Environmental Liabilities and Expenditures (Details) $ in Millions	1 Months Ended	3 Months Ended	9 Months Ended
	Mar. 31, 2016 mi	Sep. 30, 2016 USD ($)	Sep. 30, 2018 USD ($) site category	Dec. 31, 2017 USD ($)
Environmental remediation reserves
Number of Sites | site			146
Environmental remediation reserves, current, included in accrued liabilities			$ 136
Environmental remediation reserves, non-current, included in deferred credits and other liabilities - other			$ 740	$ 728
Number of non-NPL sites categories | category			3
Reserve Balance			$ 876
Environmental reserves, exceeding $ ten million, threshold value			$ 10
Environmental reserves, exceeding $ ten million, number of sites | site			16
Environmental reserves, range between zero to $ one million site category, number of sites | site			90
Expected expend funds of environmental reserves (as a percent)			5000.00%
Minimum period of expending second half of environmental reserves			10 years
Environmental remediation additional loss range			$ 1,100
Low end of range
Environmental remediation reserves
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
NPL sites
Environmental remediation reserves
Number of Sites | site			34
Reserve Balance			$ 453
Third-party sites
Environmental remediation reserves
Number of Sites | site			69
Reserve Balance			$ 172
Occidental-operated sites
Environmental remediation reserves
Number of Sites | site			14
Reserve Balance			$ 114
Closed or non-operated Occidental sites
Environmental remediation reserves
Number of Sites | site			29
Reserve Balance			$ 137
Lower Passaic River
Environmental remediation reserves
Stretch of Lower Passaic river requiring remedial actions | mi	8.3
Stretch of Lower Passaic river not covered by remedial actions | mi	9
Clean-up estimated cost		$ 165