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Benefit Plans (Allocation Of Plan Assets) (Details) | 12 Months Ended
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Dec. 31, 2017
Pension Plans, Defined Benefit [Member] | Cash and equivalents [Member] |
Defined Benefit Plan Disclosure [Line Items] |
Target range allocation, minimum | 0.00%
Target range allocation, maximum | 5.00%
Actual allocation | 3.00%
Pension Plans, Defined Benefit [Member] | Equity securites - U.S. [Member] |
Defined Benefit Plan Disclosure [Line Items] |
Target range allocation, minimum | 11.00%
Target range allocation, maximum | 41.00%
Actual allocation | 24.00%
Pension Plans, Defined Benefit [Member] | Equity securities - international [Member] |
Defined Benefit Plan Disclosure [Line Items] |
Target range allocation, minimum | 14.00%
Target range allocation, maximum | 34.00%
Actual allocation | 23.00%
Pension Plans, Defined Benefit [Member] | Global asset securities [Member] |
Defined Benefit Plan Disclosure [Line Items] |
Target range allocation, minimum | 5.00%
Target range allocation, maximum | 15.00%
Actual allocation | 10.00%
Pension Plans, Defined Benefit [Member] | Risk parity securities [Member] |
Defined Benefit Plan Disclosure [Line Items] |
Target range allocation, minimum | 5.00%
Target range allocation, maximum | 15.00%
Actual allocation | 10.00%
Pension Plans, Defined Benefit [Member] | Fixed income securities [Member] |
Defined Benefit Plan Disclosure [Line Items] |
Target range allocation, minimum | 20.00%
Target range allocation, maximum | 40.00%
Actual allocation | 30.00%
Other Postretirement Benefits Plans [Member] | Cash and equivalents [Member] |
Defined Benefit Plan Disclosure [Line Items] |
Target range allocation, minimum | 0.00%
Target range allocation, maximum | 5.00%
Actual allocation | 1.00%
Other Postretirement Benefits Plans [Member] | Equity securites - U.S. [Member] |
Defined Benefit Plan Disclosure [Line Items] |
Target range allocation, minimum | 0.00%
Target range allocation, maximum | 50.00%
Actual allocation | 26.00%
Other Postretirement Benefits Plans [Member] | Equity securities - international [Member] |
Defined Benefit Plan Disclosure [Line Items] |
Target range allocation, minimum | 0.00%
Target range allocation, maximum | 34.00%
Actual allocation | 10.00%
Other Postretirement Benefits Plans [Member] | Fixed income securities [Member] |
Defined Benefit Plan Disclosure [Line Items] |
Target range allocation, minimum | 20.00%
Target range allocation, maximum | 100.00%
Actual allocation | 63.00%

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- Definition Target allocation maximum percentage of investments of this type to total plan assets presented on a weighted average basis. + 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)(i) -URI http://asc.fasb.org/extlink&oid=65897934&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)(i) -URI http://asc.fasb.org/extlink&oid=65897934&loc=d3e1928-114920 + Details
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