Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Statement of Comprehensive Income [Abstract]
Net income	$ 356.3	$ 408.7	$ 359.0
Other comprehensive income (loss):
Foreign currency translation adjustments	0.8	3.7	(16.9)
Reclassification of foreign currency translation adjustments into earnings	0.0	(2.1)	(27.9)
Net change in pension and post-retirement benefit liabilities	(8.7)	(7.1)	(14.2)
Change in fair value of available-for-sale marketable equity securities	0.0	0.0	(1.8)
Net change in fair value of cash flow hedges	7.0	1.3	(13.6)
Reclassification of pension and post-retirement benefit losses into earnings	5.9	5.7	9.3
non-cash pension settlement loss	0.6	99.2	0.4
Reclassification of cash flow hedge losses into earnings	3.7	6.9	(6.1)
Other comprehensive income (loss) before taxes	8.1	111.8	(15.0)
Tax expense	(1.5)	(26.8)	(16.4)
Other comprehensive income (loss), net of tax	6.6	85.0	(31.4)
Comprehensive income	362.9	493.7	327.6
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net Income (Loss) Attributable to Parent	356.3	408.7	359.0
Foreign currency translation adjustments	0.8	3.7	(16.9)
Reclassification of foreign currency translation adjustments into earnings	0.0	(2.1)	(27.9)
Other Comprehensive (Income) Loss, Defined Benefit Plan, before Reclassification Adjustment and Tax	8.7	7.1	14.2
Net change in fair value of cash flow hedges	7.0	1.3	(13.6)
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, before Tax	(5.9)	(5.7)	(9.3)
non-cash pension settlement loss	0.6	99.2	0.4
Change in fair value of available-for-sale marketable equity securities	0.0	0.0	(1.8)
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives, Net of Tax	(3.7)	(6.9)	6.1
Other Comprehensive Income (Loss), before Tax, Portion Attributable to Parent	8.1	111.8	(15.0)
Other Comprehensive Income (Loss), Tax	1.5	26.8	16.4
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	6.6	85.0	(31.4)
Comprehensive Income (Loss), Net of Tax, Attributable to Parent	362.9	493.7	327.6
Accumulated Other Comprehensive Income (Loss) [Member]
Other comprehensive income (loss):
Share of equity method investments other comprehensive income	(1.2)	0.0	0.0
Accumulated Other Comprehensive Income (Loss) [Line Items]
Share of equity method investments other comprehensive income	$ (1.2)	$ 0.0	$ 0.0