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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
	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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