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Employee Benefits - Summary of Total Expense (Benefit) Related to All Postretirement Benefit Plans (Details) - USD ($) $ in Millions | 3 Months Ended | 9 Months Ended
--- | --- | ---
Sep. 30, 2023 | Sep. 30, 2022 | Sep. 30, 2023 | Sep. 30, 2022
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Net periodic postretirement benefit cost relating to defined benefit plans | $ 2.2 | $ 1.4 | $ 6.1 | $ 4.3
Postretirement Benefit Plans |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Defined contribution plan, cost | 4.3 | 3.9 | 14.4 | 13.6
Deferred compensation arrangement with individual, compensation expense |  | (0.1) | 0.6 | (0.9)
Multiemployer plan, contributions by employer | 1.4 | 1.3 | 4.2 | 3.9
Net periodic postretirement benefit cost relating to defined benefit plans | 3.3 | 3.1 | 9.7 | 9.6
Total other employee benefit plans | $ 9.0 | $ 8.2 | $ 28.9 | $ 26.2

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