ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) - Summary of Changes in AOCI by Component (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2026	Mar. 31, 2025
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, beginning of period (in usd)	$ 6,102	$ 7,024
Net other comprehensive income (loss)	(48)	(47)
Balance, end of period (in usd)	6,016	7,054
Total
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, beginning of period (in usd)	(3,754)	(4,010)
Other comprehensive income (loss) before reclassifications	(51)	(43)
Amounts reclassified from AOCI	3	111
Net other comprehensive income (loss)	(48)	(47)
Net other comprehensive income (loss)		68
Balance, end of period (in usd)	(3,802)	(3,942)
CTA
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, beginning of period (in usd)	(3,133)	(3,430)
Other comprehensive income (loss) before reclassifications	(52)	(57)
Amounts reclassified from AOCI	0	126
Net other comprehensive income (loss)	(52)
Net other comprehensive income (loss)		69
Balance, end of period (in usd)	(3,185)	(3,361)
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	14
Amounts reclassified from AOCI	2	(13)
Net other comprehensive income (loss)	3
Net other comprehensive income (loss)		1
Balance, end of period (in usd)	(511)	(474)
Hedging activities
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, beginning of period (in usd)	(110)	(108)
Other comprehensive income (loss) before reclassifications	0	0
Amounts reclassified from AOCI	1	(2)
Net other comprehensive income (loss)	1
Net other comprehensive income (loss)		(2)
Balance, end of period (in usd)	(109)	(110)
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