ENVIRONMENTAL LIABILITIES AND EXPENDITURES (Details) $ in Millions	12 Months Ended
	Dec. 31, 2015 USD ($) site	Dec. 31, 2014 USD ($) site	Dec. 31, 2013 USD ($) site	Dec. 31, 2012 USD ($)
Environmental Liabilities and Expenditures
Environmental remediation reserves, current, included in accrued liabilities	$ 70	$ 79	$ 78
Environmental remediation reserves, noncurrent, included in deferred credits and other liabilities - other	$ 316	$ 255	$ 252
Environmental remediation reserves
Number of Sites | site	149	145	157
Reserve Balance	$ 386	$ 334	$ 330	$ 344
Environmental reserves, exceeding $ ten million, threshold value	$ 10
Environmental reserves, exceeding $ ten million, number of sites | site	13
Environmental reserves, range between zero to $ one million site category, number of sites | site	101
Minimum period of expending second half of environmental reserves	10 years
Environmental remediation additional loss range	$ 370
Environmental costs, including certain estimates by segment
Operating Expenses	180	194	188
Capital Expenditures	167	189	86
Low end of range
Environmental remediation reserves
Environmental reserves, range between zero to $ one million site category	$ 0
Period of expending first half of environmental reserves	3 years
High end of range
Environmental remediation reserves
Environmental reserves, range between zero to $ one million site category	$ 1
Period of expending first half of environmental reserves	4 years
Oil and Gas
Environmental costs, including certain estimates by segment
Operating Expenses	$ 93	103	100
Capital Expenditures	122	143	67
Chemical
Environmental costs, including certain estimates by segment
Operating Expenses	74	80	75
Capital Expenditures	41	35	14
Midstream, Marketing and Other
Environmental costs, including certain estimates by segment
Operating Expenses	13	11	13
Capital Expenditures	4	11	5
Corporate
Environmental costs, including certain estimates by segment
Remediation Expenses	$ 117	$ 79	$ 60
NPL sites
Environmental remediation reserves
Number of Sites | site	34	30	31
Reserve Balance	$ 27	$ 23	$ 25
Number of sites with significant environmental remediation reserves | site	2
Percentage of environmental reserves accounted for by associated sites	62.00%
Number of sites indemnified by third party | site	14
Third-party sites
Environmental remediation reserves
Number of Sites | site	66	67	74
Reserve Balance	$ 128	$ 101	$ 83
Number of sites with significant environmental remediation reserves | site	3
Percentage of environmental reserves accounted for by associated sites	50.00%
Number of sites indemnified by third party | site	8
Number of sites not indemnified by third party | site	58
Occidental-operated sites
Environmental remediation reserves
Number of Sites | site	18	17	20
Reserve Balance	$ 107	$ 107	$ 118
Number of sites with significant environmental remediation reserves | site	4
Percentage of environmental reserves accounted for by associated sites	59.00%
Closed or non-operated Occidental sites
Environmental remediation reserves
Number of Sites | site	31	31	32
Reserve Balance	$ 124	$ 103	$ 104
Number of sites with significant environmental remediation reserves | site	5
Percentage of environmental reserves accounted for by associated sites	70.00%