Pension and Postretirement Benefits (Funded Status) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Postretirement Medical Benefits
Funded status of plan:
Benefit Obligation	$ (23,882)	$ (27,317)	$ (28,614)
Funded status	(23,882)	(27,317)
Domestic Plan
Funded status of plan:
Plan assets, at fair value	464,779	418,854	408,218
Benefit Obligation	(461,355)	(449,601)	(426,248)
Funded status	3,424	(30,747)
Foreign Plan
Funded status of plan:
Plan assets, at fair value	248,733	223,491	230,827
Benefit Obligation	(413,960)	(383,947)	$ (386,175)
Funded status	$ (165,227)	$ (160,456)

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

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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

+ Details

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- Definition

Amount of funded (unfunded) status of defined benefit plan, measured as difference between fair value of plan assets and benefit obligation. Includes, but is not limited to, overfunded (underfunded) status.

+ 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 (c)
-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 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=64852052&loc=d3e1703-114919

+ Details

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- References

No definition available.

+ Details

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- Details

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