Business Segments (Segment Net Sales, Profit (Loss), Assets, Depreciation and Amortization, and Capital Expenditures) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Segment Reporting Information
Net Sales	$ 536,377	$ 483,514	$ 624,523
Segment Profit	27,685	(134,165)	(41,349)
Segment Assets	396,556	393,023	566,660
Depreciation/Amortization	19,841	23,492	26,674
Expenditures for Long-Lived Assets	6,149	7,664	15,201
Operating Segments
Segment Reporting Information
Net Sales	536,377	483,514	624,523
Segment Profit	27,685	(134,165)	(41,349)
Segment Assets	375,898	355,129	544,272
Depreciation/Amortization	18,369	22,176	25,675
Expenditures for Long-Lived Assets	5,587	5,353	9,836
Operating Segments | Rail Products and Services
Segment Reporting Information
Net Sales	256,127	239,127	328,982
Segment Profit	12,216	(26,228)	27,037
Segment Assets	192,038	174,049	241,222
Depreciation/Amortization	7,004	7,276	8,098
Expenditures for Long-Lived Assets	2,915	856	4,273
Operating Segments | Construction Products
Segment Reporting Information
Net Sales	161,801	145,602	176,394
Segment Profit	11,620	8,189	12,958
Segment Assets	83,154	81,074	86,335
Depreciation/Amortization	1,955	2,256	2,720
Expenditures for Long-Lived Assets	1,390	687	1,260
Operating Segments | Tubular and Energy Services
Segment Reporting Information
Net Sales	118,449	98,785	119,147
Segment Profit	3,849	(116,126)	(81,344)
Segment Assets	100,706	100,006	216,715
Depreciation/Amortization	9,410	12,644	14,857
Expenditures for Long-Lived Assets	$ 1,282	$ 3,810	$ 4,303