Condensed Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2023	Mar. 31, 2022
Statement of Comprehensive Income [Abstract]
Net loss		$ (2,171)	$ (1,586)
Other comprehensive income (loss), net of tax:
Foreign currency translation adjustment		1,247	(880)
Unrealized (loss) gain on cash flow hedges, net of tax benefit of $0 and $188, respectively		(418)	551
Cash flow hedges reclassified to earnings, net of tax expense of $0 and $66, respectively		0	93
Reclassification of pension liability adjustments to earnings, net of tax expense of $2 and $16, respectively*	[1]	40	49
Total comprehensive loss		(1,302)	(1,773)
Less comprehensive (loss) income attributable to noncontrolling interest:
Net loss attributable to noncontrolling interest		(19)	(20)
Foreign currency translation adjustment		4	85
Amounts attributable to noncontrolling interest		(15)	65
Comprehensive loss attributable to L.B. Foster Company		$ (1,287)	$ (1,838)

[1] Reclassifications out of “Accumulated other comprehensive loss” for pension obligations are charged to “Selling and administrative expenses” within the Condensed Consolidated Statements of Operations.