Accounting Policies - Accumulated Other Comprehensive Loss by Component, Net of Tax (Details) - USD ($) $ in Millions	3 Months Ended						9 Months Ended
	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2021	Sep. 30, 2020
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	$ 10,327.8	$ 10,177.1	$ 10,152.7	$ 9,880.6	$ 9,797.7	$ 9,993.6	$ 10,152.7	$ 9,993.6
Other comprehensive (loss) income before reclassifications	(57.5)			54.9			(95.7)	(101.8)
Amounts reclassified from Accumulated other comprehensive loss	0.7			0.7			2.2	2.2
Other comprehensive (loss) income, net	(56.8)	33.2	(69.9)	55.6	22.8	(178.0)	(93.5)	(99.6)
Ending Balance	10,191.2	10,327.8	10,177.1	10,052.4	9,880.6	9,797.7	10,191.2	10,052.4
Foreign currency translation
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	(288.1)		(260.2)	(460.8)		(308.6)	(260.2)	(308.6)
Other comprehensive (loss) income before reclassifications	(59.9)			53.8			(87.8)	(98.4)
Amounts reclassified from Accumulated other comprehensive loss	0.0			0.0			0.0	0.0
Other comprehensive (loss) income, net	(59.9)			53.8			(87.8)	(98.4)
Ending Balance	(348.0)	(288.1)		(407.0)	(460.8)		(348.0)	(407.0)
Derivative contracts
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	(3.1)		2.4	(4.1)		(3.3)	2.4	(3.3)
Other comprehensive (loss) income before reclassifications	(0.3)			2.2			(5.8)	1.4
Amounts reclassified from Accumulated other comprehensive loss	0.0			0.0			0.0	0.0
Other comprehensive (loss) income, net	(0.3)			2.2			(5.8)	1.4
Ending Balance	(3.4)	(3.1)		(1.9)	(4.1)		(3.4)	(1.9)
Pension and post retirement benefit plans
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	(84.6)		(81.3)	(72.9)		(70.7)	(81.3)	(70.7)
Other comprehensive (loss) income before reclassifications	2.7			(1.1)			(2.1)	(4.8)
Amounts reclassified from Accumulated other comprehensive loss	0.7			0.7			2.2	2.2
Other comprehensive (loss) income, net	3.4			(0.4)			0.1	(2.6)
Ending Balance	(81.2)	(84.6)		(73.3)	(72.9)		(81.2)	(73.3)
AOCI Attributable to Parent
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	(375.8)	(409.0)	(339.1)	(537.8)	(560.6)	(382.6)	(339.1)	(382.6)
Other comprehensive (loss) income, net	(56.8)	33.2	(69.9)	55.6	22.8	(178.0)
Ending Balance	$ (432.6)	$ (375.8)	$ (409.0)	$ (482.2)	$ (537.8)	$ (560.6)	$ (432.6)	$ (482.2)