Retirement Plans (Other Post-Retirement Retirement Plan) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
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
Other Post-Retirement Benefit Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
General Discussion of Pension and Other Postretirement Benefits	At Rail Technologies' operation near Montreal, Quebec, Canada, it maintains a post-retirement benefit plan, which provides retiree life insurance, health care benefits and, for a closed group of employees, dental care. Retiring employees with a minimum of 10 years of service are eligible for the plan benefits. The plan is not funded. Cost of benefits earned by employees is charged to expense as services are rendered. The expense related to this plan was not material for 2012 and 2011. Rail Technologies' accrued benefit obligation was $1,130,000 and $879,000 as of December 31, 2012 and 2011, respectively. Benefit payments anticipated for 2012 are not material. Accordingly, this obligation is recognized within other long-term liabilities
Pension and Other Postretirement Defined Benefit Plans, Liabilities, Noncurrent	$ 1,130	$ 879
Projected benefit obligation: Discount rate	4.40%	5.30%
Weighted average health care trend rate	6.60%	7.00%
Defined Benefit Plan, Ultimate Health Care Cost Trend Rate	4.40%