Supplementary Financial Statement Information (Schedule Of Interest Income And Interest Expense) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Supplementary Financial Statement Information [Abstract]
Interest expense	$ 677us-gaap_InterestExpense	$ 669us-gaap_InterestExpense	$ 742us-gaap_InterestExpense
Interest income	70us-gaap_InvestmentIncomeInterest	57us-gaap_InvestmentIncomeInterest	71us-gaap_InvestmentIncomeInterest
Capitalized interest costs	$ 23us-gaap_InterestCostsCapitalized	$ 17us-gaap_InterestCostsCapitalized	$ 37us-gaap_InterestCostsCapitalized

Amount of the cost of borrowed funds accounted for as interest expense.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 835

-SubTopic 20

-Section 50

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6450988&loc=d3e26243-108391

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 225

-Section S99

-Paragraph 1

-Subparagraph (SX 210.9-04.9)

-URI http://asc.fasb.org/extlink&oid=6879574&loc=d3e536633-122882

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

-Paragraph 9

-Article 9

Name:	us-gaap_InterestExpense
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration