Components of Comprehensive Income, Net of Related Tax (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Statement Of Income And Comprehensive Income [Abstract]
Net income	$ 600.5	$ 470.8
Other comprehensive income (loss) (OCI):
Unrealized gains on derivative contracts	36.1	22.3
Tax effect	(9.7)	(4.1)
Net current period OCI, unrealized gains (losses) on derivative contracts	26.4	18.2
Unrealized losses on marketable debt securities	(34.1)	(6.6)
Tax effect	8.5	1.6
Net current period OCI, unrealized gains and (losses) on marketable debt securities	(25.6)	(5.0)
Pension plans	10.3	12.9
Tax effect	(2.4)	(3.1)
Net current period OCI, pension plans	7.9	9.8
Foreign currency translation gains (losses)	34.7	(89.1)
Net other comprehensive income (loss)	43.4	(66.1)
Comprehensive income	$ 643.9	$ 404.7