Retirement Plans (Details 2) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
U.S. Pension Plans
Change in Benefit Obligation [Roll Forward]
Projected benefit obligation, beginning balance	$ 159,416	$ 155,003
Service cost	450	377
Interest cost	6,829	6,931	$ 6,128
Actuarial losses (gains)	8,658	2,338
Benefits paid	(5,058)	(5,233)
Plan obligation settlement	(2,231)
Projected benefit obligation, ending balance	168,064	159,416	155,003
U.S. Retiree Healthcare Plan
Change in Benefit Obligation [Roll Forward]
Projected benefit obligation, beginning balance	14,921	12,963
Service cost	546	473	577
Employee contributions	1,041	987
Interest cost	618	557	470
Actuarial losses (gains)	942	586
Benefits paid	(947)	(645)
Projected benefit obligation, ending balance	17,121	14,921	12,963
Non-U.S. Pension Plans
Change in Benefit Obligation [Roll Forward]
Projected benefit obligation, beginning balance	85,311	75,677
Service cost	5,082	4,954	5,087
Employee contributions	605	584
Interest cost	1,518	1,699	1,503
Actuarial losses (gains)	(2,590)	6,510
Benefits paid	(2,078)	(2,141)
Plan amendments impact on projected benefit obligation	636
Plan obligation settlement	(1,229)
Other plans' impact on projected benefit obligations	196	1,305
Foreign currency impact on projected benefit obligation	8,927	(3,277)
Projected benefit obligation, ending balance	$ 96,378	$ 85,311	$ 75,677

Amount of gain (loss) from change in actuarial assumptions which (increases) decreases benefit obligation of defined benefit plan. Assumptions include, but are not limited to, interest, mortality, employee turnover, salary, and temporary deviation from substantive plan.

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- Definition

Amount of actuarial present value of benefits attributed to service rendered by employee for defined benefit plan.

+ References

+ Details

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- Definition

Amount of payment to participant of defined benefit plan which decreases benefit obligation. For pension plan, payment includes, but is not limited to, pension benefits and death benefits. For other postretirement plan, payment includes, but is not limited to, prescription drug benefits, health care benefits, life insurance benefits, and legal, educational and advisory services.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 60
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=6414203&loc=d3e39716-114964

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (a)(6)
-URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e1928-114920

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- Definition

Amount of contributions received by defined benefit plan from participant which increase benefit obligation.

+ References

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- Definition

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

+ References

No definition available.

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- Definition

Amount of foreign currency translation gain (loss) which (increases) decreases benefit obligation of defined benefit plan.

+ References

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- Definition

Amount of cost recognized for passage of time related to defined benefit plan.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (h)(2)
-URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e1928-114920

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (a)(2)
-URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e1928-114920

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- Definition

Amount of increase (decrease) in benefit obligation of defined benefit plan from change, classified as other.

+ References

No definition available.

+ Details

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Amount of increase (decrease) in benefit obligation of defined benefit plan from change in terms of existing plan or initiation of new plan.

+ References

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- Definition

Amount of cost for actuarial present value of benefits attributed to service rendered by employee for defined benefit plan.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (h)(1)
-URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e1928-114920

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e1928-114920

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- Definition

Amount of (increase) decrease to benefit obligation of defined benefit plan from irrevocable action relieving primary responsibility for benefit obligation and eliminating risk for obligation and assets used to effect settlement. Includes, but is not limited to, lump-sum cash payment to participant in exchange for right to receive specified benefits, purchase of nonparticipating annuity contract and change from remeasurement.

+ References

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