Environmental Liabilities and Expenditures (Details)	1 Months Ended		3 Months Ended	9 Months Ended
	Sep. 30, 2021 USD ($) site mi	Mar. 31, 2016 mi	Sep. 30, 2016 USD ($)	Sep. 30, 2021 USD ($) site	Dec. 31, 2020 USD ($)
Environmental remediation reserves
Number of Sites | site	165			165
Environmental remediation reserves, current, included in accrued liabilities	$ 1,123,000,000			$ 1,123,000,000
Environmental remediation reserves, non-current, included in deferred credits and other liabilities - other	1,000,000,000			1,000,000,000	$ 1,028,000,000
Environmental reserves, exceeding ten million, threshold value	$ 10,000,000			$ 10,000,000
Environmental reserves, exceeding ten million, number of sites | site	18			18
Environmental reserves, number of sites | site	95			95
Percent of reserve to be funded over the next three to four years				40.00%
Period of expending remaining environmental reserves (or more)				10 years
Environmental remediation additional loss range	$ 1,100,000,000			$ 1,100,000,000
Low end of range
Environmental remediation reserves
Environmental reserves, range between zero to one million site category	0			$ 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			$ 1,000,000
Period of expending first half of environmental reserves				4 years
NPL sites
Environmental remediation reserves
Number of Sites | site	30			30
Environmental remediation reserves, current, included in accrued liabilities	$ 427,000,000			$ 427,000,000
Third-party sites
Environmental remediation reserves
Number of Sites | site	69			69
Environmental remediation reserves, current, included in accrued liabilities	$ 298,000,000			$ 298,000,000
Occidental-operated sites
Environmental remediation reserves
Number of Sites | site	16			16
Environmental remediation reserves, current, included in accrued liabilities	$ 131,000,000			$ 131,000,000
Closed or non-operated Occidental sites
Environmental remediation reserves
Number of Sites | site	50			50
Environmental remediation reserves, current, included in accrued liabilities	$ 267,000,000			$ 267,000,000
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	9
Clean-up estimated cost			$ 165,000,000
Accrued liabilities
Environmental remediation reserves
Environmental remediation reserves, current, included in accrued liabilities	$ 123,000,000			123,000,000
Deferred credits and other liabilities - other
Environmental remediation reserves
Environmental remediation reserves, non-current, included in deferred credits and other liabilities - other	$ 1,000,000,000			$ 1,000,000,000