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Note 1 - Summary of Significant Accounting Policies (Details Textual) $ in Thousands | 12 Months Ended
--- | ---
Dec. 31, 2020 USD ($) | Dec. 31, 2019 USD ($) | Dec. 31, 2018 USD ($)
Percentage of LIFO Inventory | 71.00% | 72.00% |
Depreciation, Total | $ 11,400 | $ 12,600 | $ 13,300
Goodwill, Impairment Loss | 0 | 0 | 0
Advertising Expense | 2,100 | 3,000 | 3,000
Performance Shares [Member] |  |  |
Share-based Payment Arrangement, Expense | $ 300 | $ 700 | $ 1,300
The 2015 Omnibus Incentive Plan [Member] |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period (Year) | 3 years |  |
Customer Concentration Risk [Member] | Revenue Benchmark [Member] |  |  |
Number of Major Customers | 0 | 0 | 0

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- Definition Amount charged to advertising expense for the period, which are expenses incurred with the objective of increasing revenue for a specified brand, product or product line. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 720 -SubTopic 35 -Section 50 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=6420018&loc=d3e36677-107848 + Details
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