Retirement Plans (Narrative) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended	9 Months Ended			12 Months Ended		9 Months Ended	12 Months Ended		9 Months Ended		12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012 Salaried Benefit Plan [Member]	Sep. 30, 2012 Union Benefit Plan [Member]	Sep. 30, 2012 United Kingdom Benefit Plans [Member]	Dec. 31, 2012 United Kingdom Benefit Plans [Member]	Dec. 31, 2011 United Kingdom Benefit Plans [Member]	Sep. 30, 2012 Kelsan Benefit Plan [Member]	Dec. 31, 2012 United States Pension Plans of US Entity, Defined Benefit [Member]	Dec. 31, 2011 United States Pension Plans of US Entity, Defined Benefit [Member]	Sep. 30, 2012 Canadian Employees [Member]	Dec. 31, 2013 Subsequent Event [Member] United Kingdom Benefit Plans [Member]	Dec. 31, 2013 Subsequent Event [Member] United States Pension Plans of US Entity, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
General Discussion of Pension and Other Postretirement Benefits	The Company has five retirement plans which cover its hourly and salaried employees in the United States: three defined benefit plans (one active / two frozen) and two defined contribution plans. Employees are eligible to participate in the appropriate plan based on employment classification. The Company's funding to the defined benefit and defined contribution plans are governed by the Employee Retirement Income Security Act of 1974 (ERISA), applicable plan policy and investment guidelines. The Company policy is to contribute at least the minimum in accordance with the funding standards of ERISA.The Company's subsidiary, L.B. Foster Rail Technologies (Rail Technologies), maintains two defined contribution plans for its employees in Canada, as well as a post-retirement benefit plan. In the United Kingdom, Rail Technologies maintains both a defined contribution plan and a defined benefit plan. These plans are discussed in further detail below				During 2010, the Conveyors International Limited Pension Plan (Conveyors plan) was merged with the Portec Rail Products (UK) Limited Pension Plan (Portec Rail Plan) a defined benefit pension plan in the United Kingdom. The combined Portec Rail Plan covers some current employees, former employees and retirees of the original Portec Rail Plan along with former employees of the Conveyors plan. The Portec Rail Plan has been frozen to new entrants since April 1, 1997 and also covers the former employees of the Conveyors plan after January 2002. Benefits under the Portec Rail Plan, including the former Conveyors plan, were based on years of service and eligible compensation during defined periods of service. Our funding policy for the Portec Rail Plan is to make minimum annual contributions required by applicable regulations
Defined Benefit Plan, Actuarial Gain (Loss)					$ 652	$ 544		$ 980	$ 1,896			$ (212)
Defined Benefit Plan, Estimated Future Employer Contributions in Next Fiscal Year											228	555
Defined Benefit Plan, Contributions by Employer					$ 297	$ 235		$ 758	$ 1,083
Description of Postemployment Benefits		The Company has a domestic defined contribution plan that covers all non-union hourly and all salaried employees (Salaried Plan). The Salaried Plan permits both pre-tax and after-tax employee contributions. Participants can contribute, subject to statutory limitations, between 1% and 75% of eligible pre-tax pay and between 1% and 100% of eligible after-tax pay. The Company's employer match is 100% of the first 1% of deferred eligible compensation and up to 50% of the next 6%, based on years of service, of deferred eligible compensation, for a total maximum potential match of 4%. The Company may also make discretionary contributions to the Salaried Plan.	The Company also has a domestic defined contribution plan for union hourly employees with contributions made by both the participants and the Company based on various formulas (Union Plan).	The Company's Rail Technologies subsidiary also maintains a defined contribution plan covering substantially all employees at its United Kingdom locations (U.K. Plan). Benefits under the U.K. Plan are provided under no formal written agreement. Under the terms of the defined contribution U.K. Plan, Rail Technologies may make non-elective contributions of between 3% and 10% of each employee's compensation.			Finally, the Company's Rail Technologies subsidiary maintains a defined contribution plan covering substantially all of the employees of at its Burnaby, British Columbia, Canada location (Burnaby Plan). Under the terms of the Burnaby Plan, Rail Technologies makes a non-elective contribution of 4% of each employee's compensation and may also contribute 30% of the first 6% of each employee's compensation contributed to the Burnaby Plan. The following table summarizes the expense associated with the contributions made to these plans. Due to the Company not acquiring Rail Technologies until December 15, 2010, there were no contributions made by the Company to the Montreal, U.K. or Burnaby Plans in 2010.			The Company's Rail Technologies subsidiary maintains a defined contribution plan covering all non-union employees at its Montreal, Quebec, Canada location (Montreal Plan). Under the terms of the Montreal Plan, Rail Technologies may contribute 4% of each employee's compensation as a non-elective contribution and may also contribute 30% of the first 6% of each employee's compensation contributed to the Montreal Plan.