Note 5 - Allowance for Loan Losses - Segregated by Impairment Methodology (Details) - USD ($)	Jun. 30, 2019	Dec. 31, 2018	Jun. 30, 2018	Dec. 31, 2017
Ending Allowance Balance, individually evaluated for impairment	$ 1,566,000		$ 1,474,000
Ending Allowance Balance, collectively evaluated for impairment	5,223,000		5,685,000
Related allowance	1,566,000	$ 1,418,000	1,474,000
Ending Allowance Balance Total	6,789,000	7,277,000	7,159,000	$ 7,508,000
Ending Loan Balance, individually evaluated for impairment	20,196,000		18,692,000
Ending Loan Balance, collectively evaluated for impairment	914,910,000		748,104,000
Impaired balance	24,179,000	24,473,000	21,789,000
Loans	935,271,000	782,027,000	766,796,000
Financial Asset Acquired with Credit Deterioration [Member]
Related allowance		0	0
Impaired balance	165,000	0	0
Real Estate Portfolio Segment [Member] \| Financial Asset Acquired with Credit Deterioration [Member]
Impaired balance	69,000
Commercial [Member] \| Commercial and Agricultural Portfolio Segment [Member]
Ending Allowance Balance, individually evaluated for impairment			0
Ending Allowance Balance, collectively evaluated for impairment	383,000		444,000
Related allowance		6,000	0
Ending Allowance Balance Total	383,000	370,000	444,000	447,000
Ending Loan Balance, individually evaluated for impairment	16,000		77,000
Ending Loan Balance, collectively evaluated for impairment	68,477,000		44,952,000
Impaired balance	484,000	637,000	367,000
Loans	68,535,000	57,410,000	45,029,000
Commercial [Member] \| Commercial and Agricultural Portfolio Segment [Member] \| Financial Asset Acquired with Credit Deterioration [Member]
Related allowance
Impaired balance	42,000
Commercial [Member] \| Real Estate Portfolio Segment [Member]
Ending Allowance Balance, individually evaluated for impairment	897,000		1,371,000
Ending Allowance Balance, collectively evaluated for impairment	2,844,000		3,035,000
Related allowance	897,000	1,276,000	1,371,000
Ending Allowance Balance Total	3,741,000	4,549,000	4,406,000	3,874,000
Ending Loan Balance, individually evaluated for impairment	14,243,000		15,187,000
Ending Loan Balance, collectively evaluated for impairment	419,573,000		336,876,000
Impaired balance	14,535,000	15,855,000	15,248,000
Loans	433,816,000	373,534,000	352,063,000
Commercial [Member] \| Real Estate Portfolio Segment [Member] \| Financial Asset Acquired with Credit Deterioration [Member]
Related allowance
Impaired balance
Agricultural [Member] \| Commercial and Agricultural Portfolio Segment [Member]
Ending Allowance Balance, individually evaluated for impairment	588,000		0
Ending Allowance Balance, collectively evaluated for impairment	450,000		262,000
Related allowance	588,000	0	0
Ending Allowance Balance Total	1,038,000	248,000	262,000	186,000
Ending Loan Balance, individually evaluated for impairment	850,000		5,000
Ending Loan Balance, collectively evaluated for impairment	18,011,000		20,032,000
Impaired balance	1,304,000	413,000	290,000
Loans	18,861,000	16,799,000	20,037,000
Agricultural [Member] \| Commercial and Agricultural Portfolio Segment [Member] \| Financial Asset Acquired with Credit Deterioration [Member]
Related allowance
Impaired balance
Commercial Construction [Member] \| Real Estate Portfolio Segment [Member]
Ending Allowance Balance, individually evaluated for impairment			54,000
Ending Allowance Balance, collectively evaluated for impairment	10,000		28,000
Related allowance		39,000	54,000
Ending Allowance Balance Total	10,000	115,000	82,000	1,216,000
Ending Loan Balance, individually evaluated for impairment	67,000		481,000
Ending Loan Balance, collectively evaluated for impairment	72,842,000		48,428,000
Impaired balance	173,000	531,000	498,000
Loans	72,978,000	47,849,000	48,909,000
Commercial Construction [Member] \| Real Estate Portfolio Segment [Member] \| Financial Asset Acquired with Credit Deterioration [Member]
Related allowance
Impaired balance	69,000
Residential Construction [Member] \| Real Estate Portfolio Segment [Member]
Ending Allowance Balance, individually evaluated for impairment			0
Ending Allowance Balance, collectively evaluated for impairment	2,000		0
Related allowance		0	0
Ending Allowance Balance Total	2,000	16,000
Ending Loan Balance, individually evaluated for impairment	354,000		0
Ending Loan Balance, collectively evaluated for impairment	18,268,000		11,541,000
Impaired balance	354,000
Loans	18,622,000	12,500,000	11,541,000
Residential Construction [Member] \| Real Estate Portfolio Segment [Member] \| Financial Asset Acquired with Credit Deterioration [Member]
Related allowance
Impaired balance
Residential [Member] \| Real Estate Portfolio Segment [Member]
Ending Allowance Balance, individually evaluated for impairment	49,000		21,000
Ending Allowance Balance, collectively evaluated for impairment	796,000		1,045,000
Related allowance	49,000	61,000	21,000
Ending Allowance Balance Total	845,000	1,181,000	1,066,000	968,000
Ending Loan Balance, individually evaluated for impairment	1,914,000		1,910,000
Ending Loan Balance, collectively evaluated for impairment	203,260,000		185,681,000
Impaired balance	4,130,000	4,404,000	3,841,000
Loans	205,188,000	187,714,000	187,591,000
Residential [Member] \| Real Estate Portfolio Segment [Member] \| Financial Asset Acquired with Credit Deterioration [Member]
Related allowance
Impaired balance	14,000
Farmland [Member] \| Real Estate Portfolio Segment [Member]
Ending Allowance Balance, individually evaluated for impairment	32,000		28,000
Ending Allowance Balance, collectively evaluated for impairment	657,000		840,000
Related allowance	32,000	36,000	28,000
Ending Allowance Balance Total	689,000	702,000	868,000	780,000
Ending Loan Balance, individually evaluated for impairment	2,752,000		1,032,000
Ending Loan Balance, collectively evaluated for impairment	71,480,000		66,835,000
Impaired balance	3,067,000	2,416,000	1,345,000
Loans	74,272,000	62,709,000	67,867,000
Farmland [Member] \| Real Estate Portfolio Segment [Member] \| Financial Asset Acquired with Credit Deterioration [Member]
Related allowance
Impaired balance	40,000
Consumer [Member] \| Consumer and Other Portfolio Segment [Member]
Ending Allowance Balance, individually evaluated for impairment			0
Ending Allowance Balance, collectively evaluated for impairment	63,000		30,000
Related allowance		0	0
Ending Allowance Balance Total	63,000	86,000	30,000	34,000
Ending Loan Balance, individually evaluated for impairment			0
Ending Loan Balance, collectively evaluated for impairment	23,066,000		18,746,000
Impaired balance	132,000	213,000	200,000
Loans	23,066,000	18,485,000	18,746,000
Consumer [Member] \| Consumer and Other Portfolio Segment [Member] \| Financial Asset Acquired with Credit Deterioration [Member]
Related allowance
Impaired balance
Other [Member] \| Consumer and Other Portfolio Segment [Member]
Ending Allowance Balance, individually evaluated for impairment			0
Ending Allowance Balance, collectively evaluated for impairment	18,000		1,000
Related allowance		0	0
Ending Allowance Balance Total	18,000	10,000	1,000	$ 3,000
Ending Loan Balance, individually evaluated for impairment			0
Ending Loan Balance, collectively evaluated for impairment	19,933,000		15,013,000
Impaired balance		4,000	0
Loans	19,933,000	$ 5,027,000	$ 15,013,000
Other [Member] \| Consumer and Other Portfolio Segment [Member] \| Financial Asset Acquired with Credit Deterioration [Member]
Related allowance
Impaired balance

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

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