Benefit Plans - Components of Net Periodic Benefit Cost (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Domestic Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 2.6	$ 2.8	$ 7.8	$ 8.4
Interest cost	4.1	4.1	12.3	12.3
Expected return on plan assets	(2.9)	(2.9)	(8.7)	(8.6)
Net periodic benefit cost	3.8	4.0	11.4	12.1
Foreign Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	1.8	2.1	5.4	6.2
Interest cost	0.9	1.1	2.7	3.3
Expected return on plan assets	(0.3)	(0.4)	(0.9)	(1.2)
Net periodic benefit cost	$ 2.4	$ 2.8	$ 7.2	$ 8.3