Derivatives (Schedule of Effect on Operating Results) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Commodity derivatives - futures and call options | Cost of Goods and Services Sold
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in Income	$ (646)	$ (7,434)
Preferred Distribution Rate Reset Election | Other income (expense)
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in Income	32,545	(2,976)
Contracts designated as hedges under accounting guidance | Commodity derivatives - futures and call options | Cost of Goods and Services Sold | Onshore facilities and transportation product costs
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in Income	729	(742)
Contracts not considered hedges under accounting guidance | Commodity derivatives - futures and call options | Cost of Goods and Services Sold | Onshore facilities and transportation product costs, sodium minerals and sulfur services operating costs
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in Income	(1,375)	(6,692)
Contracts not considered hedges under accounting guidance | Natural Gas Swap Liability | Cost of Goods and Services Sold | Sodium minerals and sulfur services operating costs
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in Income	$ (432)	$ 1,519