Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Statement Of Income And Comprehensive Income [Abstract]
Net income	$ 1,298.4	$ 2,387.9	$ 2,195.1
Unrealized (losses) gains on derivative contracts
Net (loss) gain arising during the period	(105.3)	(76.1)	121.6
Tax effect	26.9	19.1	(30.7)
Reclassification adjustment	87.6	51.7	(121.5)
Tax effect	(23.1)	(12.0)	31.0
Net current period OCI, unrealized gains and (losses) on derivative contracts	(13.9)	(17.3)	0.4
Unrealized gains on marketable debt securities
Net holding gain	13.6	11.6	0.2
Tax effect	(3.3)	(2.9)	(0.1)
Reclassification adjustment	(2.4)	(0.4)	(0.2)
Tax effect	0.6	0.1	0.1
Net current period OCI, unrealized gains on marketable debt securities	8.5	8.4
Pension plans
Net loss arising during the period	(132.4)	(74.8)	(114.0)
Tax effect	28.4	18.0	27.2
Reclassification adjustment	57.3	21.9	36.7
Tax effect	(13.7)	(5.0)	(8.7)
Net current period OCI, pension plans	(60.4)	(39.9)	(58.8)
Foreign currency translation gain (loss)	115.6	47.2	(213.3)
Net other comprehensive income (loss)	49.8	(1.6)	(271.7)
Comprehensive Income	$ 1,348.2	$ 2,386.3	$ 1,923.4