Environmental Liabilities and Expenditures (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014 site	Dec. 31, 2013 site	Dec. 31, 2012 site	Dec. 31, 2011
Environmental Liabilities and Expenditures
Environmental remediation reserves, current, included in accrued liabilities	$ 79	$ 78	$ 80
Environmental remediation reserves, noncurrent, included in deferred credits and other liabilities - other	255	252	264
Environmental remediation reserves
Number of Sites	145	157	161
Reserve Balance	334	330	344	360
Environmental reserves, exceeding $ ten million, threshold value	10
Environmental reserves, exceeding $ ten million, number of sites	11
Environmental reserves, range between zero to $ one million site category, number of sites	98
Minimum period of expending second half of environmental reserves	10 years
Environmental remediation additional loss range	380
Environmental costs, including certain estimates by segment
Operating Expenses	194	188	199
Capital Expenditures	189	86	105
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	103	100	116
Capital Expenditures	143	67	79
Chemical
Environmental costs, including certain estimates by segment
Operating Expenses	80	75	70
Capital Expenditures	35	14	18
Midstream, Marketing and Other
Environmental costs, including certain estimates by segment
Operating Expenses	11	13	13
Capital Expenditures	11	5	8
Corporate
Environmental costs, including certain estimates by segment
Remediation Expenses	79	60	56
NPL sites
Environmental remediation reserves
Number of Sites	30	31	35
Reserve Balance	23	25	54
Number of sites with significant environmental remediation reserves	2
Percentage of environmental reserves accounted for by associated sites	62.00%
Number of sites indemnified by third party	14
Third-party sites
Environmental remediation reserves
Number of Sites	67	74	75
Reserve Balance	101	83	84
Number of sites with significant environmental remediation reserves	4
Percentage of environmental reserves accounted for by associated sites	56.00%
Number of sites indemnified by third party	8
Number of sites not indemnified by third party	59
Occidental-operated sites
Environmental remediation reserves
Number of Sites	17	20	22
Reserve Balance	107	118	123
Number of sites with significant environmental remediation reserves	4
Percentage of environmental reserves accounted for by associated sites	62.00%
Closed or non-operated Occidental sites
Environmental remediation reserves
Number of Sites	31	32	29
Reserve Balance	$ 103	$ 104	$ 83
Number of sites with significant environmental remediation reserves	4
Percentage of environmental reserves accounted for by associated sites	63.00%