Benefit Plans (Allocation Of Plan Assets) (Details)	12 Months Ended
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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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

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Target allocation minimum 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 1
-Subparagraph (d)(i)
-URI http://asc.fasb.org/extlink&oid=65897934&loc=d3e1928-114920

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-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

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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=65897934&loc=d3e2446-114920

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-Publisher FASB
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-URI http://asc.fasb.org/extlink&oid=65897934&loc=d3e1928-114920

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