Retirement Benefits - Changes in Benefit Obligations and Plan Assets as Well as Funded Status of Retirement Plans (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2019 USD ($) Investment	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Defined Benefit Plan Disclosure [Line Items]
Domestic Pension Plans, Funded Percentage	116.00%	112.00%
Number Of Indexed Funds | Investment	6
Change in plan assets
Fair value of plan assets at beginning of year	$ 732,502
Fair value of plan assets at end of year	869,070	$ 732,502
Foreign Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan with Accumulated Benefit Obligation in Excess of Plan Assets, Accumulated Benefit Obligation	103,900	93,100
Defined Benefit Plan, Pension Plan with Accumulated Benefit Obligation in Excess of Plan Assets, Projected Benefit Obligation	109,000	95,600
Pension Plan [Member]
Change in benefit obligation [Roll Forward]
Obligation at beginning of year	751,625	808,149
Service cost	12,505	14,238	$ 13,372
Interest cost	28,316	25,316	25,501
Actuarial losses (gains)	103,918	(53,044)
Plan amendments	528	0
Benefits paid	(39,508)	(38,335)
Participant contributions	0	0
Foreign currency exchange rate changes	(1,875)	(4,699)
Obligation at end of year	855,509	751,625	808,149
Change in plan assets
Fair value of plan assets at beginning of year	732,502	825,806
Actual return on plan assets	174,014	(57,082)
Employer contributions	2,062	2,113
Participant contributions	0	0
Benefits paid	(39,508)	(38,335)
Fair value of plan assets at end of year	869,070	732,502	825,806
Funded status	13,561	(19,123)
Amounts recognized in the consolidated balance sheets
Non-current assets	122,552	76,443
Current liabilities	(2,225)	(2,174)
Non-current liabilities	(106,766)	(93,392)
Net amount recognized	13,561	(19,123)
Amounts recognized in accumulated other comprehensive loss (income)
Net actuarial loss (gain)	193,061	218,867
Prior service cost (credit)	1,179	765
Net amount recognized	194,240	219,632
Other Postretirement Benefits Plan [Member]
Change in benefit obligation [Roll Forward]
Obligation at beginning of year	19,186	20,939
Service cost	80	99	104
Interest cost	759	640	692
Actuarial losses (gains)	3,477	(2,031)
Plan amendments	0	1,210
Benefits paid	(1,888)	(1,764)
Participant contributions	104	93
Foreign currency exchange rate changes	0	0
Obligation at end of year	21,718	19,186	20,939
Change in plan assets
Fair value of plan assets at beginning of year	0	0
Actual return on plan assets	0	0
Employer contributions	1,784	1,671
Participant contributions	104	93
Benefits paid	(1,888)	(1,764)
Fair value of plan assets at end of year	0	0	$ 0
Funded status	(21,718)	(19,186)
Amounts recognized in the consolidated balance sheets
Non-current assets	0	0
Current liabilities	(1,794)	(1,924)
Non-current liabilities	(19,924)	(17,262)
Net amount recognized	(21,718)	(19,186)
Amounts recognized in accumulated other comprehensive loss (income)
Net actuarial loss (gain)	(3,123)	(7,087)
Prior service cost (credit)	(6,405)	(8,735)
Net amount recognized	$ (9,528)	$ (15,822)
Pension Fund All Other [Member]
Defined Benefit Plan Disclosure [Line Items]
Multi Employer Plans Status Funded Percentage	89.00%