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Employee Benefits - Summary of Total Expense (Benefit) Related to All Postretirement Benefit Plans (Details) - USD ($) $ in Millions | 3 Months Ended | 6 Months Ended
--- | --- | ---
Jun. 30, 2023 | Jun. 30, 2022 | Jun. 30, 2023 | Jun. 30, 2022
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Net periodic postretirement benefit cost relating to defined benefit plans | $ 1.9 | $ 1.5 | $ 3.9 | $ 2.9
Postretirement Benefit Plans |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Defined contribution plan, cost | 4.3 | 4.0 | 10.1 | 9.7
Deferred compensation arrangement with individual, compensation expense | 0.4 | (0.5) | 0.6 | (0.8)
Multiemployer plan, contributions by employer | 1.4 | 1.4 | 2.8 | 2.6
Net periodic postretirement benefit cost relating to defined benefit plans | 3.3 | 3.3 | 6.4 | 6.5
Total other employee benefit plans | $ 9.4 | $ 8.2 | $ 19.9 | $ 18.0

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