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Note 2 - Summary of Significant Accounting Policies (Details Textual) $ in Thousands		3 Months Ended								12 Months Ended
	Jan. 01, 2019 USD ($)	Dec. 31, 2019 USD ($)	Sep. 30, 2019 USD ($)	Jun. 30, 2019 USD ($)	Mar. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Sep. 30, 2018 USD ($)	Jun. 30, 2018 USD ($)	Mar. 31, 2018 USD ($)	Dec. 31, 2019 USD ($) shares	Dec. 31, 2018 USD ($) shares	Dec. 31, 2017 USD ($) shares
Revenue from Contract with Customer, Including Assessed Tax		$ 72,245	$ 75,226	$ 69,203	$ 62,643	$ 57,544	$ 52,455	$ 28,785	$ 33,365	$ 279,317	$ 172,149	$ 132,780
Book Overdrafts		0				0				0	0
Workers' Compensation Liability		1,700				2,700				1,700	2,700
Workers' Compensation Liability, Current		$ 269				452				269	452
Foreign Currency Transaction Gain (Loss), Realized										$ 500	$ (400)	$ (200)
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount | shares										0	63,000	196,000
Restricted Stock Units and Performance Share Award Target Level, Percentage		100.00%								100.00%
Number of Customers with Receivable Balance in Excess of Ten Percent of Receivables										1	1
Accounting Standards Update 2016-02 [Member]
Operating Lease, Right-of-Use Asset	$ 8,000
Operating Lease, Liability, Total	8,000
Accounting Standards Update 2018-02 [Member]
Tax Cuts and Jobs Act, Reclassification from AOCI to Retained Earnings, Tax Effect	$ 200
Performance Shares [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount | shares											39,000
Accrued Liability [Member]
Workers' Compensation Liability, Current		$ 300				500				$ 300	$ 500
Other Long-term Liabilities [Member]
Workers' Compensation Liability, Noncurrent		$ 1,400				$ 2,200				$ 1,400	$ 2,200
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
Out of Period Adjustment [Member]
Revenue from Contract with Customer, Including Assessed Tax					$ (1,200)

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