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Summary of Significant Accounting Policies - Summary of Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2023 | Dec. 31, 2022 | Dec. 31, 2021
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |  |
Accumulated other comprehensive income (loss) | $ (11.9) | $ (24.8) |
Other comprehensive income (loss) before reclassifications | 2.5 | (2.1) |
Amounts reclassified from accumulated other comprehensive income (loss) | 1.0 | 1.4 |
Settlement cost | 1.2 | 13.6 | $ 6.0
Net current period other comprehensive income (loss) | 4.7 | 12.9 | 7.3
Accumulated other comprehensive income (loss) | (7.2) | (11.9) | (24.8)
Accumulated other comprehensive loss, net of tax | (7.2) | (11.9) |
Net current period other comprehensive income (loss) | 4.7 | 12.9 | 7.3
Other Postretirement Benefits Plan [Member] |  |  |
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |  |
Net current period other comprehensive income (loss) | 0.0 |  |
Defined Benefit Plans Income Loss [Member] | Pension Plans, Defined Benefit [Member] |  |  |
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |  |
Accumulated other comprehensive income (loss) | (17.5) | (24.9) |
Other comprehensive income (loss) before reclassifications | 3.3 | (7.6) |
Amounts reclassified from accumulated other comprehensive income (loss) | 0.9 | 1.4 |
Net current period other comprehensive income (loss) | 5.4 | 7.4 |
Accumulated other comprehensive income (loss) | (12.1) | (17.5) | (24.9)
Defined Benefit Plans Income Loss [Member] | Other Postretirement Benefits Plan [Member] |  |  |
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |  |
Accumulated other comprehensive income (loss) | 6.6 | 1.1 |
Other comprehensive income (loss) before reclassifications | (0.8) | 5.5 |
Amounts reclassified from accumulated other comprehensive income (loss) | (0.1) | 0.0 |
Net current period other comprehensive income (loss) | (0.9) | 5.5 |
Accumulated other comprehensive income (loss) | 5.7 | 6.6 | 1.1
Defined Benefit Plan Prior Service Cost [Member] | Pension Plans, Defined Benefit [Member] |  |  |
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |  |
Accumulated other comprehensive income (loss) | (1.0) | (1.2) |
Other comprehensive income (loss) before reclassifications | 0.0 | 0.0 |
Amounts reclassified from accumulated other comprehensive income (loss) | 0.2 | 0.2 |
Net current period other comprehensive income (loss) | 0.2 | 0.2 |
Accumulated other comprehensive income (loss) | (0.8) | (1.0) | (1.2)
Defined Benefit Plan Prior Service Cost [Member] | Other Postretirement Benefits Plan [Member] |  |  |
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |  |
Accumulated other comprehensive income (loss) | 0.0 | 0.2 |
Other comprehensive income (loss) before reclassifications | 0.0 | 0.0 |
Amounts reclassified from accumulated other comprehensive income (loss) | 0.0 | (0.2) |
Net current period other comprehensive income (loss) |  | (0.2) |
Accumulated other comprehensive income (loss) | 0.0 | 0.0 | $ 0.2
Settlement Cost [Member] | Defined Benefit Plans Income Loss [Member] | Pension Plans, Defined Benefit [Member] |  |  |
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |  |
Settlement cost | 1.2 | 13.6 |
Settlement Cost [Member] | Defined Benefit Plan Prior Service Cost [Member] | Pension Plans, Defined Benefit [Member] |  |  |
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |  |
Settlement cost | 0.0 | 0.0 |
Settlement Cost [Member] | Defined Benefit Plan Prior Service Cost [Member] | Other Postretirement Benefits Plan [Member] |  |  |
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |  |
Settlement cost | $ 0.0 | $ 0.0 |

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