Components of Change in Projected Benefit Obligation and Change in Plan Assets (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Change in projected benefit obligation:
Benefit obligation, beginning balance	$ 2,655.4	$ 2,820.7
Service cost	102.0	108.3	$ 92.9
Interest cost	95.6	85.8	81.1
Benefits paid	(127.0)	(87.6)
Actuarial loss (gain)	478.0	(232.6)
Currency translation and other	30.0	(39.6)
Participant contributions	0.4	0.4
Projected benefit obligation, ending balance	3,234.4	2,655.4	2,820.7
Change in plan assets:
Fair value of plan assets, beginning balance	2,699.2	2,919.6
Employer contributions	35.7	88.9
Actual return on plan assets	588.1	(177.5)
Benefits paid	(127.0)	(87.6)
Currency translation and other	30.0	(44.6)
Participant contributions	0.4	0.4
Fair value of plan assets, ending balance	3,226.4	2,699.2	$ 2,919.6
Funded status, ending balance	(8.0)	43.8
Amounts recorded on Balance Sheet:
Other noncurrent assets	146.5	174.7
Accounts payable, accrued expenses and other	39.9	4.9
Other liabilities	114.6	126.0
Accumulated other comprehensive loss:
Actuarial loss	512.5	471.5
Prior service cost	5.1	6.2
Net initial transition amount	$ 0.1	$ 0.1