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Income Taxes - Narrative (Details) - USD ($) $ in Millions | 12 Months Ended |  |  |
--- | --- | --- | --- | ---
Dec. 31, 2021 | Dec. 31, 2020 | Dec. 31, 2019 | Dec. 31, 2018
Operating Loss Carryforwards [Line Items] |  |  |  |
Valuation allowance | $ 485.8 | $ 499.4 |  |
Unrecognized tax benefits | 4.0 | 6.5 | $ 8.2 | $ 9.5
Unrecognized tax benefits that would impact effective tax rate | 1.4 | $ 1.4 |  |
Helguvik |  |  |  |
Operating Loss Carryforwards [Line Items] |  |  |  |
Discrete tax benefit (expense) | 49.8 |  |  |
All U.S. and Portion of Icelandic Deferred Tax Assets |  |  |  |
Operating Loss Carryforwards [Line Items] |  |  |  |
Valuation allowance | $ 485.8 |  |  |

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