Exit Costs and Assets Held for Sale (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2018	Dec. 31, 2017
Restructuring Cost and Reserve [Line Items]
Assets held for sale	$ 8,383	$ 29,527	$ 37,859
Exit charges	$ 11,500
Rail Group
Restructuring Cost and Reserve [Line Items]
Assets held for sale		25,100
Disposal Group, Held-for-sale, Not Discontinued Operations
Restructuring Cost and Reserve [Line Items]
Assets held for sale			37,900
Property, plan and equipment held-for-sale		4,400
Disposal Group, Held-for-sale, Not Discontinued Operations | Retail Store
Restructuring Cost and Reserve [Line Items]
Property, plan and equipment held-for-sale		4,200	4,200
Disposal Group, Held-for-sale, Not Discontinued Operations | Plant Nutrient Group
Restructuring Cost and Reserve [Line Items]
Property, plan and equipment held-for-sale		$ 200	1,600
Disposal Group, Held-for-sale, Not Discontinued Operations | TENNESSEE | Grain Group
Restructuring Cost and Reserve [Line Items]
Property, plan and equipment held-for-sale			19,500
Inventory, held-for-sale			11,400
Commodity derivative, held-for-sale			$ 1,200