POSTRETIREMENT BENEFIT PLANS - Cost of Postretirement Benefit Plans and Changes in Other Comprehensive Income (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Principal pension
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Cost (income) of postretirement benefit plans	$ (741)	$ (1,108)	$ 575
Prior service cost (credit) - current year	0	49	0
Net loss (gain) - current year (a)	262	1,588	(1,533)
Reclassifications out of AOCI
Curtailment/settlement gain (loss)	0	0	0
Dispositions	185	1,989	0
Amortization of net gain (loss)	468	723	(1,422)
Amortization of prior service credit (cost)	(6)	(5)	(5)
Total changes in other comprehensive loss (income)	909	4,344	(2,960)
Cost (income) of postretirement benefit plans and changes in other comprehensive loss (income)	168	3,236	(2,385)
Other pension
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Cost (income) of postretirement benefit plans	(21)	(118)	(396)
Prior service cost (credit) - current year	0	0	0
Net loss (gain) - current year (a)	(52)	721	(128)
Reclassifications out of AOCI
Curtailment/settlement gain (loss)	0	6	6
Dispositions	(761)	(792)	0
Amortization of net gain (loss)	(41)	(20)	(101)
Amortization of prior service credit (cost)	1	4	8
Total changes in other comprehensive loss (income)	(853)	(81)	(215)
Cost (income) of postretirement benefit plans and changes in other comprehensive loss (income)	(874)	(199)	(611)
Principal retiree benefit
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Cost (income) of postretirement benefit plans	(101)	(144)	(203)
Prior service cost (credit) - current year	0	0	0
Net loss (gain) - current year (a)	(15)	(5)	(778)
Reclassifications out of AOCI
Curtailment/settlement gain (loss)	0	0	0
Dispositions	715	1,216	0
Amortization of net gain (loss)	82	124	115
Amortization of prior service credit (cost)	103	148	235
Total changes in other comprehensive loss (income)	885	1,483	(428)
Cost (income) of postretirement benefit plans and changes in other comprehensive loss (income)	$ 784	$ 1,339	$ (631)