RETIREMENT BENEFITS - Contributions (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
U.S. | Pension Plans
Defined Benefit Plan, Expected Future Employer Contributions [Abstract]
Company contributions	$ 41	$ 42
Company contributions expected to be made during the remainder of the year	16	14
U.S. | Postretirement Benefit Plans
Defined Benefit Plan, Expected Future Employer Contributions [Abstract]
Company contributions	19	0
Company contributions expected to be made during the remainder of the year	2
Company reimbursements expected to be received during the remainder of the year		(15)
Non-U.S. plans | Pension Plans
Defined Benefit Plan, Expected Future Employer Contributions [Abstract]
Company contributions	116	111
Company contributions expected to be made during the remainder of the year	36	47
Non-U.S. plans | Postretirement Benefit Plans
Defined Benefit Plan, Expected Future Employer Contributions [Abstract]
Company contributions	6	6
Company contributions expected to be made during the remainder of the year	$ 2	$ 3