Pensions - Schedule of Defined Benefit Pension Plans (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of plans' assets at beginning of period	$ 299,419
Fair value of plans' assets at end of period	321,891	$ 299,419
Funded status of the plans	12,434
UNITED STATES
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Benefit obligations at beginning of year	22,436	25,633
Service cost	103	118	$ 308
Interest cost	680	864	1,198
Actuarial loss (gain)	1,603	1,697
Defined Benefit Plan, Benefit Obligation, Benefits Paid	1,403	1,491
Foreign currency exchange rate effect	0	0
Defined Benefit Plan, Benefit Obligation, Business Combination	0	(4,405)
Other	0	20
Benefit obligation at end of year	23,419	22,436	25,633
Funded status of the plans	(23,419)	(22,436)
Foreign Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Benefit obligations at beginning of year	23,949	21,981
Service cost	404	397	495
Interest cost	726	752	789
Actuarial loss (gain)	2,221	1,705
Defined Benefit Plan, Benefit Obligation, Benefits Paid	663	570
Foreign currency exchange rate effect	395	1,136
Defined Benefit Plan, Benefit Obligation, Business Combination	0	(1,513)
Other	0	61
Benefit obligation at end of year	27,032	23,949	21,981
Funded status of the plans	(27,032)	(23,949)
Pension Plan [Member] | UNITED STATES
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Benefit obligations at beginning of year	255,935	288,223
Service cost	853	809	852
Interest cost	8,132	10,955	10,824
Actuarial loss (gain)	19,755	28,771
Defined Benefit Plan, Benefit Obligation, Benefits Paid	13,278	14,625
Foreign currency exchange rate effect	0	0
Defined Benefit Plan, Benefit Obligation, (Increase) Decrease for Settlement	0	58,198
Defined Benefit Plan, Benefit Obligation, Business Combination	0	0
Other	0	0
Benefit obligation at end of year	271,397	255,935	288,223
Fair value of plans' assets at beginning of period	244,613	265,019
Actual return on plans' assets	34,971	50,488
Employer contributions	1,037	1,929
Defined Benefit Plan, Plan Assets, Benefits Paid	13,278	14,625
Foreign currency exchange rate effect	0	0
Settlements	0	(58,198)
Defined Benefit Plan, Plan Assets, Divestiture	0	0
Defined Benefit Plan, Plan Assets, Business Combination	0	0
Fair value of plans' assets at end of period	267,343	244,613	265,019
Funded status of the plans	(4,054)	(11,322)
Pension Plan [Member] | Foreign Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Benefit obligations at beginning of year	184,364	183,850
Service cost	3,992	3,893	4,383
Interest cost	3,200	4,037	4,207
Actuarial loss (gain)	8,704	17,756
Defined Benefit Plan, Benefit Obligation, Benefits Paid	6,925	6,038
Foreign currency exchange rate effect	11,582	11
Defined Benefit Plan, Benefit Obligation, (Increase) Decrease for Settlement	5,170	2,263
Defined Benefit Plan, Benefit Obligation, Business Combination	(4,392)	(16,953)
Other	52	71
Benefit obligation at end of year	195,407	184,364	183,850
Fair value of plans' assets at beginning of period	54,806	47,692
Actual return on plans' assets	5,313	6,948
Employer contributions	5,673	6,646
Defined Benefit Plan, Plan Assets, Benefits Paid	6,925	6,038
Foreign currency exchange rate effect	940	2,399
Settlements	(5,170)	(2,841)
Defined Benefit Plan, Plan Assets, Divestiture	108	0
Defined Benefit Plan, Plan Assets, Business Combination	19	0
Fair value of plans' assets at end of period	54,548	54,806	$ 47,692
Funded status of the plans	$ (140,859)	$ (129,558)