Accumulated Other Comprehensive Loss (Changes In Accumlated Other Comprehensive Income (Loss)) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance			$ 930.5
Retained Earnings	$ 906.1		906.1		$ 725.1
Ending balance	1,163.6		1,163.6
Amounts reclassified from accumulated other comprehensive loss, tax	(6.5)	$ (6.5)	(11.0)	$ (10.4)
Actuarial loss, tax	(5.1)	3.5	(5.1)	3.5
Foreign Currency
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(1.7)	(12.7)	(5.1)	(7.7)
Other comprehensive (loss) income before reclassifications	(3.3)	2.1	0.1	(2.9)
Amounts reclassified from accumulated other comprehensive loss (net of tax)
Actuarial gain (loss) (net of tax)
Net current-period other comprehensive (loss) income	(3.3)	2.1	0.1	(2.9)
Ending balance	(5.0)	(10.6)	(5.0)	(10.6)
Pension and Other Postretirement Benefits
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(228.8)	(231.7)	(241.6)	(242.9)
Other comprehensive (loss) income before reclassifications
Amounts reclassified from accumulated other comprehensive loss (net of tax)	18.8	18.8	31.6	30.0
Actuarial gain (loss) (net of tax)	14.9	(10.2)	14.9	(10.2)
Net current-period other comprehensive (loss) income	33.7	8.6	46.5	19.8
Ending balance	(195.1)	(223.1)	(195.1)	(223.1)
Accumulated Other Comprehensive Loss
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(230.5)	(244.4)	(246.7)	(250.6)
Other comprehensive (loss) income before reclassifications	(3.3)	2.1	0.1	(2.9)
Amounts reclassified from accumulated other comprehensive loss (net of tax)	18.8	18.8	31.6	30.0
Actuarial gain (loss) (net of tax)	14.9	(10.2)	14.9	(10.2)
Net current-period other comprehensive (loss) income	30.4	10.7	46.6	16.9
Ending balance	$ (200.1)	$ (233.7)	$ (200.1)	$ (233.7)