Environmental Liabilities and Expenditures (Details) $ in Millions	1 Months Ended	3 Months Ended
	Mar. 31, 2016 mi	Mar. 31, 2017 USD ($) site	Sep. 30, 2016 USD ($)
Environmental remediation reserves
Number of Sites | site		147
Environmental remediation reserves, current, included in accrued liabilities		$ 131
Environmental remediation reserves, noncurrent, included in deferred credits and other liabilities - other		736
Reserve Balance		867
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		88
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
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
NPL sites
Environmental remediation reserves
Number of Sites | site		33
Reserve Balance		$ 460
Third-party sites
Environmental remediation reserves
Number of Sites | site		68
Reserve Balance		$ 160
Occidental-operated sites
Environmental remediation reserves
Number of Sites | site		17
Reserve Balance		$ 110
Closed or non-operated Occidental sites
Environmental remediation reserves
Number of Sites | site		29
Reserve Balance		$ 137