Business Segments - Schedule of Reconciliation of Operating Income to Income Before Taxes (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Segment Reporting Information
Net sales	$ 138,286	$ 137,466	$ 379,636	$ 402,582
Less:
Cost of sales	(107,220)	(104,708)	(297,519)	(313,135)
Amortization expense			(2,656)	(3,486)
Operating income	8,295	7,323	14,050	17,461
Gain on sale of former joint venture facility	0	0	0	3,477
Interest expense - net	(1,254)	(1,358)	(3,887)	(3,976)
Other income - net	96	188	509	525
Income before income taxes	7,137	6,153	10,672	14,010
Rail, Technologies, and Services
Segment Reporting Information
Net sales	77,788	79,498	207,776	247,715
Infrastructure Solutions
Segment Reporting Information
Net sales	60,498	57,968	171,860	154,867
Operating Segments
Segment Reporting Information
Net sales	138,286	137,466	379,636	402,582
Less:
Cost of sales	(107,220)	(104,708)	(297,519)	(313,135)
Selling and administrative employment costs	(13,986)	(14,505)	(40,088)	(41,957)
Purchased services	(3,395)	(3,425)	(9,359)	(10,274)
General administrative costs	(2,949)	(3,639)	(9,759)	(9,173)
Amortization expense	(694)	(1,146)	(2,656)	(3,486)
Operating income	10,042	10,043	20,255	24,557
Operating Segments | Rail, Technologies, and Services
Segment Reporting Information
Net sales	77,788	79,498	207,776	247,715
Less:
Cost of sales	(60,042)	(61,027)	(162,869)	(192,798)
Selling and administrative employment costs	(7,900)	(8,475)	(22,536)	(24,083)
Purchased services	(1,787)	(1,841)	(5,120)	(5,590)
General administrative costs	(1,765)	(2,378)	(5,707)	(5,524)
Amortization expense	(399)	(844)	(1,758)	(2,508)
Operating income	5,895	4,933	9,786	17,212
Operating Segments | Infrastructure Solutions
Segment Reporting Information
Net sales	60,498	57,968	171,860	154,867
Less:
Cost of sales	(47,178)	(43,681)	(134,650)	(120,337)
Selling and administrative employment costs	(6,086)	(6,030)	(17,552)	(17,874)
Purchased services	(1,608)	(1,584)	(4,239)	(4,684)
General administrative costs	(1,184)	(1,261)	(4,052)	(3,649)
Amortization expense	(295)	(302)	(898)	(978)
Operating income	4,147	5,110	10,469	7,345
Corporate And Reconciling Items
Less:
Gain on sale of former joint venture facility			0	3,477
Interest expense - net	(1,254)	(1,358)	(3,887)	(3,976)
Other income - net	96	188	509	525
Public company costs	(1,162)	(1,327)	(3,633)	(4,167)
Corporate executive management costs	(175)	(839)	(1,123)	(4,131)
Corporate management stock-based compensation	(672)	(339)	(1,711)	(1,818)
Other corporate expenses - net	$ 262	$ (215)	$ 262	$ (457)