RETIREMENT BENEFITS - Funded Status and Accumulated Other Comprehensive Income (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
U.S. Plans | Pension Plans
Change in projected benefit obligation
Projected benefit obligation at beginning of year	$ 9,741
Service cost	0	$ 0
Interest cost on benefit obligation	127	86
Change in plan assets
Plan assets at fair value at beginning of year	10,145
Net amount recognized at period end
Benefit asset	938
Benefit liability	(532)
Net amount recognized on the balance sheet—Significant Plans	406
Amounts recognized in AOCI at period end(3)
Prior service (expense) benefit	0
Net actuarial (loss) gain	(6,467)
Net amount recognized in equity-pretax	(6,467)
Accumulated benefit obligation at period end—Significant Plans	9,881
U.S. Plans | Pension Plans | Other than Significant Plans Measured Annually
Change in projected benefit obligation
Projected benefit obligation at beginning of year	19
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	9,722
Service cost	0
Interest cost on benefit obligation	127
Actuarial (gain)	253
Benefits paid, net of participants’ contributions	(220)
Foreign exchange impact and other	0
Projected benefit obligation at period end—Significant Plans	9,882
Change in plan assets
Plan assets at fair value at beginning of year	10,145
Actual return on plan assets	349
Company contributions, net of reimbursements	14
Benefits paid, net of participants’ contributions	(220)
Foreign exchange impact and other	0
Plan assets at fair value at period end—Significant Plans	10,288
Funded status of the Significant Plans	406
U.S. Plans | Postretirement Benefit Plans
Change in projected benefit obligation
Projected benefit obligation at beginning of year	375
Service cost	0	0
Interest cost on benefit obligation	5	3
Change in plan assets
Plan assets at fair value at beginning of year	253
Net amount recognized at period end
Benefit asset	0
Benefit liability	(116)
Net amount recognized on the balance sheet—Significant Plans	(116)
Amounts recognized in AOCI at period end(3)
Prior service (expense) benefit	80
Net actuarial (loss) gain	112
Net amount recognized in equity-pretax	192
Accumulated benefit obligation at period end—Significant Plans	374
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
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	375
Service cost	0
Interest cost on benefit obligation	5
Actuarial (gain)	9
Benefits paid, net of participants’ contributions	(15)
Foreign exchange impact and other	0
Projected benefit obligation at period end—Significant Plans	374
Change in plan assets
Plan assets at fair value at beginning of year	253
Actual return on plan assets	7
Company contributions, net of reimbursements	13
Benefits paid, net of participants’ contributions	(15)
Foreign exchange impact and other	0
Plan assets at fair value at period end—Significant Plans	258
Funded status of the Significant Plans	(116)
Non-U.S. plans | Pension Plans
Change in projected benefit obligation
Projected benefit obligation at beginning of year	6,375
Service cost	28	34
Interest cost on benefit obligation	98	73
Change in plan assets
Plan assets at fair value at beginning of year	6,086
Net amount recognized at period end
Benefit asset	787
Benefit liability	(544)
Net amount recognized on the balance sheet—Significant Plans	243
Amounts recognized in AOCI at period end(3)
Prior service (expense) benefit	(2)
Net actuarial (loss) gain	(1,363)
Net amount recognized in equity-pretax	(1,365)
Accumulated benefit obligation at period end—Significant Plans	4,688
Non-U.S. plans | Pension Plans | Other than Significant Plans Measured Annually
Change in projected benefit obligation
Projected benefit obligation at beginning of year	1,774
Change in plan assets
Plan assets at fair value at beginning of year	1,226
Non-U.S. plans | Pension Plans | Significant Plans Measured Quarterly
Change in projected benefit obligation
Projected benefit obligation at beginning of year	4,601
Service cost	10
Interest cost on benefit obligation	80
Actuarial (gain)	20
Benefits paid, net of participants’ contributions	(68)
Foreign exchange impact and other	199
Projected benefit obligation at period end—Significant Plans	4,842
Change in plan assets
Plan assets at fair value at beginning of year	4,860
Actual return on plan assets	115
Company contributions, net of reimbursements	11
Benefits paid, net of participants’ contributions	(68)
Foreign exchange impact and other	167
Plan assets at fair value at period end—Significant Plans	5,085
Funded status of the Significant Plans	243
Non-U.S. plans | Postretirement Benefit Plans
Change in projected benefit obligation
Projected benefit obligation at beginning of year	1,013
Service cost	0	1
Interest cost on benefit obligation	25	$ 23
Change in plan assets
Plan assets at fair value at beginning of year	855
Net amount recognized at period end
Benefit asset	31
Benefit liability	0
Net amount recognized on the balance sheet—Significant Plans	31
Amounts recognized in AOCI at period end(3)
Prior service (expense) benefit	36
Net actuarial (loss) gain	(274)
Net amount recognized in equity-pretax	(238)
Accumulated benefit obligation at period end—Significant Plans	890
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	193
Change in plan assets
Plan assets at fair value at beginning of year	7
Non-U.S. plans | Postretirement Benefit Plans | Significant Plans Measured Quarterly
Change in projected benefit obligation
Projected benefit obligation at beginning of year	820
Service cost	0
Interest cost on benefit obligation	22
Actuarial (gain)	(8)
Benefits paid, net of participants’ contributions	(12)
Foreign exchange impact and other	68
Projected benefit obligation at period end—Significant Plans	890
Change in plan assets
Plan assets at fair value at beginning of year	848
Actual return on plan assets	15
Company contributions, net of reimbursements	0
Benefits paid, net of participants’ contributions	(12)
Foreign exchange impact and other	70
Plan assets at fair value at period end—Significant Plans	921
Funded status of the Significant Plans	31
Qualified plans | U.S. Plans | Pension Plans | Significant Plans Measured Quarterly
Change in plan assets
Funded status of the Significant Plans	938
Qualified plans | U.S. Plans | Postretirement Benefit Plans | Significant Plans Measured Quarterly
Change in plan assets
Funded status of the Significant Plans	(116)
Qualified plans | Non-U.S. plans | Pension Plans | Significant Plans Measured Quarterly
Change in plan assets
Funded status of the Significant Plans	243
Qualified plans | Non-U.S. plans | Postretirement Benefit Plans | Significant Plans Measured Quarterly
Change in plan assets
Funded status of the Significant Plans	31
Nonqualified plans | U.S. Plans | Pension Plans | Significant Plans Measured Quarterly
Change in plan assets
Funded status of the Significant Plans	(532)
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