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Description Of Company And Significant Accounting Policies (Schedule Of Revenue And Receivables From Major Customers) (Details) - USD ($)
$ in Millions
3 Months Ended 12 Months Ended
Dec. 31, 2015
Sep. 30, 2015
Jun. 30, 2015
Mar. 31, 2015
Dec. 31, 2014
Sep. 30, 2014
Jun. 30, 2014
Mar. 31, 2014
Dec. 31, 2015
Dec. 31, 2014
Dec. 31, 2013
Revenue, Major Customer [Line Items]                      
Revenue $ 1,080 $ 1,199 $ 1,381 $ 1,436 $ 1,417 $ 1,657 $ 1,659 $ 1,633 $ 5,096 $ 6,366 $ 7,214
Chevron [Member]                      
Revenue, Major Customer [Line Items]                      
Revenue                 $ 523 $ 1,069 $ 1,859
Revenue percentage                 10.00% 17.00% 26.00%
Receivables percentage                 5.00% 9.00% 13.00%