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Note 4 - Loans and Related Allowance for Loan and Lease Losses - Impaired Loans by Class (Details) - USD ($) $ in Thousands | Dec. 31, 2017 | Dec. 31, 2016
--- | --- | ---
Recorded investment, with no related allowance | $ 4,053 | $ 5,405
Unpaid principal balance, with no related allowance | 4,942 | 5,394
Recorded investment, with related allowance | 8,056 | 7,025
Unpaid principal balance, with related allowance | 8,980 | 7,011
Related allowance | 1,567 | 527
Recorded investment | 12,109 | 12,430
Unpaid principal balance | 13,922 | 12,405
Commercial Loans [Member] |  |
Recorded investment, with related allowance | 3,740 |
Unpaid principal balance, with related allowance | 3,913 |
Related allowance | 733 |
Commercial And Industrial [Member] |  |
Recorded investment, with no related allowance | 450 | 319
Unpaid principal balance, with no related allowance | 1,006 | 318
Recorded investment, with related allowance | 3,177 | 871
Unpaid principal balance, with related allowance | 3,888 | 868
Related allowance | 694 | 90
Recorded investment | 3,627 | 1,190
Unpaid principal balance | 4,894 | 1,186
Real Estate Construction Porfolio Segment [Member] |  |
Recorded investment, with no related allowance | 44 | 913
Unpaid principal balance, with no related allowance | 44 | 909
Recorded investment, with related allowance | 44 | 913
Unpaid principal balance, with related allowance | 44 | 909
Related allowance |  |
Real Estate Construction Porfolio Segment [Member] | Residential Loan [Member] |  |
Recorded investment, with related allowance | 1,139 |
Unpaid principal balance, with related allowance | 1,179 |
Related allowance | 140 |
Real Estate Mortgage Portfolio Segment [Member] | Residential Loan [Member] |  |
Recorded investment, with no related allowance | 1,685 | 2,142
Unpaid principal balance, with no related allowance | 1,904 | 2,140
Recorded investment, with related allowance |  | 993
Unpaid principal balance, with related allowance |  | 991
Related allowance | 140 | 251
Recorded investment | 2,824 | 3,135
Unpaid principal balance | 3,083 | 3,131
Real Estate Mortgage Portfolio Segment [Member] | Commercial Loans [Member] |  |
Recorded investment, with no related allowance | 1,870 | 2,031
Unpaid principal balance, with no related allowance | 1,984 | 2,027
Recorded investment, with related allowance |  | 5,156
Unpaid principal balance, with related allowance |  | 5,147
Related allowance | 733 | 186
Recorded investment | 5,610 | 7,187
Unpaid principal balance | 5,897 | 7,174
Consumer Portfolio Segment [Member] |  |
Recorded investment, with no related allowance |  | 5
Unpaid principal balance, with no related allowance |  | 5
Recorded investment, with related allowance | 4 | 5
Unpaid principal balance, with related allowance | 4 | $ 5
Related allowance |  |
Recorded investment | 4 |
Unpaid principal balance | $ 4 |

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- Definition Amount of investment of impaired financing receivables with related allowance for credit losses and without a related allowance for credit losses. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -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 + Details
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- Definition Amount of allowance for credit losses related to recorded investment. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 15 -Subparagraph (a)(3) -URI http://asc.fasb.org/extlink&oid=84173941&loc=d3e5212-111524 + Details
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- Definition Amount of unpaid principal balance of impaired financing receivables with related allowance for credit losses and without related allowance for credit losses. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 15 -Subparagraph (a)(4) -URI http://asc.fasb.org/extlink&oid=84173941&loc=d3e5212-111524 + Details
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