Business Segments (Reconciliation of Revenue from Segments to Consolidated) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Segment Reporting Information
Net Sales	$ 626,969	$ 536,377
Segment Profit	38,913	28,601
Assets	383,249	401,743
Depreciation/Amortization	18,593	19,841
Expenditures for Long-Lived Assets	5,251	6,149
Rail Products and Services
Segment Reporting Information
Net Sales	319,524	256,127
Construction Products
Segment Reporting Information
Net Sales	158,653	161,801
Tubular and Energy Services
Segment Reporting Information
Net Sales	148,792	118,449
Operating Segments
Segment Reporting Information
Net Sales	626,969	536,377
Segment Profit	38,913	28,601
Assets	363,239	375,898
Depreciation/Amortization	17,328	18,369
Expenditures for Long-Lived Assets	4,949	5,587
Operating Segments | Rail Products and Services
Segment Reporting Information
Net Sales	319,524	256,127
Segment Profit	19,468	11,078
Assets	175,704	192,038
Depreciation/Amortization	6,810	7,004
Expenditures for Long-Lived Assets	941	2,915
Operating Segments | Construction Products
Segment Reporting Information
Net Sales	158,653	161,801
Segment Profit	6,798	14,040
Assets	97,133	83,154
Depreciation/Amortization	1,728	1,955
Expenditures for Long-Lived Assets	796	1,390
Operating Segments | Tubular and Energy Services
Segment Reporting Information
Net Sales	148,792	118,449
Segment Profit	12,647	3,483
Assets	90,402	100,706
Depreciation/Amortization	8,790	9,410
Expenditures for Long-Lived Assets	$ 3,212	$ 1,282