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Summary of Significant Accounting Policies (Details)
$ in Millions
 12 Months Ended
Dec. 31, 2020
USD ($)
pot_line
Dec. 31, 2019
USD ($)
Schedule of Equity Method Investments [Line Items]    
Allowance for expected losses | $ $ 1.0 $ 1.0
Property, Plant and Equipment [Line Items]    
Number of potlines rebuilt | pot_line 2  
Glencore [Member]    
Schedule of Equity Method Investments [Line Items]    
Glencore beneficial ownership 42.90%  
Glencore economic ownership 46.80%  
Minimum [Member] | Building and Improvements [Member]    
Property, Plant and Equipment [Line Items]    
Useful life 10 years  
Minimum [Member] | Machinery and Equipment [Member]    
Property, Plant and Equipment [Line Items]    
Useful life 5 years  
Minimum [Member] | Technology and Software [Member]    
Property, Plant and Equipment [Line Items]    
Useful life 3 years  
Maximum [Member] | Building and Improvements [Member]    
Property, Plant and Equipment [Line Items]    
Useful life 45 years  
Maximum [Member] | Machinery and Equipment [Member]    
Property, Plant and Equipment [Line Items]    
Useful life 35 years  
Maximum [Member] | Technology and Software [Member]    
Property, Plant and Equipment [Line Items]    
Useful life 7 years