Note 5 - Loans and Allowance for Loan Losses - Impaired Loans (Details) - USD ($) $ in Thousands	6 Months Ended
Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Valuation allowance	$ 1,287		$ 1,249
Loans recorded balance	15,483		10,827
Loans unpaid principal	16,716		12,060
Loans interest income recognized	46
Loans average investment in impaired loans	12,978	8,923
Residential Portfolio Segment [Member] \| Real Estate Residential, One To Four Family Units [Member]
Loans without a specific valuation allowance, recorded balance	2,129		3,180
Loans without a specific valuation allowance, unpaid principal	2,129		3,180
Loans with a specific valuation allowance, recorded balance	2,267		1,244
Loans with a specific valuation allowance, unpaid principal	2,267		1,244
Valuation allowance	322		127
Loans recorded balance	4,396		4,424
Loans unpaid principal	4,396		4,424
Loans without a specific valuation allowance, average investment in impaired loans	1,961	1,856
Loans interest income recognized
Loans with a specific valuation allowance, average investment in impaired loans	2,353	43
Loans average investment in impaired loans	4,314	1,899
Residential Portfolio Segment [Member] \| Real Estate Residential, Multi Family Units [Member]
Loans without a specific valuation allowance, recorded balance			775
Loans without a specific valuation allowance, unpaid principal			775
Valuation allowance
Loans recorded balance			775
Loans unpaid principal			775
Loans without a specific valuation allowance, average investment in impaired loans	509
Loans interest income recognized
Loans with a specific valuation allowance, average investment in impaired loans
Loans average investment in impaired loans	509
Residential Portfolio Segment [Member] \| Construction Loans [Member]
Loans without a specific valuation allowance, average investment in impaired loans	2,287	2,978
Loans interest income recognized
Loans with a specific valuation allowance, average investment in impaired loans	2,055	2,406
Loans average investment in impaired loans	4,342	5,384
Real Estate, Construction [Member]
Loans without a specific valuation allowance, recorded balance	2,686		2,840
Loans without a specific valuation allowance, unpaid principal	2,686		2,840
Loans with a specific valuation allowance, recorded balance	1,612		1,612
Loans with a specific valuation allowance, unpaid principal	2,845		2,845
Valuation allowance	738		738
Loans recorded balance	4,298		4,452
Loans unpaid principal	5,531		5,685
Commercial Real Estate Portfolio Segment [Member]
Loans without a specific valuation allowance, recorded balance	4,544		161
Loans without a specific valuation allowance, unpaid principal	4,544		161
Loans with a specific valuation allowance, recorded balance
Loans with a specific valuation allowance, unpaid principal
Valuation allowance
Loans recorded balance	4,544		161
Loans unpaid principal	4,544		161
Loans without a specific valuation allowance, average investment in impaired loans	2,326	460
Loans interest income recognized	46
Loans with a specific valuation allowance, average investment in impaired loans	27
Loans average investment in impaired loans	2,353	460
Commercial Portfolio Segment [Member]
Loans without a specific valuation allowance, recorded balance	1,542		465
Loans without a specific valuation allowance, unpaid principal	1,542		465
Loans with a specific valuation allowance, recorded balance	413		274
Loans with a specific valuation allowance, unpaid principal	413		274
Valuation allowance	213		246
Loans recorded balance	1,955		739
Loans unpaid principal	1,955		739
Loans without a specific valuation allowance, average investment in impaired loans	916	583
Loans interest income recognized
Loans with a specific valuation allowance, average investment in impaired loans	403	507
Loans average investment in impaired loans	1,319	1,090
Consumer and Other Loans [Member]
Loans without a specific valuation allowance, recorded balance	201		3
Loans without a specific valuation allowance, unpaid principal	201		3
Loans with a specific valuation allowance, recorded balance	89		273
Loans with a specific valuation allowance, unpaid principal	89		273
Valuation allowance	14		138
Loans recorded balance	290		276
Loans unpaid principal	290		$ 276
Consumer Portfolio Segment [Member]
Loans without a specific valuation allowance, average investment in impaired loans	9	11
Loans interest income recognized
Loans with a specific valuation allowance, average investment in impaired loans	132	79
Loans average investment in impaired loans	$ 141	$ 90

Average amount of investment of impaired financing receivables with related allowance for credit losses and without a related allowance for credit losses.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 15
-Subparagraph (c)(1)
-URI http://asc.fasb.org/extlink&oid=84173941&loc=d3e5212-111524

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 17
-URI http://asc.fasb.org/extlink&oid=84173941&loc=d3e5258-111524

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