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Related Party Transactions - Narrative (Details) - USD ($)
$ in Millions
3 Months Ended
Mar. 31, 2020
Mar. 31, 2019
Apr. 29, 2019
Related Party Transaction [Line Items]      
Related parties $ 271.0 $ 311.3  
Glencore [Member]      
Related Party Transaction [Line Items]      
Related parties 271.0 $ 311.3  
Hawesville [Member]      
Related Party Transaction [Line Items]      
Term loan - less current portion     $ 40.0
Aluminum [Member] | Glencore [Member]      
Related Party Transaction [Line Items]      
Related parties $ 0.3    
Consolidated Sales [Member] | Customer Concentration Risk [Member] | Glencore [Member]      
Related Party Transaction [Line Items]      
Major customer, percentage of revenue, net (percent) 64.00% 64.00%  
Glencore [Member]      
Related Party Transaction [Line Items]      
Ownership percentage by noncontrolling owners 42.90%    
Economic ownership percentage by related party 46.80%