Property, Plant and Equipment (Details Textual) (USD $) In Millions, unless otherwise specified	6 Months Ended		12 Months Ended
	Jun. 30, 2012 Railcars	Jun. 30, 2011 Railcars	Dec. 31, 2011
Property, Plant and Equipment [Abstract]
Depreciation expense on property, plant and equipment	$ 12.0	$ 9.9	$ 20.4
Railcars	23,100	22,400
Depreciation expense on railcar assets leased to others	$ 7.8	$ 6.7	$ 13.8