Acquisitions and Divestitures - Schedule of Business Acquisition, Pro Forma Information (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Business Acquisition [Line Items]
Diluted earnings per share (usd per share)	$ (0.20)	$ 0.22	$ (0.16)	$ 0.37
VanHooseCo acquisition
Business Acquisition [Line Items]
Net sales			$ 385,824
Net loss attributable to L.B. Foster Company			$ (633)
Diluted earnings per share, pro forma (usd per share)			$ (0.06)