RETIREMENT BENEFITS - Contributions (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
U.S. | Pension Plans
Defined Benefit Plan, Expected Future Employer Contributions [Abstract]
Company contributions	$ 27	$ 28
Company contributions expected to be made during the remainder of the year	32	28
U.S. | Postretirement Benefit Plans
Defined Benefit Plan, Expected Future Employer Contributions [Abstract]
Company contributions	9	0
Company contributions expected to be made during the remainder of the year	3
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	78	72
Company contributions expected to be made during the remainder of the year	78	86
Non-U.S. plans | Postretirement Benefit Plans
Defined Benefit Plan, Expected Future Employer Contributions [Abstract]
Company contributions	4	5
Company contributions expected to be made during the remainder of the year	$ 4	$ 4