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Weighted Average Grant Date Fair Value Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract] Current portion of accrued settlement (Note 13) Accrued Legal Settlement Current Accrued Legal Settlement Current Restructuring Reserve [Roll Forward] Restructuring Reserve [Roll Forward] Revenue remaining performance obligation (percentage) Revenue, Remaining Performance Obligation, Percentage Income Taxes Income Tax Disclosure [Text Block] Per share data attributable to L.B. Foster shareholders: Earnings Per Share [Abstract] Numerator for basic and diluted earnings per common share: Net Income (Loss) Attributable to Parent [Abstract] Recoveries of previous write-offs Recoveries of previous write-offs Accounts Receivable, Allowance for Credit Loss, Recoveries of Previous Writeoff Accounts Receivable, Allowance for Credit Loss, Recoveries of Previous Writeoff Litigation settlement amount warded to other party Litigation Settlement Amount Awarded To Other Party Scheduled Payment Remainder Of Year Litigation Settlement Amount Awarded To Other Party Scheduled Payment Remainder Of Year Raw materials Inventory, Raw Materials, Net of Reserves Net loss attributable to noncontrolling interest Income (Loss) from Continuing Operations, Net of Tax, Attributable to Noncontrolling Interest Retained earnings Retained Earnings (Accumulated Deficit) Schedule of Nonvested Share Activity Schedule of Nonvested Share Activity [Table Text Block] Over time sales, percentage Over Time Sales, Percent Over Time Sales, Percent Domestic Plan Domestic Plan [Member] Inventories Increase (Decrease) in Inventories Litigation settlement amount Litigation Settlement, Amount Awarded to Other Party Organization, Consolidation and Presentation of Financial Statements [Abstract] Aggregate Available Trading Arrangement, Securities Aggregate Available Amount Equity Awards Adjustments Equity Awards Adjustments [Member] Net cash provided by (used in) financing activities Net Cash Provided by (Used in) Financing Activities Underlying Securities Award Underlying Securities Amount Performance-Based Stock and Share Units Performance Shares [Member] Credit Facility [Axis] Credit Facility [Axis] Amendment Flag Amendment Flag Entity Registrant Name Entity Registrant Name (Gain) on sale of former joint venture facility Gain on sale of former joint venture facility Gain (Loss) on Disposition of Property Plant Equipment Point in time Transferred at Point in Time [Member] Adjustment to Non-PEO NEO Compensation Footnote Adjustment to Non-PEO NEO Compensation Footnote [Text Block] Stock Appreciation Rights (SARs) Stock Appreciation Rights (SARs) [Member] Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Table] Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Table] Timing of Transfer of Good or Service [Axis] Timing of Transfer of Good or Service [Axis] Gross profit Gross profit Gross Profit Foreign currency translation adjustment Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax, Portion Attributable to Parent Fair Value as of Grant Date Award Grant Date Fair Value Schedule of Reconciliation of Assets from Segment to Consolidated Reconciliation of Assets from Segment to Consolidated [Table Text Block] Level 2 Fair Value, Inputs, Level 2 [Member] Long-Term Debt and Related Matters Debt Disclosure [Text Block] Fair Value, Measurements, Fair Value Hierarchy [Domain] Fair Value Hierarchy and NAV [Domain] Recovery of Erroneously Awarded Compensation Disclosure [Line Items] Schedule of Disaggregation of Revenue Disaggregation of Revenue [Table Text Block] Issuance of common shares, net of share withheld for taxes Stock Issued During Period, Value, New Issues Technology Technology-Based Intangible Assets [Member] Entity Address, Postal Zip Code Entity Address, Postal Zip Code Restructuring Cost [Table] Restructuring Cost [Table] Restatement Determination Date: Restatement Determination Date [Axis] Title of 12(b) Security Title of 12(b) Security Disposal Group, Not Discontinued Operations Disposal Group, Not Discontinued Operations [Member] Common stock, par value $0.01, authorized 20,000,000 shares; shares issued at September 30, 2024 and December 31, 2023, 11,115,779; shares outstanding at September 30, 2024 and December 31, 2023, 10,657,554 and 10,733,935, respectively Common Stock, Value, Issued Employee-related Liabilities [Abstract] Environmental loss contingency statement of financial position extensible enumeration not disclosed flag Environmental Loss Contingency Statement Of Financial Position Extensible Enumeration Not Disclosed Flag Environmental Loss Contingency Statement Of Financial Position Extensible Enumeration Not Disclosed Flag Accounts Receivable Additional Disclosures [Abstract] Line of credit facility, maximum increase in commitments Line Of Credit Facility, Maximum Increase In Commitments Line Of Credit Facility, Maximum Increase In Commitments Cash and cash equivalents Cash and Cash Equivalents, at Carrying Value Year-over-Year Change in Fair Value of Equity Awards Granted in Prior Years That are Outstanding and Unvested Year-over-Year Change in Fair Value of Equity Awards Granted in Prior Years That are Outstanding and Unvested [Member] Finite-Lived Intangible Assets Finite-Lived Intangible Assets [Line Items] Bridge Grid Deck Product Bridge Grid Deck Product [Member] Bridge Grid Deck Product Cancelled and forfeited (in USD per share) Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Forfeitures, Weighted Average Grant Date Fair Value Effect of exchange rate changes on cash and cash equivalents Effect of Exchange Rate on Cash, Cash Equivalents, Restricted Cash, and Restricted Cash Equivalents, Including Disposal Group and Discontinued Operations CASH FLOWS FROM FINANCING ACTIVITIES: Net Cash Provided by (Used in) Financing Activities [Abstract] Year-end Fair Value of Equity Awards Granted in Covered Year that are Outstanding and Unvested Year-end Fair Value of Equity Awards Granted in Covered Year that are Outstanding and Unvested [Member] Global Friction Management Global Friction Management [Member] Global Friction Management Reporting Unit [Domain] Reporting Unit [Domain] Adjustment for incentive awards expected to vest (in shares) Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Adjustment For Incentive Awards Expected To Vest Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Adjustment For Incentive Awards Expected To Vest Basic earnings per common share (in USD per share) Earnings Per Share, Basic Number of defined benefit plans Defined Benefit Plan, Number Accounts payable Increase (Decrease) in Accounts Payable Adjustment To PEO Compensation, Footnote Adjustment To PEO Compensation, Footnote [Text Block] Award Timing MNPI Disclosure Award Timing MNPI Disclosure [Text Block] Property, plant, and equipment - net Property, Plant, and Equipment and Finance Lease Right-of-Use Asset, after Accumulated Depreciation and Amortization Coatings and Measurement Coatings and Measurement [Member] Coatings and Measurement Aggregate Pension Adjustments Service Cost Aggregate Pension Adjustments Service Cost [Member] Schedule of Goodwill [Table] Goodwill [Table] Amortization Amortization Compensation Actually Paid vs. Other Measure Compensation Actually Paid vs. Other Measure [Text Block] Total current liabilities Liabilities, Current Vesting Date Fair Value of Equity Awards Granted and Vested in Covered Year Vesting Date Fair Value of Equity Awards Granted and Vested in Covered Year [Member] As Previously Reported Previously Reported [Member] TOTAL ASSETS Assets Assets Revolving credit facility Line of credit facility, amount outstanding Long-Term Line of Credit Granted (in shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Grants in Period Investment of noncontrolling interest Noncontrolling Interest, Increase from Subsidiary Equity Issuance Capital expenditures on property, plant, and equipment Payments to Acquire Property, Plant, and Equipment Other long-term liabilities Other Liabilities, Noncurrent Increase in billings in excess of cost, excluding revenue recognized Contract with Customer, Liability, Increase from Cash Receipts Contract with Customer, Liability, Increase from Cash Receipts Forgone Recovery due to Violation of Home Country Law, Amount Forgone Recovery due to Violation of Home Country Law, Amount Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] Financing Receivable, Allowance for Credit Loss [Line Items] Financing Receivable, Allowance for Credit Loss [Line Items] Termination Date Trading Arrangement Termination Date Stock-Based Compensation Share-Based Payment Arrangement [Text Block] Rail Products Rail Products Business Unit [Member] Rail Products Business Unit Consideration transferred to acquire operating assets Asset Acquisition, Consideration Transferred Entity Address, City Entity Address, City or Town Over time output method Over Time Output Method [Member] Over Time Output Method Debt Instrument [Axis] Debt Instrument [Axis] Stock-based compensation Share-Based Payment Arrangement, Expense Net income attributable to L.B. Foster Company Net income attributable to L.B. Foster Company Net Income (Loss) Attributable to Parent Trading Arrangement: Trading Arrangement [Axis] Total net sales Net Sales Revenue from Contract with Customer, Including Assessed Tax Pay vs Performance Disclosure, Table Pay vs Performance [Table Text Block] Cancelled and forfeited (in shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Forfeited in Period Schedule of Finite-Lived Intangible Assets Schedule of Finite-Lived Intangible Assets [Table Text Block] Equity in loss of nonconsolidated investments Equity Loss Income and Remeasurement Gain Equity Loss Income and Remeasurement Gain Equity Awards Adjustments, Excluding Value Reported in Compensation Table Equity Awards Adjustments, Excluding Value Reported in the Compensation Table [Member] Dividends or Other Earnings Paid on Equity Awards not Otherwise Reflected in Total Compensation for Covered Year Dividends or Other Earnings Paid on Equity Awards not Otherwise Reflected in Total Compensation for Covered Year [Member] Commission File Number Entity File Number Financing Receivable, Allowance for Credit Loss [Table] Financing Receivable, Allowance for Credit Loss [Table] Revenue Revenue from Contract with Customer [Text Block] Document Fiscal Year Focus Document Fiscal Year Focus Noncontrolling Interest Noncontrolling Interest [Member] Income Statement [Abstract] Entity Address, Street Name Entity Address, Address Line One Personnel expenses Personnel Expenses Personnel Expenses Entity Address, Suite Entity Address, Address Line Two Debt Instrument, Name [Domain] Debt Instrument, Name [Domain] Corporate executive management costs Corporate Executive Management Costs Corporate Executive Management Costs Denominator: Weighted Average Number of Shares Outstanding, Basic [Abstract] Total assets Assets, Fair Value Disclosure Name Forgone Recovery, Individual Name Schedule of Costs of Retirement Plans Schedule of Costs of Retirement Plans [Table Text Block] Document Period End Date Document Period End Date Investment of noncontrolling interest Proceeds from Noncontrolling Interests Finished goods Inventory, Finished Goods, Net of Reserves Award Timing MNPI Considered Award Timing MNPI Considered [Flag] Outstanding, beginning balance (in shares) Outstanding, ending balance (in shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Nonvested, Number Line of Credit Facility, Lender [Domain] Line of Credit Facility, Lender [Domain] Cougar purchase accounting adjustment Cougar Mountain Precast, LLC [Member] Cougar Mountain Precast, LLC Insider Trading Arrangements [Line Items] Line of Credit Facility Line of Credit Facility [Line Items] Contract assets - net (Note 3) Balance as of December 31, 2023 Balance as of September 30, 2024 Contract with Customer, Asset, after Allowance for Credit Loss Timing of Transfer of Good or Service [Domain] Timing of Transfer of Good or Service [Domain] Inventory Disclosure [Abstract] Outstanding Aggregate Erroneous Compensation Amount Outstanding Aggregate Erroneous Compensation Amount Fair Value, Balance Sheet Grouping, Financial Statement Captions Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] Other current assets Increase (Decrease) in Other Current Assets Rail Products Rail Products [Member] Rail Products PEO Actually Paid Compensation Amount PEO Actually Paid Compensation Amount Litigation settlement amount, current Litigation Settlement, Amount Awarded to Other Party, Current Litigation Settlement, Amount Awarded to Other Party, Current Total cost of sales Cost of Revenue Revenue recognized from contract liabilities Contract with Customer, Liability, Revenue Recognized Adjustment to Compensation: Adjustment to Compensation [Axis] Net loss attributable to noncontrolling interest Net Income (Loss) Attributable to Noncontrolling Interest Accounts receivable - net (Note 5) Accounts and Financing Receivable, after Allowance for Credit Loss, Current Document Transition Report Document Transition Report Document Quarterly Report Document Quarterly Report Pension liability adjustment Other Comprehensive (Income) Loss, Defined Benefit Plan, after Tax and Reclassification Adjustment, Attributable to Parent Customer [Domain] Customer [Domain] Less comprehensive (loss) income attributable to noncontrolling interest: Comprehensive Income (Loss), Net of Tax, Attributable to Noncontrolling Interest [Abstract] Accumulated other comprehensive loss Accumulated Other Comprehensive Income (Loss), Net of Tax Entity Current Reporting Status Entity Current Reporting Status Retained Earnings Retained Earnings [Member] Pension Adjustments Service Cost Pension Adjustments Service Cost [Member] Asset Acquisition [Domain] Asset Acquisition [Domain] Basic weighted average shares outstanding (in shares) Denominator for basic earnings per common share (in shares) Weighted Average Number of Shares Outstanding, Basic Stock Price or TSR Estimation Method Stock Price or TSR Estimation Method [Text Block] Defined benefit plan, expected future employer contributions, current fiscal year Defined Benefit Plan, Expected Future Employer Contributions, Current Fiscal Year Total stockholders’ equity Beginning balance Ending balance Equity, Including Portion Attributable to Noncontrolling Interest Increase (Decrease) in Stockholders' Equity Increase (Decrease) in Stockholders' Equity [Roll Forward] Executive Category: Executive Category [Axis] Name Awards Close in Time to MNPI Disclosures, Individual Name Repayments of debt Repayments of Other Long-Term Debt Entity Filer Category Entity Filer Category Restructuring reserve, beginning balance Restructuring reserve, ending balance Restructuring Reserve Revenue remaining performance obligation Revenue, Remaining Performance Obligation, Amount Income Statement Location [Domain] Statement of Income Location, Balance [Domain] Company Selected Measure Name Company Selected Measure Name