Employee Benefits - Net Periodic Pension Expense (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Weighted-Average Assumptions:
Expected Long-Term Rate of Return on Assets	5.25%
Supplemental Plan
Defined Benefit plan Net periodic benefit cost
Service Cost	$ 4.6	$ 4.1	$ 4.3
Interest Cost	4.8	5.8	5.3
Settlement Expense	0.0	0.0	0.0
Amortization:
Net Actuarial Loss	7.0	5.6	7.4
Prior Service (Benefit) Cost	0.2	0.2	0.2
Net Periodic Pension Expense	$ 16.6	$ 15.7	$ 17.2
Weighted-Average Assumptions:
Discount Rates	3.37%	4.47%	3.79%
Rate of Increase in Compensation Level	4.97%	4.39%	4.39%
U.S. Plan | Pension Plans, Defined Benefit
Defined Benefit plan Net periodic benefit cost
Service Cost	$ 47.4	$ 41.6	$ 41.4
Interest Cost	43.3	47.2	44.3
Expected Return on Plan Assets	(76.8)	(86.9)	(88.2)
Settlement Expense	0.0	0.0	0.0
Amortization:
Net Actuarial Loss	35.0	17.2	28.2
Prior Service (Benefit) Cost	(0.4)	(0.4)	(0.4)
Net Periodic Pension Expense	$ 48.5	$ 18.7	$ 25.3
Weighted-Average Assumptions:
Discount Rates	3.37%	4.47%	3.79%
Rate of Increase in Compensation Level	4.97%	4.39%	4.39%
Expected Long-Term Rate of Return on Assets	5.25%	6.00%	6.00%
Non U.S. Plans | Pension Plans, Defined Benefit
Defined Benefit plan Net periodic benefit cost
Service Cost	$ 1.9	$ 2.0	$ 1.7
Interest Cost	2.9	3.9	4.0
Expected Return on Plan Assets	(3.1)	(4.4)	(4.4)
Settlement Expense	0.8	0.0	0.5
Amortization:
Net Actuarial Loss	0.8	0.6	0.9
Prior Service (Benefit) Cost	0.4	0.3	0.2
Net Periodic Pension Expense	$ 3.7	$ 2.4	$ 2.9
Weighted-Average Assumptions:
Discount Rates	1.40%	2.16%	2.08%
Rate of Increase in Compensation Level	1.50%	1.75%	1.75%
Expected Long-Term Rate of Return on Assets	1.72%	2.39%	2.61%