Average amount of investment of impaired financing receivables with related allowance for credit losses and without a related allowance for credit losses.

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Note 4 - Loans and the Allowance for Loan Losses - Impaired Loans (Details) - USD ($)	3 Months Ended		12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Recorded investment with no related allowance recorded	$ 841,000		$ 851,000
Recorded investment with an allowance	897,000		424,000
Impaired Financing Receivable, Related Allowance	229,000		181,000
Recorded investment	1,738,000		1,275,000
Unpaid principal balance	1,767,000		1,299,000
Average recorded investment	1,352,000	$ 2,002,000	1,160,000
Interest income recognized	18,000	$ 18,000	71,000
Commercial Portfolio Segment [Member] \| Commercial Loans [Member]
Recorded investment with no related allowance recorded
Unpaid principal balance with no related allowance recorded
Average recorded investment with no related allowance recorded
Interest income recognized with no related allowance recorded
Recorded investment with an allowance	123,000		128,000
Unpaid principal balance with allowance	128,000		128,000
Impaired Financing Receivable, Related Allowance	123,000		128,000
Average recorded investment with an allowance	123,000		1,000
Interest income recognized with an allowance
Recorded investment	123,000		128,000
Unpaid principal balance	128,000		128,000
Average recorded investment	123,000		1,000
Interest income recognized
Commercial Portfolio Segment [Member] \| Agricultural Loans [Member]
Recorded investment with no related allowance recorded	250,000		250,000
Unpaid principal balance with no related allowance recorded	250,000		250,000
Average recorded investment with no related allowance recorded	250,000		252,000
Interest income recognized with no related allowance recorded	5,000		19,000
Recorded investment with an allowance
Unpaid principal balance with allowance
Impaired Financing Receivable, Related Allowance
Average recorded investment with an allowance
Interest income recognized with an allowance
Recorded investment	250,000		250,000
Unpaid principal balance	250,000		250,000
Average recorded investment	250,000		252,000
Interest income recognized	5,000		19,000
Commercial Portfolio Segment [Member] \| Real Estate Loan [Member]
Recorded investment with no related allowance recorded	131,000		131,000
Unpaid principal balance with no related allowance recorded	144,000		144,000
Average recorded investment with no related allowance recorded	131,000		136,000
Interest income recognized with no related allowance recorded
Recorded investment with an allowance	480,000
Unpaid principal balance with allowance	480,000
Impaired Financing Receivable, Related Allowance	61,000
Average recorded investment with an allowance	91,000
Interest income recognized with an allowance
Recorded investment	611,000		131,000
Unpaid principal balance	624,000		144,000
Average recorded investment	222,000		136,000
Interest income recognized
Commercial Portfolio Segment [Member] \| Construction Loans [Member]
Recorded investment with no related allowance recorded
Unpaid principal balance with no related allowance recorded
Average recorded investment with no related allowance recorded
Interest income recognized with no related allowance recorded
Recorded investment with an allowance	115,000		117,000
Unpaid principal balance with allowance	115,000		117,000
Impaired Financing Receivable, Related Allowance	10,000		12,000
Average recorded investment with an allowance	116,000		120,000
Interest income recognized with an allowance	2,000		7,000
Recorded investment	115,000		117,000
Unpaid principal balance	115,000		117,000
Average recorded investment	116,000		120,000
Interest income recognized	2,000		7,000
Residential Portfolio Segment [Member] \| Real Estate Loan [Member]
Recorded investment with no related allowance recorded	460,000		470,000
Unpaid principal balance with no related allowance recorded	471,000		481,000
Average recorded investment with no related allowance recorded	462,000		470,000
Interest income recognized with no related allowance recorded	9,000		38,000
Recorded investment with an allowance	179,000		179,000
Unpaid principal balance with allowance	179,000		179,000
Impaired Financing Receivable, Related Allowance	35,000		41,000
Average recorded investment with an allowance	179,000		181,000
Interest income recognized with an allowance	2,000		7,000
Recorded investment	639,000		649,000
Unpaid principal balance	650,000		660,000
Average recorded investment	641,000		651,000
Interest income recognized	11,000		45,000
Residential Portfolio Segment [Member] \| Equity Lines of Credit [Member]
Recorded investment with no related allowance recorded
Unpaid principal balance with no related allowance recorded
Average recorded investment with no related allowance recorded
Interest income recognized with no related allowance recorded
Recorded investment with an allowance
Unpaid principal balance with allowance
Impaired Financing Receivable, Related Allowance
Average recorded investment with an allowance
Interest income recognized with an allowance
Recorded investment
Unpaid principal balance
Average recorded investment
Interest income recognized
Consumer Portfolio Segment [Member] \| Automobile Loan [Member]
Recorded investment with no related allowance recorded
Unpaid principal balance with no related allowance recorded
Average recorded investment with no related allowance recorded
Interest income recognized with no related allowance recorded
Recorded investment with an allowance
Unpaid principal balance with allowance
Impaired Financing Receivable, Related Allowance
Average recorded investment with an allowance
Interest income recognized with an allowance
Recorded investment
Unpaid principal balance
Average recorded investment
Interest income recognized
Consumer Portfolio Segment [Member] \| Other Loans [Member]
Recorded investment with no related allowance recorded
Unpaid principal balance with no related allowance recorded
Average recorded investment with no related allowance recorded
Interest income recognized with no related allowance recorded
Recorded investment with an allowance
Unpaid principal balance with allowance
Impaired Financing Receivable, Related Allowance
Average recorded investment with an allowance
Interest income recognized with an allowance
Recorded investment
Unpaid principal balance
Average recorded investment
Interest income recognized