Changes in Accumulated Other Comprehensive Income (Loss) by Component (Detail) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2021	Mar. 31, 2020
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	[1]	$ 10,390.0
Reclassified out of AOCI		2.6	$ (44.0)
Net other comprehensive income (loss)		(66.1)	(283.8)
Ending balance		10,717.7	9,637.4
Derivative Contracts
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance		(29.2)	(15.3)
Recorded into AOCI		26.1	98.6
Reclassified out of AOCI		(7.9)	(57.2)
Net other comprehensive income (loss)		18.2	41.4
Ending balance		(11.0)	26.1
Marketable Debt Securities
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance		14.6	6.1
Recorded into AOCI		(4.5)	(1.3)
Reclassified out of AOCI		(0.5)	(0.3)
Net other comprehensive income (loss)		(5.0)	(1.6)
Ending balance		9.6	4.5
Pension Plans
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance		(578.1)	(517.7)
Recorded into AOCI		(1.2)	10.0
Reclassified out of AOCI		11.0	13.5
Net other comprehensive income (loss)		9.8	23.5
Ending balance		(568.3)	(494.2)
Foreign Currency Translation
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance		(457.6)	(573.2)
Recorded into AOCI		(89.1)	(347.1)
Net other comprehensive income (loss)		(89.1)	(347.1)
Ending balance		(546.7)	(920.3)
Accumulated Other Comprehensive Income (Loss)
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance		(1,050.3)	(1,100.1)
Recorded into AOCI		(68.7)	(239.8)
Reclassified out of AOCI		2.6	(44.0)
Net other comprehensive income (loss)		(66.1)	(283.8)
Ending balance		$ (1,116.4)	$ (1,383.9)

[1] The December 31, 2020 consolidated balance sheet has been derived from audited financial statements.