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Note 20 - Quarterly Data (Unaudited) (Details Textual) - USD ($) $ in Thousands		1 Months Ended		3 Months Ended			12 Months Ended
	Jul. 27, 2018	Dec. 31, 2018	Aug. 31, 2018	Dec. 31, 2018	Sep. 30, 2018	Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Gain (Loss) on Disposition of Property Plant Equipment, Total							$ (222)	$ 51	$ (19)
Business Combination, Bargain Purchase, Gain Recognized, Amount					$ 21,900		$ 20,080
Cost of Sales [Member]
Workers Compensation Expense						$ 1,200
Ameron Water Transmission Group, LLC [Member]
Business Combination, Bargain Purchase, Gain Recognized, Amount	$ 20,080
Business Combination, Bargain Purchase, Increase (Decrease) in Gain Recognized, Measurement Period Adjustment				$ (1,800)
Property in Houston, Texas [Member]
Gain (Loss) on Disposition of Property Plant Equipment, Total			$ 2,800		$ 2,800
Monterrey, Mexico Facility [Member]
Gain (Loss) on Disposition of Property Plant Equipment, Total		$ 200		$ 200

X

- Definition

In a business combination in which the amount of net identifiable assets acquired and liabilities assumed exceeds the aggregate consideration transferred or to be transferred (as defined) due to measurement period adjustment, this element represents the increase (decrease) amount of gain recognized by the entity.

+ References

No definition available.

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X

- Definition

Amount of workers compensation charge related to a change in estimate to workers compensation reserves.

+ References

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- Definition

In a business combination in which the amount of net identifiable assets acquired and liabilities assumed exceeds the aggregate consideration transferred or to be transferred (as defined), this element represents the amount of gain recognized by the entity.

+ References

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- Definition

Amount of gain (loss) on sale or disposal of property, plant and equipment assets, including oil and gas property and timber property.

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