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Supplemental Oil and Gas Information (Results of Operations for Oil andGas Producing Activities) (Details) (USD $)
 3 Months Ended 12 Months Ended
Dec. 31, 2014
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Revenues        
Revenues   $ 5,273,100,000us-gaap_ResultsOfOperationsSalesRevenueToUnaffiliatedEnterprises [1] $ 5,306,300,000us-gaap_ResultsOfOperationsSalesRevenueToUnaffiliatedEnterprises [1] $ 4,599,600,000us-gaap_ResultsOfOperationsSalesRevenueToUnaffiliatedEnterprises [1]
Other operating revenues   149,600,000us-gaap_ResultsOfOperationsRevenueOther [1] 6,300,000us-gaap_ResultsOfOperationsRevenueOther [1] 8,500,000us-gaap_ResultsOfOperationsRevenueOther [1]
Results of Operations, Revenue from Oil and Gas Producing Activities, Total   5,422,700,000us-gaap_ResultsOfOperationsRevenueFromOilAndGasProducingActivities [1] 5,312,600,000us-gaap_ResultsOfOperationsRevenueFromOilAndGasProducingActivities [1] 4,608,100,000us-gaap_ResultsOfOperationsRevenueFromOilAndGasProducingActivities [1]
Costs and expenses        
Lease operating expenses   1,089,900,000us-gaap_ResultsOfOperationsProductionOrLiftingCosts [1] 1,252,900,000us-gaap_ResultsOfOperationsProductionOrLiftingCosts [1] 1,079,200,000us-gaap_ResultsOfOperationsProductionOrLiftingCosts [1]
Severance and ad valorem taxes   107,200,000mur_ResultsOfOperationsSeveranceAndAdValoremTaxes [1] 87,300,000mur_ResultsOfOperationsSeveranceAndAdValoremTaxes [1] 35,600,000mur_ResultsOfOperationsSeveranceAndAdValoremTaxes [1]
Exploration costs charged to expense   439,200,000mur_ResultsOfOperationsExplorationExpenseIncludingDiscontinuedOperations [1] 435,300,000mur_ResultsOfOperationsExplorationExpenseIncludingDiscontinuedOperations [1] 251,100,000mur_ResultsOfOperationsExplorationExpenseIncludingDiscontinuedOperations [1]
Undeveloped lease amortization   74,400,000mur_ResultsOfOperationsUndevelopedLeaseAmortization [1] 66,900,000mur_ResultsOfOperationsUndevelopedLeaseAmortization [1] 129,800,000mur_ResultsOfOperationsUndevelopedLeaseAmortization [1]
Depreciation, depletion and amortization   1,897,500,000us-gaap_ResultsOfOperationsDepreciationDepletionAndAmortizationAndValuationProvisions [1] 1,543,600,000us-gaap_ResultsOfOperationsDepreciationDepletionAndAmortizationAndValuationProvisions [1] 1,244,400,000us-gaap_ResultsOfOperationsDepreciationDepletionAndAmortizationAndValuationProvisions [1]
Accretion of asset retirement obligations   50,800,000us-gaap_ResultsOfOperationsAccretionOfAssetRetirementObligations [1] 49,000,000us-gaap_ResultsOfOperationsAccretionOfAssetRetirementObligations [1] 38,400,000us-gaap_ResultsOfOperationsAccretionOfAssetRetirementObligations [1]
Impairment of assets   51,314,000us-gaap_ImpairmentOfOilAndGasProperties 21,587,000us-gaap_ImpairmentOfOilAndGasProperties 200,000,000us-gaap_ImpairmentOfOilAndGasProperties [1]
Selling and general expenses   212,000,000us-gaap_ResultsOfOperationsGeneralAndAdministrativeRelatedToOilAndGasProducingActivities [1] 170,900,000us-gaap_ResultsOfOperationsGeneralAndAdministrativeRelatedToOilAndGasProducingActivities [1] 119,600,000us-gaap_ResultsOfOperationsGeneralAndAdministrativeRelatedToOilAndGasProducingActivities [1]
Other expenses   24,900,000mur_ResultsOfOperationsOtherExpenses [1]    
Other expenses   169,200,000us-gaap_ResultsOfOperationsExpenseOther 172,400,000us-gaap_ResultsOfOperationsExpenseOther 69,000,000us-gaap_ResultsOfOperationsExpenseOther
Total costs and expenses   3,947,200,000us-gaap_ResultsOfOperationsExpenseFromOilAndGasProducingActivities [1] 3,627,500,000us-gaap_ResultsOfOperationsExpenseFromOilAndGasProducingActivities [1] 3,098,100,000us-gaap_ResultsOfOperationsExpenseFromOilAndGasProducingActivities [1]
Results of operations before taxes   1,475,500,000us-gaap_ResultsOfOperationsIncomeBeforeIncomeTaxes [1] 1,685,100,000us-gaap_ResultsOfOperationsIncomeBeforeIncomeTaxes [1] 1,510,000,000us-gaap_ResultsOfOperationsIncomeBeforeIncomeTaxes [1]
Income tax expense (benefit)   285,700,000us-gaap_ResultsOfOperationsIncomeTaxExpense [1] 656,300,000us-gaap_ResultsOfOperationsIncomeTaxExpense [1] 605,000,000us-gaap_ResultsOfOperationsIncomeTaxExpense [1]
Results of operations   1,189,800,000us-gaap_ResultsOfOperationsOilAndGasProducingActivitiesNetIncomeExcludingCorporateOverheadAndInterestCosts [1] 1,028,800,000us-gaap_ResultsOfOperationsOilAndGasProducingActivitiesNetIncomeExcludingCorporateOverheadAndInterestCosts [1] 905,000,000us-gaap_ResultsOfOperationsOilAndGasProducingActivitiesNetIncomeExcludingCorporateOverheadAndInterestCosts [1]
Crude Oil and Natural Gas Liquids [Member]        
Revenues        
Revenues   4,587,100,000us-gaap_ResultsOfOperationsSalesRevenueToUnaffiliatedEnterprises
/ us-gaap_OilAndGasDeliveryCommitmentsAndContractsAxis
= mur_CrudeOilAndNaturalGasMember		 [1] 4,631,500,000us-gaap_ResultsOfOperationsSalesRevenueToUnaffiliatedEnterprises
/ us-gaap_OilAndGasDeliveryCommitmentsAndContractsAxis
= mur_CrudeOilAndNaturalGasMember		 [1] 3,854,500,000us-gaap_ResultsOfOperationsSalesRevenueToUnaffiliatedEnterprises
/ us-gaap_OilAndGasDeliveryCommitmentsAndContractsAxis
= mur_CrudeOilAndNaturalGasMember		 [1]
Natural Gas [Member]        
Revenues        
Revenues   686,000,000us-gaap_ResultsOfOperationsSalesRevenueToUnaffiliatedEnterprises
/ us-gaap_OilAndGasDeliveryCommitmentsAndContractsAxis
= mur_NaturalGasMember		 [1] 674,800,000us-gaap_ResultsOfOperationsSalesRevenueToUnaffiliatedEnterprises
/ us-gaap_OilAndGasDeliveryCommitmentsAndContractsAxis
= mur_NaturalGasMember		 [1] 745,100,000us-gaap_ResultsOfOperationsSalesRevenueToUnaffiliatedEnterprises
/ us-gaap_OilAndGasDeliveryCommitmentsAndContractsAxis
= mur_NaturalGasMember		 [1]
United States [Member]        
Costs and expenses        
Other expenses   37,700,000us-gaap_ResultsOfOperationsExpenseOther
/ us-gaap_StatementGeographicalAxis
= country_US		 29,100,000us-gaap_ResultsOfOperationsExpenseOther
/ us-gaap_StatementGeographicalAxis
= country_US		 19,600,000us-gaap_ResultsOfOperationsExpenseOther
/ us-gaap_StatementGeographicalAxis
= country_US
United States [Member] | Oil Reserves [Member]        
Revenues        
Revenues   2,189,300,000us-gaap_ResultsOfOperationsSalesRevenueToUnaffiliatedEnterprises
/ us-gaap_ProductOrServiceAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= country_US		 [1] 1,797,400,000us-gaap_ResultsOfOperationsSalesRevenueToUnaffiliatedEnterprises
/ us-gaap_ProductOrServiceAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= country_US		 [1] 1,030,300,000us-gaap_ResultsOfOperationsSalesRevenueToUnaffiliatedEnterprises
/ us-gaap_ProductOrServiceAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= country_US		 [1]
Other operating revenues   7,100,000us-gaap_ResultsOfOperationsRevenueOther
/ us-gaap_ProductOrServiceAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= country_US		 [1] 6,400,000us-gaap_ResultsOfOperationsRevenueOther
/ us-gaap_ProductOrServiceAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= country_US		 [1] 7,700,000us-gaap_ResultsOfOperationsRevenueOther
/ us-gaap_ProductOrServiceAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= country_US		 [1]
Results of Operations, Revenue from Oil and Gas Producing Activities, Total   2,196,400,000us-gaap_ResultsOfOperationsRevenueFromOilAndGasProducingActivities
/ us-gaap_ProductOrServiceAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= country_US		 [1] 1,803,800,000us-gaap_ResultsOfOperationsRevenueFromOilAndGasProducingActivities
/ us-gaap_ProductOrServiceAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= country_US		 [1] 1,038,000,000us-gaap_ResultsOfOperationsRevenueFromOilAndGasProducingActivities
/ us-gaap_ProductOrServiceAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= country_US		 [1]
Costs and expenses        
Lease operating expenses   345,500,000us-gaap_ResultsOfOperationsProductionOrLiftingCosts
/ us-gaap_ProductOrServiceAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= country_US		 [1] 273,600,000us-gaap_ResultsOfOperationsProductionOrLiftingCosts
/ us-gaap_ProductOrServiceAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= country_US		 [1] 225,400,000us-gaap_ResultsOfOperationsProductionOrLiftingCosts
/ us-gaap_ProductOrServiceAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= country_US		 [1]
Severance and ad valorem taxes   96,500,000mur_ResultsOfOperationsSeveranceAndAdValoremTaxes
/ us-gaap_ProductOrServiceAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= country_US		 [1] 77,500,000mur_ResultsOfOperationsSeveranceAndAdValoremTaxes
/ us-gaap_ProductOrServiceAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= country_US		 [1] 27,000,000mur_ResultsOfOperationsSeveranceAndAdValoremTaxes
/ us-gaap_ProductOrServiceAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= country_US		 [1]
Exploration costs charged to expense   129,800,000mur_ResultsOfOperationsExplorationExpenseIncludingDiscontinuedOperations
/ us-gaap_ProductOrServiceAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= country_US		 [1] 75,200,000mur_ResultsOfOperationsExplorationExpenseIncludingDiscontinuedOperations
/ us-gaap_ProductOrServiceAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= country_US		 [1] 51,900,000mur_ResultsOfOperationsExplorationExpenseIncludingDiscontinuedOperations
/ us-gaap_ProductOrServiceAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= country_US		 [1]
Undeveloped lease amortization   50,100,000mur_ResultsOfOperationsUndevelopedLeaseAmortization
/ us-gaap_ProductOrServiceAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= country_US		 [1] 30,300,000mur_ResultsOfOperationsUndevelopedLeaseAmortization
/ us-gaap_ProductOrServiceAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= country_US		 [1] 71,600,000mur_ResultsOfOperationsUndevelopedLeaseAmortization
/ us-gaap_ProductOrServiceAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= country_US		 [1]
Depreciation, depletion and amortization   840,700,000us-gaap_ResultsOfOperationsDepreciationDepletionAndAmortizationAndValuationProvisions
/ us-gaap_ProductOrServiceAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= country_US		 [1] 576,300,000us-gaap_ResultsOfOperationsDepreciationDepletionAndAmortizationAndValuationProvisions
/ us-gaap_ProductOrServiceAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= country_US		 [1] 330,200,000us-gaap_ResultsOfOperationsDepreciationDepletionAndAmortizationAndValuationProvisions
/ us-gaap_ProductOrServiceAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= country_US		 [1]
Accretion of asset retirement obligations   17,500,000us-gaap_ResultsOfOperationsAccretionOfAssetRetirementObligations
/ us-gaap_ProductOrServiceAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= country_US		 [1] 13,500,000us-gaap_ResultsOfOperationsAccretionOfAssetRetirementObligations
/ us-gaap_ProductOrServiceAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= country_US		 [1] 11,400,000us-gaap_ResultsOfOperationsAccretionOfAssetRetirementObligations
/ us-gaap_ProductOrServiceAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= country_US		 [1]
Impairment of assets   14,300,000us-gaap_ImpairmentOfOilAndGasProperties
/ us-gaap_ProductOrServiceAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= country_US		 [1]    
Selling and general expenses   95,200,000us-gaap_ResultsOfOperationsGeneralAndAdministrativeRelatedToOilAndGasProducingActivities
/ us-gaap_ProductOrServiceAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= country_US		 [1] 80,400,000us-gaap_ResultsOfOperationsGeneralAndAdministrativeRelatedToOilAndGasProducingActivities
/ us-gaap_ProductOrServiceAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= country_US		 [1] 52,700,000us-gaap_ResultsOfOperationsGeneralAndAdministrativeRelatedToOilAndGasProducingActivities
/ us-gaap_ProductOrServiceAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= country_US		 [1]
Other expenses   4,900,000mur_ResultsOfOperationsOtherExpenses
/ us-gaap_ProductOrServiceAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= country_US		 [1]    
Total costs and expenses   1,594,500,000us-gaap_ResultsOfOperationsExpenseFromOilAndGasProducingActivities
/ us-gaap_ProductOrServiceAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= country_US		 [1] 1,126,800,000us-gaap_ResultsOfOperationsExpenseFromOilAndGasProducingActivities
/ us-gaap_ProductOrServiceAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= country_US		 [1] 770,200,000us-gaap_ResultsOfOperationsExpenseFromOilAndGasProducingActivities
/ us-gaap_ProductOrServiceAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= country_US		 [1]
Results of operations before taxes   601,900,000us-gaap_ResultsOfOperationsIncomeBeforeIncomeTaxes
/ us-gaap_ProductOrServiceAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= country_US		 [1] 677,000,000us-gaap_ResultsOfOperationsIncomeBeforeIncomeTaxes
/ us-gaap_ProductOrServiceAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= country_US		 [1] 267,800,000us-gaap_ResultsOfOperationsIncomeBeforeIncomeTaxes
/ us-gaap_ProductOrServiceAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= country_US		 [1]
Income tax expense (benefit)   214,800,000us-gaap_ResultsOfOperationsIncomeTaxExpense
/ us-gaap_ProductOrServiceAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= country_US		 [1] 241,600,000us-gaap_ResultsOfOperationsIncomeTaxExpense
/ us-gaap_ProductOrServiceAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= country_US		 [1] 99,800,000us-gaap_ResultsOfOperationsIncomeTaxExpense
/ us-gaap_ProductOrServiceAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= country_US		 [1]
Results of operations   387,100,000us-gaap_ResultsOfOperationsOilAndGasProducingActivitiesNetIncomeExcludingCorporateOverheadAndInterestCosts
/ us-gaap_ProductOrServiceAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= country_US		 [1] 435,400,000us-gaap_ResultsOfOperationsOilAndGasProducingActivitiesNetIncomeExcludingCorporateOverheadAndInterestCosts
/ us-gaap_ProductOrServiceAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= country_US		 [1] 168,000,000us-gaap_ResultsOfOperationsOilAndGasProducingActivitiesNetIncomeExcludingCorporateOverheadAndInterestCosts
/ us-gaap_ProductOrServiceAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= country_US		 [1]
United States [Member] | Crude Oil and Natural Gas Liquids [Member] | Oil Reserves [Member]        
Revenues        
Revenues   2,062,100,000us-gaap_ResultsOfOperationsSalesRevenueToUnaffiliatedEnterprises
/ us-gaap_OilAndGasDeliveryCommitmentsAndContractsAxis
= mur_CrudeOilAndNaturalGasMember
/ us-gaap_ProductOrServiceAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= country_US		 [1] 1,724,700,000us-gaap_ResultsOfOperationsSalesRevenueToUnaffiliatedEnterprises
/ us-gaap_OilAndGasDeliveryCommitmentsAndContractsAxis
= mur_CrudeOilAndNaturalGasMember
/ us-gaap_ProductOrServiceAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= country_US		 [1] 976,100,000us-gaap_ResultsOfOperationsSalesRevenueToUnaffiliatedEnterprises
/ us-gaap_OilAndGasDeliveryCommitmentsAndContractsAxis
= mur_CrudeOilAndNaturalGasMember
/ us-gaap_ProductOrServiceAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= country_US		 [1]
United States [Member] | Natural Gas [Member] | Oil Reserves [Member]        
Revenues        
Revenues   127,200,000us-gaap_ResultsOfOperationsSalesRevenueToUnaffiliatedEnterprises
/ us-gaap_OilAndGasDeliveryCommitmentsAndContractsAxis
= mur_NaturalGasMember
/ us-gaap_ProductOrServiceAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= country_US		 [1] 72,700,000us-gaap_ResultsOfOperationsSalesRevenueToUnaffiliatedEnterprises
/ us-gaap_OilAndGasDeliveryCommitmentsAndContractsAxis
= mur_NaturalGasMember
/ us-gaap_ProductOrServiceAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= country_US		 [1] 54,200,000us-gaap_ResultsOfOperationsSalesRevenueToUnaffiliatedEnterprises
/ us-gaap_OilAndGasDeliveryCommitmentsAndContractsAxis
= mur_NaturalGasMember
/ us-gaap_ProductOrServiceAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= country_US		 [1]
Canada [Member]        
Costs and expenses        
Impairment of assets 37,047,000us-gaap_ImpairmentOfOilAndGasProperties
/ us-gaap_StatementGeographicalAxis
= country_CA		      
Other expenses   1,700,000us-gaap_ResultsOfOperationsExpenseOther
/ us-gaap_StatementGeographicalAxis
= country_CA		 700,000us-gaap_ResultsOfOperationsExpenseOther
/ us-gaap_StatementGeographicalAxis
= country_CA		 2,500,000us-gaap_ResultsOfOperationsExpenseOther
/ us-gaap_StatementGeographicalAxis
= country_CA
Canada [Member] | Conventional [Member]        
Revenues        
Revenues   654,600,000us-gaap_ResultsOfOperationsSalesRevenueToUnaffiliatedEnterprises
/ us-gaap_ProductOrServiceAxis
= mur_ConventionalGasMember
/ us-gaap_StatementGeographicalAxis
= country_CA		 [1] 705,300,000us-gaap_ResultsOfOperationsSalesRevenueToUnaffiliatedEnterprises
/ us-gaap_ProductOrServiceAxis
= mur_ConventionalGasMember
/ us-gaap_StatementGeographicalAxis
= country_CA		 [1] 621,500,000us-gaap_ResultsOfOperationsSalesRevenueToUnaffiliatedEnterprises
/ us-gaap_ProductOrServiceAxis
= mur_ConventionalGasMember
/ us-gaap_StatementGeographicalAxis
= country_CA		 [1]
Other operating revenues   (2,400,000)us-gaap_ResultsOfOperationsRevenueOther
/ us-gaap_ProductOrServiceAxis
= mur_ConventionalGasMember
/ us-gaap_StatementGeographicalAxis
= country_CA		 [1] (1,900,000)us-gaap_ResultsOfOperationsRevenueOther
/ us-gaap_ProductOrServiceAxis
= mur_ConventionalGasMember
/ us-gaap_StatementGeographicalAxis
= country_CA		 [1] (900,000)us-gaap_ResultsOfOperationsRevenueOther
/ us-gaap_ProductOrServiceAxis
= mur_ConventionalGasMember
/ us-gaap_StatementGeographicalAxis
= country_CA		 [1]
Results of Operations, Revenue from Oil and Gas Producing Activities, Total   652,200,000us-gaap_ResultsOfOperationsRevenueFromOilAndGasProducingActivities
/ us-gaap_ProductOrServiceAxis
= mur_ConventionalGasMember
/ us-gaap_StatementGeographicalAxis
= country_CA		 [1] 703,400,000us-gaap_ResultsOfOperationsRevenueFromOilAndGasProducingActivities
/ us-gaap_ProductOrServiceAxis
= mur_ConventionalGasMember
/ us-gaap_StatementGeographicalAxis
= country_CA		 [1] 620,600,000us-gaap_ResultsOfOperationsRevenueFromOilAndGasProducingActivities
/ us-gaap_ProductOrServiceAxis
= mur_ConventionalGasMember
/ us-gaap_StatementGeographicalAxis
= country_CA		 [1]
Costs and expenses        
Lease operating expenses   160,300,000us-gaap_ResultsOfOperationsProductionOrLiftingCosts
/ us-gaap_ProductOrServiceAxis
= mur_ConventionalGasMember
/ us-gaap_StatementGeographicalAxis
= country_CA		 [1] 180,500,000us-gaap_ResultsOfOperationsProductionOrLiftingCosts
/ us-gaap_ProductOrServiceAxis
= mur_ConventionalGasMember
/ us-gaap_StatementGeographicalAxis
= country_CA		 [1] 163,700,000us-gaap_ResultsOfOperationsProductionOrLiftingCosts
/ us-gaap_ProductOrServiceAxis
= mur_ConventionalGasMember
/ us-gaap_StatementGeographicalAxis
= country_CA		 [1]
Severance and ad valorem taxes   5,600,000mur_ResultsOfOperationsSeveranceAndAdValoremTaxes
/ us-gaap_ProductOrServiceAxis
= mur_ConventionalGasMember
/ us-gaap_StatementGeographicalAxis
= country_CA		 [1] 5,000,000mur_ResultsOfOperationsSeveranceAndAdValoremTaxes
/ us-gaap_ProductOrServiceAxis
= mur_ConventionalGasMember
/ us-gaap_StatementGeographicalAxis
= country_CA		 [1] 3,500,000mur_ResultsOfOperationsSeveranceAndAdValoremTaxes
/ us-gaap_ProductOrServiceAxis
= mur_ConventionalGasMember
/ us-gaap_StatementGeographicalAxis
= country_CA		 [1]
Exploration costs charged to expense   1,700,000mur_ResultsOfOperationsExplorationExpenseIncludingDiscontinuedOperations
/ us-gaap_ProductOrServiceAxis
= mur_ConventionalGasMember
/ us-gaap_StatementGeographicalAxis
= country_CA		 [1] 32,800,000mur_ResultsOfOperationsExplorationExpenseIncludingDiscontinuedOperations
/ us-gaap_ProductOrServiceAxis
= mur_ConventionalGasMember
/ us-gaap_StatementGeographicalAxis
= country_CA		 [1] 10,500,000mur_ResultsOfOperationsExplorationExpenseIncludingDiscontinuedOperations
/ us-gaap_ProductOrServiceAxis
= mur_ConventionalGasMember
/ us-gaap_StatementGeographicalAxis
= country_CA		 [1]
Undeveloped lease amortization   19,400,000mur_ResultsOfOperationsUndevelopedLeaseAmortization
/ us-gaap_ProductOrServiceAxis
= mur_ConventionalGasMember
/ us-gaap_StatementGeographicalAxis
= country_CA		 [1] 21,000,000mur_ResultsOfOperationsUndevelopedLeaseAmortization
/ us-gaap_ProductOrServiceAxis
= mur_ConventionalGasMember
/ us-gaap_StatementGeographicalAxis
= country_CA		 [1] 29,300,000mur_ResultsOfOperationsUndevelopedLeaseAmortization
/ us-gaap_ProductOrServiceAxis
= mur_ConventionalGasMember
/ us-gaap_StatementGeographicalAxis
= country_CA		 [1]
Depreciation, depletion and amortization   262,700,000us-gaap_ResultsOfOperationsDepreciationDepletionAndAmortizationAndValuationProvisions
/ us-gaap_ProductOrServiceAxis
= mur_ConventionalGasMember
/ us-gaap_StatementGeographicalAxis
= country_CA		 [1] 319,200,000us-gaap_ResultsOfOperationsDepreciationDepletionAndAmortizationAndValuationProvisions
/ us-gaap_ProductOrServiceAxis
= mur_ConventionalGasMember
/ us-gaap_StatementGeographicalAxis
= country_CA		 [1] 290,500,000us-gaap_ResultsOfOperationsDepreciationDepletionAndAmortizationAndValuationProvisions
/ us-gaap_ProductOrServiceAxis
= mur_ConventionalGasMember
/ us-gaap_StatementGeographicalAxis
= country_CA		 [1]
Accretion of asset retirement obligations   6,000,000us-gaap_ResultsOfOperationsAccretionOfAssetRetirementObligations
/ us-gaap_ProductOrServiceAxis
= mur_ConventionalGasMember
/ us-gaap_StatementGeographicalAxis
= country_CA		 [1] 5,900,000us-gaap_ResultsOfOperationsAccretionOfAssetRetirementObligations
/ us-gaap_ProductOrServiceAxis
= mur_ConventionalGasMember
/ us-gaap_StatementGeographicalAxis
= country_CA		 [1] 5,100,000us-gaap_ResultsOfOperationsAccretionOfAssetRetirementObligations
/ us-gaap_ProductOrServiceAxis
= mur_ConventionalGasMember
/ us-gaap_StatementGeographicalAxis
= country_CA		 [1]
Impairment of assets   37,000,000us-gaap_ImpairmentOfOilAndGasProperties
/ us-gaap_ProductOrServiceAxis
= mur_ConventionalGasMember
/ us-gaap_StatementGeographicalAxis
= country_CA		 [1] 21,600,000us-gaap_ImpairmentOfOilAndGasProperties
/ us-gaap_ProductOrServiceAxis
= mur_ConventionalGasMember
/ us-gaap_StatementGeographicalAxis
= country_CA		 [1]  
Selling and general expenses   26,700,000us-gaap_ResultsOfOperationsGeneralAndAdministrativeRelatedToOilAndGasProducingActivities
/ us-gaap_ProductOrServiceAxis
= mur_ConventionalGasMember
/ us-gaap_StatementGeographicalAxis
= country_CA		 [1] 25,300,000us-gaap_ResultsOfOperationsGeneralAndAdministrativeRelatedToOilAndGasProducingActivities
/ us-gaap_ProductOrServiceAxis
= mur_ConventionalGasMember
/ us-gaap_StatementGeographicalAxis
= country_CA		 [1] 19,700,000us-gaap_ResultsOfOperationsGeneralAndAdministrativeRelatedToOilAndGasProducingActivities
/ us-gaap_ProductOrServiceAxis
= mur_ConventionalGasMember
/ us-gaap_StatementGeographicalAxis
= country_CA		 [1]
Other expenses   1,000,000mur_ResultsOfOperationsOtherExpenses
/ us-gaap_ProductOrServiceAxis
= mur_ConventionalGasMember
/ us-gaap_StatementGeographicalAxis
= country_CA		 [1]    
Total costs and expenses   520,400,000us-gaap_ResultsOfOperationsExpenseFromOilAndGasProducingActivities
/ us-gaap_ProductOrServiceAxis
= mur_ConventionalGasMember
/ us-gaap_StatementGeographicalAxis
= country_CA		 [1] 611,300,000us-gaap_ResultsOfOperationsExpenseFromOilAndGasProducingActivities
/ us-gaap_ProductOrServiceAxis
= mur_ConventionalGasMember
/ us-gaap_StatementGeographicalAxis
= country_CA		 [1] 522,300,000us-gaap_ResultsOfOperationsExpenseFromOilAndGasProducingActivities
/ us-gaap_ProductOrServiceAxis
= mur_ConventionalGasMember
/ us-gaap_StatementGeographicalAxis
= country_CA		 [1]
Results of operations before taxes   131,800,000us-gaap_ResultsOfOperationsIncomeBeforeIncomeTaxes
/ us-gaap_ProductOrServiceAxis
= mur_ConventionalGasMember
/ us-gaap_StatementGeographicalAxis
= country_CA		 [1] 92,100,000us-gaap_ResultsOfOperationsIncomeBeforeIncomeTaxes
/ us-gaap_ProductOrServiceAxis
= mur_ConventionalGasMember
/ us-gaap_StatementGeographicalAxis
= country_CA		 [1] 98,300,000us-gaap_ResultsOfOperationsIncomeBeforeIncomeTaxes
/ us-gaap_ProductOrServiceAxis
= mur_ConventionalGasMember
/ us-gaap_StatementGeographicalAxis
= country_CA		 [1]
Income tax expense (benefit)   42,400,000us-gaap_ResultsOfOperationsIncomeTaxExpense
/ us-gaap_ProductOrServiceAxis
= mur_ConventionalGasMember
/ us-gaap_StatementGeographicalAxis
= country_CA		 [1] 19,900,000us-gaap_ResultsOfOperationsIncomeTaxExpense
/ us-gaap_ProductOrServiceAxis
= mur_ConventionalGasMember
/ us-gaap_StatementGeographicalAxis
= country_CA		 [1] 25,100,000us-gaap_ResultsOfOperationsIncomeTaxExpense
/ us-gaap_ProductOrServiceAxis
= mur_ConventionalGasMember
/ us-gaap_StatementGeographicalAxis
= country_CA		 [1]
Results of operations   89,400,000us-gaap_ResultsOfOperationsOilAndGasProducingActivitiesNetIncomeExcludingCorporateOverheadAndInterestCosts
/ us-gaap_ProductOrServiceAxis
= mur_ConventionalGasMember
/ us-gaap_StatementGeographicalAxis
= country_CA		 [1] 72,200,000us-gaap_ResultsOfOperationsOilAndGasProducingActivitiesNetIncomeExcludingCorporateOverheadAndInterestCosts
/ us-gaap_ProductOrServiceAxis
= mur_ConventionalGasMember
/ us-gaap_StatementGeographicalAxis
= country_CA		 [1] 73,200,000us-gaap_ResultsOfOperationsOilAndGasProducingActivitiesNetIncomeExcludingCorporateOverheadAndInterestCosts
/ us-gaap_ProductOrServiceAxis
= mur_ConventionalGasMember
/ us-gaap_StatementGeographicalAxis
= country_CA		 [1]
Canada [Member] | Synthetic Oil [Member]        
Revenues        
Revenues   391,500,000us-gaap_ResultsOfOperationsSalesRevenueToUnaffiliatedEnterprises
/ us-gaap_ProductOrServiceAxis
= us-gaap_SyntheticOilMember
/ us-gaap_StatementGeographicalAxis
= country_CA		 [1] 441,000,000us-gaap_ResultsOfOperationsSalesRevenueToUnaffiliatedEnterprises
/ us-gaap_ProductOrServiceAxis
= us-gaap_SyntheticOilMember
/ us-gaap_StatementGeographicalAxis
= country_CA		 [1] 463,100,000us-gaap_ResultsOfOperationsSalesRevenueToUnaffiliatedEnterprises
/ us-gaap_ProductOrServiceAxis
= us-gaap_SyntheticOilMember
/ us-gaap_StatementGeographicalAxis
= country_CA		 [1]
Other operating revenues   400,000us-gaap_ResultsOfOperationsRevenueOther
/ us-gaap_ProductOrServiceAxis
= us-gaap_SyntheticOilMember
/ us-gaap_StatementGeographicalAxis
= country_CA		 [1] 300,000us-gaap_ResultsOfOperationsRevenueOther
/ us-gaap_ProductOrServiceAxis
= us-gaap_SyntheticOilMember
/ us-gaap_StatementGeographicalAxis
= country_CA		 [1] 600,000us-gaap_ResultsOfOperationsRevenueOther
/ us-gaap_ProductOrServiceAxis
= us-gaap_SyntheticOilMember
/ us-gaap_StatementGeographicalAxis
= country_CA		 [1]
Results of Operations, Revenue from Oil and Gas Producing Activities, Total   391,900,000us-gaap_ResultsOfOperationsRevenueFromOilAndGasProducingActivities
/ us-gaap_ProductOrServiceAxis
= us-gaap_SyntheticOilMember
/ us-gaap_StatementGeographicalAxis
= country_CA		 [1] 441,300,000us-gaap_ResultsOfOperationsRevenueFromOilAndGasProducingActivities
/ us-gaap_ProductOrServiceAxis
= us-gaap_SyntheticOilMember
/ us-gaap_StatementGeographicalAxis
= country_CA		 [1] 463,700,000us-gaap_ResultsOfOperationsRevenueFromOilAndGasProducingActivities
/ us-gaap_ProductOrServiceAxis
= us-gaap_SyntheticOilMember
/ us-gaap_StatementGeographicalAxis
= country_CA		 [1]
Costs and expenses        
Lease operating expenses   233,800,000us-gaap_ResultsOfOperationsProductionOrLiftingCosts
/ us-gaap_ProductOrServiceAxis
= us-gaap_SyntheticOilMember
/ us-gaap_StatementGeographicalAxis
= country_CA		 [1] 223,400,000us-gaap_ResultsOfOperationsProductionOrLiftingCosts
/ us-gaap_ProductOrServiceAxis
= us-gaap_SyntheticOilMember
/ us-gaap_StatementGeographicalAxis
= country_CA		 [1] 219,000,000us-gaap_ResultsOfOperationsProductionOrLiftingCosts
/ us-gaap_ProductOrServiceAxis
= us-gaap_SyntheticOilMember
/ us-gaap_StatementGeographicalAxis
= country_CA		 [1]
Severance and ad valorem taxes   5,100,000mur_ResultsOfOperationsSeveranceAndAdValoremTaxes
/ us-gaap_ProductOrServiceAxis
= us-gaap_SyntheticOilMember
/ us-gaap_StatementGeographicalAxis
= country_CA		 [1] 4,800,000mur_ResultsOfOperationsSeveranceAndAdValoremTaxes
/ us-gaap_ProductOrServiceAxis
= us-gaap_SyntheticOilMember
/ us-gaap_StatementGeographicalAxis
= country_CA		 [1] 5,100,000mur_ResultsOfOperationsSeveranceAndAdValoremTaxes
/ us-gaap_ProductOrServiceAxis
= us-gaap_SyntheticOilMember
/ us-gaap_StatementGeographicalAxis
= country_CA		 [1]
Depreciation, depletion and amortization   54,000,000us-gaap_ResultsOfOperationsDepreciationDepletionAndAmortizationAndValuationProvisions
/ us-gaap_ProductOrServiceAxis
= us-gaap_SyntheticOilMember
/ us-gaap_StatementGeographicalAxis
= country_CA		 [1] 55,400,000us-gaap_ResultsOfOperationsDepreciationDepletionAndAmortizationAndValuationProvisions
/ us-gaap_ProductOrServiceAxis
= us-gaap_SyntheticOilMember
/ us-gaap_StatementGeographicalAxis
= country_CA		 [1] 55,300,000us-gaap_ResultsOfOperationsDepreciationDepletionAndAmortizationAndValuationProvisions
/ us-gaap_ProductOrServiceAxis
= us-gaap_SyntheticOilMember
/ us-gaap_StatementGeographicalAxis
= country_CA		 [1]
Accretion of asset retirement obligations   9,200,000us-gaap_ResultsOfOperationsAccretionOfAssetRetirementObligations
/ us-gaap_ProductOrServiceAxis
= us-gaap_SyntheticOilMember
/ us-gaap_StatementGeographicalAxis
= country_CA		 [1] 10,300,000us-gaap_ResultsOfOperationsAccretionOfAssetRetirementObligations
/ us-gaap_ProductOrServiceAxis
= us-gaap_SyntheticOilMember
/ us-gaap_StatementGeographicalAxis
= country_CA		 [1] 8,500,000us-gaap_ResultsOfOperationsAccretionOfAssetRetirementObligations
/ us-gaap_ProductOrServiceAxis
= us-gaap_SyntheticOilMember
/ us-gaap_StatementGeographicalAxis
= country_CA		 [1]
Selling and general expenses   900,000us-gaap_ResultsOfOperationsGeneralAndAdministrativeRelatedToOilAndGasProducingActivities
/ us-gaap_ProductOrServiceAxis
= us-gaap_SyntheticOilMember
/ us-gaap_StatementGeographicalAxis
= country_CA		 [1] 900,000us-gaap_ResultsOfOperationsGeneralAndAdministrativeRelatedToOilAndGasProducingActivities
/ us-gaap_ProductOrServiceAxis
= us-gaap_SyntheticOilMember
/ us-gaap_StatementGeographicalAxis
= country_CA		 [1] 900,000us-gaap_ResultsOfOperationsGeneralAndAdministrativeRelatedToOilAndGasProducingActivities
/ us-gaap_ProductOrServiceAxis
= us-gaap_SyntheticOilMember
/ us-gaap_StatementGeographicalAxis
= country_CA		 [1]
Total costs and expenses   303,000,000us-gaap_ResultsOfOperationsExpenseFromOilAndGasProducingActivities
/ us-gaap_ProductOrServiceAxis
= us-gaap_SyntheticOilMember
/ us-gaap_StatementGeographicalAxis
= country_CA		 [1] 294,800,000us-gaap_ResultsOfOperationsExpenseFromOilAndGasProducingActivities
/ us-gaap_ProductOrServiceAxis
= us-gaap_SyntheticOilMember
/ us-gaap_StatementGeographicalAxis
= country_CA		 [1] 288,800,000us-gaap_ResultsOfOperationsExpenseFromOilAndGasProducingActivities
/ us-gaap_ProductOrServiceAxis
= us-gaap_SyntheticOilMember
/ us-gaap_StatementGeographicalAxis
= country_CA		 [1]
Results of operations before taxes   88,900,000us-gaap_ResultsOfOperationsIncomeBeforeIncomeTaxes
/ us-gaap_ProductOrServiceAxis
= us-gaap_SyntheticOilMember
/ us-gaap_StatementGeographicalAxis
= country_CA		 [1] 146,500,000us-gaap_ResultsOfOperationsIncomeBeforeIncomeTaxes
/ us-gaap_ProductOrServiceAxis
= us-gaap_SyntheticOilMember
/ us-gaap_StatementGeographicalAxis
= country_CA		 [1] 174,900,000us-gaap_ResultsOfOperationsIncomeBeforeIncomeTaxes
/ us-gaap_ProductOrServiceAxis
= us-gaap_SyntheticOilMember
/ us-gaap_StatementGeographicalAxis
= country_CA		 [1]
Income tax expense (benefit)   21,800,000us-gaap_ResultsOfOperationsIncomeTaxExpense
/ us-gaap_ProductOrServiceAxis
= us-gaap_SyntheticOilMember
/ us-gaap_StatementGeographicalAxis
= country_CA		 [1] 37,900,000us-gaap_ResultsOfOperationsIncomeTaxExpense
/ us-gaap_ProductOrServiceAxis
= us-gaap_SyntheticOilMember
/ us-gaap_StatementGeographicalAxis
= country_CA		 [1] 40,000,000us-gaap_ResultsOfOperationsIncomeTaxExpense
/ us-gaap_ProductOrServiceAxis
= us-gaap_SyntheticOilMember
/ us-gaap_StatementGeographicalAxis
= country_CA		 [1]
Results of operations   67,100,000us-gaap_ResultsOfOperationsOilAndGasProducingActivitiesNetIncomeExcludingCorporateOverheadAndInterestCosts
/ us-gaap_ProductOrServiceAxis
= us-gaap_SyntheticOilMember
/ us-gaap_StatementGeographicalAxis
= country_CA		 [1] 108,600,000us-gaap_ResultsOfOperationsOilAndGasProducingActivitiesNetIncomeExcludingCorporateOverheadAndInterestCosts
/ us-gaap_ProductOrServiceAxis
= us-gaap_SyntheticOilMember
/ us-gaap_StatementGeographicalAxis
= country_CA		 [1] 134,900,000us-gaap_ResultsOfOperationsOilAndGasProducingActivitiesNetIncomeExcludingCorporateOverheadAndInterestCosts
/ us-gaap_ProductOrServiceAxis
= us-gaap_SyntheticOilMember
/ us-gaap_StatementGeographicalAxis
= country_CA		 [1]
Canada [Member] | Crude Oil and Natural Gas Liquids [Member] | Conventional [Member]        
Revenues        
Revenues   453,300,000us-gaap_ResultsOfOperationsSalesRevenueToUnaffiliatedEnterprises
/ us-gaap_OilAndGasDeliveryCommitmentsAndContractsAxis
= mur_CrudeOilAndNaturalGasMember
/ us-gaap_ProductOrServiceAxis
= mur_ConventionalGasMember
/ us-gaap_StatementGeographicalAxis
= country_CA		 [1] 507,200,000us-gaap_ResultsOfOperationsSalesRevenueToUnaffiliatedEnterprises
/ us-gaap_OilAndGasDeliveryCommitmentsAndContractsAxis
= mur_CrudeOilAndNaturalGasMember
/ us-gaap_ProductOrServiceAxis
= mur_ConventionalGasMember
/ us-gaap_StatementGeographicalAxis
= country_CA		 [1] 411,700,000us-gaap_ResultsOfOperationsSalesRevenueToUnaffiliatedEnterprises
/ us-gaap_OilAndGasDeliveryCommitmentsAndContractsAxis
= mur_CrudeOilAndNaturalGasMember
/ us-gaap_ProductOrServiceAxis
= mur_ConventionalGasMember
/ us-gaap_StatementGeographicalAxis
= country_CA		 [1]
Canada [Member] | Crude Oil and Natural Gas Liquids [Member] | Synthetic Oil [Member]        
Revenues        
Revenues   391,500,000us-gaap_ResultsOfOperationsSalesRevenueToUnaffiliatedEnterprises
/ us-gaap_OilAndGasDeliveryCommitmentsAndContractsAxis
= mur_CrudeOilAndNaturalGasMember
/ us-gaap_ProductOrServiceAxis
= us-gaap_SyntheticOilMember
/ us-gaap_StatementGeographicalAxis
= country_CA		 [1] 441,000,000us-gaap_ResultsOfOperationsSalesRevenueToUnaffiliatedEnterprises
/ us-gaap_OilAndGasDeliveryCommitmentsAndContractsAxis
= mur_CrudeOilAndNaturalGasMember
/ us-gaap_ProductOrServiceAxis
= us-gaap_SyntheticOilMember
/ us-gaap_StatementGeographicalAxis
= country_CA		 [1] 463,100,000us-gaap_ResultsOfOperationsSalesRevenueToUnaffiliatedEnterprises
/ us-gaap_OilAndGasDeliveryCommitmentsAndContractsAxis
= mur_CrudeOilAndNaturalGasMember
/ us-gaap_ProductOrServiceAxis
= us-gaap_SyntheticOilMember
/ us-gaap_StatementGeographicalAxis
= country_CA		 [1]
Canada [Member] | Natural Gas [Member] | Conventional [Member]        
Revenues        
Revenues   201,300,000us-gaap_ResultsOfOperationsSalesRevenueToUnaffiliatedEnterprises
/ us-gaap_OilAndGasDeliveryCommitmentsAndContractsAxis
= mur_NaturalGasMember
/ us-gaap_ProductOrServiceAxis
= mur_ConventionalGasMember
/ us-gaap_StatementGeographicalAxis
= country_CA		 [1] 198,100,000us-gaap_ResultsOfOperationsSalesRevenueToUnaffiliatedEnterprises
/ us-gaap_OilAndGasDeliveryCommitmentsAndContractsAxis
= mur_NaturalGasMember
/ us-gaap_ProductOrServiceAxis
= mur_ConventionalGasMember
/ us-gaap_StatementGeographicalAxis
= country_CA		 [1] 209,800,000us-gaap_ResultsOfOperationsSalesRevenueToUnaffiliatedEnterprises
/ us-gaap_OilAndGasDeliveryCommitmentsAndContractsAxis
= mur_NaturalGasMember
/ us-gaap_ProductOrServiceAxis
= mur_ConventionalGasMember
/ us-gaap_StatementGeographicalAxis
= country_CA		 [1]
Malaysia [Member]        
Costs and expenses        
Other expenses   1,300,000us-gaap_ResultsOfOperationsExpenseOther
/ us-gaap_StatementGeographicalAxis
= country_MY		 4,600,000us-gaap_ResultsOfOperationsExpenseOther
/ us-gaap_StatementGeographicalAxis
= country_MY		 1,100,000us-gaap_ResultsOfOperationsExpenseOther
/ us-gaap_StatementGeographicalAxis
= country_MY
Malaysia [Member] | Oil Reserves [Member]        
Revenues        
Revenues   2,037,700,000us-gaap_ResultsOfOperationsSalesRevenueToUnaffiliatedEnterprises
/ us-gaap_ProductOrServiceAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= country_MY		 [1] 2,279,000,000us-gaap_ResultsOfOperationsSalesRevenueToUnaffiliatedEnterprises
/ us-gaap_ProductOrServiceAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= country_MY		 [1] 2,427,100,000us-gaap_ResultsOfOperationsSalesRevenueToUnaffiliatedEnterprises
/ us-gaap_ProductOrServiceAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= country_MY		 [1]
Other operating revenues   145,800,000us-gaap_ResultsOfOperationsRevenueOther
/ us-gaap_ProductOrServiceAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= country_MY		 [1] 1,500,000us-gaap_ResultsOfOperationsRevenueOther
/ us-gaap_ProductOrServiceAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= country_MY		 [1] 1,000,000us-gaap_ResultsOfOperationsRevenueOther
/ us-gaap_ProductOrServiceAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= country_MY		 [1]
Results of Operations, Revenue from Oil and Gas Producing Activities, Total   2,183,500,000us-gaap_ResultsOfOperationsRevenueFromOilAndGasProducingActivities
/ us-gaap_ProductOrServiceAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= country_MY		 [1] 2,280,500,000us-gaap_ResultsOfOperationsRevenueFromOilAndGasProducingActivities
/ us-gaap_ProductOrServiceAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= country_MY		 [1] 2,428,100,000us-gaap_ResultsOfOperationsRevenueFromOilAndGasProducingActivities
/ us-gaap_ProductOrServiceAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= country_MY		 [1]
Costs and expenses        
Lease operating expenses   350,300,000us-gaap_ResultsOfOperationsProductionOrLiftingCosts
/ us-gaap_ProductOrServiceAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= country_MY		 [1] 384,400,000us-gaap_ResultsOfOperationsProductionOrLiftingCosts
/ us-gaap_ProductOrServiceAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= country_MY		 [1] 422,700,000us-gaap_ResultsOfOperationsProductionOrLiftingCosts
/ us-gaap_ProductOrServiceAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= country_MY		 [1]
Exploration costs charged to expense   48,700,000mur_ResultsOfOperationsExplorationExpenseIncludingDiscontinuedOperations
/ us-gaap_ProductOrServiceAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= country_MY		 [1] 25,300,000mur_ResultsOfOperationsExplorationExpenseIncludingDiscontinuedOperations
/ us-gaap_ProductOrServiceAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= country_MY		 [1] 27,200,000mur_ResultsOfOperationsExplorationExpenseIncludingDiscontinuedOperations
/ us-gaap_ProductOrServiceAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= country_MY		 [1]
Depreciation, depletion and amortization   735,000,000us-gaap_ResultsOfOperationsDepreciationDepletionAndAmortizationAndValuationProvisions
/ us-gaap_ProductOrServiceAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= country_MY		 [1] 588,200,000us-gaap_ResultsOfOperationsDepreciationDepletionAndAmortizationAndValuationProvisions
/ us-gaap_ProductOrServiceAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= country_MY		 [1] 532,100,000us-gaap_ResultsOfOperationsDepreciationDepletionAndAmortizationAndValuationProvisions
/ us-gaap_ProductOrServiceAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= country_MY		 [1]
Accretion of asset retirement obligations   18,100,000us-gaap_ResultsOfOperationsAccretionOfAssetRetirementObligations
/ us-gaap_ProductOrServiceAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= country_MY		 [1] 15,000,000us-gaap_ResultsOfOperationsAccretionOfAssetRetirementObligations
/ us-gaap_ProductOrServiceAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= country_MY		 [1] 12,500,000us-gaap_ResultsOfOperationsAccretionOfAssetRetirementObligations
/ us-gaap_ProductOrServiceAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= country_MY		 [1]
Selling and general expenses   15,700,000us-gaap_ResultsOfOperationsGeneralAndAdministrativeRelatedToOilAndGasProducingActivities
/ us-gaap_ProductOrServiceAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= country_MY		 [1] 3,500,000us-gaap_ResultsOfOperationsGeneralAndAdministrativeRelatedToOilAndGasProducingActivities
/ us-gaap_ProductOrServiceAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= country_MY		 [1] (5,300,000)us-gaap_ResultsOfOperationsGeneralAndAdministrativeRelatedToOilAndGasProducingActivities
/ us-gaap_ProductOrServiceAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= country_MY		 [1]
Other expenses   16,900,000mur_ResultsOfOperationsOtherExpenses
/ us-gaap_ProductOrServiceAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= country_MY		 [1]    
Total costs and expenses   1,184,700,000us-gaap_ResultsOfOperationsExpenseFromOilAndGasProducingActivities
/ us-gaap_ProductOrServiceAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= country_MY		 [1] 1,016,400,000us-gaap_ResultsOfOperationsExpenseFromOilAndGasProducingActivities
/ us-gaap_ProductOrServiceAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= country_MY		 [1] 989,200,000us-gaap_ResultsOfOperationsExpenseFromOilAndGasProducingActivities
/ us-gaap_ProductOrServiceAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= country_MY		 [1]
Results of operations before taxes   998,800,000us-gaap_ResultsOfOperationsIncomeBeforeIncomeTaxes
/ us-gaap_ProductOrServiceAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= country_MY		 [1] 1,264,100,000us-gaap_ResultsOfOperationsIncomeBeforeIncomeTaxes
/ us-gaap_ProductOrServiceAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= country_MY		 [1] 1,438,900,000us-gaap_ResultsOfOperationsIncomeBeforeIncomeTaxes
/ us-gaap_ProductOrServiceAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= country_MY		 [1]
Income tax expense (benefit)   102,600,000us-gaap_ResultsOfOperationsIncomeTaxExpense
/ us-gaap_ProductOrServiceAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= country_MY		 [1] 477,700,000us-gaap_ResultsOfOperationsIncomeTaxExpense
/ us-gaap_ProductOrServiceAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= country_MY		 [1] 544,700,000us-gaap_ResultsOfOperationsIncomeTaxExpense
/ us-gaap_ProductOrServiceAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= country_MY		 [1]
Results of operations   896,200,000us-gaap_ResultsOfOperationsOilAndGasProducingActivitiesNetIncomeExcludingCorporateOverheadAndInterestCosts
/ us-gaap_ProductOrServiceAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= country_MY		 [1] 786,400,000us-gaap_ResultsOfOperationsOilAndGasProducingActivitiesNetIncomeExcludingCorporateOverheadAndInterestCosts
/ us-gaap_ProductOrServiceAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= country_MY		 [1] 894,200,000us-gaap_ResultsOfOperationsOilAndGasProducingActivitiesNetIncomeExcludingCorporateOverheadAndInterestCosts
/ us-gaap_ProductOrServiceAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= country_MY		 [1]
Malaysia [Member] | Crude Oil and Natural Gas Liquids [Member] | Oil Reserves [Member]        
Revenues        
Revenues   1,680,200,000us-gaap_ResultsOfOperationsSalesRevenueToUnaffiliatedEnterprises
/ us-gaap_OilAndGasDeliveryCommitmentsAndContractsAxis
= mur_CrudeOilAndNaturalGasMember
/ us-gaap_ProductOrServiceAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= country_MY		 [1] 1,875,000,000us-gaap_ResultsOfOperationsSalesRevenueToUnaffiliatedEnterprises
/ us-gaap_OilAndGasDeliveryCommitmentsAndContractsAxis
= mur_CrudeOilAndNaturalGasMember
/ us-gaap_ProductOrServiceAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= country_MY		 [1] 1,946,000,000us-gaap_ResultsOfOperationsSalesRevenueToUnaffiliatedEnterprises
/ us-gaap_OilAndGasDeliveryCommitmentsAndContractsAxis
= mur_CrudeOilAndNaturalGasMember
/ us-gaap_ProductOrServiceAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= country_MY		 [1]
Malaysia [Member] | Natural Gas [Member] | Oil Reserves [Member]        
Revenues        
Revenues   357,500,000us-gaap_ResultsOfOperationsSalesRevenueToUnaffiliatedEnterprises
/ us-gaap_OilAndGasDeliveryCommitmentsAndContractsAxis
= mur_NaturalGasMember
/ us-gaap_ProductOrServiceAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= country_MY		 [1] 404,000,000us-gaap_ResultsOfOperationsSalesRevenueToUnaffiliatedEnterprises
/ us-gaap_OilAndGasDeliveryCommitmentsAndContractsAxis
= mur_NaturalGasMember
/ us-gaap_ProductOrServiceAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= country_MY		 [1] 481,100,000us-gaap_ResultsOfOperationsSalesRevenueToUnaffiliatedEnterprises
/ us-gaap_OilAndGasDeliveryCommitmentsAndContractsAxis
= mur_NaturalGasMember
/ us-gaap_ProductOrServiceAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= country_MY		 [1]
Other Regions [Member]        
Costs and expenses        
Other expenses   128,500,000us-gaap_ResultsOfOperationsExpenseOther
/ us-gaap_StatementGeographicalAxis
= mur_OtherRegionsMember		 [2] 138,000,000us-gaap_ResultsOfOperationsExpenseOther
/ us-gaap_StatementGeographicalAxis
= mur_OtherRegionsMember		 [2] 46,000,000us-gaap_ResultsOfOperationsExpenseOther
/ us-gaap_StatementGeographicalAxis
= mur_OtherRegionsMember		 [2]
Other Regions [Member] | Oil Reserves [Member]        
Revenues        
Revenues     83,600,000us-gaap_ResultsOfOperationsSalesRevenueToUnaffiliatedEnterprises
/ us-gaap_ProductOrServiceAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= mur_OtherRegionsMember		 [1],[3] 57,600,000us-gaap_ResultsOfOperationsSalesRevenueToUnaffiliatedEnterprises
/ us-gaap_ProductOrServiceAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= mur_OtherRegionsMember		 [1],[3]
Other operating revenues   (1,300,000)us-gaap_ResultsOfOperationsRevenueOther
/ us-gaap_ProductOrServiceAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= mur_OtherRegionsMember		 [1],[3]   100,000us-gaap_ResultsOfOperationsRevenueOther
/ us-gaap_ProductOrServiceAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= mur_OtherRegionsMember		 [1],[3]
Results of Operations, Revenue from Oil and Gas Producing Activities, Total   (1,300,000)us-gaap_ResultsOfOperationsRevenueFromOilAndGasProducingActivities
/ us-gaap_ProductOrServiceAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= mur_OtherRegionsMember		 [1],[3] 83,600,000us-gaap_ResultsOfOperationsRevenueFromOilAndGasProducingActivities
/ us-gaap_ProductOrServiceAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= mur_OtherRegionsMember		 [1],[3] 57,700,000us-gaap_ResultsOfOperationsRevenueFromOilAndGasProducingActivities
/ us-gaap_ProductOrServiceAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= mur_OtherRegionsMember		 [1],[3]
Costs and expenses        
Lease operating expenses     191,000,000us-gaap_ResultsOfOperationsProductionOrLiftingCosts
/ us-gaap_ProductOrServiceAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= mur_OtherRegionsMember		 [1],[3] 48,400,000us-gaap_ResultsOfOperationsProductionOrLiftingCosts
/ us-gaap_ProductOrServiceAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= mur_OtherRegionsMember		 [1],[3]
Exploration costs charged to expense   259,000,000mur_ResultsOfOperationsExplorationExpenseIncludingDiscontinuedOperations
/ us-gaap_ProductOrServiceAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= mur_OtherRegionsMember		 [1],[3] 302,000,000mur_ResultsOfOperationsExplorationExpenseIncludingDiscontinuedOperations
/ us-gaap_ProductOrServiceAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= mur_OtherRegionsMember		 [1],[3] 161,500,000mur_ResultsOfOperationsExplorationExpenseIncludingDiscontinuedOperations
/ us-gaap_ProductOrServiceAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= mur_OtherRegionsMember		 [1],[3]
Undeveloped lease amortization   4,900,000mur_ResultsOfOperationsUndevelopedLeaseAmortization
/ us-gaap_ProductOrServiceAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= mur_OtherRegionsMember		 [1],[3] 15,600,000mur_ResultsOfOperationsUndevelopedLeaseAmortization
/ us-gaap_ProductOrServiceAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= mur_OtherRegionsMember		 [1],[3] 28,900,000mur_ResultsOfOperationsUndevelopedLeaseAmortization
/ us-gaap_ProductOrServiceAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= mur_OtherRegionsMember		 [1],[3]
Depreciation, depletion and amortization   5,100,000us-gaap_ResultsOfOperationsDepreciationDepletionAndAmortizationAndValuationProvisions
/ us-gaap_ProductOrServiceAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= mur_OtherRegionsMember		 [1],[3] 4,500,000us-gaap_ResultsOfOperationsDepreciationDepletionAndAmortizationAndValuationProvisions
/ us-gaap_ProductOrServiceAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= mur_OtherRegionsMember		 [1],[3] 36,300,000us-gaap_ResultsOfOperationsDepreciationDepletionAndAmortizationAndValuationProvisions
/ us-gaap_ProductOrServiceAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= mur_OtherRegionsMember		 [1],[3]
Accretion of asset retirement obligations     4,300,000us-gaap_ResultsOfOperationsAccretionOfAssetRetirementObligations
/ us-gaap_ProductOrServiceAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= mur_OtherRegionsMember		 [1],[3] 900,000us-gaap_ResultsOfOperationsAccretionOfAssetRetirementObligations
/ us-gaap_ProductOrServiceAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= mur_OtherRegionsMember		 [1],[3]
Impairment of assets       200,000,000us-gaap_ImpairmentOfOilAndGasProperties
/ us-gaap_ProductOrServiceAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= mur_OtherRegionsMember		 [1],[3]
Selling and general expenses   73,500,000us-gaap_ResultsOfOperationsGeneralAndAdministrativeRelatedToOilAndGasProducingActivities
/ us-gaap_ProductOrServiceAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= mur_OtherRegionsMember		 [1],[3] 60,800,000us-gaap_ResultsOfOperationsGeneralAndAdministrativeRelatedToOilAndGasProducingActivities
/ us-gaap_ProductOrServiceAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= mur_OtherRegionsMember		 [1],[3] 51,600,000us-gaap_ResultsOfOperationsGeneralAndAdministrativeRelatedToOilAndGasProducingActivities
/ us-gaap_ProductOrServiceAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= mur_OtherRegionsMember		 [1],[3]
Other expenses   2,100,000mur_ResultsOfOperationsOtherExpenses
/ us-gaap_ProductOrServiceAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= mur_OtherRegionsMember		 [1],[3]    
Total costs and expenses   344,600,000us-gaap_ResultsOfOperationsExpenseFromOilAndGasProducingActivities
/ us-gaap_ProductOrServiceAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= mur_OtherRegionsMember		 [1],[3] 578,200,000us-gaap_ResultsOfOperationsExpenseFromOilAndGasProducingActivities
/ us-gaap_ProductOrServiceAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= mur_OtherRegionsMember		 [1],[3] 527,600,000us-gaap_ResultsOfOperationsExpenseFromOilAndGasProducingActivities
/ us-gaap_ProductOrServiceAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= mur_OtherRegionsMember		 [1],[3]
Results of operations before taxes   (345,900,000)us-gaap_ResultsOfOperationsIncomeBeforeIncomeTaxes
/ us-gaap_ProductOrServiceAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= mur_OtherRegionsMember		 [1],[3] (494,600,000)us-gaap_ResultsOfOperationsIncomeBeforeIncomeTaxes
/ us-gaap_ProductOrServiceAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= mur_OtherRegionsMember		 [1],[3] (469,900,000)us-gaap_ResultsOfOperationsIncomeBeforeIncomeTaxes
/ us-gaap_ProductOrServiceAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= mur_OtherRegionsMember		 [1],[3]
Income tax expense (benefit)   (95,900,000)us-gaap_ResultsOfOperationsIncomeTaxExpense
/ us-gaap_ProductOrServiceAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= mur_OtherRegionsMember		 [1],[3] (120,800,000)us-gaap_ResultsOfOperationsIncomeTaxExpense
/ us-gaap_ProductOrServiceAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= mur_OtherRegionsMember		 [1],[3] (104,600,000)us-gaap_ResultsOfOperationsIncomeTaxExpense
/ us-gaap_ProductOrServiceAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= mur_OtherRegionsMember		 [1],[3]
Results of operations   (250,000,000)us-gaap_ResultsOfOperationsOilAndGasProducingActivitiesNetIncomeExcludingCorporateOverheadAndInterestCosts
/ us-gaap_ProductOrServiceAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= mur_OtherRegionsMember		 [1],[3] (373,800,000)us-gaap_ResultsOfOperationsOilAndGasProducingActivitiesNetIncomeExcludingCorporateOverheadAndInterestCosts
/ us-gaap_ProductOrServiceAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= mur_OtherRegionsMember		 [1],[3] (365,300,000)us-gaap_ResultsOfOperationsOilAndGasProducingActivitiesNetIncomeExcludingCorporateOverheadAndInterestCosts
/ us-gaap_ProductOrServiceAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= mur_OtherRegionsMember		 [1],[3]
Other Regions [Member] | Crude Oil and Natural Gas Liquids [Member] | Oil Reserves [Member]        
Revenues        
Revenues     $ 83,600,000us-gaap_ResultsOfOperationsSalesRevenueToUnaffiliatedEnterprises
/ us-gaap_OilAndGasDeliveryCommitmentsAndContractsAxis
= mur_CrudeOilAndNaturalGasMember
/ us-gaap_ProductOrServiceAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= mur_OtherRegionsMember		 [1],[3] $ 57,600,000us-gaap_ResultsOfOperationsSalesRevenueToUnaffiliatedEnterprises
/ us-gaap_OilAndGasDeliveryCommitmentsAndContractsAxis
= mur_CrudeOilAndNaturalGasMember
/ us-gaap_ProductOrServiceAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= mur_OtherRegionsMember		 [1],[3]
[1] Results exclude corporate overhead, interest and discontinued operations.
[2] Due to the shutdown of production operations in Republic of the Congo, the Company now includes the result of these operations in the Other exploration and production segment in the above table.
[3] Due to the shutdown of production operations in Republic of the Congo, the Company now includes the results of these operations in the Other exploration and production segment in the above table.