v3.26.1
ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) - Summary of Changes in AOCI by Component (Details) - USD ($)
$ in Millions
 3 Months Ended 6 Months Ended
Jun. 30, 2026
Jun. 30, 2025
Jun. 30, 2026
Jun. 30, 2025
Increase (Decrease) in Stockholders' Equity [Roll Forward]        
Balance, beginning of period (in usd) $ 6,016 $ 7,054 $ 6,102 $ 7,024
Net other comprehensive income (loss) (17) 196 (65) 149
Balance, end of period (in usd) 6,179 7,293 6,179 7,293
Total        
Increase (Decrease) in Stockholders' Equity [Roll Forward]        
Balance, beginning of period (in usd) (3,802) (3,942) (3,754) (4,010)
Other comprehensive income (loss) before reclassifications     (71) 155
Amounts reclassified from AOCI     6 109
Net other comprehensive income (loss) (17) 196 (65) 149
Net other comprehensive income (loss)       264
Balance, end of period (in usd) (3,819) (3,746) (3,819) (3,746)
CTA        
Increase (Decrease) in Stockholders' Equity [Roll Forward]        
Balance, beginning of period (in usd)     (3,133) (3,430)
Other comprehensive income (loss) before reclassifications     (72) 146
Amounts reclassified from AOCI     0 126
Net other comprehensive income (loss)     (72)  
Net other comprehensive income (loss)       272
Balance, end of period (in usd) (3,205) (3,158) (3,205) (3,158)
Pension and OPEB plans        
Increase (Decrease) in Stockholders' Equity [Roll Forward]        
Balance, beginning of period (in usd)     (514) (475)
Other comprehensive income (loss) before reclassifications     1 10
Amounts reclassified from AOCI     4 (15)
Net other comprehensive income (loss)     5  
Net other comprehensive income (loss)       (5)
Balance, end of period (in usd) (509) (480) (509) (480)
Hedging activities        
Increase (Decrease) in Stockholders' Equity [Roll Forward]        
Balance, beginning of period (in usd)     (110) (108)
Other comprehensive income (loss) before reclassifications     0 (1)
Amounts reclassified from AOCI     2 (2)
Net other comprehensive income (loss)     2  
Net other comprehensive income (loss)       (3)
Balance, end of period (in usd) (108) (111) (108) (111)
Available-for-sale debt securities        
Increase (Decrease) in Stockholders' Equity [Roll Forward]        
Balance, beginning of period (in usd)     3 3
Other comprehensive income (loss) before reclassifications     0 0
Amounts reclassified from AOCI     0 0
Net other comprehensive income (loss)     0  
Net other comprehensive income (loss)       0
Balance, end of period (in usd) $ 3 $ 3 $ 3 $ 3