Note 4 - Loans Receivables and Allowance for Loan Losses - Delinquency Status of Performing and Non-performing Loans (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Loans receivable, gross	$ 719,647	$ 581,657
Non-accruing loans	3,778	1,821
Commercial Real Estate Portfolio Segment [Member]
Loans receivable, gross	299,925	271,229
Non-accruing loans
Residential Portfolio Segment [Member]
Loans receivable, gross	146,377	86,514
Non-accruing loans	3,028	1,590
Commercial Portfolio Segment [Member]
Loans receivable, gross	131,161	60,977
Non-accruing loans	748	231
Consumer Portfolio Segment [Member]
Loans receivable, gross	87,707	101,449
Non-accruing loans	2
Construction Portfolio Segment [Member]
Loans receivable, gross	47,619	53,895
Construction to Permanent Portfolio Segment [Member]
Loans receivable, gross	6,858	7,593
Pass [Member]
Loans receivable, gross	699,862	573,850
Non-accruing loans
Pass [Member] \| Commercial Real Estate Portfolio Segment [Member]
Loans receivable, gross	286,428	265,246
Non-accruing loans
Pass [Member] \| Residential Portfolio Segment [Member]
Loans receivable, gross	141,820	84,924
Non-accruing loans
Pass [Member] \| Commercial Portfolio Segment [Member]
Loans receivable, gross	129,432	60,743
Non-accruing loans
Pass [Member] \| Consumer Portfolio Segment [Member]
Loans receivable, gross	87,705	101,449
Non-accruing loans
Pass [Member] \| Construction Portfolio Segment [Member]
Loans receivable, gross	47,619	53,895
Non-accruing loans
Pass [Member] \| Construction to Permanent Portfolio Segment [Member]
Loans receivable, gross	6,858	7,593
Non-accruing loans
Special Mention [Member]
Loans receivable, gross	11,967	4,531
Non-accruing loans
Special Mention [Member] \| Commercial Real Estate Portfolio Segment [Member]
Loans receivable, gross	10,438	4,531
Non-accruing loans
Special Mention [Member] \| Residential Portfolio Segment [Member]
Loans receivable, gross	1,529
Non-accruing loans
Special Mention [Member] \| Commercial Portfolio Segment [Member]
Loans receivable, gross
Non-accruing loans
Substandard [Member]
Loans receivable, gross	7,818	3,276
Non-accruing loans	3,778	1,821
Substandard [Member] \| Commercial Real Estate Portfolio Segment [Member]
Loans receivable, gross	3,059	1,452
Non-accruing loans
Substandard [Member] \| Residential Portfolio Segment [Member]
Loans receivable, gross	3,028	1,590
Non-accruing loans	3,028	1,590
Substandard [Member] \| Commercial Portfolio Segment [Member]
Loans receivable, gross	1,729	234
Non-accruing loans	748	231
Substandard [Member] \| Consumer Portfolio Segment [Member]
Loans receivable, gross	2
Non-accruing loans	2
Performing Financial Instruments [Member]
Performing (accruing) loans, past due	9,515	1,718
Performing (accruing) loans, current	706,354	578,118
Loans receivable, gross	715,869	579,836
Performing Financial Instruments [Member] \| Commercial Real Estate Portfolio Segment [Member]
Performing (accruing) loans, past due	2,809
Performing (accruing) loans, current	297,116	271,229
Loans receivable, gross	299,925	271,229
Performing Financial Instruments [Member] \| Residential Portfolio Segment [Member]
Performing (accruing) loans, past due	2,852	1,589
Performing (accruing) loans, current	140,497	83,335
Loans receivable, gross	143,349	84,924
Performing Financial Instruments [Member] \| Commercial Portfolio Segment [Member]
Performing (accruing) loans, past due	3,356	51
Performing (accruing) loans, current	127,057	60,695
Loans receivable, gross	130,413	60,746
Performing Financial Instruments [Member] \| Consumer Portfolio Segment [Member]
Performing (accruing) loans, past due	498
Performing (accruing) loans, current	87,207
Loans receivable, gross	87,705
Performing Financial Instruments [Member] \| Pass [Member]
Performing (accruing) loans, past due	4,196	1,718
Performing (accruing) loans, current	695,666	572,132
Loans receivable, gross	699,862	573,850
Performing Financial Instruments [Member] \| Pass [Member] \| Commercial Real Estate Portfolio Segment [Member]
Performing (accruing) loans, past due
Performing (accruing) loans, current	286,428	265,246
Loans receivable, gross	286,428	265,246
Performing Financial Instruments [Member] \| Pass [Member] \| Residential Portfolio Segment [Member]
Performing (accruing) loans, past due	1,323	1,589
Performing (accruing) loans, current	140,497	83,335
Loans receivable, gross	141,820	84,924
Performing Financial Instruments [Member] \| Pass [Member] \| Commercial Portfolio Segment [Member]
Performing (accruing) loans, past due	2,375	51
Performing (accruing) loans, current	127,057	60,692
Loans receivable, gross	129,432	60,743
Performing Financial Instruments [Member] \| Pass [Member] \| Consumer Portfolio Segment [Member]
Performing (accruing) loans, past due	498	78
Performing (accruing) loans, current	87,207	101,371
Loans receivable, gross	87,705	101,449
Performing Financial Instruments [Member] \| Pass [Member] \| Construction Portfolio Segment [Member]
Performing (accruing) loans, past due
Performing (accruing) loans, current	47,619	53,895
Loans receivable, gross	47,619	53,895
Performing Financial Instruments [Member] \| Pass [Member] \| Construction to Permanent Portfolio Segment [Member]
Performing (accruing) loans, past due
Performing (accruing) loans, current	6,858	7,593
Loans receivable, gross	6,858	7,593
Performing Financial Instruments [Member] \| Special Mention [Member]
Performing (accruing) loans, past due	2,650
Performing (accruing) loans, current	9,317	4,531
Loans receivable, gross	11,967	4,531
Performing Financial Instruments [Member] \| Special Mention [Member] \| Commercial Real Estate Portfolio Segment [Member]
Performing (accruing) loans, past due	1,121
Performing (accruing) loans, current	9,317	4,531
Loans receivable, gross	10,438	4,531
Performing Financial Instruments [Member] \| Special Mention [Member] \| Residential Portfolio Segment [Member]
Performing (accruing) loans, past due	1,529
Performing (accruing) loans, current
Loans receivable, gross	1,529
Performing Financial Instruments [Member] \| Special Mention [Member] \| Commercial Portfolio Segment [Member]
Performing (accruing) loans, past due
Performing (accruing) loans, current
Loans receivable, gross
Performing Financial Instruments [Member] \| Substandard [Member]
Performing (accruing) loans, past due	2,669
Performing (accruing) loans, current	1,371	1,455
Loans receivable, gross	4,040	1,455
Performing Financial Instruments [Member] \| Substandard [Member] \| Commercial Real Estate Portfolio Segment [Member]
Performing (accruing) loans, past due	1,688
Performing (accruing) loans, current	1,371	1,452
Loans receivable, gross	3,059	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	981
Performing (accruing) loans, current		3
Loans receivable, gross	981	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	1,566	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
Financing Receivables, 30 to 59 Days Past Due [Member] \| Performing Financial Instruments [Member] \| Residential Portfolio Segment [Member]
Performing (accruing) loans, past due	1,068	131
Financing Receivables, 30 to 59 Days Past Due [Member] \| Performing Financial Instruments [Member] \| Commercial Portfolio Segment [Member]
Performing (accruing) loans, past due		47
Financing Receivables, 30 to 59 Days Past Due [Member] \| Performing Financial Instruments [Member] \| Consumer Portfolio Segment [Member]
Performing (accruing) loans, past due	498
Financing Receivables, 30 to 59 Days Past Due [Member] \| Performing Financial Instruments [Member] \| Pass [Member]
Performing (accruing) loans, past due	1,566	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
Financing Receivables, 30 to 59 Days Past Due [Member] \| Performing Financial Instruments [Member] \| Pass [Member] \| Residential Portfolio Segment [Member]
Performing (accruing) loans, past due	1,068	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		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	498	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
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
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] \| Special Mention [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]
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	6,593	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	2,809
Financing Receivables, 60 to 89 Days Past Due [Member] \| Performing Financial Instruments [Member] \| Residential Portfolio Segment [Member]
Performing (accruing) loans, past due	1,784	9
Financing Receivables, 60 to 89 Days Past Due [Member] \| Performing Financial Instruments [Member] \| Commercial Portfolio Segment [Member]
Performing (accruing) loans, past due	2,000	4
Financing Receivables, 60 to 89 Days Past Due [Member] \| Performing Financial Instruments [Member] \| Consumer Portfolio Segment [Member]
Performing (accruing) loans, past due
Financing Receivables, 60 to 89 Days Past Due [Member] \| Performing Financial Instruments [Member] \| Pass [Member]
Performing (accruing) loans, past due	2,255	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	255	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	2,000	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
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	2,650
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	1,121
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	1,529
Financing Receivables, 60 to 89 Days Past Due [Member] \| Performing Financial Instruments [Member] \| Special Mention [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]
Performing (accruing) loans, past due	1,688
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	1,688
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	1,356	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		1,449
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] \| Performing Financial Instruments [Member] \| Commercial Portfolio Segment [Member]
Performing (accruing) loans, past due	1,356
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	375	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		1,449
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	375
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] \| Special Mention [Member] \| Commercial 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	981
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	981
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

Note 4 - Loans Receivables and Allowance for Loan Losses - Delinquency Status of Performing and Non-performing Loans (Details) - USD ($)
$ in Thousands