Retirement Benefit Plans - Components of Net Periodic Pension Expense (Detail) - US and Foreign [Member] - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Schedule of Expected Future Pension Benefit Payment [Line Items]
Service cost	$ 6.7	$ 7.5
Interest cost	6.2	5.5
Expected return on plan assets	(11.5)	(11.8)
Amortization of prior service cost	(1.8)	(2.5)
Amortization of unrecognized actuarial loss	5.3	6.1
Net periodic pension expense	$ 4.9	$ 4.8