Commitments and Contingencies - Leased Assets Class (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Jan. 01, 2019
Lessee, Lease, Description [Line Items]
Operating Lease Liability	$ 67,436	$ 70,900
Weighted Average in Months	82 months 6 days
Railcars
Lessee, Lease, Description [Line Items]
Average Months Remaining on the Lease	51 months
Weighted Average in Months	18 months 21 days
Buildings
Lessee, Lease, Description [Line Items]
Average Months Remaining on the Lease	34 months
Weighted Average in Months	11 months 21 days
Equipment
Lessee, Lease, Description [Line Items]
Average Months Remaining on the Lease	30 months
Weighted Average in Months	5 months 6 days
Land
Lessee, Lease, Description [Line Items]
Average Months Remaining on the Lease	475 months
Weighted Average in Months	46 months 3 days
Other
Lessee, Lease, Description [Line Items]
Average Months Remaining on the Lease	25 months
Weighted Average in Months	12 days
Operating Lease, Concentration Risk | Operating Lease Liability | Railcars
Lessee, Lease, Description [Line Items]
Percentage	36.70%
Operating Lease, Concentration Risk | Operating Lease Liability | Buildings
Lessee, Lease, Description [Line Items]
Percentage	34.50%
Operating Lease, Concentration Risk | Operating Lease Liability | Equipment
Lessee, Lease, Description [Line Items]
Percentage	17.40%
Operating Lease, Concentration Risk | Operating Lease Liability | Land
Lessee, Lease, Description [Line Items]
Percentage	9.70%
Operating Lease, Concentration Risk | Operating Lease Liability | Other
Lessee, Lease, Description [Line Items]
Percentage	1.70%
Polymer
Lessee, Lease, Description [Line Items]
Operating Lease Liability	$ 22,464
Polymer | Railcars
Lessee, Lease, Description [Line Items]
Operating Lease Liability	697
Polymer | Buildings
Lessee, Lease, Description [Line Items]
Operating Lease Liability	13,439
Polymer | Equipment
Lessee, Lease, Description [Line Items]
Operating Lease Liability	1,251
Polymer | Land
Lessee, Lease, Description [Line Items]
Operating Lease Liability	6,509
Polymer | Other
Lessee, Lease, Description [Line Items]
Operating Lease Liability	568
Chemical
Lessee, Lease, Description [Line Items]
Operating Lease Liability	44,972
Chemical | Railcars
Lessee, Lease, Description [Line Items]
Operating Lease Liability	24,066
Chemical | Buildings
Lessee, Lease, Description [Line Items]
Operating Lease Liability	9,820
Chemical | Equipment
Lessee, Lease, Description [Line Items]
Operating Lease Liability	10,461
Chemical | Land
Lessee, Lease, Description [Line Items]
Operating Lease Liability	42
Chemical | Other
Lessee, Lease, Description [Line Items]
Operating Lease Liability	$ 583