Business Segment - Sales by Major Product Line (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Revenue from External Customer
Net Sales	$ 513,620	$ 497,411
Rail, Technologies, and Services
Revenue from External Customer
Net Sales	299,749	276,447
Precast Concrete Products
Revenue from External Customer
Net Sales	70,990	63,314
Steel Products and Measurement
Revenue from External Customer
Net Sales	142,881	157,650
Rail Products and Friction Management | Rail, Technologies, and Services
Revenue from External Customer
Net Sales	248,237	231,726
Technology Services and Solutions | Rail, Technologies, and Services
Revenue from External Customer
Net Sales	51,512	44,721
Precast Concrete Buildings | Precast Concrete Products
Revenue from External Customer
Net Sales	55,993	51,111
Other Precast Concrete Products | Precast Concrete Products
Revenue from External Customer
Net Sales	14,997	12,203
Coatings and Measurement | Steel Products and Measurement
Revenue from External Customer
Net Sales	27,833	59,037
Fabricated Steel Products | Steel Products and Measurement
Revenue from External Customer
Net Sales	$ 115,048	$ 98,613