Defined Contribution and Defined Benefit Retirement - Components of Net Periodic Defined Benefit Pension Benefit Cost (Credit) (Detail) - Defined Benefit Pension Plans - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
U.S.
Defined Benefit Plan Disclosure [Line Items]
Interest cost	$ 1.9	$ 2.3	$ 2.2
Expected return on plan assets	(2.1)	(2.3)	(3.4)
Amortization of unrecognized net actuarial loss	2.1	2.2	2.0
Total	1.9	2.2	0.8
Non U.S.
Defined Benefit Plan Disclosure [Line Items]
Service cost	13.3	12.8	11.6
Interest cost	10.1	13.5	13.8
Expected return on plan assets	(9.0)	(11.9)	(12.7)
Amortization of unrecognized prior service credit	0.2	0.2	0.2
Amortization of unrecognized net actuarial loss	17.3	12.8	13.2
Total	$ 31.9	$ 27.4	$ 26.1