Pension and Postretirement Benefits (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan Description Of Settlements And Curtailments		During the second quarter of 2017, the Company’s U.S. pension plan offered a cash settlement to its vested terminated participants which allowed them to receive the value of their pension benefits as a single lump sum payment. As payments from the U.S. pension plan for this cash-out offering exceeded the service and interest cost components of the U.S. pension plan expense for 2017, the Company recorded a settlement charge of approximately $1.9 million. This settlement charge represents the immediate recognition into expense of a portion of the unrecognized loss within AOCI on the balance sheet in proportion to the share of the projected benefit obligation that was settled by these payments.
Pension Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Service Cost	$ 960	$ 871	$ 1,948	$ 1,789
Defined Benefit Plan, Interest Cost	1,032	1,003	2,081	2,011
Defined Benefit Plan, Expected Return on Plan Assets	(1,274)	(1,255)	(2,564)	(2,581)
Defined Benefit Plan, Settlement Charge	0	1,860	0	1,860
Defined Benefit Plan, Amortization of Losses	793	792	1,593	1,661
Defined Benefit Plan, Amortization of Prior Service Cost	(29)	(25)	(60)	(48)
Defined Benefit Plan, Net Periodic Benefit Cost	1,482	3,246	2,998	4,692
Defined Benefit Plan, Estimated Future Employer Contributions in Current Fiscal Year	9,900		9,900
Defined Benefit Plan, Contributions by Employer			4,900
Defined Benefit Plan Effect Of Settlements And Curtailments On Accumulated Benefit Obligation		4,000
Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Service Cost	3	1	5	4
Defined Benefit Plan, Interest Cost	33	39	66	72
Defined Benefit Plan, Expected Return on Plan Assets	0	0	0	0
Defined Benefit Plan, Settlement Charge	0	0	0	0
Defined Benefit Plan, Amortization of Losses	14	22	29	27
Defined Benefit Plan, Amortization of Prior Service Cost	0	0	0	0
Defined Benefit Plan, Net Periodic Benefit Cost	50	$ 62	100	$ 103
Defined Benefit Plan, Estimated Future Employer Contributions in Current Fiscal Year	$ 400		400
Defined Benefit Plan, Contributions by Employer			$ 200