Pensions and Other Postretirement Benefits (Details) $ in Thousands		12 Months Ended
		Dec. 31, 2019 USD ($) Plan	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Amounts recognized in balance sheet associated with retirement benefit plans [Abstract]
Included in other assets		$ 303	$ 356
Included in Payroll and related expenses		(8,885)	(8,147)
Accrued pension and other postretirement costs		(272,402)	(260,984)
Total actuarial items	[1]	95,764	82,986
Components of actuarial items [Abstract]
Total actuarial items	[1]	95,764	82,986
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		$ 8,000
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		$ 6,481	6,353	$ 5,843
Deferred Compensation [Member]
Defined benefit pension plans [Abstract]
Assets held in trust		24,531	18,162
Non-qualified Pension Plans [Member]
Defined benefit pension plans [Abstract]
Assets held in trust		27,012	22,409
Defined Benefit Pension [Member] | U.S. Plans [Member]
Change in benefit obligation [Roll forward]
Benefit obligation at beginning of year		38,169	39,917
Service cost		0	0	0
Interest cost		1,696	1,484	1,643
Plan amendments		0	0
Actuarial (gains) losses		4,309	(1,431)
Benefits paid		(1,791)	(1,801)
Currency translation		0	0
Benefit obligation at end of year		42,383	38,169	39,917
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		1,791	1,801
Benefits paid		(1,791)	(1,801)
Currency translation		0	0
Fair value of plan assets at end of year		0	0	0
Funded status at end of year		(42,383)	(38,169)
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		(42,348)	(38,134)
Total actuarial items		8,839	5,501
Total		(33,544)	(32,668)
Components of actuarial items [Abstract]
Unrecognized net actuarial loss (gain)		8,199	4,717
Unamortized prior service cost		640	784
Total actuarial items		8,839	5,501
Projected and accumulated benefit obligations [Abstract]
Accumulated benefit obligation, all plans		42,383	38,169
Plans for which the accumulated benefit obligation exceeds plan assets [Abstract]
Projected benefit obligation		42,383	38,169
Accumulated benefit obligation		42,383	38,169
Fair value of plan assets		0	0
Components of net periodic pension cost [Abstract]
Net service cost		0	0	0
Interest cost		1,696	1,484	1,643
Expected return on plan assets		0	0	0
Amortization of actuarial losses		827	656	587
Amortization of prior service (credit) cost		144	144	144
Curtailment and settlement losses		0	0	0
Net periodic benefit cost (benefit)		$ 2,667	$ 2,284	2,374
Weighted average assumptions used to calculate benefit obligations [Abstract]
Discount rate		3.25%	4.50%
Rate of compensation increase		0.00%	0.00%
Weighted average assumptions used calculating net periodic benefit cost [Abstract]
Discount rate		4.50%	3.75%
Rate of compensation increase		0.00%	0.00%
Expected return on plan assets		0.00%	0.00%
Estimated future benefit payments [Abstract]
2020		$ 1,872
2021		1,870
2022		8,311
2023		3,185
2024		3,183
2025-2029		17,460
Defined Benefit Pension [Member] | Non-U.S. Plans [Member]
Change in benefit obligation [Roll forward]
Benefit obligation at beginning of year		275,207	$ 294,187
Service cost		3,382	3,822	3,725
Interest cost		5,116	4,793	4,866
Plan amendments		0	125
Actuarial (gains) losses		20,115	(1,311)
Benefits paid		(18,985)	(14,397)
Currency translation		(1,274)	(12,012)
Benefit obligation at end of year		283,561	275,207	294,187
Change in plan assets [Roll forward]
Fair value of plan assets at beginning of year		70,820	70,605
Actual return on plan assets		4,614	1,412
Company contributions		15,443	16,105
Benefits paid		(18,985)	(14,397)
Currency translation		1,737	(2,905)
Fair value of plan assets at end of year		73,629	70,820	70,605
Funded status at end of year		(209,932)	(204,387)
Amounts recognized in balance sheet associated with retirement benefit plans [Abstract]
Included in other assets		303	356
Included in Payroll and related expenses		(7,362)	(7,228)
Accrued pension and other postretirement costs		(202,873)	(197,515)
Total actuarial items		84,926	76,698
Total		(125,006)	(127,689)
Components of actuarial items [Abstract]
Unrecognized net actuarial loss (gain)		84,523	76,254
Unamortized prior service cost		403	444
Total actuarial items		84,926	76,698
Projected and accumulated benefit obligations [Abstract]
Accumulated benefit obligation, all plans		264,723	258,244
Plans for which the accumulated benefit obligation exceeds plan assets [Abstract]
Projected benefit obligation		252,469	247,066
Accumulated benefit obligation		239,341	235,167
Fair value of plan assets		44,670	45,818
Components of net periodic pension cost [Abstract]
Net service cost		3,382	3,822	3,725
Interest cost		5,116	4,793	4,866
Expected return on plan assets		(1,956)	(1,889)	(2,072)
Amortization of actuarial losses		5,374	6,196	6,179
Amortization of prior service (credit) cost		197	318	150
Curtailment and settlement losses		2,183	1,111	1,360
Net periodic benefit cost (benefit)		$ 14,296	$ 14,351	14,208
Weighted average assumptions used to calculate benefit obligations [Abstract]
Discount rate		1.40%	1.96%
Rate of compensation increase		2.24%	2.17%
Weighted average assumptions used calculating net periodic benefit cost [Abstract]
Discount rate		1.96%	1.80%
Rate of compensation increase		2.17%	2.10%
Expected return on plan assets		2.77%	2.95%
Estimated future benefit payments [Abstract]
2020		$ 15,485
2021		15,064
2022		18,071
2023		16,306
2024		16,154
2025-2029		81,415
Other Postretirement Benefits [Member] | U.S. Plans [Member]
Change in benefit obligation [Roll forward]
Benefit obligation at beginning of year		6,994	$ 7,633
Service cost		157	137	131
Interest cost		286	273	311
Actuarial (gains) losses		939	(344)
Benefits paid		(687)	(705)
Currency translation		0	0
Benefit obligation at end of year		7,689	6,994	7,633
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		(7,689)	(6,994)
Amounts recognized in balance sheet associated with retirement benefit plans [Abstract]
Included in Payroll and related expenses		(872)	(703)
Accrued pension and other postretirement costs		(6,817)	(6,291)
Total actuarial items		(180)	(1,257)
Total		(7,869)	(8,251)
Components of actuarial items [Abstract]
Unrecognized net actuarial loss (gain)		(180)	(1,257)
Total actuarial items		(180)	(1,257)
Components of net periodic pension cost [Abstract]
Net service cost		157	137	131
Interest cost		286	273	311
Amortization of actuarial losses		(138)	(39)	(93)
Amortization of prior service (credit) cost		0	(148)	(837)
Net periodic benefit cost (benefit)		$ 305	$ 223	(488)
Weighted average assumptions used to calculate benefit obligations [Abstract]
Discount rate		3.25%	4.50%
Rate of compensation increase		0.00%	0.00%
Weighted average assumptions used calculating net periodic benefit cost [Abstract]
Discount rate		4.50%	3.75%
Rate of compensation increase		0.00%	0.00%
Estimated future benefit payments [Abstract]
2020		$ 872
2021		839
2022		798
2023		721
2024		670
2025-2029		2,440
Other Postretirement Benefits [Member] | Non-U.S. Plans [Member]
Change in benefit obligation [Roll forward]
Benefit obligation at beginning of year		7,953	$ 7,898
Service cost		284	288	273
Interest cost		123	114	103
Actuarial (gains) losses		311	327
Benefits paid		(413)	(303)
Currency translation		(149)	(371)
Benefit obligation at end of year		8,109	7,953	7,898
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		(8,109)	(7,953)
Amounts recognized in balance sheet associated with retirement benefit plans [Abstract]
Included in Payroll and related expenses		(616)	(181)
Accrued pension and other postretirement costs		(7,493)	(7,772)
Total actuarial items		2,179	2,044
Total		(5,930)	(5,909)
Components of actuarial items [Abstract]
Unrecognized net actuarial loss (gain)		2,179	2,044
Total actuarial items		2,179	2,044
Components of net periodic pension cost [Abstract]
Net service cost		284	288	273
Interest cost		123	114	103
Amortization of actuarial losses		107	105	76
Amortization of prior service (credit) cost		0	0	0
Net periodic benefit cost (benefit)		$ 514	$ 507	$ 452
Weighted average assumptions used to calculate benefit obligations [Abstract]
Discount rate		0.81%	1.60%
Rate of compensation increase		2.87%	3.18%
Weighted average assumptions used calculating net periodic benefit cost [Abstract]
Discount rate		1.60%	1.50%
Rate of compensation increase		3.18%	2.88%
Estimated future benefit payments [Abstract]
2020		$ 616
2021		251
2022		574
2023		266
2024		490
2025-2029		2,794
Other Retirement Obligations [Member]
Amounts recognized in balance sheet associated with retirement benefit plans [Abstract]
Accrued pension and other postretirement costs		(12,871)	$ (11,272)
Dr. Felix Zandman [Member] | Non-qualified Pension Plans [Member]
Defined benefit pension plans [Abstract]
Assets held in trust		605	$ 1,199
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.