SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - PROPERTY, PLANT AND EQUIPMENT AND GOODWILL (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Capitalized exploratory well costs for continuing operations
Balance — beginning of year	$ 112	$ 108	$ 56
Exploratory well costs acquired through the Acquisition	231	0	0
Additions to capitalized exploratory well costs pending the determination of proved reserves	383	220	201
Reclassifications to property, plant and equipment based on the determination of proved reserves	(230)	(198)	(128)
Capitalized exploratory well costs charged to expense	(72)	(18)	(21)
Balance — end of year	424	112	$ 108
Net capitalized costs attributable to unproved properties	29,500	$ 1,000
Goodwill derecognized	4,600
Anadarko Petroleum Corporation
Capitalized exploratory well costs for continuing operations
Goodwill recognized associated with the Acquisition	$ 5,800
Chemical | Low end of range
Capitalized exploratory well costs for continuing operations
The estimated useful lives of Occidental's chemical assets	3 years
Chemical | High end of range
Capitalized exploratory well costs for continuing operations
The estimated useful lives of Occidental's chemical assets	50 years
Marketing and Midstream
Capitalized exploratory well costs for continuing operations
Goodwill	$ 1,200