Employee Benefit Plans - Pre-tax Amounts Recorded in AOCI (Details) - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023
Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Net actuarial gain (loss)	$ (219.5)	$ (212.2)
Net prior service credit (cost)	0.3	0.3
Total amounts recorded	(219.2)	(211.9)
Other Postretirement Benefits Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Net actuarial gain (loss)	136.9	146.0
Net prior service credit (cost)	2.2	0.7
Total amounts recorded	$ 139.1	$ 146.7

Amount, before tax, of accumulated other comprehensive (income) loss for defined benefit plan, that has not been recognized in net periodic benefit cost (credit).

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Amount, before tax, of accumulated other comprehensive income (loss) for gain (loss) of defined benefit plan, that has not been recognized in net periodic benefit (cost) credit.

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Amount, before tax, of accumulated other comprehensive (income) loss for cost (credit) of benefit change attributable to participants' prior service from plan amendment or plan initiation of defined benefit plan, that has not been recognized in net periodic benefit cost (credit).

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