Pensions and Other Postretirement Benefits (Details) $ in Thousands		12 Months Ended
		Dec. 31, 2020 USD ($) Plan	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Amounts recognized in balance sheet associated with retirement benefit plans [Abstract]
Included in other assets		$ 312	$ 303
Included in Payroll and related expenses		(9,753)	(8,885)
Accrued pension and other postretirement costs		(300,113)	(272,402)
Total actuarial items	[1]	107,652	95,764
Components of actuarial items [Abstract]
Total actuarial items	[1]	107,652	95,764
Components of net periodic pension cost [Abstract]
Amounts that will be amortized from accumulated other comprehensive loss into net periodic pension cost during next fiscal year		$ 10,000
Other postretirement benefits [Abstract]
Number of unfunded non-pension postretirement plans | Plan		2
Number of European subsidiaries with unfunded non-pension postretirement plans | Plan		2
Other retirement obligations [Abstract]
Company's matching expense for 401(k) savings plans		$ 6,363	6,481	$ 6,353
Deferred Compensation [Member]
Defined benefit pension plans [Abstract]
Assets held in trust		27,491	24,531
Non-qualified Pension Plans [Member]
Defined benefit pension plans [Abstract]
Assets held in trust		29,157	27,012
Defined Benefit Pension [Member] | U.S. Plans [Member]
Change in benefit obligation [Roll forward]
Benefit obligation at beginning of year		42,383	38,169
Service cost		0	0	0
Interest cost		1,366	1,696	1,484
Plan amendments		0	0
Actuarial (gains) losses		3,623	4,309
Benefits paid		(1,808)	(1,791)
Curtailments and settlements		0	0
Currency translation		0	0
Benefit obligation at end of year		45,564	42,383	38,169
Change in plan assets [Roll forward]
Fair value of plan assets at beginning of year		0	0
Actual return on plan assets		0	0
Company contributions		1,808	1,791
Benefits paid		(1,808)	(1,791)
Currency translation		0	0
Fair value of plan assets at end of year		0	0	0
Funded status at end of year		(45,564)	(42,383)
Amounts recognized in balance sheet associated with retirement benefit plans [Abstract]
Included in other assets		0	0
Included in Payroll and related expenses		(35)	(35)
Accrued pension and other postretirement costs		(45,529)	(42,348)
Total actuarial items		10,709	8,839
Total		(34,855)	(33,544)
Components of actuarial items [Abstract]
Unrecognized net actuarial loss (gain)		10,212	8,199
Unamortized prior service cost		497	640
Total actuarial items		10,709	8,839
Projected and accumulated benefit obligations [Abstract]
Accumulated benefit obligation, all plans		45,564	42,383
Plans for which the accumulated benefit obligation exceeds plan assets [Abstract]
Projected benefit obligation		45,564	42,383
Accumulated benefit obligation		45,564	42,383
Fair value of plan assets		0	0
Components of net periodic pension cost [Abstract]
Net service cost		0	0	0
Interest cost		1,366	1,696	1,484
Expected return on plan assets		0	0	0
Amortization of actuarial losses		1,609	827	656
Amortization of prior service (credit) cost		144	144	144
Curtailment and settlement losses		0	0	0
Net periodic benefit cost (benefit)		$ 3,119	$ 2,667	2,284
Weighted average assumptions used to calculate benefit obligations [Abstract]
Discount rate		2.25%	3.25%
Rate of compensation increase		0.00%	0.00%
Weighted average assumptions used calculating net periodic benefit cost [Abstract]
Discount rate		3.25%	4.50%
Rate of compensation increase		0.00%	0.00%
Expected return on plan assets		0.00%	0.00%
Estimated future benefit payments [Abstract]
2021		$ 1,904
2022		1,901
2023		8,502
2024		3,260
2025		9,505
2026-2030		11,379
Defined Benefit Pension [Member] | Non-U.S. Plans [Member]
Change in benefit obligation [Roll forward]
Benefit obligation at beginning of year		283,561	$ 275,207
Service cost		4,382	3,382	3,822
Interest cost		3,783	5,116	4,793
Plan amendments		1,015	0
Actuarial (gains) losses		10,920	20,115
Benefits paid		(17,737)	(18,985)
Curtailments and settlements		(464)	0
Currency translation		22,349	(1,274)
Benefit obligation at end of year		307,809	283,561	275,207
Change in plan assets [Roll forward]
Fair value of plan assets at beginning of year		73,629	70,820
Actual return on plan assets		2,811	4,614
Company contributions		12,149	15,443
Benefits paid		(17,737)	(18,985)
Currency translation		3,482	1,737
Fair value of plan assets at end of year		74,334	73,629	70,820
Funded status at end of year		(233,475)	(209,932)
Amounts recognized in balance sheet associated with retirement benefit plans [Abstract]
Included in other assets		312	303
Included in Payroll and related expenses		(8,314)	(7,362)
Accrued pension and other postretirement costs		(225,473)	(202,873)
Total actuarial items		94,480	84,926
Total		(138,995)	(125,006)
Components of actuarial items [Abstract]
Unrecognized net actuarial loss (gain)		94,072	84,523
Unamortized prior service cost		408	403
Total actuarial items		94,480	84,926
Projected and accumulated benefit obligations [Abstract]
Accumulated benefit obligation, all plans		287,169	264,723
Plans for which the accumulated benefit obligation exceeds plan assets [Abstract]
Projected benefit obligation		288,212	252,469
Accumulated benefit obligation		275,816	239,341
Fair value of plan assets		59,070	44,670
Components of net periodic pension cost [Abstract]
Net service cost		4,382	3,382	3,822
Interest cost		3,783	5,116	4,793
Expected return on plan assets		(2,004)	(1,956)	(1,889)
Amortization of actuarial losses		6,554	5,374	6,196
Amortization of prior service (credit) cost		378	197	318
Curtailment and settlement losses		1,148	2,183	1,111
Net periodic benefit cost (benefit)		$ 14,241	$ 14,296	14,351
Weighted average assumptions used to calculate benefit obligations [Abstract]
Discount rate		1.02%	1.40%
Rate of compensation increase		2.02%	2.24%
Weighted average assumptions used calculating net periodic benefit cost [Abstract]
Discount rate		1.40%	1.96%
Rate of compensation increase		2.24%	2.17%
Expected return on plan assets		2.35%	2.77%
Estimated future benefit payments [Abstract]
2021		$ 16,593
2022		19,235
2023		17,033
2024		16,808
2025		17,957
2026-2030		84,994
Other Postretirement Benefits [Member] | U.S. Plans [Member]
Change in benefit obligation [Roll forward]
Benefit obligation at beginning of year		7,689	$ 6,994
Service cost		112	157	137
Interest cost		236	286	273
Actuarial (gains) losses		550	939
Benefits paid		(864)	(687)
Currency translation		0	0
Benefit obligation at end of year		7,723	7,689	6,994
Change in plan assets [Roll forward]
Fair value of plan assets at beginning of year		0
Fair value of plan assets at end of year		0	0
Funded status at end of year		(7,723)	(7,689)
Amounts recognized in balance sheet associated with retirement benefit plans [Abstract]
Included in Payroll and related expenses		(929)	(872)
Accrued pension and other postretirement costs		(6,794)	(6,817)
Total actuarial items		344	(180)
Total		(7,379)	(7,869)
Components of actuarial items [Abstract]
Unrecognized net actuarial loss (gain)		344	(180)
Total actuarial items		344	(180)
Components of net periodic pension cost [Abstract]
Net service cost		112	157	137
Interest cost		236	286	273
Amortization of actuarial losses		26	(138)	(39)
Amortization of prior service (credit) cost		0	0	(148)
Curtailment and settlement losses		0	0	0
Net periodic benefit cost (benefit)		$ 374	$ 305	223
Weighted average assumptions used to calculate benefit obligations [Abstract]
Discount rate		2.25%	3.25%
Rate of compensation increase		0.00%	0.00%
Weighted average assumptions used calculating net periodic benefit cost [Abstract]
Discount rate		3.25%	4.50%
Rate of compensation increase		0.00%	0.00%
Estimated future benefit payments [Abstract]
2021		$ 929
2022		855
2023		783
2024		703
2025		626
2026-2030		2,216
Other Postretirement Benefits [Member] | Non-U.S. Plans [Member]
Change in benefit obligation [Roll forward]
Benefit obligation at beginning of year		8,109	$ 7,953
Service cost		284	284	288
Interest cost		64	123	114
Actuarial (gains) losses		35	311
Benefits paid		(706)	(413)
Currency translation		724	(149)
Benefit obligation at end of year		8,510	8,109	7,953
Change in plan assets [Roll forward]
Fair value of plan assets at beginning of year		0
Fair value of plan assets at end of year		0	0
Funded status at end of year		(8,510)	(8,109)
Amounts recognized in balance sheet associated with retirement benefit plans [Abstract]
Included in Payroll and related expenses		(475)	(616)
Accrued pension and other postretirement costs		(8,035)	(7,493)
Total actuarial items		2,119	2,179
Total		(6,391)	(5,930)
Components of actuarial items [Abstract]
Unrecognized net actuarial loss (gain)		2,119	2,179
Total actuarial items		2,119	2,179
Components of net periodic pension cost [Abstract]
Net service cost		284	284	288
Interest cost		64	123	114
Amortization of actuarial losses		132	107	105
Amortization of prior service (credit) cost		0	0	0
Curtailment and settlement losses		177	0	0
Net periodic benefit cost (benefit)		$ 657	$ 514	$ 507
Weighted average assumptions used to calculate benefit obligations [Abstract]
Discount rate		0.54%	0.81%
Rate of compensation increase		2.87%	2.87%
Weighted average assumptions used calculating net periodic benefit cost [Abstract]
Discount rate		0.81%	1.60%
Rate of compensation increase		2.87%	3.18%
Estimated future benefit payments [Abstract]
2021		$ 475
2022		547
2023		275
2024		257
2025		558
2026-2030		3,243
Other Retirement Obligations [Member]
Amounts recognized in balance sheet associated with retirement benefit plans [Abstract]
Accrued pension and other postretirement costs		(14,282)	$ (12,871)
Dr. Felix Zandman [Member] | Non-qualified Pension Plans [Member]
Defined benefit pension plans [Abstract]
Assets held in trust		1,243	$ 605
Deferred compensation arrangement, annual retirement benefit to surviving spouse		$ 614

[1] Amounts included in accumulated other comprehensive loss are presented in this table pre-tax.