Leases (Supplemental Cash Flow Information And Other Information For Leases) (Details) - USD ($) $ in Millions	9 Months Ended
Sep. 30, 2020	Sep. 30, 2019
Leases [Abstract]
Operating cash flows for operating leases	$ 21	$ 17
Operating cash flows for finance leases	2	4
Financing cash flows for finance leases	28	25
ROU assets obtained in exchange for lease obligations: Operating leases	3	7
ROU assets obtained in exchange for lease obligations: Finance leases	$ 23	$ 39

Amount of interest paid on finance lease liability.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 50
-Paragraph 4
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-URI http://asc.fasb.org/extlink&oid=121609121&loc=SL77918686-209980

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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-Section 45
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- Definition

Amount of cash outflow for principal payment on finance lease.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 45
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
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- Definition

Amount of cash outflow from operating lease, excluding payments to bring another asset to condition and location necessary for its intended use.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 45
-Paragraph 5
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=121603541&loc=SL77918643-209977

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-Publisher FASB
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Amount of increase in right-of-use asset obtained in exchange for finance lease liability.

+ References

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-Publisher FASB
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Amount of increase in right-of-use asset obtained in exchange for operating lease liability.

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