Accumulated Other Comprehensive Loss (Changes In Accumulated Other Comprehensive Income (Loss)) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance			$ 1,520.0
Ending balance	$ 1,867.0		1,867.0
Amounts reclassified from accumulated other comprehensive loss, tax	0.0	$ (5.6)	(0.2)	$ (8.6)
Actuarial loss, tax	0.0	0.1	0.0	0.1
Foreign Currency
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(11.0)	(7.3)	(14.6)	(5.0)
Other comprehensive loss before reclassifications	(4.1)	(9.4)	(0.5)	(11.7)
Amounts reclassified from accumulated other comprehensive income (net of tax)
Actuarial loss (net of tax)
Net current-period other comprehensive (loss) income	(4.1)	(9.4)	(0.5)	(11.7)
Ending balance	(15.1)	(16.7)	(15.1)	(16.7)
Pension and Other Postretirement Benefits
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(137.8)	(166.8)	(138.2)	(175.5)
Other comprehensive loss before reclassifications
Amounts reclassified from accumulated other comprehensive income (net of tax)	0.3	16.1	0.7	24.8
Actuarial loss (net of tax)		(0.4)		(0.4)
Net current-period other comprehensive (loss) income	0.3	15.7	0.7	24.4
Ending balance	(137.5)	(151.1)	(137.5)	(151.1)
Accumulated Other Comprehensive Loss
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(148.8)	(174.1)	(152.8)	(180.5)
Other comprehensive loss before reclassifications	(4.1)	(9.4)	(0.5)	(11.7)
Amounts reclassified from accumulated other comprehensive income (net of tax)	0.3	16.1	0.7	24.8
Actuarial loss (net of tax)		(0.4)		(0.4)
Net current-period other comprehensive (loss) income	(3.8)	6.3	0.2	12.7
Ending balance	$ (152.6)	$ (167.8)	$ (152.6)	$ (167.8)