Contingencies (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended	12 Months Ended
	Mar. 31, 2013	Dec. 31, 2011 Railcar
Contingencies (Textual) [Abstract]
Number of tank cars voluntarily recertified by Company		948
Inspection cycle for tank cars in service minimum	3 years
Inspection cycle for tank cars in service maximum	5 years
Minimum possible loss	$ 3.9
Maximum possible loss	32.8
Total accruals	18.3
Highway Products Litigation
Contingencies (Textual) [Abstract]
Total accruals	0
Environmental and workplace matters
Contingencies (Textual) [Abstract]
Total accruals	$ 6.8