Subsequent Events (Details) - Scenario, Forecast [Member] $ in Millions	3 Months Ended
Dec. 31, 2018 USD ($)
Joint Venture With Petrobras [Member]
Subsequent Event [Line Items]
Cash consideration	$ 900
Joint Venture With Petrobras [Member] \| Price And Production Threshholds [Member]
Subsequent Event [Line Items]
Contingent consideration, maximum	150
Joint Venture With Petrobras [Member] \| Oil Recovery Projects [Member]
Subsequent Event [Line Items]
Contingent consideration, maximum	$ 50
Murphy Exploration And Production Company - USA [Member] \| Joint Venture With Petrobras [Member] \| Joint Venture With Petrobras [Member]
Subsequent Event [Line Items]
Parent ownership interest	80.00%
Petrobas America Inc [Member] \| Joint Venture With Petrobras [Member]
Subsequent Event [Line Items]
Ownership interest	20.00%

For contingent consideration arrangements recognized in connection with a business combination, this element represents an estimate of the high-end of the potential range (undiscounted) of the consideration which may be paid.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 30
-Section 50
-Paragraph 1
-Subparagraph (c)(3)
-URI http://asc.fasb.org/extlink&oid=35744584&loc=d3e6927-128479

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The equity interest of noncontrolling shareholders, partners or other equity holders in consolidated entity.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
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Balance Type:	na
Period Type:	instant

- Definition

The parent entity's interest in net assets of the subsidiary, expressed as a percentage.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

The cash outflow associated with the investment in or advances to an entity in which the reporting entity shares control of the entity with another party or group.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 13
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3213-108585

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Period Type:	duration

- Definition

Detail information of subsequent event by type. User is expected to use existing line items from elsewhere in the taxonomy as the primary line items for this disclosure, which is further associated with dimension and member elements pertaining to a subsequent event.

+ References

No definition available.

+ Details

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- Details

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- Details

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- Details

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- Details

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- Details

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- Details

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- Details

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