ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) - Summary of Changes in AOCI by Component (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, beginning of period (in usd)	$ 8,468	$ 5,895
Other comprehensive income (loss) before reclassifications	(169)	99
Amounts reclassified from AOCI	1	(5)
Net other comprehensive income (loss)	(168)	94
Balance, end of period (in usd)	8,235	5,941
CTA
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, beginning of period (in usd)	(2,985)	(3,386)
Other comprehensive income (loss) before reclassifications	(180)	102
Amounts reclassified from AOCI	0	0
Net other comprehensive income (loss)	(180)	102
Balance, end of period (in usd)	(3,165)	(3,284)
Pension and OPEB plans
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, beginning of period (in usd)	(452)	(331)
Other comprehensive income (loss) before reclassifications	5	(3)
Amounts reclassified from AOCI	(1)	(3)
Net other comprehensive income (loss)	4	(6)
Balance, end of period (in usd)	(448)	(337)
Hedging activities
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, beginning of period (in usd)	(120)	(119)
Other comprehensive income (loss) before reclassifications	6	0
Amounts reclassified from AOCI	2	(2)
Net other comprehensive income (loss)	8	(2)
Balance, end of period (in usd)	(112)	(121)
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)	(3,554)	(3,833)
Balance, end of period (in usd)	$ (3,722)	$ (3,739)