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Note 5 - Loans - Average Balance and Interest Income Recognized Related to Impaired Loans (Details) - USD ($) $ in Thousands | 12 Months Ended
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Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015
Average Recorded Investment | $ 127,067 | $ 131,019 | $ 162,945
Contractual interest due | 3,302 | 3,462 | 3,997
Commercial Portfolio Segment [Member] |  |  |
Average Recorded Investment | 26,957 | 21,199 | 23,960
Contractual interest due | 1,303 | 767 | 546
Real Estate Construction Portfolio Segment [Member] |  |  |
Average Recorded Investment | 26,695 | 10,362 | 22,066
Contractual interest due |  |  | 261
Commercial Real Estate Portfolio Segment [Member] |  |  |
Average Recorded Investment | 58,635 | 81,905 | 100,118
Contractual interest due | 1,618 | 2,214 | 2,708
Residential Mortgage and Equity Lines Portfolio Segment [Member] |  |  |
Average Recorded Investment | 14,780 | 17,553 | 16,801
Contractual interest due | $ 381 | $ 481 | $ 482

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- Definition Average 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 15 -Subparagraph (c)(1) -URI http://asc.fasb.org/extlink&oid=84173941&loc=d3e5212-111524 Reference 2: http://www.xbrl.org/2003/role/presentationRef -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 + Details
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- Definition Amount of interest income recognized that the financing receivables (with related allowance for credit losses and without a related allowance for credit losses) were impaired. + 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 (c)(2) -URI http://asc.fasb.org/extlink&oid=84173941&loc=d3e5212-111524 + Details
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