Revenue Recognition (Schedule of Impact of Adoption) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Revenue Initial Application Period Cumulative Effect Transition [Line Items]
Upstream revenues	$ 1,069	$ 1,332	$ 2,388	$ 2,873
Marketing revenues	1,180	833	2,059	1,692
Total impacted revenues	2,249	2,165	4,447	4,565
Production expenses	572	455	1,115	912
Marketing expenses	1,160	849	2,033	1,728
Total impacted expenses	1,732		3,148
Earnings (loss) from continuing operations before income taxes	(481)	$ 207	(726)	$ 520
Under ASC 605 [Member] | Accounting Standards Update 2014-09
Revenue Initial Application Period Cumulative Effect Transition [Line Items]
Upstream revenues	1,004		2,261
Marketing revenues	1,180		2,059
Total impacted revenues	2,184		4,320
Production expenses	507		988
Marketing expenses	1,160		2,033
Total impacted expenses	1,667		3,021
Earnings (loss) from continuing operations before income taxes	(481)		(726)
Increase/(Decrease) of Under ASC 606 and Under ASC 605 [Member] | Accounting Standards Update 2014-09
Revenue Initial Application Period Cumulative Effect Transition [Line Items]
Upstream revenues	65		127
Total impacted revenues	65		127
Production expenses	65		127
Total impacted expenses	$ 65		$ 127