Comprehensive Income (Changes in AOCL) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 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			6.0
Amounts reclassified from AOCL			53.2
Net other comprehensive (loss) income			59.2
Balance as of end of period	$ (129.6)		(129.6)
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			0.3
Amounts reclassified from AOCL			3.3
Net other comprehensive (loss) income			3.6
Balance as of end of period	(2.6)		(2.6)
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			1.8
Amounts reclassified from AOCL			47.8
Net other comprehensive (loss) income			49.6
Balance as of end of period	(104.9)		(104.9)
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			3.9
Amounts reclassified from AOCL	0.0	$ (22.9)	2.1	$ (22.9)
Net other comprehensive (loss) income			6.0
Balance as of end of period	$ (22.1)		$ (22.1)