Changes in Accumulated Other Comprehensive Income (Loss) by Component (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	$ 6,777.6	$ 6,940.4
Reclassified out of AOCI	114.8	18.1	$ 5.3
Net other comprehensive income (loss)	334.5	(111.1)	(437.2)
Ending balance	8,050.5	6,777.6	6,940.4
Derivative Contracts
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	(4.3)	(6.4)	(13.5)
Recorded into AOCI	(91.6)	0.2	27.9
Reclassified out of AOCI	97.1	1.9	(20.8)
Net other comprehensive income (loss)	5.5	2.1	7.1
Ending balance	1.2	(4.3)	(6.4)
Marketable Debt Securities
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	(0.3)	2.1	5.3
Recorded into AOCI	(1.1)	0.3	(1.7)
Reclassified out of AOCI	(0.4)	(2.7)	(1.5)
Net other comprehensive income (loss)	(1.5)	(2.4)	(3.2)
Ending balance	(1.8)	(0.3)	2.1
Pension Plans
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	(414.1)	(390.4)	(433.1)
Recorded into AOCI	20.4	(42.6)	15.1
Reclassified out of AOCI	18.1	18.9	27.6
Net other comprehensive income (loss)	38.5	(23.7)	42.7
Ending balance	(375.6)	(414.1)	(390.4)
Foreign Currency Translation
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	(709.4)	(622.3)	(138.5)
Recorded into AOCI	292.0	(87.1)	(483.8)
Net other comprehensive income (loss)	292.0	(87.1)	(483.8)
Ending balance	(417.4)	(709.4)	(622.3)
Accumulated Other Comprehensive Income
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	(1,128.1)	(1,017.0)	(579.8)
Recorded into AOCI	219.7	(129.2)	(442.5)
Reclassified out of AOCI	114.8	18.1	5.3
Net other comprehensive income (loss)	334.5	(111.1)	(437.2)
Ending balance	$ (793.6)	$ (1,128.1)	$ (1,017.0)