SUPPLEMENTAL OIL AND GAS DISCLOSURES (Unaudited) - Capitalized Costs (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Reserve Quantities [Line Items]
Proved properties	$ 39,197	$ 42,693
Unproved properties	1,783	1,969
Capitalized costs, gross	40,980	44,662
Accumulated DD&A	(24,711)	(26,972)
Capitalized costs, net	16,269	17,690
United States
Reserve Quantities [Line Items]
Proved properties	20,408	19,170
Unproved properties	1,312	1,465
Capitalized costs, gross	21,720	20,635
Accumulated DD&A	(10,766)	(10,034)
Capitalized costs, net	10,954	10,601
Canada
Reserve Quantities [Line Items]
Proved properties	0	5,434
Unproved properties	0	109
Capitalized costs, gross	0	5,543
Accumulated DD&A	0	(4,120)
Capitalized costs, net	0	1,423
Egypt
Reserve Quantities [Line Items]
Proved properties	10,590	10,169
Unproved properties	137	76
Capitalized costs, gross	10,727	10,245
Accumulated DD&A	(7,985)	(7,287)
Capitalized costs, net	2,742	2,958
North Sea
Reserve Quantities [Line Items]
Proved properties	8,199	7,920
Unproved properties	297	280
Capitalized costs, gross	8,496	8,200
Accumulated DD&A	(5,960)	(5,531)
Capitalized costs, net	2,536	2,669
Other International
Reserve Quantities [Line Items]
Proved properties	0	0
Unproved properties	37	39
Capitalized costs, gross	37	39
Accumulated DD&A	0	0
Capitalized costs, net	$ 37	$ 39