Revenue - Timing of Transfer (Details) - USD ($) $ in Thousands	3 Months Ended
	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