CAPITALIZED EXPLORATORY WELL COSTS - Aging of Suspended Well Balances (Details) $ in Millions	Dec. 31, 2017 USD ($) Project	Dec. 31, 2016 USD ($) Project	Dec. 31, 2015 USD ($) Project	Dec. 31, 2014 USD ($)
Extractive Industries [Abstract]
Exploratory well costs capitalized for a period of one year or less	$ 160	$ 119	$ 184
Exploratory well costs capitalized for a period greater than one year	190	145	61
Capitalized exploratory well costs	$ 350	$ 264	$ 245	$ 849
Number of projects with exploratory well costs capitalized for a period greater than one year | Project	4,000,000	3,000,000	2,000,000