Comprehensive Income (Changes in AOCL) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Changes in AOCI by component (net of tax) [Roll Forward]
Balance as of beginning of period			$ (188.8)
Other comprehensive income (loss) before reclassifications			5.4
Amounts reclassified from AOCL			56.2
Net other comprehensive (loss) income			61.6
Balance as of end of period	$ (127.2)		(127.2)
Gains (Losses) on Cash Flow Hedges [Member]
Changes in AOCI by component (net of tax) [Roll Forward]
Balance as of beginning of period			(6.2)
Other comprehensive income (loss) before reclassifications			(2.0)
Amounts reclassified from AOCL			5.3
Net other comprehensive (loss) income			3.3
Balance as of end of period	(2.9)		(2.9)
Defined Benefit Pension Plan Items [Member]
Changes in AOCI by component (net of tax) [Roll Forward]
Balance as of beginning of period			(154.5)
Other comprehensive income (loss) before reclassifications			9.8
Amounts reclassified from AOCL			48.8
Net other comprehensive (loss) income			58.6
Balance as of end of period	(95.9)		(95.9)
Accumulated Foreign Currency Adjustment Attributable to Parent [Member]
Changes in AOCI by component (net of tax) [Roll Forward]
Balance as of beginning of period			(28.1)
Other comprehensive income (loss) before reclassifications			(2.4)
Amounts reclassified from AOCL	0.0	$ 5.0	2.1	$ 27.9
Net other comprehensive (loss) income			(0.3)
Balance as of end of period	$ (28.4)		$ (28.4)