Retirement Plans (Details 3) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016
Change in Fair Value of Plan Assets [Roll Forward]
Fair value of defined benefit plan assets, beginning balance	$ 219,355
Fair value of defined benefit plan assets, ending balance	257,488	$ 219,355
U.S. Pension Plans
Change in Fair Value of Plan Assets [Roll Forward]
Fair value of defined benefit plan assets, beginning balance	144,665	136,128
Actual return on defined benefit plan assets	27,729	8,621
Company contributions	6,162	5,149
Plan settlements	(2,125)
Benefits paid	(5,058)	(5,233)
Fair value of defined benefit plan assets, ending balance	171,373	144,665
U.S. Retiree Healthcare Plan
Change in Fair Value of Plan Assets [Roll Forward]
Fair value of defined benefit plan assets, beginning balance	9,142	8,001
Actual return on defined benefit plan assets	1,542	510
Company contributions	347	289
Employee contributions	1,041	987
Benefits paid	(947)	(645)
Fair value of defined benefit plan assets, ending balance	11,125	9,142
Non-U.S. Pension Plans
Change in Fair Value of Plan Assets [Roll Forward]
Fair value of defined benefit plan assets, beginning balance	65,548	60,441
Actual return on defined benefit plan assets	390	4,741
Company contributions	4,733	4,579
Employee contributions	605	584
Plan settlements	(915)
Benefits paid	(2,078)	(2,141)
Other plans' impact on fair value of defined benefit plan assets	(213)	262
Foreign currency impact on plan assets	6,920	(2,918)
Fair value of defined benefit plan assets, ending balance	$ 74,990	$ 65,548

Amount of increase (decrease) in plan assets of defined benefit plan from actual return (loss) determined by change in fair value of plan assets adjusted for contributions, benefit payments, and other expenses.

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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

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-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 contribution received by defined benefit plan from employer which increases plan assets.

+ References

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

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- Definition

Fair value of assets that have been segregated and restricted to provide pension or postretirement benefits. Assets include, but are not limited to, stocks, bonds, other investments, earnings from investments, and contributions by the employer and employees.

+ References

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- Definition

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

+ References

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- Definition

Amount of payment, which decreases plan assets of defined benefit plan, for irrevocable action relieving primary responsibility for benefit obligation and eliminating risk for obligation and assets used to effect settlement. Transaction constituting settlement includes, but is not limited to, making lump-sum cash payment to participant in exchange for their rights to receive specified benefits and purchasing nonparticipating annuity contract.

+ 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 (d)(5)(ii)
-URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e1928-114920

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- Definition

Changes in the fair value of defined benefit plan assets, not otherwise separately disclosed in the financial statements.

+ References

No definition available.

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