Employee Benefit Plans (Target and Actual Asset Allocations) (Details)	Dec. 31, 2018	Dec. 31, 2017
Master Trust [Member]
Defined Benefit Plan Disclosure [Line Items]
Actual asset allocation	100.00%	100.00%
Target allocation	100.00%
Master Trust [Member] \| US Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Actual asset allocation	11.00%	11.00%
Target allocation	10.00%
Master Trust [Member] \| Non US Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Actual asset allocation	8.00%	8.00%
Target allocation	8.00%
Master Trust [Member] \| Global Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Actual asset allocation	10.00%	10.00%
Target allocation	10.00%
Master Trust [Member] \| Global Private Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Actual asset allocation	2.00%	2.00%
Target allocation	3.00%
Master Trust [Member] \| Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Actual asset allocation	63.00%	63.00%
Target allocation	63.00%
Master Trust [Member] \| Hedge Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Actual asset allocation	2.00%	2.00%
Target allocation	2.00%
Master Trust [Member] \| Real Estate and Cash [Member]
Defined Benefit Plan Disclosure [Line Items]
Actual asset allocation	2.00%	2.00%
Target allocation	2.00%
Master Trust [Member] \| Other Global Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Actual asset allocation	2.00%	2.00%
Target allocation	2.00%
OPEB [Member]
Defined Benefit Plan Disclosure [Line Items]
Actual asset allocation	100.00%	100.00%
Target allocation	100.00%
OPEB [Member] \| US Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Actual asset allocation	43.00%	41.00%
Target allocation	32.00%
OPEB [Member] \| Non US Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Actual asset allocation	8.00%	8.00%
Target allocation	6.00%
OPEB [Member] \| Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Actual asset allocation	40.00%	36.00%
Target allocation	45.00%
OPEB [Member] \| Real Estate [Member]
Defined Benefit Plan Disclosure [Line Items]
Actual asset allocation	2.00%	2.00%
Target allocation	2.00%
OPEB [Member] \| Cash [Member]
Defined Benefit Plan Disclosure [Line Items]
Actual asset allocation	7.00%	13.00%
Target allocation	15.00%

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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/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 55
-Paragraph 17
-URI http://asc.fasb.org/extlink&oid=112275985&loc=d3e4179-114921

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (d)(i)
-URI http://asc.fasb.org/extlink&oid=108410482&loc=d3e1928-114920

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- Definition

Percentage of actual 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/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (d)(i)
-URI http://asc.fasb.org/extlink&oid=108410482&loc=d3e1928-114920

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