Business Segments (Reconciliation of Revenue from Segments to Consolidated) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Segment Reporting Information
Total net sales	$ 154,276	$ 167,094	$ 505,678	$ 462,438
Segment Profit	7,495	11,176	32,847	27,837
Rail Products and Services
Segment Reporting Information
Total net sales	67,741	84,517	244,836	238,571
Construction Products
Segment Reporting Information
Total net sales	47,175	41,534	139,926	112,641
Tubular and Energy Services
Segment Reporting Information
Total net sales	39,360	41,043	120,916	111,226
Operating Segments
Segment Reporting Information
Total net sales	154,276	167,094	505,678	462,438
Segment Profit	7,495	11,176	32,847	27,837
Operating Segments | Rail Products and Services
Segment Reporting Information
Total net sales	67,741	84,517	244,836	238,571
Segment Profit	3,417	5,299	14,815	12,655
Operating Segments | Construction Products
Segment Reporting Information
Total net sales	47,175	41,534	139,926	112,641
Segment Profit	1,848	1,603	6,095	4,478
Operating Segments | Tubular and Energy Services
Segment Reporting Information
Total net sales	39,360	41,043	120,916	111,226
Segment Profit	$ 2,230	$ 4,274	$ 11,937	$ 10,704