Earnings Per Common Share - Schedule of Earnings Per Share, Basic and Diluted (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Numerator for basic and diluted earnings per common share:
Net income attributable to L.B. Foster Company	$ 42,946	$ 1,464
Denominator:
Weighted average shares outstanding (in shares)	10,721	10,799
Denominator for basic earnings per common share (in shares)	10,721	10,799
Effect of dilutive securities:
Stock compensation plans (in shares)	327	196
Dilutive potential common shares (in shares)	327	196
Denominator for diluted earnings per common share - adjusted weighted average shares outstanding and assumed conversions (in shares)	11,048	10,995
Basic earnings per common share (usd per share)	$ 4.01	$ 0.14
Diluted earnings per common share (usd per share)	$ 3.89	$ 0.13