Shareholders' Equity (Schedule of Accumulated Other Comprehensive (Loss) Activity) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Accumulated Other Comprehensive Income Loss [Line Items]
Balance	$ 370.4	$ 245.1	$ 364.9	$ 226.0
Impact of ASU 2017-12 adoption	812.8		812.8		$ 1,008.2
Other comprehensive income (loss) before reclassifications, net of tax benefit (expense)	(0.7)	(7.0)	(5.8)	(6.6)
Amounts reclassified from accumulated other comprehensive (loss)	(1.9)	2.5	277.6	5.1
Net current period other comprehensive income (loss)	(2.6)	(4.5)	271.8	(1.5)
Balance	402.9	243.1	402.9	243.1
ASU 2017-12 [Member] | Cumulative Effect, Period of Adoption, Adjustment [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Impact of ASU 2017-12 adoption		0.1		0.1
Foreign Currency Translation Adjustments [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Balance	7.3	(69.4)	9.4	(74.7)
Other comprehensive income (loss) before reclassifications, net of tax benefit (expense)	0.1	0.7	(2.0)	6.0
Net current period other comprehensive income (loss)	0.1	0.7	(2.0)	6.0
Balance	7.4	(68.7)	7.4	(68.7)
Derivative Gain (Loss) [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Balance	(20.3)	0.3	(8.5)	5.3
Other comprehensive income (loss) before reclassifications, net of tax benefit (expense)	(0.8)	(8.4)	(12.4)	(14.0)
Amounts reclassified from accumulated other comprehensive (loss)	(1.2)	0.3	(1.4)	0.8
Net current period other comprehensive income (loss)	(2.0)	(8.1)	(13.8)	(13.2)
Balance	(22.3)	(7.8)	(22.3)	(7.8)
Derivative Gain (Loss) [Member] | ASU 2017-12 [Member] | Cumulative Effect, Period of Adoption, Adjustment [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Impact of ASU 2017-12 adoption		0.1		0.1
Pension And Postretirement Adjustments [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Balance	(88.7)	(387.4)	(377.0)	(390.2)
Other comprehensive income (loss) before reclassifications, net of tax benefit (expense)		0.7	8.6	1.4
Amounts reclassified from accumulated other comprehensive (loss)	(0.7)	2.2	279.0	4.3
Net current period other comprehensive income (loss)	(0.7)	2.9	287.6	5.7
Balance	(89.4)	(384.5)	(89.4)	(384.5)
Accumulated Other Comprehensive (Loss) [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Balance	(101.7)	(456.5)	(376.1)	(459.6)
Balance	$ (104.3)	(461.0)	$ (104.3)	(461.0)
Accumulated Other Comprehensive (Loss) [Member] | ASU 2017-12 [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Impact of ASU 2017-12 adoption		$ 0.1		$ 0.1