Net Periodic Benefit Cost (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Impact of Adopting ASU 2017-07 ASC 715 Compensation-Retirement Benefits	$ (1,200)	$ (1,600)
Defined Benefit Plan, Service Cost	3,952	4,193
Defined Benefit Plan, Interest Cost	3,720	3,300
Defined Benefit Plan, Expected Return (Loss) on Plan Assets	(8,773)	(9,719)
Defined Benefits Plan Net amortization and deferral	(1,702)	(1,887)
Defined Benefit Plan, Benefit Obligation, Actuarial Gain (Loss)	5,591	6,698
Defined Benefit Plan, Net Periodic Benefit Cost (Credit)	2,788	2,585
Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Expected Future Employer Contributions, Remainder of Fiscal Year	25,300
Pension Plan [Member] | Domestic Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Service Cost	266	272
Defined Benefit Plan, Interest Cost	1,146	1,061
Defined Benefit Plan, Expected Return (Loss) on Plan Assets	(1,472)	(1,732)
Defined Benefits Plan Net amortization and deferral	0	0
Defined Benefit Plan, Benefit Obligation, Actuarial Gain (Loss)	593	1,451
Defined Benefit Plan, Net Periodic Benefit Cost (Credit)	533	1,052
Pension Plan [Member] | Foreign Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Service Cost	3,686	3,921
Defined Benefit Plan, Interest Cost	2,558	2,223
Defined Benefit Plan, Expected Return (Loss) on Plan Assets	(7,301)	(7,987)
Defined Benefits Plan Net amortization and deferral	(1,702)	(1,794)
Defined Benefit Plan, Benefit Obligation, Actuarial Gain (Loss)	5,171	5,560
Defined Benefit Plan, Net Periodic Benefit Cost (Credit)	2,412	1,923
Other Postretirement Benefits Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Service Cost	0	0
Defined Benefit Plan, Interest Cost	16	16
Defined Benefit Plan, Expected Return (Loss) on Plan Assets	0	0
Defined Benefits Plan Net amortization and deferral	0	(93)
Defined Benefit Plan, Benefit Obligation, Actuarial Gain (Loss)	(173)	(313)
Defined Benefit Plan, Net Periodic Benefit Cost (Credit)	(157)	$ (390)
Defined Benefit Plan, Expected Future Employer Contributions, Remainder of Fiscal Year	$ 400