Postretirement Benefit Plans - Changes in Projected Benefit Obligations of Pension and Other Employee-Related Defined Benefit Plans (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Change in benefit obligation
Benefit obligation – January 1	$ 499.8	$ 557.1
Service cost	2.1	2.6
Interest cost	16.6	16.0
Amendments	1.7	(0.1)
Actuarial loss (gain)	45.0	(33.8)
Benefits paid	(38.7)	(31.7)
Acquired	0.5	0.0
Settlement	0.0	(6.3)
Foreign currency translation	(1.6)	(4.0)
Benefit obligation – December 31	525.4	499.8	$ 557.1
Other Postretirement Benefits Plan [Member]
Change in benefit obligation
Benefit obligation – January 1	118.6	138.1
Service cost	0.7	0.9	0.8
Interest cost	4.0	4.5	4.4
Amendments	1.7	0.0
Actuarial loss (gain)	3.6	(15.8)
Benefits paid	(12.0)	(9.1)
Acquired	0.0	0.0
Settlement	0.0	0.0
Foreign currency translation	0.0	0.0
Benefit obligation – December 31	116.6	118.6	138.1
Pension Plan [Member]
Change in benefit obligation
Benefit obligation – January 1	381.2
Service cost	1.4	1.7	2.9
Interest cost	12.6	11.5	12.1
Benefit obligation – December 31	408.8	381.2
United States | Pension Plan [Member]
Change in benefit obligation
Benefit obligation – January 1	291.8	325.7
Service cost	0.2	0.4	1.5
Interest cost	11.1	10.1	10.5
Amendments	0.0	0.0
Actuarial loss (gain)	31.0	(18.9)
Benefits paid	(23.7)	(19.6)
Acquired	0.0	0.0
Settlement	0.0	(5.9)
Foreign currency translation	0.0	0.0
Benefit obligation – December 31	310.4	291.8	325.7
International Plan [Member] | Pension Plan [Member]
Change in benefit obligation
Benefit obligation – January 1	89.4	93.3
Service cost	1.2	1.3	1.4
Interest cost	1.5	1.4	1.6
Amendments	0.0	(0.1)
Actuarial loss (gain)	10.4	0.9
Benefits paid	(3.0)	(3.0)
Acquired	0.5	0.0
Settlement	0.0	(0.4)
Foreign currency translation	(1.6)	(4.0)
Benefit obligation – December 31	$ 98.4	$ 89.4	$ 93.3