Employee Benefits - Amounts Included in Accumulated Other Comprehensive Income (Detail) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Supplemental Plan
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net Actuarial Loss	$ 83.2	$ 67.4
Prior Service Cost	0.6	0.8
Gross Amount in Accumulated Other Comprehensive Income	83.8	68.2
Income Tax Effect	31.9	25.8
Net Amount in Accumulated Other Comprehensive Income	51.9	42.4
U.S. Plan | Pension Plans, Defined Benefit
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net Actuarial Loss	399.0	378.1
Prior Service Cost	(1.8)	(2.3)
Gross Amount in Accumulated Other Comprehensive Income	397.2	375.8
Income Tax Effect	151.6	142.3
Net Amount in Accumulated Other Comprehensive Income	245.6	233.5
Non U.S. Plans | Pension Plans, Defined Benefit
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net Actuarial Loss	44.2	55.8
Prior Service Cost	2.5	0.0
Gross Amount in Accumulated Other Comprehensive Income	46.7	55.8
Income Tax Effect	5.3	6.7
Net Amount in Accumulated Other Comprehensive Income	$ 41.4	$ 49.1