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Note 12 - Segment Information (Details Textual) - Operating Segments [Member] - USD ($) $ in Millions | 3 Months Ended | 9 Months Ended
--- | --- | ---
Sep. 30, 2025 | Sep. 30, 2024 | Sep. 30, 2025 | Sep. 30, 2024
Water Transmission Systems [Member] |  |  |  |
Cost, Depreciation, Amortization and Depletion | $ 3.0 | $ 3.1 | $ 8.4 | $ 8.8
Precast Infrastructure and Engineered Systems [Member] |  |  |  |
Cost, Depreciation, Amortization and Depletion | $ 1.1 | $ 0.9 | $ 2.7 | $ 2.1

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