Property, Plant and Equipment (Details 2) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Property, Plant and Equipment [Abstract]
Total depreciation expense	$ 14,572	$ 13,113	$ 42,746	$ 38,729
Depreciation expense on leased railcars	$ 8,964	$ 7,614	$ 25,859	$ 22,493