Retirement Plans (Narrative) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014 agreement	Dec. 31, 2013	Dec. 31, 2012
Defined Benefit Plan Disclosure [Line Items]
General Discussion of Pension and Other Postretirement Benefits	The Company has six retirement plans which cover its hourly and salaried employees in the United States: three defined benefit plans (one active / two frozen) and three 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
Number of retirement plans	6
Defined Benefit Plan Number	3
Active Defined Benefit Plan Number	1
Inactive Defined Benefit Plan Number	2
Defined Contribution Plan Number	3
Post-retirement benefit plan number	1
Defined Contribution Plan, Cost Recognized	$ 2,810	$ 2,553	$ 2,492
Salaried Benefit Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Description of Postemployment Benefits	The Company sponsors six defined contribution plans for hourly and salaried employees across our domestic and international facilities. The following table summarizes the expense associated with the contributions made to these plans.
Defined Contribution Plan, Cost Recognized	2,425	2,151	2,107
Canadian Employees [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Contribution Plan Number	2
United Kingdom Benefit Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
General Discussion of Pension and Other Postretirement Benefits	The Portec Rail Products (UK) Limited Pension Plan covers certain current employees, former employees, and retirees. The plan has been frozen to new entrants since April 1, 1997 and also covers the former employees of a merged plan after January 2002. Benefits under the plan were based on years of service and eligible compensation during defined periods of service. Our funding policy for the plan is to make minimum annual contributions required by applicable regulations
Defined Benefit Plan, Estimated Future Employer Contributions in Next Fiscal Year	280
Defined Benefit Plan Number	1
Defined Contribution Plan Number	1
Defined Benefit Plan, Contributions by Employer	284	303
Defined Contribution Plan, Cost Recognized	158	136	116
United States Pension Plans of US Entity, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Future Amortization of Gain (Loss)	278
Defined Benefit Plan, Contributions by Employer	$ 299	$ 496