RETIREMENT BENEFITS - Funded Status and Accumulated Other Comprehensive Income (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
U.S. plans | Pension plans
Change in projected benefit obligation
Projected benefit obligation at beginning of year	$ 9,640
Plans measured annually
Service cost	0	$ 0
Interest cost on benefit obligation	117	127
Change in plan assets
Plan assets at fair value at beginning of year	10,210
Net amount recognized at period end
Benefit asset	1,133
Benefit liability	(502)
Net amount recognized on the balance sheet—Significant Plans	631
Amounts recognized in AOCI at period end(3)
Prior service (expense) benefit	0
Net actuarial (loss) gain	(6,276)
Net amount recognized in equity-pretax	(6,276)
Accumulated benefit obligation at period end—Significant Plans	9,378
U.S. plans | Pension plans | Other than Significant Plans Measured Annually
Change in projected benefit obligation
Projected benefit obligation at beginning of year	18
Plans measured annually
Change in plan assets
Plan assets at fair value at beginning of year	0
U.S. plans | Pension plans | Significant Plans Measured Quarterly
Change in projected benefit obligation
Projected benefit obligation at beginning of year	9,622
Plans measured annually	(9,378)
Service cost	0
Interest cost on benefit obligation	116
Actuarial (gain)	(137)
Benefits paid, net of participants’ contributions	(223)
Foreign exchange impact and other	0
Projected benefit obligation at period end—Significant Plans	9,378
Change in plan assets
Plan assets at fair value at beginning of year	10,210
Actual return on plan assets	8
Company contributions, net of reimbursements	14
Benefits paid, net of participants’ contributions	(223)
Foreign exchange impact and other	0
Plan assets at fair value at period end—Significant Plans	10,009
Funded status of the Significant Plans	631
U.S. plans | Postretirement benefit plans
Change in projected benefit obligation
Projected benefit obligation at beginning of year	343
Plans measured annually
Service cost	0	0
Interest cost on benefit obligation	4	5
Change in plan assets
Plan assets at fair value at beginning of year	231
Net amount recognized at period end
Benefit asset	0
Benefit liability	(100)
Net amount recognized on the balance sheet—Significant Plans	(100)
Amounts recognized in AOCI at period end(3)
Prior service (expense) benefit	70
Net actuarial (loss) gain	113
Net amount recognized in equity-pretax	183
Accumulated benefit obligation at period end—Significant Plans	331
U.S. plans | Postretirement benefit plans | Other than Significant Plans Measured Annually
Change in projected benefit obligation
Projected benefit obligation at beginning of year	0
Plans measured annually
Change in plan assets
Plan assets at fair value at beginning of year	0
U.S. plans | Postretirement benefit plans | Significant Plans Measured Quarterly
Change in projected benefit obligation
Projected benefit obligation at beginning of year	343
Plans measured annually	(331)
Service cost	0
Interest cost on benefit obligation	4
Actuarial (gain)	(2)
Benefits paid, net of participants’ contributions	(14)
Foreign exchange impact and other	0
Projected benefit obligation at period end—Significant Plans	331
Change in plan assets
Plan assets at fair value at beginning of year	231
Actual return on plan assets	2
Company contributions, net of reimbursements	12
Benefits paid, net of participants’ contributions	(14)
Foreign exchange impact and other	0
Plan assets at fair value at period end—Significant Plans	231
Funded status of the Significant Plans	(100)
Non-U.S. plans | Pension plans
Change in projected benefit obligation
Projected benefit obligation at beginning of year	7,030
Plans measured annually
Service cost	29	28
Interest cost on benefit obligation	109	98
Change in plan assets
Plan assets at fair value at beginning of year	6,426
Net amount recognized at period end
Benefit asset	745
Benefit liability	(920)
Net amount recognized on the balance sheet—Significant Plans	(175)
Amounts recognized in AOCI at period end(3)
Prior service (expense) benefit	(4)
Net actuarial (loss) gain	(1,685)
Net amount recognized in equity-pretax	(1,689)
Accumulated benefit obligation at period end—Significant Plans	5,106
Non-U.S. plans | Pension plans | Other than Significant Plans Measured Annually
Change in projected benefit obligation
Projected benefit obligation at beginning of year	1,663
Plans measured annually
Change in plan assets
Plan assets at fair value at beginning of year	(1,198)
Non-U.S. plans | Pension plans | Significant Plans Measured Quarterly
Change in projected benefit obligation
Projected benefit obligation at beginning of year	5,367
Plans measured annually	(5,291)
Service cost	12
Interest cost on benefit obligation	91
Actuarial (gain)	(111)
Benefits paid, net of participants’ contributions	(76)
Foreign exchange impact and other	8
Projected benefit obligation at period end—Significant Plans	5,291
Change in plan assets
Plan assets at fair value at beginning of year	5,228
Actual return on plan assets	(22)
Company contributions, net of reimbursements	7
Benefits paid, net of participants’ contributions	(76)
Foreign exchange impact and other	(21)
Plan assets at fair value at period end—Significant Plans	5,116
Funded status of the Significant Plans	(175)
Non-U.S. plans | Postretirement benefit plans
Change in projected benefit obligation
Projected benefit obligation at beginning of year	1,208
Plans measured annually
Service cost	0	0
Interest cost on benefit obligation	29	$ 25
Change in plan assets
Plan assets at fair value at beginning of year	970
Net amount recognized at period end
Benefit asset	0
Benefit liability	(33)
Net amount recognized on the balance sheet—Significant Plans	(33)
Amounts recognized in AOCI at period end(3)
Prior service (expense) benefit	32
Net actuarial (loss) gain	(335)
Net amount recognized in equity-pretax	(303)
Accumulated benefit obligation at period end—Significant Plans	986
Non-U.S. plans | Postretirement benefit plans | Other than Significant Plans Measured Annually
Change in projected benefit obligation
Projected benefit obligation at beginning of year	219
Plans measured annually
Change in plan assets
Plan assets at fair value at beginning of year	(9)
Non-U.S. plans | Postretirement benefit plans | Significant Plans Measured Quarterly
Change in projected benefit obligation
Projected benefit obligation at beginning of year	989
Plans measured annually	(986)
Service cost	0
Interest cost on benefit obligation	25
Actuarial (gain)	(29)
Benefits paid, net of participants’ contributions	(22)
Foreign exchange impact and other	23
Projected benefit obligation at period end—Significant Plans	986
Change in plan assets
Plan assets at fair value at beginning of year	961
Actual return on plan assets	(9)
Company contributions, net of reimbursements	0
Benefits paid, net of participants’ contributions	(22)
Foreign exchange impact and other	23
Plan assets at fair value at period end—Significant Plans	953
Funded status of the Significant Plans	(33)
Qualified plans | U.S. plans | Pension plans | Significant Plans Measured Quarterly
Change in plan assets
Funded status of the Significant Plans	1,133
Qualified plans | U.S. plans | Postretirement benefit plans | Significant Plans Measured Quarterly
Change in plan assets
Funded status of the Significant Plans	(100)
Qualified plans | Non-U.S. plans | Pension plans | Significant Plans Measured Quarterly
Change in plan assets
Funded status of the Significant Plans	(175)
Qualified plans | Non-U.S. plans | Postretirement benefit plans | Significant Plans Measured Quarterly
Change in plan assets
Funded status of the Significant Plans	(33)
Nonqualified plans | U.S. plans | Pension plans | Significant Plans Measured Quarterly
Change in plan assets
Funded status of the Significant Plans	(502)
Nonqualified plans | U.S. plans | Postretirement benefit plans | Significant Plans Measured Quarterly
Change in plan assets
Funded status of the Significant Plans	0
Nonqualified plans | Non-U.S. plans | Pension plans | Significant Plans Measured Quarterly
Change in plan assets
Funded status of the Significant Plans	0
Nonqualified plans | Non-U.S. plans | Postretirement benefit plans | Significant Plans Measured Quarterly
Change in plan assets
Funded status of the Significant Plans	$ 0