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v3.20.2

Related Party Transactions - Narrative (Details) - USD ($) $ in Millions | 3 Months Ended | 6 Months Ended |
--- | --- | --- | ---
Jun. 30, 2020 | Jun. 30, 2019 | Jun. 30, 2020 | Jun. 30, 2019 | Apr. 29, 2019
Related Party Transaction [Line Items] |  |  |  |  |
Related parties | $ 285.6 | $ 305.0 | $ 556.6 | $ 616.4 |
Glencore [Member] |  |  |  |  |
Related Party Transaction [Line Items] |  |  |  |  |
Related parties | 285.6 | 305.0 | 556.6 | 616.4 |
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 | $ 0.9 | $ 13.6 | $ 1.2 | $ 21.7 |
Consolidated Sales [Member] | Customer Concentration Risk [Member] | Glencore [Member] |  |  |  |  |
Related Party Transaction [Line Items] |  |  |  |  |
Major customer, percentage of revenue, net (percent) | 71.00% | 64.50% | 67.60% | 64.00% |
Glencore [Member] |  |  |  |  |
Related Party Transaction [Line Items] |  |  |  |  |
Ownership percentage by noncontrolling owners | 42.90% |  | 42.90% |  |
Economic ownership percentage by related party | 46.80% |  | 46.80% |  |

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