Derivatives - Cash-Flow Hedges (Details) - Bcf	Sep. 30, 2018	Dec. 31, 2017
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Natural gas held in storage (in cubic feet)	6	7
Forecast sale of natural gas from storage designated as cash-flow hedges (in cubic feet)	4	7

This element represents the forecast sales volume of natural gas from storage in billion cubic feet designated as cash flow hedges.

No definition available.

Name:	oxy_DesignatedForecastSaleOfNaturalGasAsCashFlowHedges
Namespace Prefix:	oxy_
Data Type:	num:volumeItemType
Balance Type:	na
Period Type:	instant