RETIREMENT BENEFITS - Contributions (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
U.S. | Pension Plans
Defined Benefit Plan, Expected Future Employer Contributions [Abstract]
Company contributions	$ 14	$ 14
Company contributions expected to be made during the remainder of the year	43	42
U.S. | Postretirement Benefit Plans
Defined Benefit Plan, Expected Future Employer Contributions [Abstract]
Company contributions	5	0
Company contributions expected to be made during the remainder of the year	5
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	37	37
Company contributions expected to be made during the remainder of the year	114	121
Non-U.S. plans | Postretirement Benefit Plans
Defined Benefit Plan, Expected Future Employer Contributions [Abstract]
Company contributions	2	2
Company contributions expected to be made during the remainder of the year	$ 6	$ 7