Derivatives (Schedule of Effect on Operating Results) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
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	$ (456)	$ 321	$ (13,616)	$ (13,903)
Natural Gas Swap | 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	(55)	666	(92)	1,217
Preferred Distribution Rate Reset Election | Other income (expense)
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in Income	1,740	6,689	(31,042)	17,395
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	(285)	(854)	(7,745)	(11,061)
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	$ (171)	$ 1,175	$ (5,871)	$ (2,842)