Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Statement of Comprehensive Income [Abstract]
Net Income (Loss)	$ 21.8	$ (109.1)	$ (53.5)
Other Comprehensive (Income) Loss, Defined Benefit Plan, before Reclassification Adjustment, after Tax [Abstract]
Net actuarial gains (losses)	(62.4)	(112.7)	204.6
Settlement adjustments	12.1	64.7	2.7
Amortization of prior net losses	8.6	12.1	12.7
Amortization of prior net service credit	(0.4)	(0.4)	(0.4)
Changes in foreign currency translation, net of tax	(2.8)	0.5	0.9
Other comprehensive income (loss)	(44.9)	(35.8)	220.5
Comprehensive Income (Loss)	$ (23.1)	$ (144.9)	$ 167.0