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Income Taxes - Changes in Valuation Allowance (Details) - USD ($) $ in Millions | 12 Months Ended
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Dec. 31, 2024 | Dec. 31, 2023 | Dec. 31, 2022
Movement in Valuation Allowances and Reserves [Roll Forward] |  |  |
Balance, valuation allowance | $ 537.6 | $ 487.9 | $ 485.8
Remeasurement of deferred tax assets | 0.0 | 0.0 | 0.0
Release of valuation allowance | 0.0 | 0.0 | 0.0
Expiration of net operating losses | (6.1) | (7.2) | (15.4)
Other change in valuation allowance | (27.1) | 56.9 | 17.5
Balance, valuation allowance | $ 504.4 | $ 537.6 | $ 487.9

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