ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) - Summary of Changes in AOCI by Component (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2025	Jun. 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)	7,293	7,708
CTA
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, beginning of period (in usd)	(3,430)	(2,985)
Other comprehensive income (loss) before reclassifications	146	(288)
Amounts reclassified from AOCI	126	0
Net other comprehensive income (loss)	272	(288)
Balance, end of period (in usd)	(3,158)	(3,273)
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	10	5
Amounts reclassified from AOCI	(15)	(2)
Net other comprehensive income (loss)	(5)	3
Balance, end of period (in usd)	(480)	(449)
Hedging activities
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, beginning of period (in usd)	(108)	(120)
Other comprehensive income (loss) before reclassifications	(1)	9
Amounts reclassified from AOCI	(2)	2
Net other comprehensive income (loss)	(3)	11
Balance, end of period (in usd)	(111)	(109)
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	155	(274)
Amounts reclassified from AOCI	109	0
Net other comprehensive income (loss)	264	(274)
Balance, end of period (in usd)	$ (3,746)	$ (3,828)