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Note 2 - Summary of Significant Accounting Policies (Details Textual) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2019 USD ($)	Dec. 31, 2020 USD ($) shares	Dec. 31, 2019 USD ($) shares	Dec. 31, 2018 USD ($) shares
Revenue from Contract with Customer, Including Assessed Tax		$ 285,907	$ 279,317	$ 172,149
Workers' Compensation Liability		1,700	1,700
Workers' Compensation Liability, Current		237	269
Foreign Currency Transaction Gain (Loss), Realized		$ (1,100)	$ 500	$ (400)
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount (in shares) | shares		0	0	63,000
Restricted Stock Units and Performance Share Award Target Level, Percentage			100.00%
Number of Customers with Receivable Balance in Excess of Ten Percent of Receivables		1	1
Performance Shares [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount (in shares) | shares				39,000
Restricted Stock Units and Performance Share Award Target Level, Percentage		100.00%
Accrued Liability [Member]
Workers' Compensation Liability, Current		$ 200	$ 300
Other Long-term Liabilities [Member]
Workers' Compensation Liability, Noncurrent		$ 1,500	$ 1,400
Minimum [Member]
Finite-Lived Intangible Asset, Useful Life (Year)		3 years
Maximum [Member]
Finite-Lived Intangible Asset, Useful Life (Year)		15 years
Land Improvements [Member] | Minimum [Member]
Property, Plant and Equipment, Useful Life (Year)		15 years
Land Improvements [Member] | Maximum [Member]
Property, Plant and Equipment, Useful Life (Year)		30 years
Building [Member] | Minimum [Member]
Property, Plant and Equipment, Useful Life (Year)		20 years
Building [Member] | Maximum [Member]
Property, Plant and Equipment, Useful Life (Year)		40 years
Machinery and Equipment [Member] | Minimum [Member]
Property, Plant and Equipment, Useful Life (Year)		3 years
Machinery and Equipment [Member] | Maximum [Member]
Property, Plant and Equipment, Useful Life (Year)		30 years
Out of Period Adjustment [Member]
Revenue from Contract with Customer, Including Assessed Tax	$ (1,200)

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