Pension and Other Postretirement Benefits - Funded Status Rollforward (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair Value of Plan Assets at Beginning of Year	$ 122,857
Fair Value of Plan Assets at End of Year	136,041	$ 122,857
Defined Benefit Plan, Amounts Recognized in Balance Sheet [Abstract]
Current Liabilities	(1,086)	(1,144)
Non-current Liabilities	(38,348)	(40,689)
Domestic [Member]
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit Obligation at Beginning of Year	66,862	70,667
Service Cost	298	250	$ 250
Interest Cost	2,114	2,541	2,823
Employee Contributions	0	0
Effect of Plan Amendments		0
Benefits Paid	(4,522)	(4,249)
Plan Settlements	0	0
Plan Expenses and Premiums Paid	(275)	(250)
Actuarial (gain) Loss	2,777	(2,097)
Translation Difference and Other	0	0
Benefit Obligation at End of Year	67,254	66,862	70,667
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair Value of Plan Assets at Beginning of Year	46,701	49,689
Actual Return on Plan Assets	2,516	223
Employer Contributions	4,777	1,288
Employee Contributions	0	0
Benefits Paid	(4,522)	(4,249)
Plan Settlements	0	0
Plan Expenses and Premiums Paid	(275)	(250)
Translation Difference	0	0
Fair Value of Plan Assets at End of Year	49,197	46,701	49,689
Defined Benefit Plan, Funded Status of Plan	(18,057)	(20,161)
Defined Benefit Plan, Amounts Recognized in Balance Sheet [Abstract]
Current Liabilities	(574)	(575)
Non-current Liabilities	(17,483)	(19,586)
Net Amount Recognized	(18,057)	(20,161)
Amounts Not Yet Reflected in Net Periodic Benefit Costs and Included in Accumulated Other Comprehensive Income (Loss) [Abstract]
Prior Service credit (cost)	(122)	(185)
Accumulated Loss	(33,147)	(31,906)
Accumulated Other Comprehensive Loss ("AOCI")	(33,269)	(32,091)
Cumulative Employer Contributions In Excess Of (or Below) Net Periodic Benefit Cost	15,212	11,930
Net Amount Recognized	(18,057)	(20,161)
Foreign [Member]
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit Obligation at Beginning of Year	92,406	106,827
Service Cost	2,378	2,799	2,626
Interest Cost	2,314	2,476	3,210
Employee Contributions	71	80
Effect of Plan Amendments		0
Benefits Paid	(1,583)	(1,604)
Plan Settlements	0	(328)
Plan Expenses and Premiums Paid	(155)	(57)
Actuarial (gain) Loss	14,848	(7,799)
Translation Difference and Other	(6,788)	(9,988)
Benefit Obligation at End of Year	103,491	92,406	106,827
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair Value of Plan Assets at Beginning of Year	76,156	86,523
Actual Return on Plan Assets	14,472	(2,170)
Employer Contributions	3,103	1,804
Employee Contributions	71	80
Benefits Paid	(1,583)	(1,604)
Plan Settlements	0	(328)
Plan Expenses and Premiums Paid	(155)	(57)
Translation Difference	(5,220)	(8,092)
Fair Value of Plan Assets at End of Year	86,844	76,156	86,523
Defined Benefit Plan, Funded Status of Plan	(16,647)	(16,250)
Defined Benefit Plan, Amounts Recognized in Balance Sheet [Abstract]
Current Liabilities	(61)	(52)
Non-current Liabilities	(16,586)	(16,198)
Net Amount Recognized	(16,647)	(16,250)
Amounts Not Yet Reflected in Net Periodic Benefit Costs and Included in Accumulated Other Comprehensive Income (Loss) [Abstract]
Prior Service credit (cost)	1,687	1,910
Accumulated Loss	(20,214)	(20,058)
Accumulated Other Comprehensive Loss ("AOCI")	(18,527)	(18,148)
Cumulative Employer Contributions In Excess Of (or Below) Net Periodic Benefit Cost	1,880	1,898
Net Amount Recognized	(16,647)	(16,250)
Total Pension Plans [Member]
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit Obligation at Beginning of Year	159,268	177,494
Service Cost	2,676	3,049	2,876
Interest Cost	4,428	5,017	6,033
Employee Contributions	71	80
Effect of Plan Amendments		0
Benefits Paid	(6,105)	(5,853)
Plan Settlements	0	(328)
Plan Expenses and Premiums Paid	(430)	(307)
Actuarial (gain) Loss	17,625	(9,896)
Translation Difference and Other	(6,788)	(9,988)
Benefit Obligation at End of Year	170,745	159,268	177,494
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair Value of Plan Assets at Beginning of Year	122,857	136,212
Actual Return on Plan Assets	16,988	(1,947)
Employer Contributions	7,880	3,092
Employee Contributions	71	80
Benefits Paid	(6,105)	(5,853)
Plan Settlements	0	(328)
Plan Expenses and Premiums Paid	(430)	(307)
Translation Difference	(5,220)	(8,092)
Fair Value of Plan Assets at End of Year	136,041	122,857	136,212
Defined Benefit Plan, Funded Status of Plan	(34,704)	(36,411)
Defined Benefit Plan, Amounts Recognized in Balance Sheet [Abstract]
Current Liabilities	(635)	(627)
Non-current Liabilities	(34,069)	(35,784)
Net Amount Recognized	(34,704)	(36,411)
Amounts Not Yet Reflected in Net Periodic Benefit Costs and Included in Accumulated Other Comprehensive Income (Loss) [Abstract]
Prior Service credit (cost)	1,565	1,725
Accumulated Loss	(53,361)	(51,964)
Accumulated Other Comprehensive Loss ("AOCI")	(51,796)	(50,239)
Cumulative Employer Contributions In Excess Of (or Below) Net Periodic Benefit Cost	17,092	13,828
Net Amount Recognized	(34,704)	(36,411)
Domestic Other Postretirement Benefits [Member]
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit Obligation at Beginning of Year	5,422	6,045
Service Cost	10	17	19
Interest Cost	142	195	232
Employee Contributions	0	0
Effect of Plan Amendments		0
Benefits Paid	(443)	(533)
Plan Settlements	0	0
Plan Expenses and Premiums Paid	0	0
Actuarial (gain) Loss	(401)	(302)
Translation Difference and Other	0	0
Benefit Obligation at End of Year	4,730	5,422	6,045
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair Value of Plan Assets at Beginning of Year	0	0
Actual Return on Plan Assets	0	0
Employer Contributions	443	533
Employee Contributions	0	0
Benefits Paid	(443)	(533)
Plan Settlements	0	0
Plan Expenses and Premiums Paid	0	0
Translation Difference	0	0
Fair Value of Plan Assets at End of Year	0	0	$ 0
Defined Benefit Plan, Funded Status of Plan	(4,730)	(5,422)
Defined Benefit Plan, Amounts Recognized in Balance Sheet [Abstract]
Current Liabilities	(451)	(517)
Non-current Liabilities	(4,279)	(4,905)
Net Amount Recognized	(4,730)	(5,422)
Amounts Not Yet Reflected in Net Periodic Benefit Costs and Included in Accumulated Other Comprehensive Income (Loss) [Abstract]
Prior Service credit (cost)	0	0
Accumulated Loss	(581)	(983)
Accumulated Other Comprehensive Loss ("AOCI")	(581)	(983)
Cumulative Employer Contributions In Excess Of (or Below) Net Periodic Benefit Cost	(4,149)	(4,439)
Net Amount Recognized	$ (4,730)	$ (5,422)