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Employee Benefits - Summary of Total Expense Related to All Postretirement Benefit Plans (Details) - USD ($) $ in Millions | 3 Months Ended | 9 Months Ended
--- | --- | ---
Sep. 30, 2024 | Sep. 30, 2023 | Sep. 30, 2024 | Sep. 30, 2023
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Net periodic postretirement benefit cost relating to defined benefit plans | $ 1.5 | $ 2.2 | $ 3.3 | $ 6.1
Postretirement Benefit Plans |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Defined contribution plan, cost | 4.4 | 4.3 | 14.4 | 14.4
Deferred compensation arrangement with individual, compensation expense | 0.5 |  | 1.2 | 0.6
Multiemployer plan, contributions by employer | 1.6 | 1.4 | 4.6 | 4.2
Net periodic postretirement benefit cost relating to defined benefit plans | 2.5 | 3.3 | 6.8 | 9.7
Total other employee benefit plans | $ 9.0 | $ 9.0 | $ 27.0 | $ 28.9

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