, past due	1,447	1,449
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Performing Financial Instruments [Member] | Pass [Member] | Commercial Portfolio Segment [Member]
Performing (accruing) loans, past due	2,500
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Performing Financial Instruments [Member] | Pass [Member] | Consumer Portfolio Segment [Member]
Performing (accruing) loans, past due		3
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Performing Financial Instruments [Member] | Pass [Member] | Construction Portfolio Segment [Member]
Performing (accruing) loans, past due
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Performing Financial Instruments [Member] | Pass [Member] | Construction to Permanent Portfolio Segment [Member]
Performing (accruing) loans, past due
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Performing Financial Instruments [Member] | Special Mention [Member]
Performing (accruing) loans, past due
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Performing Financial Instruments [Member] | Special Mention [Member] | Commercial Real Estate Portfolio Segment [Member]
Performing (accruing) loans, past due
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Performing Financial Instruments [Member] | Special Mention [Member] | Residential Portfolio Segment [Member]
Performing (accruing) loans, past due
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Performing Financial Instruments [Member] | Substandard [Member]
Performing (accruing) loans, past due	500
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Performing Financial Instruments [Member] | Substandard [Member] | Commercial Real Estate Portfolio Segment [Member]
Performing (accruing) loans, past due
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Performing Financial Instruments [Member] | Substandard [Member] | Residential Portfolio Segment [Member]
Performing (accruing) loans, past due
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Performing Financial Instruments [Member] | Substandard [Member] | Commercial Portfolio Segment [Member]
Performing (accruing) loans, past due	500
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Performing Financial Instruments [Member] | Substandard [Member] | Consumer Portfolio Segment [Member]
Performing (accruing) loans, past due