v3.26.1
Derivatives (Effect of Commodity Derivative Instruments in Statements of Income) (Detail) - USD ($)
$ in Millions
 3 Months Ended 6 Months Ended
Jun. 30, 2026
Jun. 30, 2025
Jun. 30, 2026
Jun. 30, 2025
Derivative Instruments, Gain (Loss) [Line Items]        
Unrealized Gain (Loss) on Derivatives     $ (876) $ 54
Commodity derivatives        
Derivative Instruments, Gain (Loss) [Line Items]        
Gain (Loss) $ 325 $ 32 (584) (33)
Commodity derivatives | Income Statement Location [Axis]: us-gaap:CostOfGoodsAndServicesSold        
Derivative Instruments, Gain (Loss) [Line Items]        
Gain (Loss) 313 31 (527) (36)
Unrealized Gain (Loss) on Derivatives 849 26 409 13
Realized Gain (Loss), Investment and Derivative, Operating, before Tax (536) 5 (936) (49)
Commodity derivatives | Income Statement Location [Axis]: us-gaap:OtherOperatingIncome        
Derivative Instruments, Gain (Loss) [Line Items]        
Gain (Loss) (5) 1 (12) 3
Unrealized Gain (Loss) on Derivatives 19 1 (11) 0
Realized Gain (Loss), Investment and Derivative, Operating, before Tax (24) 0 (1) 3
Commodity derivatives | Income Statement Location [Axis]: us-gaap:RevenueFromContractWithCustomerExcludingAssessedTax        
Derivative Instruments, Gain (Loss) [Line Items]        
Gain (Loss) 17 0 (45) 0
Unrealized Gain (Loss) on Derivatives 44 0 (5) 0
Realized Gain (Loss), Investment and Derivative, Operating, before Tax (27) $ 0 (40) $ 0
Purchase crude oil from Strategic Petroleum Reserve        
Derivative Instruments, Gain (Loss) [Line Items]        
Derivative Liability 973   973  
Purchase crude oil from Strategic Petroleum Reserve | Balance Sheet Location [Axis]: us-gaap:DeferredCreditsAndOtherLiabilities        
Derivative Instruments, Gain (Loss) [Line Items]        
Derivative Liability 777   777  
Purchase crude oil from Strategic Petroleum Reserve | Balance Sheet Location [Axis]: us-gaap:OtherLiabilitiesCurrent        
Derivative Instruments, Gain (Loss) [Line Items]        
Derivative Liability $ 196   $ 196