RETIREMENT BENEFITS - Contributions (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
U.S. | Pension Plans
Defined Benefit Plan, Expected Future Employer Contributions [Abstract]
Estimated future cash contributions	$ 0
Cash contributions paid by the Company	0	$ 50
Estimated benefits paid directly by Company	57
Benefits paid directly by the Company	55	55
U.S. | Postretirement Benefit Plans
Defined Benefit Plan, Expected Future Employer Contributions [Abstract]
Estimated future cash contributions	0
Cash contributions paid by the Company	145	140
Estimated benefits paid directly by Company	6
Benefits paid directly by the Company	5	36
Non-U.S. | Pension Plans
Defined Benefit Plan, Expected Future Employer Contributions [Abstract]
Estimated future cash contributions	97
Cash contributions paid by the Company	140	90
Estimated benefits paid directly by Company	47
Benefits paid directly by the Company	42	45
Non-U.S. | Postretirement Benefit Plans
Defined Benefit Plan, Expected Future Employer Contributions [Abstract]
Estimated future cash contributions	4
Cash contributions paid by the Company	3	4
Estimated benefits paid directly by Company	6
Benefits paid directly by the Company	$ 6	$ 5