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Note 16 - Revenue 1 (Details Textual) $ in Millions	12 Months Ended
	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)
Increase (Decrease) in Revenue from Contract with Customers, Including Assessed Tax	$ (0.2)	$ (0.2)	$ 1.7
Contract with Customer, Liability, Revenue Recognized	2.6	$ 1.9	$ 0.5
Revenue, Remaining Performance Obligation, Amount	81.3
Ameron Water Transmission Group, LLC [Member]
Contract with Customer, Asset, Increase (Decrease) for Contract Acquired in Business Combination	12.0
Contract with Customer, Liability, Increase (Decrease) for Contract Acquired in Business Combination	$ 0.1
Sales Revenue, Net [Member] | Customer Concentration Risk [Member]
Concentration Risk, Percentage			28.00%
Number of Major Customers			1

X

- Definition

The increase (decrease) during the period of the amount, including tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer.

+ References

No definition available.

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X

- Definition

Represents the number of major customers accounting for 10% or more of the specified concentration risk benchmark, which includes, but not limited to, sales revenue, accounts receivable, etc.

+ References

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- Definition

For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

+ References

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- Definition

Amount of increase (decrease) in right to consideration in exchange for good or service transferred to customer when right is conditioned on something other than passage of time, from business combination.

+ References

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- Definition

Amount of increase (decrease) in obligation to transfer good or service to customer for which consideration from customer has been received or is due, from business combination.

+ References

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Amount of revenue recognized that was previously included in balance of obligation to transfer good or service to customer for which consideration from customer has been received or is due.

+ References

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- Definition

Amount of transaction price allocated to performance obligation that has not been recognized as revenue.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
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