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, 2020	Dec. 31, 2019	Dec. 31, 2018
Statement Of Income And Comprehensive Income [Abstract]
Foreign currency cumulative translation adjustments, before tax	$ (43.4)	$ 12.1	$ (148.7)
Unrealized cash flow hedge (losses) gains	(42.7)	34.6	81.1
Reclassification adjustments on cash flow hedges, before tax	(44.8)	(40.6)	26.8
Adjustments to prior service cost and unrecognized actuarial assumptions, before tax	(20.9)	(56.4)	(22.7)
Total Other comprehensive (Loss) Income, before tax	(151.8)	(50.3)	(63.5)
Foreign currency cumulative translation adjustments, tax	(69.0)	13.6	(13.3)
Unrealized cash flow hedge (losses) gains	(9.2)	4.0	12.9
Reclassification adjustments on cash flow hedges, tax	(6.3)	(5.5)	3.2
Adjustments to prior service cost and unrecognized actuarial assumptions, tax	(11.4)	(7.9)	(5.0)
Total Other Comprehensive (Loss) Income	(95.9)	4.2	(2.2)
Foreign currency cumulative translation adjustments, net of tax	25.6	(1.5)	(135.4)
Unrealized cash flow hedge (losses)/gains, net of tax	(33.5)	30.6	68.2
Reclassification adjustments on cash flow hedges, net of tax	(38.5)	(35.1)	23.6
Adjustments to prior service cost and unrecognized actuarial assumptions, net of tax	(9.5)	(48.5)	(17.7)
Total Other Comprehensive Loss	$ (55.9)	$ (54.5)	$ (61.3)