Changes in Benefit Obligations and Plan Assets (Detail) - Pension Plans, Defined Benefit - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
U.S. Pension Plans
Defined Benefit Plans And Other Postretirement Benefit Plans Table Text Block [Line Items]
Benefit obligation at beginning of year	$ 400.1	$ 332.1
Service cost	7.5	6.9	$ 8.7
Interest cost	12.2	14.2	12.8
Change in discount rate	46.4	67.8
Experience	(5.0)	3.0
Other assumption changes	3.2	(0.4)
Benefits paid	(3.8)	(23.5)
Plan settlements	(34.4)
Benefit obligation at end of year	426.2	400.1	332.1
Fair value of plan assets at beginning of year	323.8	273.0
Actual return on plan assets	52.5	67.0
Company contributions	16.5	7.3
Fair value of plan assets at end of year	354.6	323.8	273.0
Funded status recognized in the balance sheet	(71.6)	(76.3)
Non-U.S. Pension Plans
Defined Benefit Plans And Other Postretirement Benefit Plans Table Text Block [Line Items]
Benefit obligation at beginning of year	252.6	216.9
Service cost	12.2	10.7	10.8
Interest cost	5.8	6.4	5.7
Change in discount rate	12.9	27.7
Experience	0.1	(1.2)
Other assumption changes	(11.2)	(1.0)
Benefits paid	(9.0)	(8.4)
Plan settlements	(0.4)	(1.2)
Special termination benefits	0.0	0.5	0.5
Other	1.5	1.6
Translation difference	14.9	0.6
Benefit obligation at end of year	279.4	252.6	216.9
Fair value of plan assets at beginning of year	88.7	77.8
Actual return on plan assets	8.8	8.9
Company contributions	9.7	9.5
Translation difference	5.0	2.1
Fair value of plan assets at end of year	102.8	88.7	$ 77.8
Funded status recognized in the balance sheet	$ (176.6)	$ (163.9)