Derivative Financial Instruments (Schedule Of Derivative Financial Instruments Included In The Consolidated Comprehensive Statements Of Earnings) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Derivatives Fair Value [Line Items]
Net gains (losses) recognized in consolidated comprehensive statements of earnings	$ 58	$ 481	$ (359)	$ 606
Commodity Derivatives [Member] | Oil, Gas And NGL Derivatives [Member]
Derivatives Fair Value [Line Items]
Net gains (losses) recognized in consolidated comprehensive statements of earnings	79	414	(30)	426
Commodity Derivatives [Member] | Marketing And Midstream Revenues [Member]
Derivatives Fair Value [Line Items]
Net gains (losses) recognized in consolidated comprehensive statements of earnings	(1)	6	(7)	8
Interest Rate Derivatives [Member] | Other Nonoperating Items [Member]
Derivatives Fair Value [Line Items]
Net gains (losses) recognized in consolidated comprehensive statements of earnings	$ (20)	(30)	(163)	(28)
Foreign Currency Derivatives [Member] | Other Nonoperating Items [Member]
Derivatives Fair Value [Line Items]
Net gains (losses) recognized in consolidated comprehensive statements of earnings		$ 91	$ (159)	$ 200