RETIREMENT AND POSTRETIREMENT BENEFIT PLANS - DEFINED BENEFIT PLANS (Details)	Dec. 31, 2017 employee
Domestic Pension Benefits
DEFINED BENEFIT PLANS
Number of employees accruing benefits under defined benefit plans	500
Foreign Pension Plans
DEFINED BENEFIT PLANS
Number of employees accruing benefits under defined benefit plans	900

This element represents the number of employees currently accruing benefits under defined benefit plans.

No definition available.

Name:	oxy_DefinedBenefitPlanNumberOfParticipatingEmployees
Namespace Prefix:	oxy_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant