Business Segments - Reconciliation of Revenue from Segments to Consolidated (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Segment Reporting Information
Total net sales	$ 118,365	$ 144,848	$ 381,835	$ 475,097
Segment profit (loss)	6,117	8,970
Interest expense - net	(940)	(1,078)	(2,841)	(4,030)
Other (expense) income - net	209	374	1,909	764
Pre-tax income	2,836	4,590	11,845	21,656
Rail Products and Services
Segment Reporting Information
Total net sales	63,988	67,741	209,131	244,836
Segment profit (loss)	3,742	3,417
Construction Products
Segment Reporting Information
Total net sales	37,883	47,175	108,925	139,926
Segment profit (loss)	1,756	1,848
Tubular and Energy Services
Segment Reporting Information
Total net sales	16,494	29,932	63,779	90,335
Segment profit (loss)	619	3,705
Operating Segments
Segment Reporting Information
Total net sales			381,835	475,097
Segment profit (loss)	6,117	8,970	19,565	35,811
Interest expense - net	(940)	(1,078)	(2,841)	(4,030)
Other (expense) income - net	(243)	374	2,178	764
Unallocated corporate expenses and other unallocated charges	(2,098)	(3,676)	(7,057)	(10,889)
Pre-tax income	$ 2,836	$ 4,590	11,845	21,656
Operating Segments | Rail Products and Services
Segment Reporting Information
Total net sales			209,131	244,836
Segment profit (loss)			10,729	14,815
Operating Segments | Construction Products
Segment Reporting Information
Total net sales			108,925	139,926
Segment profit (loss)			1,623	6,095
Operating Segments | Tubular and Energy Services
Segment Reporting Information
Total net sales			63,779	90,335
Segment profit (loss)			$ 7,213	$ 14,901