Employee Benefits - Net Periodic Pension Expense (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Weighted-Average Assumptions:
Expected Long-Term Rate of Return on Assets	6.00%
Supplemental Plan
Defined Benefit plan Net periodic benefit cost
Service Cost	$ 4.3	$ 3.7	$ 3.5
Interest Cost	5.3	5.2	5.1
Settlement Expense	0.0	0.0	0.0
Amortization:
Net Loss	7.4	5.7	5.8
Prior Service Cost	0.2	0.2	0.2
Net Periodic Pension Expense	$ 17.2	$ 14.8	$ 14.6
Weighted-Average Assumptions:
Discount Rates	3.79%	4.46%	4.71%
Rate of Increase in Compensation Level	4.39%	4.39%	4.25%
U.S. Plan | Pension Plans, Defined Benefit
Defined Benefit plan Net periodic benefit cost
Service Cost	$ 41.4	$ 38.3	$ 37.4
Interest Cost	44.3	45.9	45.8
Expected Return on Plan Assets	(88.2)	(93.8)	(94.4)
Settlement Expense	0.0	0.0	0.0
Amortization:
Net Loss	28.2	19.0	18.8
Prior Service Cost	(0.4)	(0.4)	(0.4)
Net Periodic Pension Expense	$ 25.3	$ 9.0	$ 7.2
Weighted-Average Assumptions:
Discount Rates	3.79%	4.46%	4.71%
Rate of Increase in Compensation Level	4.39%	4.39%	4.25%
Expected Long-Term Rate of Return on Assets	6.00%	6.75%	7.00%
Non U.S. Plans | Pension Plans, Defined Benefit
Defined Benefit plan Net periodic benefit cost
Service Cost	$ 1.7	$ 0.4	$ 0.0
Interest Cost	4.0	4.0	4.7
Expected Return on Plan Assets	(4.4)	(4.5)	(4.6)
Settlement Expense	0.5	1.1	3.7
Amortization:
Net Loss	0.9	1.3	1.0
Prior Service Cost	0.2	0.1	0.0
Net Periodic Pension Expense	$ 2.9	$ 2.4	$ 4.8
Weighted-Average Assumptions:
Discount Rates	2.08%	2.33%	3.39%
Rate of Increase in Compensation Level	1.75%	1.75%
Expected Long-Term Rate of Return on Assets	2.61%	3.13%	3.73%