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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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