Annual report [Section 13 and 15(d), not S-K Item 405]

PENSION AND OTHER POSTRETIREMENT BENEFITS - (Details 5 ) - Level 3 Fair Value Reconciliation

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PENSION AND OTHER POSTRETIREMENT BENEFITS - (Details 5 ) - Level 3 Fair Value Reconciliation - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2025
Dec. 31, 2024
Dec. 31, 2023
UNITED STATES      
Summary of changes in the fair value of level 3 assets      
Fair value of plan assets $ 3,789 $ 3,706 $ 3,826
UNITED STATES | Fair Value, Inputs, Level 3      
Summary of changes in the fair value of level 3 assets      
Fair value of plan assets 462 500 604
Unrealized gains (losses) on assets still held at the reporting date 28 (9)  
Purchases, sales and settlements, net (66) (95)  
UNITED STATES | Fair Value, Inputs, Level 3 | Private Markets      
Summary of changes in the fair value of level 3 assets      
Fair value of plan assets 402 441 537
Unrealized gains (losses) on assets still held at the reporting date 24 (3)  
Purchases, sales and settlements, net (63) (93)  
UNITED STATES | Fair Value, Inputs, Level 3 | Real Assets      
Summary of changes in the fair value of level 3 assets      
Fair value of plan assets 60 59 67
Unrealized gains (losses) on assets still held at the reporting date 4 (6)  
Purchases, sales and settlements, net (3) (2)  
UNITED KINGDOM      
Summary of changes in the fair value of level 3 assets      
Fair value of plan assets 1,518 1,468 1,720
UNITED KINGDOM | Insurance      
Summary of changes in the fair value of level 3 assets      
Fair value of plan assets 698 383  
UNITED KINGDOM | Fair Value, Inputs, Level 3      
Summary of changes in the fair value of level 3 assets      
Fair value of plan assets 797 485 539
Unrealized gains (losses) on assets still held at the reporting date (6) (52)  
Purchases, sales and settlements, net 318 (2)  
UNITED KINGDOM | Fair Value, Inputs, Level 3 | Private Markets      
Summary of changes in the fair value of level 3 assets      
Fair value of plan assets 94 96 96
Unrealized gains (losses) on assets still held at the reporting date   1  
Purchases, sales and settlements, net (2) (1)  
UNITED KINGDOM | Fair Value, Inputs, Level 3 | Real Assets      
Summary of changes in the fair value of level 3 assets      
Fair value of plan assets 5 6 7
Unrealized gains (losses) on assets still held at the reporting date (1) 0  
Purchases, sales and settlements, net 0 (1)  
UNITED KINGDOM | Fair Value, Inputs, Level 3 | Insurance      
Summary of changes in the fair value of level 3 assets      
Fair value of plan assets 698 383 $ 436
Unrealized gains (losses) on assets still held at the reporting date (5) (53)  
Purchases, sales and settlements, net $ 320 $ 0