Note 4 - Loans - Impaired Loans (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017
Unpaid contractual principal	$ 1,269	$ 1,659
Recorded investment with no allowance	14	318
Recorded investment with allowance	906	993
Total recorded investment	920	1,311
Related allowance	680	680
Average recorded investment	1,148	2,139
Commercial Real Estate Portfolio Segment [Member] \| Construction Loans [Member]
Unpaid contractual principal	0	0
Recorded investment with no allowance	0	0
Recorded investment with allowance	0	0
Total recorded investment	0	0
Related allowance	0	0
Average recorded investment	0	0
Commercial Real Estate Portfolio Segment [Member] \| Mortgage Loans [Member]
Unpaid contractual principal	0	0
Recorded investment with no allowance	0	0
Recorded investment with allowance	0	0
Total recorded investment	0	0
Related allowance	0	0
Average recorded investment	0	0
Commercial Real Estate Portfolio Segment [Member] \| Land Loans [Member]
Unpaid contractual principal	1,222	1,309
Recorded investment with no allowance	0	0
Recorded investment with allowance	906	993
Total recorded investment	906	993
Related allowance	680	680
Average recorded investment	958	1,760
Commercial Real Estate Portfolio Segment [Member] \| Farmland Loans [Member]
Unpaid contractual principal	0	0
Recorded investment with no allowance	0	0
Recorded investment with allowance	0	0
Total recorded investment	0	0
Related allowance	0	0
Average recorded investment	0	0
Commercial Portfolio Segment [Member]
Unpaid contractual principal	32	334
Recorded investment with no allowance	0	302
Recorded investment with allowance	0	0
Total recorded investment	0	302
Related allowance	0	0
Average recorded investment	176	303
Consumer Portfolio Segment [Member]
Unpaid contractual principal	0	0
Recorded investment with no allowance	0	0
Recorded investment with allowance	0	0
Total recorded investment	0	0
Related allowance	0	0
Average recorded investment	0	0
Residential Portfolio Segment [Member]
Unpaid contractual principal	15	16
Recorded investment with no allowance	14	16
Recorded investment with allowance	0	0
Total recorded investment	14	16
Related allowance	0	0
Average recorded investment	14	76
Agriculture [Member]
Unpaid contractual principal	0	0
Recorded investment with no allowance	0	0
Recorded investment with allowance	0	0
Total recorded investment	0	0
Related allowance	0	0
Average recorded investment	$ 0	$ 0

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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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 14A
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=84173941&loc=SL6953550-111524

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