Pension and Other Postretirement Benefits - Asset Allocations (Details) - Pension Plans, Defined Benefit [Member]	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016
Domestic [Member]
Defined Benefit Plan Disclosure [Line Items]
Target Plan Asset Allocations	100.00%
Actual Plan Asset Allocations	100.00%	100.00%
Concentration Risk Percentage	3.00%	3.00%
Domestic [Member] \| Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Target Plan Asset Allocations	56.00%
Actual Plan Asset Allocations	59.00%	60.00%
Domestic [Member] \| Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Target Plan Asset Allocations	43.00%
Actual Plan Asset Allocations	40.00%	39.00%
Domestic [Member] \| Cash and Cash Equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Target Plan Asset Allocations	1.00%
Actual Plan Asset Allocations	1.00%	1.00%
Foreign [Member]
Defined Benefit Plan Disclosure [Line Items]
Target Plan Asset Allocations	100.00%
Actual Plan Asset Allocations	100.00%	100.00%
Foreign [Member] \| Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Target Plan Asset Allocations	25.00%
Actual Plan Asset Allocations	25.00%	24.00%
Foreign [Member] \| Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Target Plan Asset Allocations	75.00%
Actual Plan Asset Allocations	75.00%	76.00%

For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 275
-SubTopic 10
-Section 50
-Paragraph 18
-URI http://asc.fasb.org/extlink&oid=84177426&loc=d3e6351-108592

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 20
-URI http://asc.fasb.org/extlink&oid=77997519&loc=d3e13531-108611

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 275
-SubTopic 10
-Section 50
-Paragraph 20
-URI http://asc.fasb.org/extlink&oid=84177426&loc=d3e6404-108592

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 21
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=77997519&loc=d3e13537-108611

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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- Definition

Percentage of target investment allocation to total plan assets. Includes, but is not limited to, percentage on weighted-average basis if more than one 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 (d)(5)(i)
-URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e1928-114920

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- Definition

Percentage of fair value of investments (categorized by debt securities, equity securities, real estate and other plan assets) to the fair value of plan assets held.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 5
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e2446-114920

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

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