Condensed Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2022	Mar. 31, 2021
Statement of Comprehensive Income [Abstract]
Net loss		$ (1,586)	$ (1,270)
Other comprehensive (loss) income, net of tax:
Foreign currency translation adjustment		(880)	453
Unrealized gain on cash flow hedges, net of tax expense of $188 and $0, respectively		551	0
Cash flow hedges reclassified to earnings, net of tax expense of $66 and $98, respectively		93	136
Reclassification of pension liability adjustments to earnings, net of tax expense of $16 and $24, respectively*	[1]	49	91
Total comprehensive loss		(1,773)	(590)
Less comprehensive income (loss) attributable to noncontrolling interest:
Net loss attributable to noncontrolling interest		(20)	(12)
Foreign currency translation adjustment		85	(30)
Amounts attributable to noncontrolling interest		65	(42)
Comprehensive loss attributable to L.B. Foster Company		$ (1,838)	$ (548)

[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.