RETIREMENT BENEFITS - Funded Status and Accumulated Other Comprehensive Income (Details) - USD ($) $ in Millions	3 Months Ended			6 Months Ended
	Jun. 30, 2022	Mar. 31, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
U.S. | Pension Plans
Change in projected benefit obligation
Projected benefit obligation at beginning of year		$ 12,766		$ 12,766
Benefits earned during the period	$ 0		$ 0	0	$ 0
Interest cost on benefit obligation	105		95	191	177
Change in plan assets
Plan assets at fair value at beginning of year		12,977		12,977
Net amount recognized at period end
Benefit asset	940			940
Benefit liability	(559)			(559)
Net amount recognized on the balance sheet—Significant Plans	381			381
Amounts recognized in AOCI at period end(5)
Prior service benefit	0			0
Net actuarial (loss) gain	(6,464)			(6,464)
Net amount recognized in equity-pretax	(6,464)			(6,464)
Accumulated benefit obligation at period end—Significant Plans	10,457			10,457
U.S. | Pension Plans | Other than Significant Plans Measured Annually
Change in projected benefit obligation
Projected benefit obligation at beginning of year		23		23
Change in plan assets
Plan assets at fair value at beginning of year		0		0
U.S. | Pension Plans | Significant Plans Measured Quarterly
Change in projected benefit obligation
Projected benefit obligation at beginning of year	11,509	12,743		12,743
Quarter activity		(1,234)
Benefits earned during the period	0
Interest cost on benefit obligation	105
Actuarial (gain)	(903)
Benefits paid, net of participants’ contributions and government subsidy	(253)
Settlement (gain)	0
Curtailment (gain)	0
Foreign exchange impact and other	0
Projected benefit obligation at period end—Significant Plans	10,458	11,509		10,458
Change in plan assets
Plan assets at fair value at beginning of year	11,947	12,977		12,977
Quarterly activity		(1,030)
Actual return on plan assets				(868)
Company contributions, net of reimbursements				13
Benefits paid, net of participants’ contributions and government subsidy				(253)
Settlement gain				0
Foreign exchange impact and other				0
Plan assets at fair value at period end—Significant Plans	10,839	11,947		10,839
Funded status of the Significant Plans	381			381
U.S. | Postretirement Benefit Plans
Change in projected benefit obligation
Projected benefit obligation at beginning of year		501		501
Benefits earned during the period	0		0	0	0
Interest cost on benefit obligation	4		3	7	6
Change in plan assets
Plan assets at fair value at beginning of year		319		319
Net amount recognized at period end
Benefit asset	0			0
Benefit liability	(140)			(140)
Net amount recognized on the balance sheet—Significant Plans	(140)			(140)
Amounts recognized in AOCI at period end(5)
Prior service benefit	87			87
Net actuarial (loss) gain	119			119
Net amount recognized in equity-pretax	206			206
Accumulated benefit obligation at period end—Significant Plans	406			406
U.S. | Postretirement Benefit Plans | Other than Significant Plans Measured Annually
Change in projected benefit obligation
Projected benefit obligation at beginning of year		0		0
Change in plan assets
Plan assets at fair value at beginning of year		0		0
U.S. | Postretirement Benefit Plans | Significant Plans Measured Quarterly
Change in projected benefit obligation
Projected benefit obligation at beginning of year	451	501		501
Quarter activity		(50)
Benefits earned during the period	0
Interest cost on benefit obligation	4
Actuarial (gain)	(36)
Benefits paid, net of participants’ contributions and government subsidy	(13)
Settlement (gain)	0
Curtailment (gain)	0
Foreign exchange impact and other	0
Projected benefit obligation at period end—Significant Plans	406	451		406
Change in plan assets
Plan assets at fair value at beginning of year	300	319		319
Quarterly activity		(19)
Actual return on plan assets				(15)
Company contributions, net of reimbursements				(6)
Benefits paid, net of participants’ contributions and government subsidy				(13)
Settlement gain				0
Foreign exchange impact and other				0
Plan assets at fair value at period end—Significant Plans	266	300		266
Funded status of the Significant Plans	(140)			(140)
Non-U.S. plans | Pension Plans
Change in projected benefit obligation
Projected benefit obligation at beginning of year		8,001		8,001
Benefits earned during the period	30		38	64	77
Interest cost on benefit obligation	79		70	152	132
Change in plan assets
Plan assets at fair value at beginning of year		7,614		7,614
Net amount recognized at period end
Benefit asset	844			844
Benefit liability	(375)			(375)
Net amount recognized on the balance sheet—Significant Plans	469			469
Amounts recognized in AOCI at period end(5)
Prior service benefit	0			0
Net actuarial (loss) gain	(992)			(992)
Net amount recognized in equity-pretax	(992)			(992)
Accumulated benefit obligation at period end—Significant Plans	4,563			4,563
Non-U.S. plans | Pension Plans | Other than Significant Plans Measured Annually
Change in projected benefit obligation
Projected benefit obligation at beginning of year		2,071		2,071
Change in plan assets
Plan assets at fair value at beginning of year		1,419		1,419
Non-U.S. plans | Pension Plans | Significant Plans Measured Quarterly
Change in projected benefit obligation
Projected benefit obligation at beginning of year	5,645	5,930		5,930
Quarter activity		(285)
Benefits earned during the period	15
Interest cost on benefit obligation	68
Actuarial (gain)	(489)
Benefits paid, net of participants’ contributions and government subsidy	(69)
Settlement (gain)	(246)
Curtailment (gain)	(23)
Foreign exchange impact and other	(163)
Projected benefit obligation at period end—Significant Plans	4,738	5,645		4,738
Change in plan assets
Plan assets at fair value at beginning of year	5,969	6,195		6,195
Quarterly activity		(226)
Actual return on plan assets				(512)
Company contributions, net of reimbursements				208
Benefits paid, net of participants’ contributions and government subsidy				(69)
Settlement gain				(246)
Foreign exchange impact and other				(143)
Plan assets at fair value at period end—Significant Plans	5,207	5,969		5,207
Funded status of the Significant Plans	469			469
Non-U.S. plans | Postretirement Benefit Plans
Change in projected benefit obligation
Projected benefit obligation at beginning of year		1,169		1,169
Benefits earned during the period	0		2	1	4
Interest cost on benefit obligation	23		$ 24	46	$ 49
Change in plan assets
Plan assets at fair value at beginning of year		1,043		1,043
Net amount recognized at period end
Benefit asset	77			77
Benefit liability	0			0
Net amount recognized on the balance sheet—Significant Plans	77			77
Amounts recognized in AOCI at period end(5)
Prior service benefit	37			37
Net actuarial (loss) gain	(213)			(213)
Net amount recognized in equity-pretax	(176)			(176)
Accumulated benefit obligation at period end—Significant Plans	751			751
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		298		298
Change in plan assets
Plan assets at fair value at beginning of year		7		7
Non-U.S. plans | Postretirement Benefit Plans | Significant Plans Measured Quarterly
Change in projected benefit obligation
Projected benefit obligation at beginning of year	800	871		871
Quarter activity		(71)
Benefits earned during the period	0
Interest cost on benefit obligation	20
Actuarial (gain)	(43)
Benefits paid, net of participants’ contributions and government subsidy	(17)
Settlement (gain)	0
Curtailment (gain)	0
Foreign exchange impact and other	(9)
Projected benefit obligation at period end—Significant Plans	751	800		751
Change in plan assets
Plan assets at fair value at beginning of year	901	1,036		1,036
Quarterly activity		(135)
Actual return on plan assets				(45)
Company contributions, net of reimbursements				0
Benefits paid, net of participants’ contributions and government subsidy				(17)
Settlement gain				0
Foreign exchange impact and other				(11)
Plan assets at fair value at period end—Significant Plans	828	$ 901		828
Funded status of the Significant Plans	77			77
Qualified plans | U.S. | Pension Plans | Significant Plans Measured Quarterly
Change in plan assets
Funded status of the Significant Plans	940			940
Qualified plans | U.S. | Postretirement Benefit Plans | Significant Plans Measured Quarterly
Change in plan assets
Funded status of the Significant Plans	(140)			(140)
Qualified plans | Non-U.S. plans | Pension Plans | Significant Plans Measured Quarterly
Change in plan assets
Funded status of the Significant Plans	469			469
Qualified plans | Non-U.S. plans | Postretirement Benefit Plans | Significant Plans Measured Quarterly
Change in plan assets
Funded status of the Significant Plans	77			77
Nonqualified plans | U.S. | Pension Plans | Significant Plans Measured Quarterly
Change in plan assets
Funded status of the Significant Plans	(559)			(559)
Nonqualified plans | U.S. | Postretirement Benefit Plans | Significant Plans Measured Quarterly
Change in plan assets
Funded status of the Significant Plans	0			0
Nonqualified plans | Non-U.S. plans | Pension Plans | Significant Plans Measured Quarterly
Change in plan assets
Funded status of the Significant Plans	0			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			$ 0