Retirement Benefit Plans - Reconciliation of Beginning and Ending Balances of Foreign Pension Plan Assets Measured at Fair Value (Detail) - Foreign [Member] - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Schedule of Fair Values of Plan Assets [Line Items]
Plan assets at fair market value - beginning of year	$ 585.8	$ 574.9
Translation gain	17.7	(9.2)
Plan assets at fair market value - end of year	665.2	585.8
Fair Value Measurements at Reporting Date Using: Significant Unobservable Inputs (Level 3) [Member]
Schedule of Fair Values of Plan Assets [Line Items]
Plan assets at fair market value - beginning of year	108.9
Gain on assets sold	0.2
Change in fair value of assets	6.9
Net purchases and sales	4.8
Translation gain	2.9
Plan assets at fair market value - end of year	$ 123.7	$ 108.9