Pension and Postretirement Benefits - Accumulated Benefit Obligation in Excess of Plan Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Domestic Plans \| Funded Plans
Accumulated benefit obligation in excess of plan assets
Projected benefit obligation	$ 15,440	$ 15,027
Accumulated benefit obligation	15,440	15,027
Fair value of plan assets	11,590	10,416
Domestic Plans \| Unfunded Pension Plans
Accumulated benefit obligation in excess of plan assets
Projected benefit obligation	9,857	9,825
Accumulated benefit obligation	9,826	9,737
Foreign Pension Plans \| Funded Plans
Accumulated benefit obligation in excess of plan assets
Projected benefit obligation	9,521	10,488
Accumulated benefit obligation	8,819	9,906
Fair value of plan assets	9,493	10,576
Foreign Pension Plans \| Unfunded Pension Plans
Accumulated benefit obligation in excess of plan assets
Projected benefit obligation	2,582	2,486
Accumulated benefit obligation	$ 2,582	$ 2,486

Amount of actuarial present value of benefits attributed to employee service rendered, excluding assumptions about future compensation level.

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

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- Definition

Amount of projected benefit obligation for defined benefit pension plan with accumulated benefit obligation in excess of plan assets.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 55
-Paragraph 17
-URI http://asc.fasb.org/extlink&oid=77993564&loc=d3e4179-114921

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- Definition

Fair value of plan assets for defined benefit plan with benefit obligation in excess of plan assets.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 3
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e2417-114920

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