Income Taxes (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2019	Jun. 30, 2019
Income Tax Disclosure [Abstract]
Reduction in tax liability due to change in tax rate	$ 13	$ 13

Deferred Tax Liabilities, Reduction Due To Change In Enacted Rate

No definition available.

Name:	mur_DeferredTaxLiabilitiesReductionDueToChangeInEnactedRate
Namespace Prefix:	mur_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration