Business Segments - Schedule of Reconciliation of Operating Income to Income Before Taxes (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2025	Jun. 30, 2024	Jun. 30, 2025	Jun. 30, 2024
Segment Reporting Information
Net sales	$ 143,558	$ 140,796	$ 241,350	$ 265,116
Less:
Cost of sales	(112,658)	(110,283)	(190,299)	(208,427)
Amortization expense			(1,962)	(2,340)
Operating income	7,678	4,572	5,755	10,138
Gain on sale of former joint venture facility	0	0	0	3,477
Interest expense - net	(1,490)	(1,493)	(2,633)	(2,618)
Other income - net	95	84	413	337
Income before income taxes	6,283	3,163	3,535	7,857
Rail, Technologies, and Services
Segment Reporting Information
Net sales	75,973	85,594	129,988	168,217
Infrastructure Solutions
Segment Reporting Information
Net sales	67,585	55,202	111,362	96,899
Operating Segments
Segment Reporting Information
Net sales	143,558	140,796	241,350	265,116
Less:
Cost of sales	(112,658)	(110,283)	(190,299)	(208,427)
Selling and administrative employment costs	(13,139)	(14,152)	(26,102)	(27,452)
Purchased services	(2,933)	(3,332)	(5,964)	(6,849)
General administrative costs	(3,475)	(2,782)	(6,810)	(5,534)
Amortization expense	(840)	(1,123)	(1,962)	(2,340)
Operating income	10,513	9,124	10,213	14,514
Operating Segments | Rail, Technologies, and Services
Segment Reporting Information
Net sales	75,973	85,594	129,988	168,217
Less:
Cost of sales	(60,841)	(67,719)	(102,827)	(131,771)
Selling and administrative employment costs	(7,237)	(8,126)	(14,636)	(15,608)
Purchased services	(1,660)	(1,810)	(3,333)	(3,749)
General administrative costs	(1,949)	(1,645)	(3,942)	(3,146)
Amortization expense	(539)	(793)	(1,359)	(1,664)
Operating income	3,747	5,501	3,891	12,279
Operating Segments | Infrastructure Solutions
Segment Reporting Information
Net sales	67,585	55,202	111,362	96,899
Less:
Cost of sales	(51,817)	(42,564)	(87,472)	(76,656)
Selling and administrative employment costs	(5,902)	(6,026)	(11,466)	(11,844)
Purchased services	(1,273)	(1,522)	(2,631)	(3,100)
General administrative costs	(1,526)	(1,137)	(2,868)	(2,388)
Amortization expense	(301)	(330)	(603)	(676)
Operating income	6,766	3,623	6,322	2,235
Corporate And Reconciling Items
Less:
Gain on sale of former joint venture facility			0	3,477
Interest expense - net	(1,490)	(1,493)	(2,633)	(2,618)
Other income - net	95	84	413	337
Public company costs	(1,317)	(1,621)	(2,471)	(2,840)
Corporate executive management costs	(728)	(1,885)	(948)	(3,292)
Corporate management stock-based compensation	(761)	(880)	(1,039)	(1,479)
Other corporate expenses - net	$ (29)	$ (166)	$ 0	$ (242)