Accumulated Other Comprehensive Loss (Changes In Accumulated Other Comprehensive Income (Loss)) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	$ 1,520.0
Ending balance	1,880.5	$ 1,520.0
Amounts reclassified from accumulated other comprehensive loss, tax	(0.3)	(11.6)
Actuarial loss, tax	10.4	(1.4)
Foreign Currency [Member]
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(14.6)	(5.0)
Other comprehensive income (loss) before reclassifications	4.0	(9.6)
Amounts reclassified from accumulated other comprehensive income (net of tax)
Actuarial (loss) gain (net of tax)
Net current-period other comprehensive (loss) income	4.0	(9.6)
Ending balance	(10.6)	(14.6)
Pension and Other Postretirement Benefits [Member]
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(138.2)	(175.5)
Other comprehensive income (loss) before reclassifications
Amounts reclassified from accumulated other comprehensive income (net of tax)	0.8	33.4
Actuarial (loss) gain (net of tax)	(29.9)	3.9
Net current-period other comprehensive (loss) income	(29.1)	37.3
Ending balance	(167.3)	(138.2)
Accumulated Other Comprehensive Loss [Member]
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(152.8)	(180.5)
Other comprehensive income (loss) before reclassifications	4.0	(9.6)
Amounts reclassified from accumulated other comprehensive income (net of tax)	0.8	33.4
Actuarial (loss) gain (net of tax)	(29.9)	3.9
Net current-period other comprehensive (loss) income	(25.1)	27.7
Ending balance	$ (177.9)	$ (152.8)