Benefit Plans - Obligations and Funded Status (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Change in benefit obligations
Service cost	$ 4.1	$ 11.7	$ 12.8
Interest cost	11.5	16.4	16.5
Change in plan assets
Fair value of plan assets beginning of year	382.8
Fair value of plan assets end of year	180.7	382.8
Pension plans
Change in benefit obligations
Benefit obligation beginning of year	473.8	423.8
Service cost	4.1	11.7
Interest cost	11.5	16.4
Actuarial loss	(23.6)	41.4
Translation (gain) loss	(0.2)	0.6
Benefits paid	187.7	20.1
Benefit obligation end of year	277.9	473.8	423.8
Change in plan assets
Fair value of plan assets beginning of year	382.8	352.3
Actual return on plan assets	(21.4)	42.4
Company contributions	7.1	6.3
Translation gain (loss)	(0.1)	1.9
Benefits paid	187.7	20.1
Fair value of plan assets end of year	180.7	382.8	352.3
Funded status
Plan assets less than benefit obligation	(97.2)	(91.0)
Other post-retirement plans
Change in benefit obligations
Benefit obligation beginning of year	17.5	18.9
Service cost	0.0	0.0
Interest cost	0.6	0.7
Actuarial loss	(1.4)	(0.1)
Translation (gain) loss	0.0	0.0
Benefits paid	1.8	2.0
Benefit obligation end of year	14.9	17.5	18.9
Change in plan assets
Fair value of plan assets beginning of year	0.0	0.0
Actual return on plan assets	0.0	0.0
Company contributions	1.8	2.0
Translation gain (loss)	0.0	0.0
Benefits paid	1.8	2.0
Fair value of plan assets end of year	0.0	0.0	$ 0.0
Funded status
Plan assets less than benefit obligation	$ (14.9)	$ (17.5)