Business Segments - Reconciliation of Revenue from Segments to Consolidated (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Segment Reporting Information
Total net sales	$ 145,766	$ 200,933	$ 274,541	$ 351,402
Segment Profit (Loss)	3,217	16,351
Interest expense - net	(1,090)	(1,597)	(1,907)	(2,952)
Other income - net	(3,339)	252	(4,085)	402
Pre-tax income	1,616	11,249	(1,078)	15,577
Rail Products and Services
Segment Reporting Information
Total net sales	74,939	101,401	145,143	177,095
Segment Profit (Loss)	5,816	7,919
Construction Products
Segment Reporting Information
Total net sales	42,008	55,406	71,042	92,751
Segment Profit (Loss)	1,506	3,413
Tubular and Energy Services
Segment Reporting Information
Total net sales	28,819	44,126	58,356	81,556
Segment Profit (Loss)	(4,105)	5,019
Operating Segments
Segment Reporting Information
Total net sales			274,541	351,402
Segment Profit (Loss)	3,217	16,351	3,361	25,352
Interest expense - net	(1,090)	(1,597)	(1,907)	(2,952)
Other income - net	2,292	252	2,427	402
Unallocated corporate expenses and other unallocated charges	(2,803)	(3,757)	(4,959)	(7,225)
Pre-tax income	$ 1,616	$ 11,249	(1,078)	15,577
Operating Segments | Rail Products and Services
Segment Reporting Information
Total net sales			145,143	177,095
Segment Profit (Loss)			6,987	11,398
Operating Segments | Construction Products
Segment Reporting Information
Total net sales			71,042	92,751
Segment Profit (Loss)			(133)	4,247
Operating Segments | Tubular and Energy Services
Segment Reporting Information
Total net sales			58,356	81,556
Segment Profit (Loss)			$ (3,493)	$ 9,707