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Significant Transactions - NSM (Details) - USD ($) $ in Millions |  | 12 Months Ended
--- | --- | ---
Aug. 01, 2022 | Dec. 31, 2023 | Dec. 31, 2022 | Dec. 31, 2021
Other Significant Noncash Transactions [Line Items] |  |  |  |
Net gain (loss) from foreign currency translation from sale of discontinued operations, net of tax - NSM Group |  | $ 0.0 | $ 2.9 | $ 0.0
NSM |  |  |  |
Other Significant Noncash Transactions [Line Items] |  |  |  |
Net gain (loss) from sale of discontinued operations, net of tax |  | $ 0.0 | 886.8 | 0.0
Discontinued Operations, Disposed of by Sale | NSM |  |  |  |
Other Significant Noncash Transactions [Line Items] |  |  |  |
Disposal group, consideration | $ 1,400.0 |  |  |
Net transaction gain | 875.7 |  |  |
Net gain (loss) from sale of discontinued operations, net of tax | 886.8 |  | 886.8 | 0.0
Net gain (loss) from foreign currency translation from sale of discontinued operations, net of tax - NSM Group | 2.9 |  | 2.9 | 0.0
General and administrative expenses | $ 14.0 |  | $ 126.8 | $ 190.4

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