Derivative Financial Instruments (Schedule Of Derivative Financial Instruments Included In The Consolidated Comprehensive Statements Of Earnings) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Derivative [Line Items]
Net gains (losses) recognized in consolidated comprehensive statements of earnings	$ (479)	$ 108	$ (474)	$ 346
Commodity Derivatives [Member] | Upstream Revenues [Member]
Derivative [Line Items]
Net gains (losses) recognized in consolidated comprehensive statements of earnings	(497)	126	(538)	358
Commodity Derivatives [Member] | Marketing Revenues [Member]
Derivative [Line Items]
Net gains (losses) recognized in consolidated comprehensive statements of earnings	(1)	2	(1)	3
Interest Rate Derivatives [Member] | Other Expenses [Member]
Derivative [Line Items]
Net gains (losses) recognized in consolidated comprehensive statements of earnings	$ 19	$ (20)	$ 65	$ (15)