CAPITALIZED EXPLORATORY WELL COSTS - Aging of Suspended Well Balances (Details) $ in Millions	Dec. 31, 2018 USD ($) Project	Dec. 31, 2017 USD ($) Project	Dec. 31, 2016 USD ($) Project	Dec. 31, 2015 USD ($)
Extractive Industries [Abstract]
Exploratory well costs capitalized for a period of one year or less	$ 126	$ 160	$ 119
Exploratory well costs capitalized for a period greater than one year	33	190	145
Capitalized exploratory well costs	$ 159	$ 350	$ 264	$ 245
Number of projects with exploratory well costs capitalized for a period greater than one year | Project	2,000,000	4,000,000	3,000,000