v3.25.4
Retirement Benefits - Schedule of Fair Value Disclosures (Details) - USD ($)
$ in Millions
Dec. 31, 2025
Dec. 31, 2024
Dec. 31, 2023
Defined Benefit Pension Plans      
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Line Items]      
Fair value of plan assets $ 14,820 $ 13,658 $ 13,709
Retiree Health Benefit Plans      
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Line Items]      
Fair value of plan assets 2,775 2,566 $ 2,580
Public equity securities | Defined Benefit Pension Plans      
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Line Items]      
Fair value of plan assets 4,277 3,423  
Public equity securities | Retiree Health Benefit Plans      
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Line Items]      
Fair value of plan assets 383 288  
Fixed-income investments | Defined Benefit Pension Plans      
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Line Items]      
Fair value of plan assets 2,083 2,023  
Fixed-income investments | Retiree Health Benefit Plans      
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Line Items]      
Fair value of plan assets 77 89  
Hedge funds | Defined Benefit Pension Plans      
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Line Items]      
Fair value of plan assets 3,240 3,058  
Hedge funds | Retiree Health Benefit Plans      
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Line Items]      
Fair value of plan assets 314 285  
Private equity-like investments | Defined Benefit Pension Plans      
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Line Items]      
Fair value of plan assets 3,927 3,931  
Private equity-like investments | Retiree Health Benefit Plans      
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Line Items]      
Fair value of plan assets 363 346  
Cash value of trust owned insurance contract | Retiree Health Benefit Plans      
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Line Items]      
Fair value of plan assets 1,529 1,465  
Real estate | Defined Benefit Pension Plans      
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Line Items]      
Fair value of plan assets 460 451  
Real estate | Retiree Health Benefit Plans      
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Line Items]      
Fair value of plan assets 30 28  
Other assets | Defined Benefit Pension Plans      
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Line Items]      
Fair value of plan assets 833 773  
Other assets | Retiree Health Benefit Plans      
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Line Items]      
Fair value of plan assets 79 64  
Quoted Prices in Active Markets for Identical Assets (Level 1) | Defined Benefit Pension Plans      
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Line Items]      
Fair value of plan assets 1,595 1,409  
Quoted Prices in Active Markets for Identical Assets (Level 1) | Retiree Health Benefit Plans      
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Line Items]      
Fair value of plan assets 156 130  
Quoted Prices in Active Markets for Identical Assets (Level 1) | Public equity securities | Defined Benefit Pension Plans      
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Line Items]      
Fair value of plan assets 1,179 1,056  
Quoted Prices in Active Markets for Identical Assets (Level 1) | Public equity securities | Retiree Health Benefit Plans      
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Line Items]      
Fair value of plan assets 114 98  
Quoted Prices in Active Markets for Identical Assets (Level 1) | Fixed-income investments | Defined Benefit Pension Plans      
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Line Items]      
Fair value of plan assets 55 42  
Quoted Prices in Active Markets for Identical Assets (Level 1) | Fixed-income investments | Retiree Health Benefit Plans      
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Line Items]      
Fair value of plan assets 0 0  
Quoted Prices in Active Markets for Identical Assets (Level 1) | Hedge funds | Defined Benefit Pension Plans      
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Line Items]      
Fair value of plan assets 0 0  
Quoted Prices in Active Markets for Identical Assets (Level 1) | Hedge funds | Retiree Health Benefit Plans      
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Line Items]      
Fair value of plan assets 0 0  
Quoted Prices in Active Markets for Identical Assets (Level 1) | Private equity-like investments | Defined Benefit Pension Plans      
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Line Items]      
Fair value of plan assets 0 0  
Quoted Prices in Active Markets for Identical Assets (Level 1) | Private equity-like investments | Retiree Health Benefit Plans      
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Line Items]      
Fair value of plan assets 0 0  
Quoted Prices in Active Markets for Identical Assets (Level 1) | Cash value of trust owned insurance contract | Retiree Health Benefit Plans      
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Line Items]      
Fair value of plan assets 0 0  
Quoted Prices in Active Markets for Identical Assets (Level 1) | Real estate | Defined Benefit Pension Plans      
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Line Items]      
Fair value of plan assets 312 301  
Quoted Prices in Active Markets for Identical Assets (Level 1) | Real estate | Retiree Health Benefit Plans      
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Line Items]      
Fair value of plan assets 30 28  
Quoted Prices in Active Markets for Identical Assets (Level 1) | Other assets | Defined Benefit Pension Plans      
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Line Items]      
Fair value of plan assets 49 10  
Quoted Prices in Active Markets for Identical Assets (Level 1) | Other assets | Retiree Health Benefit Plans      
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Line Items]      
Fair value of plan assets 12 4  
Significant Other Observable Inputs (Level 2) | Defined Benefit Pension Plans      
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Line Items]      
Fair value of plan assets 2,023 1,919  
Significant Other Observable Inputs (Level 2) | Retiree Health Benefit Plans      
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Line Items]      
Fair value of plan assets 1,577 1,521  
Significant Other Observable Inputs (Level 2) | Public equity securities | Defined Benefit Pension Plans      
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Line Items]      
Fair value of plan assets 403 337  
Significant Other Observable Inputs (Level 2) | Public equity securities | Retiree Health Benefit Plans      
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Line Items]      
Fair value of plan assets 0 0  
Significant Other Observable Inputs (Level 2) | Fixed-income investments | Defined Benefit Pension Plans      
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Line Items]      
Fair value of plan assets 1,517 1,556  
Significant Other Observable Inputs (Level 2) | Fixed-income investments | Retiree Health Benefit Plans      
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Line Items]      
Fair value of plan assets 46 63  
Significant Other Observable Inputs (Level 2) | Hedge funds | Defined Benefit Pension Plans      
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Line Items]      
Fair value of plan assets 0 0  
Significant Other Observable Inputs (Level 2) | Hedge funds | Retiree Health Benefit Plans      
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Line Items]      
Fair value of plan assets 0 0  
Significant Other Observable Inputs (Level 2) | Private equity-like investments | Defined Benefit Pension Plans      
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Line Items]      
Fair value of plan assets 0 0  
Significant Other Observable Inputs (Level 2) | Private equity-like investments | Retiree Health Benefit Plans      
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Line Items]      
Fair value of plan assets 0 0  
Significant Other Observable Inputs (Level 2) | Cash value of trust owned insurance contract | Retiree Health Benefit Plans      
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Line Items]      
Fair value of plan assets 1,529 1,465  
Significant Other Observable Inputs (Level 2) | Real estate | Defined Benefit Pension Plans      
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Line Items]      
Fair value of plan assets 0 0  
Significant Other Observable Inputs (Level 2) | Real estate | Retiree Health Benefit Plans      
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Line Items]      
Fair value of plan assets 0 0  
Significant Other Observable Inputs (Level 2) | Other assets | Defined Benefit Pension Plans      
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Line Items]      
Fair value of plan assets 103 26  
Significant Other Observable Inputs (Level 2) | Other assets | Retiree Health Benefit Plans      
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Line Items]      
Fair value of plan assets 2 (7)  
Significant Unobservable Inputs (Level 3) | Defined Benefit Pension Plans      
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Line Items]      
Fair value of plan assets 6 9  
Significant Unobservable Inputs (Level 3) | Retiree Health Benefit Plans      
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Line Items]      
Fair value of plan assets 1 1  
Significant Unobservable Inputs (Level 3) | Public equity securities | Defined Benefit Pension Plans      
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Line Items]      
Fair value of plan assets 0 0  
Significant Unobservable Inputs (Level 3) | Public equity securities | Retiree Health Benefit Plans      
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Line Items]      
Fair value of plan assets 0 0  
Significant Unobservable Inputs (Level 3) | Fixed-income investments | Defined Benefit Pension Plans      
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Line Items]      
Fair value of plan assets 0 0  
Significant Unobservable Inputs (Level 3) | Fixed-income investments | Retiree Health Benefit Plans      
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Line Items]      
Fair value of plan assets 0 0  
Significant Unobservable Inputs (Level 3) | Hedge funds | Defined Benefit Pension Plans      
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Line Items]      
Fair value of plan assets 0 0  
Significant Unobservable Inputs (Level 3) | Hedge funds | Retiree Health Benefit Plans      
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Line Items]      
Fair value of plan assets 0 0  
Significant Unobservable Inputs (Level 3) | Private equity-like investments | Defined Benefit Pension Plans      
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Line Items]      
Fair value of plan assets 6 9  
Significant Unobservable Inputs (Level 3) | Private equity-like investments | Retiree Health Benefit Plans      
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Line Items]      
Fair value of plan assets 1 1  
Significant Unobservable Inputs (Level 3) | Cash value of trust owned insurance contract | Retiree Health Benefit Plans      
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Line Items]      
Fair value of plan assets 0 0  
Significant Unobservable Inputs (Level 3) | Real estate | Defined Benefit Pension Plans      
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Line Items]      
Fair value of plan assets 0 0  
Significant Unobservable Inputs (Level 3) | Real estate | Retiree Health Benefit Plans      
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Line Items]      
Fair value of plan assets 0 0  
Significant Unobservable Inputs (Level 3) | Other assets | Defined Benefit Pension Plans      
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Line Items]      
Fair value of plan assets 0 0  
Significant Unobservable Inputs (Level 3) | Other assets | Retiree Health Benefit Plans      
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Line Items]      
Fair value of plan assets 0 0  
Investments Valued at Net Asset Value | Defined Benefit Pension Plans      
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Line Items]      
Fair value of plan assets 11,196 10,321  
Investments Valued at Net Asset Value | Retiree Health Benefit Plans      
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Line Items]      
Fair value of plan assets 1,041 914  
Investments Valued at Net Asset Value | Public equity securities | Defined Benefit Pension Plans      
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Line Items]      
Fair value of plan assets 2,695 2,030  
Investments Valued at Net Asset Value | Public equity securities | Retiree Health Benefit Plans      
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Line Items]      
Fair value of plan assets 269 190  
Investments Valued at Net Asset Value | Fixed-income investments | Defined Benefit Pension Plans      
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Line Items]      
Fair value of plan assets 511 425  
Investments Valued at Net Asset Value | Fixed-income investments | Retiree Health Benefit Plans      
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Line Items]      
Fair value of plan assets 31 26  
Investments Valued at Net Asset Value | Hedge funds | Defined Benefit Pension Plans      
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Line Items]      
Fair value of plan assets 3,240 3,058  
Investments Valued at Net Asset Value | Hedge funds | Retiree Health Benefit Plans      
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Line Items]      
Fair value of plan assets 314 285  
Investments Valued at Net Asset Value | Private equity-like investments | Defined Benefit Pension Plans      
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Line Items]      
Fair value of plan assets 3,921 3,922  
Investments Valued at Net Asset Value | Private equity-like investments | Retiree Health Benefit Plans      
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Line Items]      
Fair value of plan assets 362 345  
Investments Valued at Net Asset Value | Cash value of trust owned insurance contract | Retiree Health Benefit Plans      
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Line Items]      
Fair value of plan assets 0 0  
Investments Valued at Net Asset Value | Real estate | Defined Benefit Pension Plans      
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Line Items]      
Fair value of plan assets 148 150  
Investments Valued at Net Asset Value | Real estate | Retiree Health Benefit Plans      
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Line Items]      
Fair value of plan assets 0 0  
Investments Valued at Net Asset Value | Other assets | Defined Benefit Pension Plans      
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Line Items]      
Fair value of plan assets 681 737  
Investments Valued at Net Asset Value | Other assets | Retiree Health Benefit Plans      
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Line Items]      
Fair value of plan assets $ 65 $ 68