Long-Term Investments (Schedule Of Pre-Tax Income And Income Tax Effects Related To Investments In Leveraged Leases) (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Long-term Investments [Abstract]
Pre-Tax Income (Loss) from Leases	$ (69)	$ (135)	$ 12
Income Tax Expense (Benefit) on Income from Leases	$ (26)	$ (51)	$ 5

The tax effect from the current year income from arrangements meeting the criteria for classification as a leveraged lease.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 50
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=77888424&loc=SL77920237-209979

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 840
-SubTopic 30
-Section 45
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=77907235&loc=d3e45152-112736

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration