Leases (Supplemental Cash Flow Information Related To Leases) (Details) $ in Millions	3 Months Ended
Mar. 31, 2019 USD ($)
Leases [Abstract]
Operating cash flows provided by operating leases	$ 18
Cash flows provided by operating leases	(19)
Operating cash flows used by finance leases	(4)
Financing cash flows used by finance leases	(8)
Right-of-use assets obtained in exchange for lease liabilities, Operating leases	3
Right-of-use assets obtained in exchange for lease liabilities, Finance leases	$ 4

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
-Subparagraph (g)(1)
-URI http://asc.fasb.org/extlink&oid=77888426&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
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-SubTopic 20
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- References

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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=77888419&loc=SL77918643-209977

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Amount of cash inflows from lease payments.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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Amount of increase in right-of-use asset obtained in exchange for finance lease liability.

+ References

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

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