Condensed Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2025	Jun. 30, 2024	Jun. 30, 2025	Jun. 30, 2024
Statement of Comprehensive Income [Abstract]
Net loss	$ (18.1)	$ (34.3)	$ (46.4)	$ (75.2)
Other comprehensive income (loss), net of tax:
Foreign currency translation loss	0.0	(1.0)	0.0	(3.6)
Defined benefit plans:
Net (loss) gain arising from remeasurement during the period, net of tax of $0.0, ($0.9), $0.4, ($0.9)	0.0	(2.8)	1.2	(2.8)
Amortization of prior service benefits included in loss from continuing operations, net of tax of $0.0, $0.0, ($0.1), ($0.1)	(0.2)	(0.2)	(0.3)	(0.3)
Amortization of net actuarial gain included in loss from continuing operations, net of tax of ($0.3), ($0.3), ($0.6), ($0.5)	(1.0)	(0.8)	(1.9)	(1.5)
Settlement gains reclassified to loss from continuing operations, net of tax of ($0.2), ($0.1), ($0.4), ($0.1)	(0.6)	(0.3)	(1.4)	(0.3)
Total other comprehensive loss	(1.8)	(5.1)	(2.4)	(8.5)
Total comprehensive loss	$ (19.9)	$ (39.4)	$ (48.8)	$ (83.7)