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Pension and Other Postretirement Benefit Plans - Recurring Fair Value Measures (Details) - USD ($) $ in Millions | Dec. 31, 2024 | Dec. 31, 2023 | Dec. 31, 2022
--- | --- | --- | ---
Pension |  |  |
Recurring Fair Value Measures [Line Items] |  |  |
Fair Value of Assets | $ 604.1 | $ 589.0 | $ 568.6
Pension | Level 1 |  |  |
Recurring Fair Value Measures [Line Items] |  |  |
Fair Value of Assets | 251.3 | 155.0 |
Pension | Level 2 |  |  |
Recurring Fair Value Measures [Line Items] |  |  |
Fair Value of Assets | 334.5 | 415.1 |
Pension | Level 3 |  |  |
Recurring Fair Value Measures [Line Items] |  |  |
Fair Value of Assets | 18.3 | 18.9 |
Pension | U.S. Large-cap |  |  |
Recurring Fair Value Measures [Line Items] |  |  |
Fair Value of Assets | 73.2 | 83.7 |
Pension | U.S. Large-cap | Level 1 |  |  |
Recurring Fair Value Measures [Line Items] |  |  |
Fair Value of Assets | 73.2 | 0.0 |
Pension | U.S. Large-cap | Level 2 |  |  |
Recurring Fair Value Measures [Line Items] |  |  |
Fair Value of Assets | 0.0 | 83.7 |
Pension | U.S. Large-cap | Level 3 |  |  |
Recurring Fair Value Measures [Line Items] |  |  |
Fair Value of Assets | 0.0 | 0.0 |
Pension | U.S. Mid-cap Growth |  |  |
Recurring Fair Value Measures [Line Items] |  |  |
Fair Value of Assets | 35.1 | 69.9 |
Pension | U.S. Mid-cap Growth | Level 1 |  |  |
Recurring Fair Value Measures [Line Items] |  |  |
Fair Value of Assets | 35.1 | 0.0 |
Pension | U.S. Mid-cap Growth | Level 2 |  |  |
Recurring Fair Value Measures [Line Items] |  |  |
Fair Value of Assets | 0.0 | 69.9 |
Pension | U.S. Mid-cap Growth | Level 3 |  |  |
Recurring Fair Value Measures [Line Items] |  |  |
Fair Value of Assets | 0.0 | 0.0 |
Pension | U.S. Small-cap |  |  |
Recurring Fair Value Measures [Line Items] |  |  |
Fair Value of Assets | 31.6 | 46.5 |
Pension | U.S. Small-cap | Level 1 |  |  |
Recurring Fair Value Measures [Line Items] |  |  |
Fair Value of Assets | 31.6 | 0.0 |
Pension | U.S. Small-cap | Level 2 |  |  |
Recurring Fair Value Measures [Line Items] |  |  |
Fair Value of Assets | 0.0 | 46.5 |
Pension | U.S. Small-cap | Level 3 |  |  |
Recurring Fair Value Measures [Line Items] |  |  |
Fair Value of Assets | 0.0 | 0.0 |
Pension | International |  |  |
Recurring Fair Value Measures [Line Items] |  |  |
Fair Value of Assets | 201.6 | 134.6 |
Pension | International | Level 1 |  |  |
Recurring Fair Value Measures [Line Items] |  |  |
Fair Value of Assets | 102.5 | 134.6 |
Pension | International | Level 2 |  |  |
Recurring Fair Value Measures [Line Items] |  |  |
Fair Value of Assets | 99.1 | 0.0 |
Pension | International | Level 3 |  |  |
Recurring Fair Value Measures [Line Items] |  |  |
Fair Value of Assets | 0.0 | 0.0 |
Pension | Fixed Income Securities |  |  |
Recurring Fair Value Measures [Line Items] |  |  |
Fair Value of Assets | 235.4 | 215.0 |
Pension | Fixed Income Securities | Level 1 |  |  |
Recurring Fair Value Measures [Line Items] |  |  |
Fair Value of Assets | 0.0 | 0.0 |
Pension | Fixed Income Securities | Level 2 |  |  |
Recurring Fair Value Measures [Line Items] |  |  |
Fair Value of Assets | 235.4 | 215.0 |
Pension | Fixed Income Securities | Level 3 |  |  |
Recurring Fair Value Measures [Line Items] |  |  |
Fair Value of Assets | 0.0 | 0.0 |
Pension | Cash and Cash Equivalents |  |  |
Recurring Fair Value Measures [Line Items] |  |  |
Fair Value of Assets | 8.9 | 20.4 |
Pension | Cash and Cash Equivalents | Level 1 |  |  |
Recurring Fair Value Measures [Line Items] |  |  |
Fair Value of Assets | 8.9 | 20.4 |
Pension | Cash and Cash Equivalents | Level 2 |  |  |
Recurring Fair Value Measures [Line Items] |  |  |
Fair Value of Assets | 0.0 | 0.0 |
Pension | Cash and Cash Equivalents | Level 3 |  |  |
Recurring Fair Value Measures [Line Items] |  |  |
Fair Value of Assets | 0.0 | 0.0 |
Pension | Real Estate |  |  |
Recurring Fair Value Measures [Line Items] |  |  |
Fair Value of Assets | 18.3 | 18.9 |
Pension | Real Estate | Level 1 |  |  |
Recurring Fair Value Measures [Line Items] |  |  |
Fair Value of Assets | 0.0 | 0.0 |
Pension | Real Estate | Level 2 |  |  |
Recurring Fair Value Measures [Line Items] |  |  |
Fair Value of Assets | 0.0 | 0.0 |
Pension | Real Estate | Level 3 |  |  |
Recurring Fair Value Measures [Line Items] |  |  |
Fair Value of Assets | 18.3 | 18.9 | 22.4
Postretirement Health and Life |  |  |
Recurring Fair Value Measures [Line Items] |  |  |
Fair Value of Assets | 174.2 | 173.8 | $ 162.6
Postretirement Health and Life | Level 1 |  |  |
Recurring Fair Value Measures [Line Items] |  |  |
Fair Value of Assets | 174.2 | 173.8 |
Postretirement Health and Life | Level 2 |  |  |
Recurring Fair Value Measures [Line Items] |  |  |
Fair Value of Assets | 0.0 | 0.0 |
Postretirement Health and Life | Level 3 |  |  |
Recurring Fair Value Measures [Line Items] |  |  |
Fair Value of Assets | 0.0 | 0.0 |
Postretirement Health and Life | U.S. Large-cap |  |  |
Recurring Fair Value Measures [Line Items] |  |  |
Fair Value of Assets | 32.1 | 30.0 |
Postretirement Health and Life | U.S. Large-cap | Level 1 |  |  |
Recurring Fair Value Measures [Line Items] |  |  |
Fair Value of Assets | 32.1 | 30.0 |
Postretirement Health and Life | U.S. Large-cap | Level 2 |  |  |
Recurring Fair Value Measures [Line Items] |  |  |
Fair Value of Assets | 0.0 | 0.0 |
Postretirement Health and Life | U.S. Large-cap | Level 3 |  |  |
Recurring Fair Value Measures [Line Items] |  |  |
Fair Value of Assets | 0.0 | 0.0 |
Postretirement Health and Life | U.S. Mid-cap Growth |  |  |
Recurring Fair Value Measures [Line Items] |  |  |
Fair Value of Assets | 30.0 | 28.7 |
Postretirement Health and Life | U.S. Mid-cap Growth | Level 1 |  |  |
Recurring Fair Value Measures [Line Items] |  |  |
Fair Value of Assets | 30.0 | 28.7 |
Postretirement Health and Life | U.S. Mid-cap Growth | Level 2 |  |  |
Recurring Fair Value Measures [Line Items] |  |  |
Fair Value of Assets | 0.0 | 0.0 |
Postretirement Health and Life | U.S. Mid-cap Growth | Level 3 |  |  |
Recurring Fair Value Measures [Line Items] |  |  |
Fair Value of Assets | 0.0 | 0.0 |
Postretirement Health and Life | U.S. Small-cap |  |  |
Recurring Fair Value Measures [Line Items] |  |  |
Fair Value of Assets | 15.7 | 14.9 |
Postretirement Health and Life | U.S. Small-cap | Level 1 |  |  |
Recurring Fair Value Measures [Line Items] |  |  |
Fair Value of Assets | 15.7 | 14.9 |
Postretirement Health and Life | U.S. Small-cap | Level 2 |  |  |
Recurring Fair Value Measures [Line Items] |  |  |
Fair Value of Assets | 0.0 | 0.0 |
Postretirement Health and Life | U.S. Small-cap | Level 3 |  |  |
Recurring Fair Value Measures [Line Items] |  |  |
Fair Value of Assets | 0.0 | 0.0 |
Postretirement Health and Life | International |  |  |
Recurring Fair Value Measures [Line Items] |  |  |
Fair Value of Assets | 37.9 | 41.9 |
Postretirement Health and Life | International | Level 1 |  |  |
Recurring Fair Value Measures [Line Items] |  |  |
Fair Value of Assets | 37.9 | 41.9 |
Postretirement Health and Life | International | Level 2 |  |  |
Recurring Fair Value Measures [Line Items] |  |  |
Fair Value of Assets | 0.0 | 0.0 |
Postretirement Health and Life | International | Level 3 |  |  |
Recurring Fair Value Measures [Line Items] |  |  |
Fair Value of Assets | 0.0 | 0.0 |
Postretirement Health and Life | Cash and Cash Equivalents |  |  |
Recurring Fair Value Measures [Line Items] |  |  |
Fair Value of Assets | 2.4 | 3.2 |
Postretirement Health and Life | Cash and Cash Equivalents | Level 1 |  |  |
Recurring Fair Value Measures [Line Items] |  |  |
Fair Value of Assets | 2.4 | 3.2 |
Postretirement Health and Life | Cash and Cash Equivalents | Level 2 |  |  |
Recurring Fair Value Measures [Line Items] |  |  |
Fair Value of Assets | 0.0 | 0.0 |
Postretirement Health and Life | Cash and Cash Equivalents | Level 3 |  |  |
Recurring Fair Value Measures [Line Items] |  |  |
Fair Value of Assets | 0.0 | 0.0 |
Postretirement Health and Life | Mutual Funds |  |  |
Recurring Fair Value Measures [Line Items] |  |  |
Fair Value of Assets | 56.1 | 55.1 |
Postretirement Health and Life | Mutual Funds | Level 1 |  |  |
Recurring Fair Value Measures [Line Items] |  |  |
Fair Value of Assets | 56.1 | 55.1 |
Postretirement Health and Life | Mutual Funds | Level 2 |  |  |
Recurring Fair Value Measures [Line Items] |  |  |
Fair Value of Assets | 0.0 | 0.0 |
Postretirement Health and Life | Mutual Funds | Level 3 |  |  |
Recurring Fair Value Measures [Line Items] |  |  |
Fair Value of Assets | $ 0.0 | $ 0.0 |

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