Property, Plant and Equipment (Details Textual) (USD $) In Millions, unless otherwise specified	6 Months Ended		12 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Dec. 31, 2012
Property, Plant and Equipment [Abstract]
Depreciation expense on property, plant and equipment	$ 18.5	$ 12.0	$ 27.4
Depreciation expense on railcar assets leased to others	$ 7.4	$ 7.8	$ 15.9