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Note 7 - Pensions and Other Postretirement Benefits - Allocation of Plan Assets (Details) - USD ($) $ in Thousands | Dec. 31, 2017 | Dec. 31, 2016
--- | --- | ---
Plan Fair Value Assets | $ 80,802 | $ 83,318
Plan Fair Value Assets, Percentage | 100.00% | 100.00%
Fair Value, Inputs, Level 1 [Member] |  |
Plan Fair Value Assets | $ 34,240 | $ 42,691
Plan Fair Value Assets, Percentage | 43.00% | 51.00%
Fair Value, Inputs, Level 2 [Member] |  |
Plan Fair Value Assets | $ 46,556 | $ 40,597
Plan Fair Value Assets, Percentage | 57.00% | 49.00%
Fair Value, Inputs, Level 3 [Member] |  |
Plan Fair Value Assets | $ 6 | $ 30
Plan Fair Value Assets, Percentage |  |
Equity Securities [Member] |  |
Plan Fair Value Assets, Percentage |  |
Equity Securities [Member] | Fair Value, Inputs, Level 1 [Member] |  |
Plan Fair Value Assets | $ 14,637 | $ 19,752
Plan Fair Value Assets, Percentage | 18.00% | 24.00%
Equity Securities [Member] | Fair Value, Inputs, Level 3 [Member] |  |
Plan Fair Value Assets | $ 6 | $ 30
Plan Fair Value Assets, Percentage |  |
Fixed Income Securities [Member] | Fair Value, Inputs, Level 1 [Member] |  |
Plan Fair Value Assets | $ 12,573 | $ 11,805
Plan Fair Value Assets, Percentage | 16.00% | 14.00%
Fixed Income Securities [Member] | Fair Value, Inputs, Level 2 [Member] |  |
Plan Fair Value Assets | $ 46,556 | $ 40,597
Plan Fair Value Assets, Percentage | 57.00% | 49.00%
Mutual Funds [Member] | Fair Value, Inputs, Level 1 [Member] |  |
Plan Fair Value Assets | $ 857 |
Plan Fair Value Assets, Percentage | 1.00% |
Cash and Cash Equivalents [Member] | Fair Value, Inputs, Level 1 [Member] |  |
Plan Fair Value Assets | $ 6,173 | $ 11,134
Plan Fair Value Assets, Percentage | 8.00% | 13.00%
Money Market Funds [Member] | Fair Value, Inputs, Level 2 [Member] |  |
Plan Fair Value Assets |  |
Plan Fair Value Assets, Percentage |  |

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- Definition Fair value of assets that have been segregated and restricted to provide pension or postretirement benefits. Assets include, but are not limited to, stocks, bonds, other investments, earnings from investments, and contributions by the employer and employees. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e1928-114920 + Details
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- Definition Percentage of fair value of investments (categorized by debt securities, equity securities, real estate and other plan assets) to the fair value of plan assets held. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 5 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e2446-114920 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (d)(1) -URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e1928-114920 + Details
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