Derivative Financial Instruments (Schedule Of Derivative Financial Instruments Included In The Consolidated Comprehensive Statements Of Earnings) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Derivative [Line Items]
Net gains (losses) recognized in consolidated comprehensive statements of earnings	$ (386)	$ 738	$ 2,070
Commodity Derivatives [Member] | Oil, Gas And NGL Derivatives [Member]
Derivative [Line Items]
Net gains (losses) recognized in consolidated comprehensive statements of earnings	(201)	503	1,989
Commodity Derivatives [Member] | Marketing And Midstream Revenues [Member]
Derivative [Line Items]
Net gains (losses) recognized in consolidated comprehensive statements of earnings	(13)	9	22
Interest Rate Derivatives [Member] | Other Nonoperating Items [Member]
Derivative [Line Items]
Net gains (losses) recognized in consolidated comprehensive statements of earnings	(19)	(20)	(1)
Foreign Currency Derivatives [Member] | Other Nonoperating Items [Member]
Derivative [Line Items]
Net gains (losses) recognized in consolidated comprehensive statements of earnings	$ (153)	$ 246	$ 60