Property, Plant and Equipment (Details 2) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Property, Plant and Equipment [Abstract]
Total depreciation expense	$ 12,961	$ 10,910	$ 25,616	$ 20,971
Depreciation expense on leased railcars	$ 7,504	$ 6,353	$ 14,879	$ 11,844