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Property, Plant, and Equipment (Details PPE) (USD $)
In Millions, unless otherwise specified
 12 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Property, Plant, and Equipment      
Total property, plant, and equipment, at cost $ 36,435us-gaap_PropertyPlantAndEquipmentGross $ 25,823us-gaap_PropertyPlantAndEquipmentGross  
Accumulated depreciation and amortization (8,354)us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment (7,613)us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment  
Property, plant, and equipment - net 28,081us-gaap_PropertyPlantAndEquipmentNet 18,210us-gaap_PropertyPlantAndEquipmentNet  
Depreciation and amortization 967us-gaap_Depreciation 752us-gaap_Depreciation 712us-gaap_Depreciation
Nonregulated [Member] | Natural gas gathering and processing facilities [Member]      
Property, Plant, and Equipment      
Total property, plant, and equipment, at cost 18,749us-gaap_PropertyPlantAndEquipmentGross
/ us-gaap_PropertyPlantAndEquipmentByTypeAxis
= us-gaap_GasGatheringAndProcessingEquipmentMember
/ us-gaap_PublicUtilityRegulatedOrUnregulatedStatusAxis
= us-gaap_UnregulatedOperationMember		 9,185us-gaap_PropertyPlantAndEquipmentGross
/ us-gaap_PropertyPlantAndEquipmentByTypeAxis
= us-gaap_GasGatheringAndProcessingEquipmentMember
/ us-gaap_PublicUtilityRegulatedOrUnregulatedStatusAxis
= us-gaap_UnregulatedOperationMember		  
Nonregulated [Member] | Natural gas gathering and processing facilities [Member] | Minimum [Member]      
Property, Plant, and Equipment      
Property, Plant and Equipment, Useful Life 5 years [1]    
Nonregulated [Member] | Natural gas gathering and processing facilities [Member] | Maximum [Member]      
Property, Plant, and Equipment      
Property, Plant and Equipment, Useful Life 40 years [1]    
Nonregulated [Member] | Construction in Progress [Member]      
Property, Plant, and Equipment      
Total property, plant, and equipment, at cost 2,648us-gaap_PropertyPlantAndEquipmentGross
/ us-gaap_PropertyPlantAndEquipmentByTypeAxis
= us-gaap_ConstructionInProgressMember
/ us-gaap_PublicUtilityRegulatedOrUnregulatedStatusAxis
= us-gaap_UnregulatedOperationMember		 3,123us-gaap_PropertyPlantAndEquipmentGross
/ us-gaap_PropertyPlantAndEquipmentByTypeAxis
= us-gaap_ConstructionInProgressMember
/ us-gaap_PublicUtilityRegulatedOrUnregulatedStatusAxis
= us-gaap_UnregulatedOperationMember		  
Nonregulated [Member] | Other Capitalized Property Plant and Equipment [Member]      
Property, Plant, and Equipment      
Total property, plant, and equipment, at cost 1,850us-gaap_PropertyPlantAndEquipmentGross
/ us-gaap_PropertyPlantAndEquipmentByTypeAxis
= us-gaap_OtherCapitalizedPropertyPlantAndEquipmentMember
/ us-gaap_PublicUtilityRegulatedOrUnregulatedStatusAxis
= us-gaap_UnregulatedOperationMember		 1,316us-gaap_PropertyPlantAndEquipmentGross
/ us-gaap_PropertyPlantAndEquipmentByTypeAxis
= us-gaap_OtherCapitalizedPropertyPlantAndEquipmentMember
/ us-gaap_PublicUtilityRegulatedOrUnregulatedStatusAxis
= us-gaap_UnregulatedOperationMember		  
Nonregulated [Member] | Other Capitalized Property Plant and Equipment [Member] | Minimum [Member]      
Property, Plant, and Equipment      
Property, Plant and Equipment, Useful Life 3 years [1]    
Nonregulated [Member] | Other Capitalized Property Plant and Equipment [Member] | Maximum [Member]      
Property, Plant, and Equipment      
Property, Plant and Equipment, Useful Life 45 years [1]    
Regulated [Member] | Natural gas transmission facilities [Member]      
Property, Plant, and Equipment      
Total property, plant, and equipment, at cost 10,867us-gaap_PropertyPlantAndEquipmentGross
/ us-gaap_PropertyPlantAndEquipmentByTypeAxis
= us-gaap_GasTransmissionAndDistributionEquipmentMember
/ us-gaap_PublicUtilityRegulatedOrUnregulatedStatusAxis
= us-gaap_RegulatedOperationMember		 10,633us-gaap_PropertyPlantAndEquipmentGross
/ us-gaap_PropertyPlantAndEquipmentByTypeAxis
= us-gaap_GasTransmissionAndDistributionEquipmentMember
/ us-gaap_PublicUtilityRegulatedOrUnregulatedStatusAxis
= us-gaap_RegulatedOperationMember		  
Regulated [Member] | Natural gas transmission facilities [Member] | Minimum [Member]      
Property, Plant, and Equipment      
Property, Plant, and Equipment, Depreciation Rate 1.20%wmb_RegulatedPropertyPlantandEquipmentDepreciationRate
/ us-gaap_PropertyPlantAndEquipmentByTypeAxis
= us-gaap_GasTransmissionAndDistributionEquipmentMember
/ us-gaap_PublicUtilityRegulatedOrUnregulatedStatusAxis
= us-gaap_RegulatedOperationMember
/ us-gaap_RangeAxis
= us-gaap_MinimumMember		 [1]    
Regulated [Member] | Natural gas transmission facilities [Member] | Maximum [Member]      
Property, Plant, and Equipment      
Property, Plant, and Equipment, Depreciation Rate 6.97%wmb_RegulatedPropertyPlantandEquipmentDepreciationRate
/ us-gaap_PropertyPlantAndEquipmentByTypeAxis
= us-gaap_GasTransmissionAndDistributionEquipmentMember
/ us-gaap_PublicUtilityRegulatedOrUnregulatedStatusAxis
= us-gaap_RegulatedOperationMember
/ us-gaap_RangeAxis
= us-gaap_MaximumMember		 [1]    
Regulated [Member] | Construction in Progress [Member]      
Property, Plant, and Equipment      
Total property, plant, and equipment, at cost 985us-gaap_PropertyPlantAndEquipmentGross
/ us-gaap_PropertyPlantAndEquipmentByTypeAxis
= us-gaap_ConstructionInProgressMember
/ us-gaap_PublicUtilityRegulatedOrUnregulatedStatusAxis
= us-gaap_RegulatedOperationMember		 273us-gaap_PropertyPlantAndEquipmentGross
/ us-gaap_PropertyPlantAndEquipmentByTypeAxis
= us-gaap_ConstructionInProgressMember
/ us-gaap_PublicUtilityRegulatedOrUnregulatedStatusAxis
= us-gaap_RegulatedOperationMember		  
Regulated [Member] | Other Capitalized Property Plant and Equipment [Member]      
Property, Plant, and Equipment      
Total property, plant, and equipment, at cost 1,336us-gaap_PropertyPlantAndEquipmentGross
/ us-gaap_PropertyPlantAndEquipmentByTypeAxis
= us-gaap_OtherCapitalizedPropertyPlantAndEquipmentMember
/ us-gaap_PublicUtilityRegulatedOrUnregulatedStatusAxis
= us-gaap_RegulatedOperationMember		 1,293us-gaap_PropertyPlantAndEquipmentGross
/ us-gaap_PropertyPlantAndEquipmentByTypeAxis
= us-gaap_OtherCapitalizedPropertyPlantAndEquipmentMember
/ us-gaap_PublicUtilityRegulatedOrUnregulatedStatusAxis
= us-gaap_RegulatedOperationMember		  
Regulated [Member] | Other Capitalized Property Plant and Equipment [Member] | Minimum [Member]      
Property, Plant, and Equipment      
Property, Plant, and Equipment, Depreciation Rate 1.35%wmb_RegulatedPropertyPlantandEquipmentDepreciationRate
/ us-gaap_PropertyPlantAndEquipmentByTypeAxis
= us-gaap_OtherCapitalizedPropertyPlantAndEquipmentMember
/ us-gaap_PublicUtilityRegulatedOrUnregulatedStatusAxis
= us-gaap_RegulatedOperationMember
/ us-gaap_RangeAxis
= us-gaap_MinimumMember		 [1]    
Regulated [Member] | Other Capitalized Property Plant and Equipment [Member] | Maximum [Member]      
Property, Plant, and Equipment      
Property, Plant, and Equipment, Depreciation Rate 33.33%wmb_RegulatedPropertyPlantandEquipmentDepreciationRate
/ us-gaap_PropertyPlantAndEquipmentByTypeAxis
= us-gaap_OtherCapitalizedPropertyPlantAndEquipmentMember
/ us-gaap_PublicUtilityRegulatedOrUnregulatedStatusAxis
= us-gaap_RegulatedOperationMember
/ us-gaap_RangeAxis
= us-gaap_MaximumMember		 [1]    
Regulated [Member] | Excess Of Original Cost Of Regulated Facilities [Member]      
Property, Plant, and Equipment      
Property, plant, and equipment - net $ 746us-gaap_PropertyPlantAndEquipmentNet
/ us-gaap_PropertyPlantAndEquipmentByTypeAxis
= wmb_ExcessOfOriginalCostOfRegulatedFacilitiesMember
/ us-gaap_PublicUtilityRegulatedOrUnregulatedStatusAxis
= us-gaap_RegulatedOperationMember		 $ 785us-gaap_PropertyPlantAndEquipmentNet
/ us-gaap_PropertyPlantAndEquipmentByTypeAxis
= wmb_ExcessOfOriginalCostOfRegulatedFacilitiesMember
/ us-gaap_PublicUtilityRegulatedOrUnregulatedStatusAxis
= us-gaap_RegulatedOperationMember		  
Period of straight-line amortization 40 years    
[1] Estimated useful life and depreciation rates are presented as of December 31, 2014. Depreciation rates for regulated assets are prescribed by the FERC.