Retirement Plans - Reconciliation of Benefit Obligation, Plan Assets and Funded Status of Plans (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Plan amendments and other			$ (354.8)
Pension Benefits
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit obligation at beginning of year	$ 1,044.8	$ 974.7
Service cost	0.7	0.7	1.0
Interest cost	31.3	31.6	105.7
Plan participants' contributions	0.0	0.0
Medicare reimbursements	0.0	0.0
Actuarial (gain) loss	(64.3)	53.9
Plan amendments and other	0.7	0.0
Settlements	(8.5)	(5.9)
Foreign currency translation	(26.5)	34.4
Benefits paid	(45.2)	(44.6)
Benefit obligation at end of year	933.0	1,044.8	974.7
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets at beginning of year	979.3	875.4
Actual (loss) return on assets	(31.7)	106.0
Settlements	(8.7)	(6.3)
Employer contributions	10.7	8.6
Medicare reimbursements	0.0	0.0
Plan participants' contributions	0.0	0.0
Foreign currency translation	(25.6)	34.4
Benefits paid	(45.2)	(44.6)
Fair value of plan assets at end of year	878.8	979.3	875.4
Total net pension and OPEB liability recognized as of December 31	(54.2)	(65.5)
Pension Benefits | Discontinued Operations
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Divestitures	0.0	5.8
OPEB
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit obligation at beginning of year	342.4	345.0
Service cost	(3.7)	1.3	3.8
Interest cost	9.4	11.1	11.7
Plan participants' contributions	10.1	9.0
Medicare reimbursements	6.4	5.0
Actuarial (gain) loss	(19.7)	3.0
Plan amendments and other	(32.6)	0.0
Settlements	0.0	0.0
Foreign currency translation	(1.3)	2.8
Benefits paid	(33.9)	(34.8)
Benefit obligation at end of year	277.1	342.4	345.0
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets at beginning of year	228.6	210.3
Actual (loss) return on assets	(9.5)	31.3
Settlements	0.0	0.0
Employer contributions	7.2	7.8
Medicare reimbursements	6.4	5.0
Plan participants' contributions	10.1	9.0
Foreign currency translation	0.0	0.0
Benefits paid	(33.9)	(34.8)
Fair value of plan assets at end of year	208.9	228.6	$ 210.3
Total net pension and OPEB liability recognized as of December 31	(68.2)	(113.8)
OPEB | Discontinued Operations
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Divestitures	$ 0.0	$ 0.0