Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Statement Of Income And Comprehensive Income [Abstract]
Net income	$ 2,195.1	$ 1,675.2	$ 521.7
Unrealized gains (losses) on derivative contracts
Net gain (loss) arising during the period	121.6	(125.5)	(6.5)
Tax effect	(30.7)	33.9	6.7
Reclassification adjustment	(121.5)	133.4	10.8
Tax effect	31.0	(36.3)	(8.9)
Net current period OCI, unrealized gains and (losses) on derivative contracts	0.4	5.5	2.1
Unrealized gains (losses) on marketable debt securities
Net holding gain (loss)	0.2	(1.5)	(0.1)
Tax effect	(0.1)	0.4	0.4
Reclassification adjustment	(0.2)	(0.6)	(3.7)
Tax effect	0.1	0.2	1.0
Net current period OCI, unrealized gains and (losses) on marketable debt securities	0.0	(1.5)	(2.4)
Pension plans
Net (loss) gain arising during the period	(114.0)	37.1	(50.3)
Tax effect	27.2	(16.7)	7.7
Reclassification adjustment	36.7	26.6	28.9
Tax effect	(8.7)	(8.5)	(10.0)
Net current period OCI, pension plans	(58.8)	38.5	(23.7)
Foreign currency translation (loss) gain	(213.3)	292.0	(87.1)
Net other comprehensive (loss) income	(271.7)	334.5	(111.1)
Comprehensive Income	$ 1,923.4	$ 2,009.7	$ 410.6