Accumulated Other Comprehensive Loss - Details of Comprehensive Loss (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance			$ 172.5
Other comprehensive (loss) income before reclassifications			(11.1)	$ (93.5)
Less: amounts reclassified from accumulated other comprehensive loss	$ 1.4	$ 3.7	7.0	3.6
Other comprehensive (loss) income	(22.8)	(5.9)	(4.1)	(89.9)
Ending balance	127.7		127.7
Unrecognized Pension Items
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance			(172.5)	(146.1)
Other comprehensive (loss) income before reclassifications			(1.6)	(0.4)
Less: amounts reclassified from accumulated other comprehensive loss			4.8	4.3
Other comprehensive (loss) income			3.2	3.9
Ending balance	(169.3)	(142.2)	(169.3)	(142.2)
Cumulative Translation Adjustment
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance			(721.7)	(728.6)
Other comprehensive (loss) income before reclassifications			(33.4)	(77.5)
Less: amounts reclassified from accumulated other comprehensive loss			0.0	0.0
Other comprehensive (loss) income			(33.4)	(77.5)
Ending balance	(755.1)	(806.1)	(755.1)	(806.1)
Cumulative Translation Adjustment | Intra-entity transactions
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Intra-entity currency translation adjustments in AOCI	19.4	(19.8)	19.4	(19.8)
Unrecognized (Losses) Gains on Derivative Instruments | Net investment hedge
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance			(67.5)	(34.5)
Other comprehensive (loss) income before reclassifications			21.0	(16.3)
Less: amounts reclassified from accumulated other comprehensive loss			0.0	0.0
Other comprehensive (loss) income			21.0	(16.3)
Ending balance	(46.5)	(50.8)	(46.5)	(50.8)
Unrecognized (Losses) Gains on Derivative Instruments | Cash Flow Hedge
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance			(1.8)	0.2
Other comprehensive (loss) income before reclassifications			2.9	0.7
Less: amounts reclassified from accumulated other comprehensive loss			2.2	(0.7)
Other comprehensive (loss) income			5.1	0.0
Ending balance	3.3	0.2	3.3	0.2
Accumulated Other Comprehensive Loss, Net of  Taxes
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance			(963.5)	(909.0)
Ending balance	$ (967.6)	$ (998.9)	$ (967.6)	$ (998.9)