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Revenue - Timing of Transfer (Details) - USD ($) $ in Thousands | 3 Months Ended
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Mar. 31, 2020 | Mar. 31, 2019
Disaggregation of Revenue |  |
Total net sales | $ 128,775 | $ 150,469
Point in time |  |
Disaggregation of Revenue |  |
Total net sales | 95,998 | 108,721
Over time |  |
Disaggregation of Revenue |  |
Total net sales | 32,777 | 41,748
Rail Products and Services |  |
Disaggregation of Revenue |  |
Total net sales | 70,204 | 75,694
Rail Products and Services | Point in time |  |
Disaggregation of Revenue |  |
Total net sales | 54,888 | 56,492
Rail Products and Services | Over time |  |
Disaggregation of Revenue |  |
Total net sales | 15,316 | 19,202
Construction Products |  |
Disaggregation of Revenue |  |
Total net sales | 29,034 | 37,345
Construction Products | Point in time |  |
Disaggregation of Revenue |  |
Total net sales | 16,883 | 23,095
Construction Products | Over time |  |
Disaggregation of Revenue |  |
Total net sales | 12,151 | 14,250
Tubular and Energy Services |  |
Disaggregation of Revenue |  |
Total net sales | 29,537 | 37,430
Tubular and Energy Services | Point in time |  |
Disaggregation of Revenue |  |
Total net sales | 24,227 | 29,134
Tubular and Energy Services | Over time |  |
Disaggregation of Revenue |  |
Total net sales | $ 5,310 | $ 8,296

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