Pension and Postretirement Benefits (Details) - USD ($) $ in Thousands	3 Months Ended			9 Months Ended
	Sep. 30, 2017	Jun. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Defined Benefit Plan Disclosure [Line Items]
Effect of Plan Amendment on Net Periodic Benefit Cost		$ 4,000
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 represented the immediate recognition into expense of a portion of the unrecognized loss within accumulated other comprehensive loss (“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	$ 921		$ 672	$ 2,710	$ 2,025
Defined Benefit Plan, Interest Cost	994		1,111	3,005	3,344
Defined Benefit Plan, Expected Return on Plan Assets	(1,276)		(1,329)	(3,857)	(4,027)
Defined Benefit Plan, Settlement Charge	0		0	1,860	0
Defined Benefit Plan, Amortization of Losses (Gain)	798		769	2,459	2,389
Defined Benefit Plan, Amortization of Prior Service Cost	(28)		(25)	(76)	(76)
Defined Benefit Plan, Net Periodic Benefit Cost	1,409		1,198	6,101	3,655
Defined Benefit Plan, Estimated Future Employer Contributions in Current Fiscal Year	7,800			7,800
Defined Benefit Plan, Contributions by Employer				5,100
Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Service Cost	2		0	6	8
Defined Benefit Plan, Interest Cost	36		28	108	106
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 (Gain)	13		(30)	40	0
Defined Benefit Plan, Amortization of Prior Service Cost	0		0	0	0
Defined Benefit Plan, Net Periodic Benefit Cost	51		$ (2)	154	$ 114
Defined Benefit Plan, Estimated Future Employer Contributions in Current Fiscal Year	$ 500			500
Defined Benefit Plan, Contributions by Employer				$ 300