Accumulated Other Comprehensive Income - Tax Effects on Each Component of Accumulated Other Comprehensive Income Recognized in Statements of Comprehensive Income (Loss) (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Statement Of Income And Comprehensive Income [Abstract]
Foreign currency cumulative translation adjustments, Before Tax	$ 12.1	$ (148.7)	$ 396.8
Unrealized cash flow hedge gains (losses), Before Tax	34.6	81.1	(116.0)
Reclassification adjustments on cash flow hedges, Before Tax	(40.6)	26.8	(4.6)
Adjustments to prior service cost and unrecognized actuarial assumptions, Before Tax	(56.4)	(22.7)	6.6
Total Other Comprehensive (Loss) Income, Before Tax	(50.3)	(63.5)	282.8
Foreign currency cumulative translation adjustments, Tax	13.6	(13.3)	(48.2)
Unrealized cash flow hedge gains (losses), Tax	4.0	12.9	(21.0)
Reclassification adjustments on cash flow hedges, Tax	(5.5)	3.2	(0.8)
Adjustments to prior service cost and unrecognized actuarial assumptions, Tax	(7.9)	(5.0)	2.0
Total Other Comprehensive (Loss) Income, Tax	4.2	(2.2)	(68.0)
Foreign currency cumulative translation adjustments, net of tax	(1.5)	(135.4)	445.0
Unrealized cash flow hedge gains (losses), net of tax	30.6	68.2	(95.0)
Reclassification adjustments on cash flow hedges, net of tax	(35.1)	23.6	(3.8)
Adjustments to prior service cost and unrecognized actuarial assumptions, net of tax	(48.5)	(17.7)	4.6
Total Other Comprehensive (Loss) Income	$ (54.5)	$ (61.3)	$ 350.8