Environmental Liabilities and Expenditures (Details)	1 Months Ended	3 Months Ended	9 Months Ended
	Mar. 31, 2016 mi	Sep. 30, 2016 USD ($)	Sep. 30, 2020 USD ($) site	Dec. 31, 2019 USD ($)
Environmental remediation reserves
Number of Sites | site			174
Environmental remediation reserves, current, included in accrued liabilities			$ 1,135,000,000
Environmental remediation reserves, non-current, included in deferred credits and other liabilities - other			975,000,000	$ 1,035,000,000
Environmental reserves, exceeding $ ten million, threshold value			$ 10,000,000
Environmental reserves, exceeding $ ten million, number of sites | site			19
Environmental reserves, range between zero to $ one million site category, number of sites | site			98
Expected expend funds of environmental reserves (as a percent)			45.00%
Period of expending remaining environmental reserves (or more)			10 years
Environmental remediation additional loss range			$ 1,100,000,000
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			$ 1,000,000
Period of expending first half of environmental reserves			4 years
NPL sites
Environmental remediation reserves
Number of Sites | site			35
Environmental remediation reserves, current, included in accrued liabilities			$ 451,000,000
Third-party sites
Environmental remediation reserves
Number of Sites | site			72
Environmental remediation reserves, current, included in accrued liabilities			$ 284,000,000
Occidental-operated sites
Environmental remediation reserves
Number of Sites | site			17
Environmental remediation reserves, current, included in accrued liabilities			$ 142,000,000
Closed or non-operated Occidental sites
Environmental remediation reserves
Number of Sites | site			50
Environmental remediation reserves, current, included in accrued liabilities			$ 258,000,000
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		$ 165,000,000
Accrued liabilities
Environmental remediation reserves
Environmental remediation reserves, current, included in accrued liabilities			160,000,000
Deferred credits and other liabilities - other
Environmental remediation reserves
Environmental remediation reserves, non-current, included in deferred credits and other liabilities - other			$ 975,000,000