Business Segments (Reconciliation of Revenue from Segments to Consolidated) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Segment Reporting Information
Net Sales	$ 122,454	$ 118,702
Operating Segments
Segment Reporting Information
Net Sales	122,454	118,702
Segment Profit (Loss)	3,951	1,809
Operating Segments | Rail Products and Services
Segment Reporting Information
Net Sales	62,170	56,480
Segment Profit (Loss)	2,048	823
Operating Segments | Construction Products
Segment Reporting Information
Net Sales	28,900	37,322
Segment Profit (Loss)	18	1,666
Operating Segments | Tubular and Energy Services
Segment Reporting Information
Net Sales	31,384	24,900
Segment Profit (Loss)	$ 1,885	$ (680)