Note 4 - Loans and Allowance for Loan Losses - Impaired Loans (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Valuation allowance	$ 1,612	$ 1,249
Loans recorded balance	20,552	10,827
Loans unpaid principal	21,870	12,060
Loans average investment in impaired loans	16,658	9,331
Loans interest income recognized	122	6
Residential Portfolio Segment [Member] | Real Estate Residential, One To Four Family Units [Member]
Loans without a specific valuation allowance, recorded balance	2	3,180
Loans without a specific valuation allowance, unpaid principal	2	3,180
Loans without a specific valuation allowance, average investment in impaired loans	1,429	2,170
Loans without a specific valuation allowance, interest income recognized	1	0
Loans with a specific valuation allowance, recorded balance	4,518	1,244
Loans with a specific valuation allowance, unpaid principal	4,518	1,244
Valuation allowance	573	127
Loans with a specific valuation allowance, average investment in impaired loans	2,858	247
Loans with a specific valuation allowance, interest income recognized	0	0
Loans recorded balance	4,520	4,424
Loans unpaid principal	4,520	4,424
Loans average investment in impaired loans	4,287	2,417
Loans interest income recognized	1	0
Residential Portfolio Segment [Member] | Real Estate Residential, Multi Family Units [Member]
Loans without a specific valuation allowance, recorded balance	5,952	775
Loans without a specific valuation allowance, unpaid principal	5,952	775
Loans without a specific valuation allowance, average investment in impaired loans	2,246	130
Loans without a specific valuation allowance, interest income recognized	75	5
Loans with a specific valuation allowance, recorded balance	0	0
Loans with a specific valuation allowance, unpaid principal	0	0
Valuation allowance	0	0
Loans with a specific valuation allowance, average investment in impaired loans	499	0
Loans with a specific valuation allowance, interest income recognized	0	0
Loans recorded balance	5,952	775
Loans unpaid principal	5,952	775
Loans average investment in impaired loans	2,745	130
Loans interest income recognized	75	5
Real Estate, Construction [Member]
Loans without a specific valuation allowance, recorded balance		2,840
Loans without a specific valuation allowance, unpaid principal		2,840
Loans without a specific valuation allowance, average investment in impaired loans	1,144	2,940
Loans without a specific valuation allowance, interest income recognized	0	0
Loans with a specific valuation allowance, recorded balance	4,088	1,612
Loans with a specific valuation allowance, unpaid principal	5,321	2,845
Valuation allowance	552	738
Loans with a specific valuation allowance, average investment in impaired loans	3,009	2,326
Loans with a specific valuation allowance, interest income recognized	0	0
Loans recorded balance	4,088	4,452
Loans unpaid principal	5,321	5,685
Loans average investment in impaired loans	4,153	5,266
Loans interest income recognized	0	0
Commercial Real Estate Portfolio Segment [Member]
Loans without a specific valuation allowance, recorded balance	3,138	161
Loans without a specific valuation allowance, unpaid principal	3,138	161
Loans without a specific valuation allowance, average investment in impaired loans	3,764	311
Loans without a specific valuation allowance, interest income recognized	46	0
Loans with a specific valuation allowance, recorded balance	1,232	0
Loans with a specific valuation allowance, unpaid principal	1,317	0
Valuation allowance	106	0
Loans with a specific valuation allowance, average investment in impaired loans	154
Loans with a specific valuation allowance, interest income recognized	0	0
Loans recorded balance	4,370	161
Loans unpaid principal	4,455	161
Loans average investment in impaired loans	3,918	311
Loans interest income recognized	46	0
Commercial Portfolio Segment [Member]
Loans without a specific valuation allowance, recorded balance	216	465
Loans without a specific valuation allowance, unpaid principal	216	465
Loans without a specific valuation allowance, average investment in impaired loans	596	536
Loans without a specific valuation allowance, interest income recognized	0	0
Loans with a specific valuation allowance, recorded balance	1,062	274
Loans with a specific valuation allowance, unpaid principal	1,062	274
Valuation allowance	363	246
Loans with a specific valuation allowance, average investment in impaired loans	522	456
Loans with a specific valuation allowance, interest income recognized	0	0
Loans recorded balance	1,278	739
Loans unpaid principal	1,278	739
Loans average investment in impaired loans	1,118	992
Loans interest income recognized	0	0
Consumer and Other Loans [Member]
Loans without a specific valuation allowance, recorded balance	225	3
Loans without a specific valuation allowance, unpaid principal	225	3
Loans without a specific valuation allowance, average investment in impaired loans	316	7
Loans without a specific valuation allowance, interest income recognized		1
Loans with a specific valuation allowance, recorded balance	119	273
Loans with a specific valuation allowance, unpaid principal	119	273
Valuation allowance	18	138
Loans with a specific valuation allowance, average investment in impaired loans	121	208
Loans with a specific valuation allowance, interest income recognized	0	0
Loans recorded balance	344	276
Loans unpaid principal	344	276
Loans average investment in impaired loans	437	215
Loans interest income recognized		$ 1