v3.26.1
Fair Value Measurements (Assets and Liabilities Accounted for at Fair Value on Recurring Basis) (Detail) - USD ($)
$ in Millions
Mar. 31, 2026
Dec. 31, 2025
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Cash collateral netted with derivative liabilities $ 511 $ 10
Fair Value, Recurring    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Contingent consideration 239 236
Fair Value, Recurring | Commodity derivatives    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Commodity derivative instruments, assets - netting and collateral (3,127) (226)
Derivative asset, net carrying value on balance sheet 13 17
Commodity derivative instruments, assets - collateral pledged not offset 347 10
Commodity derivative instruments, liabilities - netting and collateral (3,638) (236)
Derivative liability, net carrying value on balance sheet 7 0
Commodity derivative instruments, liabilities - collateral pledged not offset 0 0
Fair Value, Recurring | Embedded derivatives in commodity contracts    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Commodity derivative instruments, liabilities - netting and collateral 0 0
Derivative liability, net carrying value on balance sheet 54 41
Commodity derivative instruments, liabilities - collateral pledged not offset 0 0
Fair Value, Recurring | Level 1    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Contingent consideration 0 0
Fair Value, Recurring | Level 1 | Commodity derivatives    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Commodity derivative instruments, assets - gross 3,140 243
Commodity derivative instruments, liabilities - gross 3,638 236
Fair Value, Recurring | Level 1 | Embedded derivatives in commodity contracts    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Commodity derivative instruments, liabilities - gross 0 0
Fair Value, Recurring | Level 2    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Contingent consideration 0 0
Fair Value, Recurring | Level 2 | Commodity derivatives    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Commodity derivative instruments, assets - gross 0 0
Commodity derivative instruments, liabilities - gross 0 0
Fair Value, Recurring | Level 2 | Embedded derivatives in commodity contracts    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Commodity derivative instruments, liabilities - gross 0 0
Fair Value, Recurring | Level 3    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Contingent consideration 239 236
Fair Value, Recurring | Level 3 | Commodity derivatives    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Commodity derivative instruments, assets - gross 0 0
Commodity derivative instruments, liabilities - gross 7 0
Fair Value, Recurring | Level 3 | Embedded derivatives in commodity contracts    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Commodity derivative instruments, liabilities - gross $ 54 $ 41