Derivatives (Effects on Consolidated Statements of Operations and Other Comprehensive Income (Loss)) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Embedded Derivative Financial Instruments | Other income (expense)
Derivative Instruments, Gain (Loss) [Line Items]
Derivatives, amount of gain (loss) recognized in income	$ (857)	$ (9,026)	$ 8,360
Designated as Hedging Instrument | Commodity Derivatives | Cost of goods and services sold | Onshore facilities and transportation product costs
Derivative Instruments, Gain (Loss) [Line Items]
Derivatives, amount of gain (loss) recognized in income	(14,454)	(786)	(544)
Not Designated As Hedging Instrument | Commodity Derivatives | Cost of goods and services sold
Derivative Instruments, Gain (Loss) [Line Items]
Derivatives, amount of gain (loss) recognized in income	(19,929)	(8,576)	3,370
Not Designated As Hedging Instrument | Commodity Derivatives | 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]
Derivatives, amount of gain (loss) recognized in income	(5,475)	(7,790)	3,914
Not Designated As Hedging Instrument | Swap | Cost of goods and services sold | Sodium minerals and sulfur services operating costs
Derivative Instruments, Gain (Loss) [Line Items]
Derivatives, amount of gain (loss) recognized in income	$ 1,186	$ 1,941	$ 1,906