RETIREMENT BENEFITS - Defined Contribution Plans and Postemployment Plans (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Postemployment Retirement Benefits
Defined Benefit Plan Disclosure
Interest cost on benefit obligation	$ 1	$ 0	$ 1	$ 1
Expected return on plan assets	0	0	0	(1)
Amortization of unrecognized:
Net actuarial loss	0	1	1	2
Total service-related benefit	1	1	2	2
Non-service-related expense	4	4	12	10
Total net (benefit) expense	5	5	14	12
U.S. | Postretirement Benefit Plans
Defined Benefit Plan Disclosure
Company's contributions for defined contribution plans	101	99	304	296
Interest cost on benefit obligation	4	6	14	19
Expected return on plan assets	(4)	(5)	(13)	(14)
Amortization of unrecognized:
Total net (benefit) expense	0	1	1	5
Non-U.S. plans | Postretirement Benefit Plans
Defined Benefit Plan Disclosure
Company's contributions for defined contribution plans	73	71	223	209
Interest cost on benefit obligation	22	25	68	77
Expected return on plan assets	(18)	(20)	(56)	(62)
Amortization of unrecognized:
Total net (benefit) expense	$ 8	$ 10	$ 26	$ 30