Property, Plant and Equipment (Details 2) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Property, Plant and Equipment [Abstract]
Total depreciation expense	$ 6,860	$ 5,884	$ 13,395	$ 11,286
Depreciation expense on leased railcars	$ 2,300	$ 945	$ 4,415	$ 1,422