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Summary of Significant Accounting Policies - Additional Information (Details)
$ in Millions
12 Months Ended
Dec. 31, 2017
USD ($)
segment
Dec. 31, 2016
USD ($)
Dec. 31, 2015
USD ($)
Dec. 31, 2014
Property, Plant and Equipment [Line Items]        
Number of operating segments | segment 2      
Advertising costs $ 24 $ 22 $ 22  
Assets Held-for-sale, Not Part of Disposal Group, Current 3,313 177    
Excise and sales taxes $ 234 $ 243 $ 231  
Percentage of qualifying income 90.00% 90.00%   90.00%
assets held for sale, current and noncurrent   $ 3,600    
Minimum [Member]        
Property, Plant and Equipment [Line Items]        
Intangible asset, useful life 5 years      
Lease term 5 years      
Minimum [Member] | Supply Agreements [Member]        
Property, Plant and Equipment [Line Items]        
Intangible assets, weighted average useful life 5 years      
Maximum [Member]        
Property, Plant and Equipment [Line Items]        
Intangible asset, useful life 20 years      
Lease term 15 years      
Maximum [Member] | Supply Agreements [Member]        
Property, Plant and Equipment [Line Items]        
Intangible assets, weighted average useful life 15 years      
Building [Member]        
Property, Plant and Equipment [Line Items]        
PP&E, useful life 40 years      
Equipment [Member] | Minimum [Member]        
Property, Plant and Equipment [Line Items]        
PP&E, useful life 3 years      
Equipment [Member] | Maximum [Member]        
Property, Plant and Equipment [Line Items]        
PP&E, useful life 15 years      
Underground Storage Tanks [Member]        
Property, Plant and Equipment [Line Items]        
PP&E, useful life 30 years      
Land Improvements [Member]        
Property, Plant and Equipment [Line Items]        
PP&E, useful life 20 years      
Vehicles [Member]        
Property, Plant and Equipment [Line Items]        
Lease term 5 years