Business Segments - Reconciliation of Revenue from Segments to Consolidated (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Segment Reporting Information
Net Sales	$ 513,620	$ 497,411
Segment Operating Profit (Loss)	4,471	15,633
Segment Assets	342,595	370,395
Depreciation/Amortization	13,887	13,579
Expenditures for Long-Lived Assets	4,620	9,179
Rail, Technologies, and Services
Segment Reporting Information
Net Sales	299,749	276,447
Precast Concrete Products
Segment Reporting Information
Net Sales	70,990	63,314
Steel Products and Measurement
Segment Reporting Information
Net Sales	142,881	157,650
Operating Segments
Segment Reporting Information
Net Sales	513,620	497,411
Segment Operating Profit (Loss)	13,308	21,696
Segment Assets	278,725	299,004
Depreciation/Amortization	12,543	12,222
Expenditures for Long-Lived Assets	3,600	8,504
Operating Segments | Rail, Technologies, and Services
Segment Reporting Information
Net Sales	299,749	276,447
Segment Operating Profit (Loss)	14,165	13,185
Segment Assets	171,608	161,485
Depreciation/Amortization	6,089	6,138
Expenditures for Long-Lived Assets	1,081	4,599
Operating Segments | Precast Concrete Products
Segment Reporting Information
Net Sales	70,990	63,314
Segment Operating Profit (Loss)	1,545	566
Segment Assets	48,740	44,510
Depreciation/Amortization	1,716	1,125
Expenditures for Long-Lived Assets	2,441	3,560
Operating Segments | Steel Products and Measurement
Segment Reporting Information
Net Sales	142,881	157,650
Segment Operating Profit (Loss)	(2,402)	7,945
Segment Assets	58,377	93,009
Depreciation/Amortization	4,738	4,959
Expenditures for Long-Lived Assets	$ 78	$ 345