Pension and Post-Employment Benefits - Plan Net Pension Credit (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
United Kingdom Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Interest cost on projected benefit obligation	$ (2.8)	$ (3.9)
Expected return on plan assets	4.5	5.6
Amortization of prior service credit	0.2	0.2
Amortization of actuarial net losses	(0.2)	0.0
Net pension credit total	1.7	1.9
GERMANY
Defined Benefit Plan Disclosure [Line Items]
Interest cost on projected benefit obligation	(0.0)	(0.1)
Amortization of actuarial net losses	(0.2)	(0.1)
Net pension credit total	$ (0.2)	$ (0.2)