Other Postretirement Benefit Plans - AOCL (Details) - Postretirement Plan - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Amounts recognized in accumulated other comprehensive loss:
Net prior service credit	$ (71.9)	$ (81.4)
Accumulated other comprehensive loss	$ (71.9)	$ (81.4)	$ (91.5)

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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-Name Accounting Standards Codification
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-Name Accounting Standards Codification
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-Publisher FASB
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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant