Equity - Schedule of Changes in Accumulated Other Comprehensive Income (Loss) by Component (Details) - USD ($) $ in Millions		4 Months Ended	8 Months Ended	12 Months Ended
		Dec. 31, 2021	Sep. 07, 2021	Dec. 31, 2023	Dec. 31, 2022
Changes in Accumulated Other Comprehensive Loss by Component [Roll Forward]
Beginning balance				$ 19.5	$ 1.2
Remeasurement of benefit obligations		$ 2.6	$ 6.0	10.5	25.1
Reclassifications, net	[1]			(4.4)	(0.6)
Foreign currency gain (loss)		(1.4)	$ 1.2	2.6	(6.2)
Ending balance		1.2		28.2	19.5
Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member]
Changes in Accumulated Other Comprehensive Loss by Component [Roll Forward]
Beginning balance				27.1	2.6
Remeasurement of benefit obligations				10.5	25.1
Reclassifications, net	[1]			(4.4)	(0.6)
Foreign currency gain (loss)				0.0	0.0
Ending balance		2.6		33.2	27.1
Accumulated Foreign Currency Adjustment Attributable to Parent [Member]
Changes in Accumulated Other Comprehensive Loss by Component [Roll Forward]
Beginning balance				(7.6)	(1.4)
Remeasurement of benefit obligations				0.0	0.0
Reclassifications, net				0.0	0.0
Foreign currency gain (loss)				2.6	(6.2)
Ending balance		$ (1.4)		$ (5.0)	$ (7.6)

[1] These reclassifications are included in the other components of net periodic pension and postretirement benefit plans expense and represent amortization of prior service benefit and actuarial gain, net of tax. The other components of net periodic pension and postretirement benefit plans expense are recorded in "Other components of pension and postretirement benefit plans expense (benefit)" on the Consolidated Statements of Operations. See Note 11 for further disclosures.