ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) - Summary of Changes in AOCI by Component (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, beginning of period (in usd)	$ 7,024	$ 8,468
Balance, end of period (in usd)	7,214	7,942
CTA
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, beginning of period (in usd)	(3,430)	(2,985)
Other comprehensive income (loss) before reclassifications	159	(92)
Amounts reclassified from AOCI	126	0
Net other comprehensive income (loss)	285	(92)
Balance, end of period (in usd)	(3,145)	(3,077)
Pension and OPEB plans
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, beginning of period (in usd)	(475)	(452)
Other comprehensive income (loss) before reclassifications	12	0
Amounts reclassified from AOCI	(18)	(3)
Net other comprehensive income (loss)	(6)	(3)
Balance, end of period (in usd)	(481)	(455)
Hedging activities
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, beginning of period (in usd)	(108)	(120)
Other comprehensive income (loss) before reclassifications	(1)	2
Amounts reclassified from AOCI	(1)	0
Net other comprehensive income (loss)	(2)	2
Balance, end of period (in usd)	(110)	(118)
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	0
Balance, end of period (in usd)	3	3
Total
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, beginning of period (in usd)	(4,010)	(3,554)
Other comprehensive income (loss) before reclassifications	170	(90)
Amounts reclassified from AOCI	107	(3)
Net other comprehensive income (loss)	277	(93)
Balance, end of period (in usd)	$ (3,733)	$ (3,647)