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Postretirement Health Care and Life Insurance Benefits - Pre-Tax Amounts Recorded in Accumulated Other Comprehensive Loss (Details) - Postretirement Health Care and Life Insurance Benefits - USD ($) $ in Millions | 12 Months Ended
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Dec. 31, 2025 | Dec. 31, 2024 | Dec. 31, 2023
Defined Benefit Plan Disclosure [Line Items] |  |  |
Prior service credit arising during year | $ 0.0 | $ (6.5) | $ 0.0
Amortization Abstract |  |  |
Prior service credit | 40.8 | 53.0 | 53.8
Total recorded in "Accumulated other comprehensive income" | $ 40.8 | $ 46.5 | $ 53.8

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