Note 4 - Loans and the Allowance for Loan Losses - Allocation of the Allowance for Loan Losses (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019	Mar. 31, 2020	Dec. 31, 2019
Beginning balance	$ 7,243	$ 6,958	$ 6,958
Charge-offs	(268)	(351)	(1,521)
Recoveries	79	60	306
Provision	750	400	1,500
Ending balance	7,804	7,067	7,243
Allowance for loan losses, individually evaluated for impairment				$ 154	$ 154
Allowance for loan losses, collectively evaluated for impairment				7,650	7,089
Allowance for loan losses	7,243	7,067	6,958	7,804	7,243
Loans, individually evaluated for impairment				2,247	2,244
Loans, collectively evaluated for impairment				621,496	617,474
Loans				623,743	619,718
Commercial Portfolio Segment [Member] \| Commercial Loans [Member]
Beginning balance	617	914	914
Charge-offs	(131)	(16)
Recoveries	2	9
Provision	226	(111)
Ending balance	714	796	617
Allowance for loan losses, individually evaluated for impairment
Allowance for loan losses, collectively evaluated for impairment				714	617
Allowance for loan losses	714	796	914	714	617
Loans, individually evaluated for impairment					25
Loans, collectively evaluated for impairment				49,246	47,867
Loans				49,246	47,892
Commercial Portfolio Segment [Member] \| Agricultural Loans [Member]
Beginning balance	653	538	538
Charge-offs
Recoveries
Provision	(31)	4
Ending balance	622	542	653
Allowance for loan losses, individually evaluated for impairment
Allowance for loan losses, collectively evaluated for impairment				622	653
Allowance for loan losses	622	542	538	622	653
Loans, individually evaluated for impairment				247	248
Loans, collectively evaluated for impairment				75,797	78,537
Loans				76,044	78,785
Commercial Portfolio Segment [Member] \| Real Estate Loan [Member]
Beginning balance	3,426	2,686	2,686
Charge-offs
Recoveries	1
Provision	403	283
Ending balance	3,830	2,969	3,426
Allowance for loan losses, individually evaluated for impairment				121	121
Allowance for loan losses, collectively evaluated for impairment				3,709	3,305
Allowance for loan losses	3,830	2,969	2,686	3,830	3,426
Loans, individually evaluated for impairment				805	815
Loans, collectively evaluated for impairment				331,489	316,171
Loans				332,294	316,986
Commercial Portfolio Segment [Member] \| Construction Loans [Member]
Beginning balance	481	758	758
Charge-offs
Recoveries
Provision	(84)	(117)
Ending balance	397	641	481
Allowance for loan losses, individually evaluated for impairment				5	5
Allowance for loan losses, collectively evaluated for impairment				392	476
Allowance for loan losses	397	641	758	397	481
Loans, individually evaluated for impairment				109	110
Loans, collectively evaluated for impairment				19,565	31,071
Loans				19,674	31,181
Residential Portfolio Segment [Member] \| Real Estate Loan [Member]
Beginning balance	163	214	214
Charge-offs
Recoveries	1	1
Provision	7	(20)
Ending balance	171	195	163
Allowance for loan losses, individually evaluated for impairment				28	28
Allowance for loan losses, collectively evaluated for impairment				143	135
Allowance for loan losses	171	195	214	171	163
Loans, individually evaluated for impairment				656	612
Loans, collectively evaluated for impairment				13,164	13,918
Loans				13,820	14,530
Residential Portfolio Segment [Member] \| Equity Lines of Credit [Member]
Beginning balance	393	464	464
Charge-offs
Recoveries	1	1
Provision	28	(15)
Ending balance	422	450	393
Allowance for loan losses, individually evaluated for impairment
Allowance for loan losses, collectively evaluated for impairment				422	393
Allowance for loan losses	422	450	464	422	393
Loans, individually evaluated for impairment				430	434
Loans, collectively evaluated for impairment				34,832	35,037
Loans				35,262	35,471
Consumer Portfolio Segment [Member] \| Automobile Loan [Member]
Beginning balance	1,409	1,289	1,289
Charge-offs	(134)	(312)
Recoveries	70	47
Provision	196	360
Ending balance	1,541	1,384	1,409
Allowance for loan losses, individually evaluated for impairment
Allowance for loan losses, collectively evaluated for impairment				1,541	1,409
Allowance for loan losses	1,541	1,384	1,289	1,541	1,409
Loans, individually evaluated for impairment
Loans, collectively evaluated for impairment				92,862	90,310
Loans				92,862	90,310
Consumer Portfolio Segment [Member] \| Other Loans [Member]
Beginning balance	101	95	95
Charge-offs	(3)	(23)
Recoveries	4	2
Provision	5	16
Ending balance	107	90	101
Allowance for loan losses, individually evaluated for impairment
Allowance for loan losses, collectively evaluated for impairment				107	101
Allowance for loan losses	$ 107	$ 90	$ 95	107	101
Loans, individually evaluated for impairment
Loans, collectively evaluated for impairment				4,541	4,563
Loans				$ 4,541	$ 4,563

Amount of recovery of loans and lease receivables which had previously been fully or partially written-off as bad debts.

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Amount of loans and leases that have been written off from both loan receivables and allowance reserve for credit loss.

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The valuation allowance for financing receivables that are expected to be uncollectible that were collectively evaluated for impairment.

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Amount of valuation allowance for financing receivables that are expected to be uncollectible that were individually evaluated for impairment.

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The balance of financing receivables that were collectively evaluated for impairment.

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Amount of allowance to cover probable credit losses on loans and leases. Includes carryover of or adjustments to the allowance for loan losses in connection with business combinations. Excludes allowance for loans and leases covered under loss sharing agreements.

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Amount before allowance of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Includes deferred interest and fees, undisbursed portion of loan balance, unamortized costs and premiums and discounts from face amounts. Excludes loans and leases covered under loss sharing agreements.

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Amount of expense related to estimated loss from loan and lease transactions.

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