RETIREMENT BENEFITS - Contributions (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
U.S. | Pension Plans
Defined Benefit Plan, Expected Future Employer Contributions [Abstract]
Estimated future contributions made by the Company	$ 0
Cash contributions made by the Company	0	$ 425
Estimated benefits paid directly by (reimbursements to) the Company	57
Benefits paid directly by (reimbursements to) the Company	56	56
U.S. | Postretirement Benefit Plans
Defined Benefit Plan, Expected Future Employer Contributions [Abstract]
Estimated future contributions made by the Company	0
Cash contributions made by the Company	0	0
Estimated benefits paid directly by (reimbursements to) the Company	6
Benefits paid directly by (reimbursements to) the Company	(15)	4
Non-U.S. | Pension Plans
Defined Benefit Plan, Expected Future Employer Contributions [Abstract]
Estimated future contributions made by the Company	97
Cash contributions made by the Company	115	111
Estimated benefits paid directly by (reimbursements to) the Company	58
Benefits paid directly by (reimbursements to) the Company	43	39
Non-U.S. | Postretirement Benefit Plans
Defined Benefit Plan, Expected Future Employer Contributions [Abstract]
Estimated future contributions made by the Company	3
Cash contributions made by the Company	4	221
Estimated benefits paid directly by (reimbursements to) the Company	5
Benefits paid directly by (reimbursements to) the Company	$ 5	$ 4