Note 4 - Loans and Allowance for Loan Losses - Impaired Loans (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Valuation allowance	$ 1,272		$ 1,249
Loans recorded balance	10,273		10,827
Loans unpaid principal	11,506		12,060
Loans interest income recognized	5
Loans average investment in impaired loans	10,463	9,103
Residential Portfolio Segment [Member] \| Real Estate Residential, One To Four Family Units [Member]
Loans without a specific valuation allowance, recorded balance	1,778		3,180
Loans without a specific valuation allowance, unpaid principal	1,778		3,180
Loans with a specific valuation allowance, recorded balance	2,481		1,244
Loans with a specific valuation allowance, unpaid principal	2,481		1,244
Valuation allowance	302		127
Loans recorded balance	4,259		4,424
Loans unpaid principal	4,259		4,424
Loans without a specific valuation allowance, average investment in impaired loans	2,688	1,888
Loans interest income recognized
Loans with a specific valuation allowance, average investment in impaired loans	1,607	41
Loans average investment in impaired loans	4,295	1,929
Residential Portfolio Segment [Member] \| Real Estate Residential, Multi Family Units [Member]
Loans without a specific valuation allowance, recorded balance	762		775
Loans without a specific valuation allowance, unpaid principal	762		775
Valuation allowance
Loans recorded balance	762		775
Loans unpaid principal	762		775
Loans without a specific valuation allowance, average investment in impaired loans	765
Loans interest income recognized	5
Loans with a specific valuation allowance, average investment in impaired loans
Loans average investment in impaired loans	765
Residential Portfolio Segment [Member] \| Construction Loans [Member]
Loans without a specific valuation allowance, average investment in impaired loans	2,775	2,990
Loans interest income recognized
Loans with a specific valuation allowance, average investment in impaired loans	1,612	2,415
Loans average investment in impaired loans	4,387	5,405
Real Estate, Construction [Member]
Loans without a specific valuation allowance, recorded balance	2,742		2,840
Loans without a specific valuation allowance, unpaid principal	2,742		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	741		738
Loans recorded balance	4,354		4,452
Loans unpaid principal	5,587		5,685
Commercial Real Estate Portfolio Segment [Member]
Loans without a specific valuation allowance, recorded balance	161		161
Loans without a specific valuation allowance, unpaid principal	161		161
Loans with a specific valuation allowance, recorded balance
Loans with a specific valuation allowance, unpaid principal
Valuation allowance
Loans recorded balance	161		161
Loans unpaid principal	161		161
Loans without a specific valuation allowance, average investment in impaired loans	161	521
Loans interest income recognized
Loans with a specific valuation allowance, average investment in impaired loans
Loans average investment in impaired loans	161	521
Commercial Portfolio Segment [Member]
Loans without a specific valuation allowance, recorded balance	170		465
Loans without a specific valuation allowance, unpaid principal	170		465
Loans with a specific valuation allowance, recorded balance	486		274
Loans with a specific valuation allowance, unpaid principal	486		274
Valuation allowance	219		246
Loans recorded balance	656		739
Loans unpaid principal	656		739
Loans without a specific valuation allowance, average investment in impaired loans	349	601
Loans interest income recognized
Loans with a specific valuation allowance, average investment in impaired loans	323	550
Loans average investment in impaired loans	672	1,151
Consumer and Other Loans [Member]
Loans without a specific valuation allowance, recorded balance			3
Loans without a specific valuation allowance, unpaid principal			3
Loans with a specific valuation allowance, recorded balance	81		273
Loans with a specific valuation allowance, unpaid principal	81		273
Valuation allowance	10		138
Loans recorded balance	81		276
Loans unpaid principal	81		$ 276
Consumer Portfolio Segment [Member]
Loans without a specific valuation allowance, average investment in impaired loans	2	10
Loans interest income recognized
Loans with a specific valuation allowance, average investment in impaired loans	181	87
Loans average investment in impaired loans	$ 183	$ 97

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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