Accumulated Other Comprehensive Loss (Changes In Accumulated Other Comprehensive Income (Loss)) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	$ 892.9
Retained Earnings	725.1	$ 694.0	$ 678.1
Ending balance	930.5	892.9
Foreign Currency
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(7.7)	(12.4)
Other comprehensive income before reclassifications	2.6	4.7
Amounts reclassified from accumulated other comprehensive loss (net of tax $(15.1) and $(5.0))
Actuarial loss, (net of tax $14.6 and $10.2)
Net current-period other comprehensive income (loss)	2.6	4.7
Ending balance	(5.1)	(7.7)
Pension and Other Postretirement Benefits
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(242.9)	(227.9)
Other comprehensive income before reclassifications
Amounts reclassified from accumulated other comprehensive loss (net of tax $(15.1) and $(5.0))	43.5	14.4
Actuarial loss, (net of tax $14.6 and $10.2)	(42.2)	(29.4)
Net current-period other comprehensive income (loss)	1.3	(15.0)
Ending balance	(241.6)	(242.9)
Accumulated Other Comprehensive Loss
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(250.6)	(240.3)
Other comprehensive income before reclassifications	2.6	4.7
Amounts reclassified from accumulated other comprehensive loss (net of tax $(15.1) and $(5.0))	43.5	14.4
Actuarial loss, (net of tax $14.6 and $10.2)	(42.2)	(29.4)
Net current-period other comprehensive income (loss)	3.9	(10.3)
Ending balance	$ (246.7)	$ (250.6)