Note 4 - Loans and Allowance for Loan Losses - Impaired Loans (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Valuation allowance	$ 421	$ 1,096
Loans recorded balance	19,014	11,968
Loans unpaid principal	20,985	13,201
Loans average investment in impaired loans	11,908	17,291
Loans interest income recognized	17	7
Residential Portfolio Segment [Member] | Real Estate Residential, One To Four Family Units [Member]
Loans without a specific valuation allowance, recorded balance	2,780	1,392
Loans without a specific valuation allowance, unpaid principal	2,780	1,392
Loans without a specific valuation allowance, average investment in impaired loans	1,199	1,075
Loans without a specific valuation allowance, interest income recognized	0	1
Loans with a specific valuation allowance, recorded balance	330	1,221
Loans with a specific valuation allowance, unpaid principal	330	1,221
Valuation allowance	112	197
Loans with a specific valuation allowance, average investment in impaired loans	1,183	1,781
Loans with a specific valuation allowance, interest income recognized	0	0
Loans recorded balance	3,110	2,613
Loans unpaid principal	3,110	2,613
Loans average investment in impaired loans	2,382	2,856
Loans interest income recognized	0	1
Residential Portfolio Segment [Member] | Real Estate Residential, Multi Family Units [Member]
Loans without a specific valuation allowance, recorded balance	0	0
Loans without a specific valuation allowance, unpaid principal	0	0
Loans without a specific valuation allowance, average investment in impaired loans	0	5,438
Loans without a specific valuation allowance, interest income recognized	0	0
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	0	0
Loans with a specific valuation allowance, interest income recognized	0	0
Loans recorded balance	0	0
Loans unpaid principal	0	0
Loans average investment in impaired loans	0	5,438
Loans interest income recognized	0	0
Real Estate, Construction [Member]
Loans without a specific valuation allowance, recorded balance	5,081	0
Loans without a specific valuation allowance, unpaid principal	5,081	0
Loans without a specific valuation allowance, average investment in impaired loans	423	0
Loans without a specific valuation allowance, interest income recognized	0	0
Loans with a specific valuation allowance, recorded balance	1,158	4,742
Loans with a specific valuation allowance, unpaid principal	3,129	5,975
Valuation allowance	114	553
Loans with a specific valuation allowance, average investment in impaired loans	4,093	3,924
Loans with a specific valuation allowance, interest income recognized	0	0
Loans recorded balance	6,239	4,742
Loans unpaid principal	8,210	5,975
Loans average investment in impaired loans	4,516	3,924
Loans interest income recognized	0	0
Commercial Real Estate Portfolio Segment [Member]
Loans without a specific valuation allowance, recorded balance	3,419	3,199
Loans without a specific valuation allowance, unpaid principal	3,419	3,199
Loans without a specific valuation allowance, average investment in impaired loans	3,152	3,274
Loans without a specific valuation allowance, interest income recognized	4	4
Loans with a specific valuation allowance, recorded balance	801	162
Loans with a specific valuation allowance, unpaid principal	801	162
Valuation allowance	117	24
Loans with a specific valuation allowance, average investment in impaired loans	365	533
Loans with a specific valuation allowance, interest income recognized	0	0
Loans recorded balance	4,220	3,361
Loans unpaid principal	4,220	3,361
Loans average investment in impaired loans	3,517	3,807
Loans interest income recognized	4	4
Commercial Portfolio Segment [Member]
Loans without a specific valuation allowance, recorded balance	4,902	33
Loans without a specific valuation allowance, unpaid principal	4,902	33
Loans without a specific valuation allowance, average investment in impaired loans	455	127
Loans without a specific valuation allowance, interest income recognized	0	0
Loans with a specific valuation allowance, recorded balance	341	999
Loans with a specific valuation allowance, unpaid principal	341	999
Valuation allowance	63	301
Loans with a specific valuation allowance, average investment in impaired loans	792	756
Loans with a specific valuation allowance, interest income recognized	0	0
Loans recorded balance	5,243	1,032
Loans unpaid principal	5,243	1,032
Loans average investment in impaired loans	1,247	883
Loans interest income recognized	0	0
Consumer and Other Loans [Member]
Loans without a specific valuation allowance, recorded balance	100	70
Loans without a specific valuation allowance, unpaid principal	100	70
Loans without a specific valuation allowance, average investment in impaired loans	110	230
Loans without a specific valuation allowance, interest income recognized	13	2
Loans with a specific valuation allowance, recorded balance	102	150
Loans with a specific valuation allowance, unpaid principal	102	150
Valuation allowance	15	21
Loans with a specific valuation allowance, average investment in impaired loans	136	153
Loans with a specific valuation allowance, interest income recognized	0	0
Loans recorded balance	202	220
Loans unpaid principal	202	220
Loans average investment in impaired loans	246	383
Loans interest income recognized	$ 13	$ 2