Property, Plant and Equipment (Details 2) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Property, Plant and Equipment [Abstract]
Total depreciation expense	$ 7,989	$ 6,860	$ 15,672	$ 13,395
Depreciation expense on leased railcars	$ 3,659	$ 2,300	$ 6,990	$ 4,415