Litigation And Other Contingencies (Narrative) (Details) - USD ($) $ in Millions	Mar. 09, 2017	Oct. 09, 2014	Oct. 24, 2011	Jun. 27, 2007	May 01, 2007
Production Sharing Contract (PSC) [Member]
Litigation And Other Contingencies [Line Items]
Percent interest in Erha block PSC			56.25%
Pending Or Threatened Litigation [Member]
Litigation And Other Contingencies [Line Items]
Amount of award relating to excess lifting of crude oil			$ 1,800
Accrued interest relating to award for excess lifting of crude oil			$ 234
Expropriation Of Assets [Member] | Mobil Cerro Negro, Ltd. (MCN) [Member]
Litigation And Other Contingencies [Line Items]
Percentage ownership interest in Cerro Negro Project				41.67%	41.67%
Final award related to Cerro Negro Project arbitration		$ 1,600
Interest rate on award for Cerro Negro Project		3.25%
Earlier Cerro Negro award for breach of contractual obligations		$ 908
Annulled portion of award for Cerro Negro Project	$ 1,400
Retained portion of award for Cerro Negro Project	260
Portion of award agreed to be paid by Venezuela for Cerro Negro Project	$ 260