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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, 2022 | Sep. 30, 2021 | Sep. 30, 2022 | Sep. 30, 2021
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total net periodic postretirement benefit cost | $ 1.4 | $ 1.2 | $ 4.3 | $ 3.0
Other Postretirement Benefits Plan |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Defined contribution plan, cost | 3.9 | 3.4 | 13.6 | 10.4
Deferred compensation arrangement with individual, compensation expense | (0.1) | 0.2 | (0.9) | 0.6
Multiemployer plan, contributions by employer | 1.3 | 1.3 | 3.9 | 3.7
Total net periodic postretirement benefit cost | 0.9 | 0.9 | 2.8 | 1.9
Total other employee benefit plans | 8.2 | 7.8 | 26.2 | 21.2
Postretirement Health Coverage | Salaried VEBA |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total net periodic postretirement benefit cost | 0.9 | 0.6 | 2.8 | 1.7
Pension Plans |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total net periodic postretirement benefit cost | $ 1.3 | $ 1.4 | $ 4.0 | $ 2.9

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