Fixed Assets, Mineral Leaseholds, and Asset Retirement Obligations (Fixed Assets, Net) (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Property, Plant and Equipment [Line Items]
Fixed assets, at cost	$ 5,471,477	$ 5,440,858
Less: Accumulated depreciation	(1,093,199)	(1,023,825)
Net fixed assets	4,378,278	4,417,033
Crude oil pipelines and natural gas pipelines and related assets
Property, Plant and Equipment [Line Items]
Fixed assets, at cost	2,918,841	2,918,285
Onshore facilities, machinery, and equipment
Property, Plant and Equipment [Line Items]
Fixed assets, at cost	639,623	639,023
Onshore facilities, machinery, and equipment | Alkali Business
Property, Plant and Equipment [Line Items]
Fixed assets, at cost	536,987	533,924
Transportation equipment
Property, Plant and Equipment [Line Items]
Fixed assets, at cost	19,415	20,102
Marine vessels
Property, Plant and Equipment [Line Items]
Fixed assets, at cost	957,846	951,597
Land, buildings and improvements
Property, Plant and Equipment [Line Items]
Fixed assets, at cost	222,249	222,242
Office equipment, furniture and fixtures
Property, Plant and Equipment [Line Items]
Fixed assets, at cost	20,505	20,505
Construction in progress
Property, Plant and Equipment [Line Items]
Fixed assets, at cost	114,856	94,025
Other
Property, Plant and Equipment [Line Items]
Fixed assets, at cost	$ 41,155	$ 41,155