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Note 2 - Summary of Significant Accounting Policies (Details Textual)	12 Months Ended
	Dec. 31, 2018 USD ($) shares	Dec. 31, 2017 USD ($) shares	Dec. 31, 2016 USD ($) shares	Jan. 01, 2019 USD ($)
Book Overdrafts	$ 0	$ 0
Workers' Compensation Liability	2,700,000	3,700,000
Workers' Compensation Liability, Current	452,000	422,000
Foreign Currency Transaction Gain (Loss), Realized	$ (400,000)	$ (200,000)	$ 100,000
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount | shares	63,000	196,000	198,000
Number of Customers with Receivable Balance in Excess of Ten Percent of Receivables	1	2
Subsequent Event [Member] | Accounting Standards Update 2016-02 [Member]
Operating Lease, Right-of-Use Asset				$ 8,000,000
Operating Lease, Liability, Total				$ 8,000,000
Reclassification from Cost of Sales to Other Income Expense [Member]
Prior Period Reclassification Adjustment		$ 0	$ 400,000
Performance Shares [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount | shares	39,000
Accrued Liability [Member]
Workers' Compensation Liability, Current	$ 500,000	400,000
Other Long-term Liabilities [Member]
Workers' Compensation Liability, Noncurrent	$ 2,200,000	$ 3,300,000
Minimum [Member]
Finite-Lived Intangible Asset, Useful Life	330 days
Maximum [Member]
Finite-Lived Intangible Asset, Useful Life	15 years
Land Improvements [Member] | Minimum [Member]
Property, Plant and Equipment, Useful Life	15 years
Land Improvements [Member] | Maximum [Member]
Property, Plant and Equipment, Useful Life	30 years
Building [Member] | Minimum [Member]
Property, Plant and Equipment, Useful Life	20 years
Building [Member] | Maximum [Member]
Property, Plant and Equipment, Useful Life	40 years
Machinery and Equipment [Member] | Minimum [Member]
Property, Plant and Equipment, Useful Life	3 years
Machinery and Equipment [Member] | Maximum [Member]
Property, Plant and Equipment, Useful Life	30 years

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