Comprehensive Income (Changes in AOCI) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Changes in AOCI by component (net of tax) [Roll Forward]
Beginning balance	$ (103.8)	$ (188.8)
Other comprehensive income (loss) before reclassifications	(1.1)	(1.1)
Amounts reclassified from AOCL	7.7	86.1
Net other comprehensive income (loss)	6.6	85.0
Ending balance	(97.2)	(103.8)
Gains (Losses) on Cash Flow Hedges [Member]
Changes in AOCI by component (net of tax) [Roll Forward]
Beginning balance	0.0	(6.2)
Other comprehensive income (loss) before reclassifications	5.4	0.9
Amounts reclassified from AOCL	2.8	5.3
Net other comprehensive income (loss)	8.2	6.2
Ending balance	8.2	0.0
Defined Benefit Plan Items [Member]
Changes in AOCI by component (net of tax) [Roll Forward]
Beginning balance	(81.5)	(154.5)
Other comprehensive income (loss) before reclassifications	(6.1)	(5.7)
Amounts reclassified from AOCL	4.9	78.7
Net other comprehensive income (loss)	(1.2)	73.0
Ending balance	(82.7)	(81.5)
Foreign Currency Translation Adjustments [Member]
Changes in AOCI by component (net of tax) [Roll Forward]
Beginning balance	(22.3)	(28.1)
Other comprehensive income (loss) before reclassifications	0.8	3.7
Amounts reclassified from AOCL	0.0	2.1
Net other comprehensive income (loss)	0.8	5.8
Ending balance	(21.5)	(22.3)
Accumulated Defined Benefit Plans Adjustment Attributable to Noncontrolling Interest [Member]
Changes in AOCI by component (net of tax) [Roll Forward]
Beginning balance	0.0	0.0
Other comprehensive income (loss) before reclassifications	(1.2)	0.0
Amounts reclassified from AOCL	0.0	0.0
Net other comprehensive income (loss)	(1.2)	0.0
Ending balance	$ (1.2)	$ 0.0