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Note 6 - Investment Securities Available for Sale - Gross Unrealized Losses and Fair Value (Details) - USD ($) | Sep. 30, 2016 | Dec. 31, 2015
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US Government Agencies Debt Securities [Member] |  |
Less than Twelve Months, Fair Value | $ 2,000,000 | $ 3,818,000
Less than Twelve Months, Gross Unrealized Losses | 0 | (57,000)
Twelve Months or Greater, Fair Value | 1,465,000 | 10,872,000
Twelve Months or Greater, Gross Unrealized Losses | (12,000) | (214,000)
Total, Fair Value | 3,465,000 | 14,690,000
Total, Gross Unrealized Losses | (12,000) | (271,000)
US States and Political Subdivisions Debt Securities [Member] | Tax Exempt [Member] |  |
Less than Twelve Months, Fair Value | 608,000 | 1,268,000
Less than Twelve Months, Gross Unrealized Losses | 0 | (9,000)
Twelve Months or Greater, Fair Value | 0 | 9,394,000
Twelve Months or Greater, Gross Unrealized Losses | (5,000) | (166,000)
Total, Fair Value | 608,000 | 10,662,000
Total, Gross Unrealized Losses | (5,000) | (175,000)
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member] |  |
Less than Twelve Months, Fair Value | 0 | 8,725,000
Less than Twelve Months, Gross Unrealized Losses | 0 | (86,000)
Twelve Months or Greater, Fair Value | 4,709,000 | 6,685,000
Twelve Months or Greater, Gross Unrealized Losses | (44,000) | (186,000)
Total, Fair Value | 4,709,000 | 15,410,000
Total, Gross Unrealized Losses | (44,000) | (272,000)
Mortgage-backed Securities, Issued by Private Enterprises [Member] |  |
Less than Twelve Months, Fair Value | 75,000 |
Less than Twelve Months, Gross Unrealized Losses | 0 |
Twelve Months or Greater, Fair Value | 0 |
Twelve Months or Greater, Gross Unrealized Losses | 0 |
Total, Fair Value | 75,000 |
Total, Gross Unrealized Losses | 0 |
Less than Twelve Months, Fair Value | 2,683,000 | 13,811,000
Less than Twelve Months, Gross Unrealized Losses | 0 | (152,000)
Twelve Months or Greater, Fair Value | 6,174,000 | 26,951,000
Twelve Months or Greater, Gross Unrealized Losses | (61,000) | (566,000)
Total, Fair Value | 8,857,000 | 40,762,000
Total, Gross Unrealized Losses | $ (61,000) | $ (718,000)

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- Definition Amount of accumulated unrealized loss on investments in debt and equity securities classified as available-for-sale that have been in a continuous loss position for twelve months or longer. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 6 -Subparagraph (a)(2) -URI http://asc.fasb.org/extlink&oid=73527792&loc=d3e27290-111563 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 7 -URI http://asc.fasb.org/extlink&oid=73527792&loc=d3e27337-111563 + Details
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- Definition Amount of accumulated unrealized loss on investments in debt and equity securities classified as available-for-sale in a continuous loss position. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 7 -URI http://asc.fasb.org/extlink&oid=73527792&loc=d3e27337-111563 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 6 -Subparagraph (a)(2) -URI http://asc.fasb.org/extlink&oid=73527792&loc=d3e27290-111563 + Details
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- Definition This item represents the aggregate fair value of investments in debt and equity securities in an unrealized loss position which are categorized neither as held-to-maturity nor trading securities. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 6 -Subparagraph (a)(1) -URI http://asc.fasb.org/extlink&oid=73527792&loc=d3e27290-111563 + Details
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- Definition Amount of accumulated unrealized loss on investments in debt and equity securities classified as available-for-sale that have been in a continuous loss position for less than twelve months. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 6 -Subparagraph (a)(2) -URI http://asc.fasb.org/extlink&oid=73527792&loc=d3e27290-111563 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 7 -URI http://asc.fasb.org/extlink&oid=73527792&loc=d3e27337-111563 + Details
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