SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - ENVIRONMENTAL LIABILITIES AND EXPENDITURES (Details)	12 Months Ended
Dec. 31, 2019
ENVIRONMENTAL LIABILITIES AND EXPENDITURES
Minimum period of investigations and cleanup for Comprehensive Environmental Response, Compensation and Liability Act National Priorities List sites	10 years

Minimum period of investigation and cleanup for Comprehensive Environmental Response Compensation and Liability Act (CERCLA) National Priorities List (NPL) sites.

No definition available.

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Namespace Prefix:	oxy_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration