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Note 2 - Summary of Significant Accounting Policies (Details Textual) shares in Thousands, $ in Thousands	3 Months Ended									12 Months Ended
	Dec. 31, 2021 USD ($)	Sep. 30, 2021 USD ($)	Jun. 30, 2021 USD ($)	Mar. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)	Sep. 30, 2020 USD ($)	Jun. 30, 2020 USD ($)	Mar. 31, 2020 USD ($)	Mar. 31, 2019 USD ($)	Dec. 31, 2021 USD ($) shares	Dec. 31, 2020 USD ($) shares	Dec. 31, 2019 USD ($) shares
Revenue from Contract with Customer, Including Assessed Tax	$ 102,547	$ 84,643	$ 73,812	$ 72,311	$ 69,381	$ 77,632	$ 69,971	$ 68,923		$ 333,313	$ 285,907	$ 279,317
Book Overdrafts	4,100				0					4,100	0
Workers' Compensation Liability	1,700				1,700					1,700	1,700
Workers' Compensation Liability, Current	366				237					366	237
Foreign Currency Transaction Gain (Loss), Realized										$ (500)	$ (1,100)	$ 500
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount (in shares) | shares										0	0	0
Number of Customers with Receivable Balance in Excess of Ten Percent of Receivables										0	1
Accrued Liability [Member]
Workers' Compensation Liability, Current	400				200					$ 400	$ 200
Other Long-term Liabilities [Member]
Workers' Compensation Liability, Noncurrent	$ 1,300				$ 1,500					$ 1,300	$ 1,500
Minimum [Member]
Finite-Lived Intangible Asset, Useful Life (Month)										7 months
Maximum [Member]
Finite-Lived Intangible Asset, Useful Life (Month)										21 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
Leasehold Improvements [Member] | Minimum [Member]
Property, Plant and Equipment, Useful Life (Year)										5 years
Leasehold Improvements [Member] | Maximum [Member]
Property, Plant and Equipment, Useful Life (Year)										30 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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