Derivatives - Derivative Instruments (Details) $ in Millions	9 Months Ended
Sep. 30, 2020 USD ($) MMBbls $ / Barrel
Derivative [Line Items]
Cash received \| $	$ 643
Crude Oil \| 2020 Settlement - oil
Derivative [Line Items]
Derivative instruments (mmbls/day) \| MMBbls	32.2
Crude Oil \| 2020 Settlement - oil \| Short position
Derivative [Line Items]
Ceiling sold price (dollars per barrel)	74.16
Purchase price (dollars per barrel)	45.00
Crude Oil \| 2020 Settlement - oil \| Long position
Derivative [Line Items]
Purchase price (dollars per barrel)	55.00
Crude Oil \| 2021 Settlement - oil
Derivative [Line Items]
Derivative instruments (mmbls/day) \| MMBbls	127.8
Crude Oil \| 2021 Settlement - oil \| Short position
Derivative [Line Items]
Ceiling sold price (dollars per barrel)	74.16
Gas \| 2021 Settlement - oil
Derivative [Line Items]
Derivative instruments (mmbls/day) \| MMBbls	182,500,000,000
Gas \| 2021 Settlement - oil \| Short position
Derivative [Line Items]
Ceiling sold price (dollars per barrel)	3.61
Gas \| 2021 Settlement - oil \| Long position
Derivative [Line Items]
Purchase price (dollars per barrel)	2.50

Derivative, Contractual Commodity, Price

No definition available.

Name:	oxy_DerivativeContractualCommodityPrice
Namespace Prefix:	oxy_
Data Type:	xbrli:decimalItemType
Balance Type:	na
Period Type:	instant

- Definition

The average cap rate on a group of price risk derivatives such as caps or collars. A payment or receipt is triggered if the market rate exceeds the cap rate on the contract.

+ References

No definition available.

+ Details

Name:	us-gaap_DerivativeAverageCapPrice
Namespace Prefix:	us-gaap_
Data Type:	srt-types:perUnitItemType
Balance Type:	na
Period Type:	instant

- Definition

The average floor rate on a group of price risk derivatives such as floors or collars. A payment or receipt is triggered if the market rate falls below the floor rate on the contract.

+ References

No definition available.

+ Details

Name:	us-gaap_DerivativeAverageFloorPrice
Namespace Prefix:	us-gaap_
Data Type:	srt-types:perUnitItemType
Balance Type:	na
Period Type:	instant

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_DerivativeLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The cash inflow provided by derivative instruments during the period, which are classified as investing activities, excluding those designated as hedging instruments.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 12
-URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3179-108585

+ Details

Name:	us-gaap_ProceedsFromDerivativeInstrumentInvestingActivities
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Details

Name:	srt_EnergyAxis=srt_CrudeOilMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=oxy_Settlement2020Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PositionAxis=us-gaap_ShortMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PositionAxis=us-gaap_LongMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=oxy_Settlement2021Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_EnergyAxis=srt_NaturalGasReservesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: