RETIREMENT BENEFITS - Defined Contribution Plans and Postemployment Plans (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Postemployment Retirement Benefits
Defined Benefit Plan Disclosure
Non-service-related expense	$ 5	$ 5
Total net (benefit) expense	5	5
U.S. | Postretirement Benefit Plans
Defined Benefit Plan Disclosure
Company's contributions for defined contribution plans	105	101
Total net (benefit) expense	(3)	0
Non-U.S. plans | Postretirement Benefit Plans
Defined Benefit Plan Disclosure
Company's contributions for defined contribution plans	92	76
Total net (benefit) expense	$ 8	$ 9