v3.26.1
Retirement and Benefit Plans - Schedule of Qualified Plan Assets at Fair Value (Details) - USD ($)
$ in Millions
Mar. 31, 2026
Dec. 31, 2025
Defined Benefit Plan, Plan Assets, Category [Line Items]    
Accrued interest receivable $ 775 $ 534
Pension Plan    
Defined Benefit Plan, Plan Assets, Category [Line Items]    
Plan assets at fair value 2,948  
Interest receivable excluded from plan assets 22  
Pension Plan | Level 1    
Defined Benefit Plan, Plan Assets, Category [Line Items]    
Plan assets in the fair value hierarchy 700  
Pension Plan | Level 2    
Defined Benefit Plan, Plan Assets, Category [Line Items]    
Plan assets in the fair value hierarchy 983  
Pension Plan | Level 3    
Defined Benefit Plan, Plan Assets, Category [Line Items]    
Plan assets in the fair value hierarchy 0  
Pension Plan | Total Fair Value    
Defined Benefit Plan, Plan Assets, Category [Line Items]    
Plan assets in the fair value hierarchy 1,683  
Pension Plan | Debt Securities | Level 1    
Defined Benefit Plan, Plan Assets, Category [Line Items]    
Plan assets in the fair value hierarchy 700  
Pension Plan | Debt Securities | Level 2    
Defined Benefit Plan, Plan Assets, Category [Line Items]    
Plan assets in the fair value hierarchy 983  
Pension Plan | Debt Securities | Level 3    
Defined Benefit Plan, Plan Assets, Category [Line Items]    
Plan assets in the fair value hierarchy 0  
Pension Plan | Debt Securities | Total Fair Value    
Defined Benefit Plan, Plan Assets, Category [Line Items]    
Plan assets in the fair value hierarchy 1,683  
Pension Plan | U.S. Treasury and federal agencies securities | Level 1    
Defined Benefit Plan, Plan Assets, Category [Line Items]    
Plan assets in the fair value hierarchy 700  
Pension Plan | U.S. Treasury and federal agencies securities | Level 2    
Defined Benefit Plan, Plan Assets, Category [Line Items]    
Plan assets in the fair value hierarchy 6  
Pension Plan | U.S. Treasury and federal agencies securities | Level 3    
Defined Benefit Plan, Plan Assets, Category [Line Items]    
Plan assets in the fair value hierarchy 0  
Pension Plan | U.S. Treasury and federal agencies securities | Total Fair Value    
Defined Benefit Plan, Plan Assets, Category [Line Items]    
Plan assets in the fair value hierarchy 706  
Pension Plan | Asset-Backed Securities | Level 1    
Defined Benefit Plan, Plan Assets, Category [Line Items]    
Plan assets in the fair value hierarchy 0  
Pension Plan | Asset-Backed Securities | Level 2    
Defined Benefit Plan, Plan Assets, Category [Line Items]    
Plan assets in the fair value hierarchy 936  
Pension Plan | Asset-Backed Securities | Level 3    
Defined Benefit Plan, Plan Assets, Category [Line Items]    
Plan assets in the fair value hierarchy 0  
Pension Plan | Asset-Backed Securities | Total Fair Value    
Defined Benefit Plan, Plan Assets, Category [Line Items]    
Plan assets in the fair value hierarchy 936  
Pension Plan | Private Placement Securities | Level 1    
Defined Benefit Plan, Plan Assets, Category [Line Items]    
Plan assets in the fair value hierarchy 0  
Pension Plan | Private Placement Securities | Level 2    
Defined Benefit Plan, Plan Assets, Category [Line Items]    
Plan assets in the fair value hierarchy 41  
Pension Plan | Private Placement Securities | Level 3    
Defined Benefit Plan, Plan Assets, Category [Line Items]    
Plan assets in the fair value hierarchy 0  
Pension Plan | Private Placement Securities | Total Fair Value    
Defined Benefit Plan, Plan Assets, Category [Line Items]    
Plan assets in the fair value hierarchy 41  
Pension Plan | Collective Investment Funds | Investments measured at NAV    
Defined Benefit Plan, Plan Assets, Category [Line Items]    
Plan assets in the fair value hierarchy $ 1,265