Accumulated Other Comprehensive Income (Loss) - Reclassification Adjustments (Details) - USD ($) $ in Millions	1 Months Ended	2 Months Ended	3 Months Ended	7 Months Ended	9 Months Ended
Aug. 11, 2023	Sep. 30, 2023	Sep. 30, 2024	Aug. 11, 2023	Sep. 30, 2024
Miscellaneous gain (loss), net	$ 6.2	$ (0.8)	$ 1.7	$ 12.3	$ 5.3
Net actuarial gain (loss) amortized, tax	(3.1)	0.0	6.8	(3.8)	4.6
Reclassification \| Net prior service benefit
Miscellaneous gain (loss), net	$ 1.1	$ 0.0	$ 8.1	$ 3.2	$ 15.0

Amount of tax expense (benefit) of reclassification adjustment from accumulated other comprehensive income (loss) for gain (loss) of defined benefit plan.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Section 45
-Paragraph 12
-SubTopic 10
-Topic 220
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482790/220-10-45-12

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