Shareholders' Equity (Schedule of Accumulated Other Comprehensive (Loss) Activity) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Accumulated Other Comprehensive Income Loss [Line Items]
Balance	$ 473.6	$ 370.4	$ 450.9	$ 364.9
Other comprehensive (loss) income before reclassifications, net of tax benefit (expense)	3.3		9.2
Amounts reclassified from accumulated other comprehensive (loss)	(1.5)		(2.8)
Net current period other comprehensive (loss) income	1.8		6.4
Balance	498.3	402.9	498.3	402.9
Foreign Currency Translation Adjustments [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Balance	2.9	7.3	2.3	9.4
Other comprehensive (loss) income before reclassifications, net of tax benefit (expense)	0.5	0.1	1.1	(2.0)
Net current period other comprehensive (loss) income	0.5	0.1	1.1	(2.0)
Balance	3.4	7.4	3.4	7.4
Derivative Gain (Loss) [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Balance	(15.2)	(20.3)	(19.0)	(8.5)
Other comprehensive (loss) income before reclassifications, net of tax benefit (expense)	2.8	(0.8)	8.1	(12.4)
Amounts reclassified from accumulated other comprehensive (loss)	(1.7)	(1.2)	(3.2)	(1.4)
Net current period other comprehensive (loss) income	1.1	(2.0)	4.9	(13.8)
Balance	(14.1)	(22.3)	(14.1)	(22.3)
Pension And Postretirement Adjustments [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Balance	(92.4)	(88.7)	(92.6)	(377.0)
Other comprehensive (loss) income before reclassifications, net of tax benefit (expense)				8.6
Amounts reclassified from accumulated other comprehensive (loss)	0.2	(0.7)	0.4	279.0
Net current period other comprehensive (loss) income	0.2	(0.7)	0.4	287.6
Balance	(92.2)	(89.4)	(92.2)	(89.4)
Accumulated Other Comprehensive (Loss) [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Balance	(104.7)	(101.7)	(109.3)	(376.1)
Other comprehensive (loss) income before reclassifications, net of tax benefit (expense)		(0.7)		(5.8)
Amounts reclassified from accumulated other comprehensive (loss)		(1.9)		277.6
Net current period other comprehensive (loss) income		(2.6)		271.8
Balance	$ (102.9)	$ (104.3)	$ (102.9)	$ (104.3)