Savings Plans, Pension Plans and Other Postretirement Employee Benefits (Weighted Average Assumptions Used to Determine the Benefit Obligation) (Details)	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Pension Plans [Member]
Discount rate	3.85%	4.40%	4.65%
Rate of salaried compensation increase	3.00%	3.00%	3.00%
OPEB [Member]
Discount rate	3.65%	4.10%	4.25%

Weighted average rate increase of compensation, used to determine benefit obligation of defined benefit plan. Plan includes, but is not limited to, pay-related defined benefit plan.

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

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