Employee Benefits - Change in Projected Benefit Obligation (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Supplemental Plan
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Beginning Balance	$ 121.1	$ 113.9
Service Cost	3.7	3.5	$ 3.6
Interest Cost	5.2	5.1	5.0
Employee Contributions	0.0	0.0
Plan Amendment	0.0	0.0
Actuarial (Gain) Loss	21.5	7.4
Settlement	0.0	0.0
Acquisitions/Divestitures	0.0	0.0
Benefits Paid	(7.0)	(8.8)
Foreign Exchange Rate Changes	0.0	0.0
Ending Balance	144.5	121.1	113.9
U.S. Plan | Pension Plans, Defined Benefit
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Beginning Balance	1,062.7	1,006.5
Service Cost	38.3	37.4	37.8
Interest Cost	45.9	45.8	44.7
Employee Contributions	0.0	0.0
Plan Amendment	0.0	0.0
Actuarial (Gain) Loss	142.6	31.5
Settlement	0.0	0.0
Acquisitions/Divestitures	0.0	0.0
Benefits Paid	(79.6)	(58.5)
Foreign Exchange Rate Changes	0.0	0.0
Ending Balance	1,209.9	1,062.7	1,006.5
Non U.S. Plans | Pension Plans, Defined Benefit
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Beginning Balance	155.9	156.5
Service Cost	0.4	0.0	0.0
Interest Cost	4.0	4.7	5.7
Employee Contributions	0.1	0.0
Plan Amendment	2.5	0.0
Actuarial (Gain) Loss	0.4	26.0
Settlement	(6.8)	(7.3)
Acquisitions/Divestitures	27.0	0.0
Benefits Paid	(3.0)	(2.4)
Foreign Exchange Rate Changes	17.8	(21.6)
Ending Balance	$ 198.3	$ 155.9	$ 156.5